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Electrochemically Induced Mesomorphism Switching in a Chlorpromazine Hydrochloride Lyotropic Liquid Crystal
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  • Robert D. Crapnell
    Robert D. Crapnell
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Huda S. Alhasan
    Huda S. Alhasan
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Lee I. Partington
    Lee I. Partington
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Yan Zhou
    Yan Zhou
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Ziauddin Ahmed
    Ziauddin Ahmed
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Amal A. Altalhi
    Amal A. Altalhi
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Thomas S. Varley
    Thomas S. Varley
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Nadiyah Alahmadi
    Nadiyah Alahmadi
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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  • Georg H. Mehl
    Georg H. Mehl
    Department of Chemistry, University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom
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    Orcidhttp://orcid.org/0000-0002-2421-4869
  • Stephen M. Kelly
    Stephen M. Kelly
    Organic and Materials Chemistry, Department of Chemistry, Liquid Crystals and Organophotonics Research Group, University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom
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    Orcidhttp://orcid.org/0000-0003-0668-6253
  • Nathan S. Lawrence
    Nathan S. Lawrence
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
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    Frank Marken
    Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
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    Orcidhttp://orcid.org/0000-0003-3177-4562
  • Jay D. Wadhawan*
    Jay D. Wadhawan
    Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
    *Email: [email protected]
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    Orcidhttp://orcid.org/0000-0002-1691-7169
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ACS Omega

Cite this: ACS Omega 2021, 6, 7, 4630–4640
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https://doi.org/10.1021/acsomega.0c05284
Published February 5, 2021

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Abstract

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The discovery of electrochemical switching of the Lα phase of chlorpromazine hydrochloride in water is reported. The phase is characterized using polarizing microscopy, X-ray scattering, rheological measurements, and microelectrode voltammetry. Fast, heterogeneous oxidation of the lyotropic liquid crystal is shown to cause a phase change resulting from the disordering of the structural order in a stepwise process. The underlying molecular dynamics is considered to be a cooperative effect of both increasing electrostatic interactions and an unfolding of the monomers from “butterfly”-shaped in the reduced form to planar in the oxidized form.

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Introduction

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Conformational changes in redox-active molecules can be triggered electrochemically. (1) Such changes do not always have to occur simultaneously with heterogeneous electron transfer; they can both precede, or follow from, the electron transfer event (2) so that voltammetry can identify intermediates and evaluate their lifetimes. One of the characteristics of conformational change occurring in concert with electron transfer is sluggish electrode kinetics, since this can affect the reorganization energy for the heterogeneous electron transfer, (3) as seen for the reduction of cyclooctatetraene (1,3,4) and some of its derivatives (1) and nitrogen analogues, (1,5) wherein a nonplanar, “tub”-shaped neutral molecule affords a planar anion radical. (1,3−5) A second, more important, feature is due to the fact that any intermediate state does not last more than a few vibrations (6) so that the observation is that there is a complete absence of an intermediate, even at the fastest, nanosecond timescales (corresponding to a few million volts per second scan rates) that can be explored voltammetrically. (7,8) Complications in the following conformation change resulting from heterogeneous electron transfer include ion pairing (1) and potential inversions for two-electron transfers. (9) In this article, following reports of electron transfer-induced mesomorphism in thermotropic liquid crystals based on ferrocene derivatives, (10−12) and in nickel(II)-based mesogenic systems, (13) we investigate whether the mechanism of electrochemically trigged conformational change can change as a result of close-packing monomers within a self-assembled, redox-active, liquid nanosystem (viz., lyotropic liquid crystal) based on chlorpromazine hydrochloride.
The tranquilizing drug, chlorpromazine (Figure 1a), and its derivatives are often used as one-electron mediators in electrochemistry, (14) as well as in the treatment of schizophrenia; (15) its biological activity is thought to derive from its facile oxidation and photo-oxidation to a stable cation radical (16−40) and its flexibility: (31−37) in the solid state and in solution, the neutral molecule folds about the N–S axis with the central six-ring in a boat confirmation (“butterfly”-shaped, dihedral angle of 139–153°, Figure 1a), with rapid molecular motions that include those associated with the side chain, pyramidal inversion at nitrogen and ring inversion, even at low temperatures. (35) Oxidation to the cation radical flattens the ring system through relaxing steric repulsions and readjusting the side chain, (33) so that the dihedral angle opens up to 170–180°. (31−37) In contrast, further oxidation to the dication followed by hydrolysis with water yields the corresponding sulfoxide, which is thought to exist with the central six-ring in the boat conformation, at least in the solid state. (36) Accordingly, the conformational change on oxidation to the cation radical affords a bathochromic shift in the absorption: slightly yellow chlorpromazine (24,25,41) (white as the hydrochloride on the side chain, (21,38,41) pKBH+ = 9.15–9.3) converts to the pink cation radical (22,38) (λmax = 526–534, 775–865 nm); the sulfoxide is known to be red. (22) Chlorpromazine is a surfactant, (42−56) affording “cup-stack” micelles (54) (where the hydrophobic core comprises the aromatic rings, with the alkyl chains penetrating into the aqueous pseudophase, enabling the formation of a micellar palisade layer), with a critical micelle concentration (cmc) that depends on the ionic strength, electrolyte nature and temperature of the aqueous solution: (42,43,46−52,55) it ranges between 21 and 27 mM at ambient temperature in water, decreasing to between 2 and 8 mM (aggregation number between 6 and 40) in the presence of 0.1 M NaCl. It is notable that even at concentrations two orders lower than the cmc, self-association of chlorpromazine can occur. (45) Indeed, we have been able to observe aggregates (7.5 ± 2.0 nm radius, assumed spherical, Figure 1b) in an aqueous solution containing 13.1 mM chlorpromazine hydrochloride and 36.0 mM zinc chloride (corresponding to an ionic strength of ca. 0.1 M), roughly in agreement with cmc aggregation numbers for micelles in which the hydrophobic core is a stacked bilayer of aromatic rings: (54) treating chlorpromazine hydrochloride as having planar dimensions of 1 nm × 1 nm, with 0.33 nm interplanar distance between monomers, (54) and assuming the aggregates illustrated in Figure 1b as having a longest length of 15 nm, the monolayer aggregation number n can be estimated from the relationship: n(1 nm) + (n – 1)(0.33 nm) = 15 nm, yielding n ∼ 10, and thus a micelle aggregation number, N ∼ 20 for a bilayer system. This is in agreement with experimental estimates (42,43,49,51) of between 12 and 40 for chlorpromazine hydrochloride at the cmc (8 mM for 0.1 M NaCl). Surprisingly, however, lyotropic liquid crystals of chlorpromazine in water have never been reported. Accordingly, we first examine the electrochemical switching behavior of chlorpromazine hydrochloride in dilute solution, and subsequently investigate both structural and electrochemical effects within its lyotropic liquid crystalline phase.

Figure 1

Figure 1. (a) Structure of chlorpromazine hydrochloride in planar (left) and quasi-equatorial (right) conformations. The latter has been drawn to emphasize the boat conformation of the central six-ring. (b) Transmission electron micrograph of chlorpromazine hydrochloride aggregates obtained in an aqueous solution comprising 13.1 mM chlorpromazine hydrochloride and 36.0 mM zinc chloride. The scale bar corresponds to 50 nm.

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Results and Discussion

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One-electron voltammetric oxidation of chlorpromazine (in aqueous 0.1 M KCl) yields the cation radical (Figure 2a). In the absence of nucleophiles or electron donors, (18−22,57−66) this species is considered to be stable in solution (decaying in unbuffered water at pH 7 with a first-order rate constant of 2.9 × 10–3 s–1 at ambient temperature). (19) As evidenced in Figure 2b, the electron transfer is Nernstian at low scan rates (<100 mV s–1), where the peak oxidation ( EpOx) and reduction (EpRed) potentials become independent of the voltammetric timescale. The second oxidation to afford the dication (not shown) occurs typically at ca. 400 mV greater potentials. At chlorpromazine concentrations below (or near) the cmc, the peak-to-peak potential difference (ΔEpp) also indicates slight deviation from electrochemical reversibility (75.8 ± 10.6 mV), this changes to electrochemical quasi-reversibility above the cmc (ΔEpp = 97.6 ± 13.8 mV). Curiously, the oxidative peak potential shifts positively by 24.4 mV/decadic change in chlorpromazine concentration, whilst the reverse peak moves only by 11.9 mV/decade. This has the effect of making the oxidation process more difficult as the degree of aggregation increases, with Emid = (EpOx + EpRed) varying by 18.2 mV/decade. This is in agreement with literature studies on the influence of self-assembly on redox properties. (65−68) Accordingly, we suggest this reflects the additional energy required to separate aggregated molecules, owing to both the increased charge and the “butterfly-shaped”-to-planar transition that occurs on oxidation, which is manifested through an intrinsic activation barrier. (6) Given that ring inversion in dilute solutions of chlorpromazine is considered to be rapid, even at low temperature, (35,54) we thus suggest that these data are consistent with conformational change occurring in concert with electron transfer.

Figure 2

Figure 2. (a) Cyclic voltammograms (fourth scan from a series of four cycles illustrated) for the oxidation of 1.0  mM chlorpromazine hydrochloride in aqueous 0.1  M aqueous potassium chloride solution, recorded using a 3.0  mm diameter glassy carbon working electrode swept at a rate of 0.1 V  s–1  (green), 0.5  V  s–1 (black), 1.0  V  s–1 (blue), and 2.0 V  s–1  (red) . (b) Variation of the voltammetric peak potentials (from the first scan) with experimental timescale at various concentrations of chlorpromazine hydrochloride: 1.0  mM (red circles), 10  mM (blue squares), 100  mM (black diamonds); open symbols refer to the oxidative peak, with filled symbols corresponding to the re-reductive peak. Data points are plotted as the average over two measurements, with error bars indicating one standard deviation. (c) Variation of the diffusion coefficient, D, (left) and aqueous solution (0.1  M KCl) viscosity, η (right), with chlorpromazine hydrochloride concentration (c0). For the left panel, the aqueous solution was 0.1  M KCl (green diamonds and blue squares as an internal laboratory repeat), pH  4 acetate buffer with 0.1  M KCl (magenta triangles), from cyclic voltammetric measurements at a 3.0  mm glassy carbon electrode, and 0.1  M KCl using steady-state currents at a 5.5  mm ×  4.5  mm platinum channel flow electrode (red circles). The black line is the average of all of the data illustrated, with the error bar representing one standard deviation.

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The growth of the aggregates to afford micelles and then larger micelles can be inferred from the voltammetric data in Figure 2a, (69) through the extraction of the diffusion coefficient (D) from Randles–Ševčík plots illustrating the variation of the peak oxidative current (ipOx, from the first cycle) with scan rate (v), using the equation where F is the Faraday constant (96 485.3 C mol–1), S is the geometric area of the working electrode, T is the absolute temperature, and R is the molar gas constant (8.3145 J mol–1 K–1). As indicated in Figure 2c, the diffusion coefficient decreases with increasing chlorpromazine concentration, even when corrected for the increased viscosity of the solution. (70) Note that the data reported in Figure 2c were also extracted from peak oxidation currents from cyclic voltammograms in aqueous acetate buffer at pH 4, and through Levich plots of the limiting current of steady-state voltammograms (ilim) obtained at a channel flow electrode against the cube root of the volume flow rate (Vf), over a limited range of volumetric flow rates (5–50 μL s–1). In the latter, diffusion coefficients were determined using the expressions, (71)ilim = FSc0km and , where km is the average mass transport coefficient, Sh is the Sherwood number, Pe is the Péclet number, de is the hydraulic diameter, and xe is the electrode length. The data in Figure 2c indicate consistency in the measurements made with different techniques, and suggest a cmc of ca. 10 mM, with self-association of chlorpromazine hydrochloride occurring well below this concentration, in agreement with the literature. (42−54) The continual decrease of diffusion coefficient with increasing chlorpromazine concentration, which is consistent with the notion of increasing micellar size, prompted the investigation as to whether a lyotropic mesophase could be formulated—while N-alkyl-phenothiazines have been studied when incorporated into lyotropic liquid crystals, (72) to the best of our knowledge, no lyotropic liquid crystals based on such derivatives have been reported. Here, the idea was to seek to magnify the effect of conformational change through cooperative effects associated with self-assembly into tight liquid nanosystems. (65)
Formulations of 1.0 and 2.0 mol kg–1 chlorpromazine in water appeared dark when viewed under crossed-polarizers, indicative of the normal micellar phase; further addition of chlorpromazine to 5.0 mol kg–1 yielded transient birefringence and Myelin figures, which on further addition to 10.0 mol kg–1, yielded stable, long-lasting birefringence, even in the presence of mechanical agitation of the phase. Under crossed-polarizers, classical, rough, oily-streak textures were observed (Figure 3a). These are typical of lamellar (Lα) lyotropic liquid crystals. Concurrent with this was the change in the color of the chlorpromazine/water mixture: dilute aqueous solutions are clear and colorless; this changed to a cloudy, pale yellow viscous mixture by 10.0 mol kg–1, with a large absorption band occurring in the violet-to-blue region (300–420 nm, Figure 3b), which is in contrast to the well-defined peaks that occur in dilute solution. (53) The onset of liquid crystallinity in the formulation is marked by the discontinuous increase in the viscosity measured at a constant shear rate of 1.13 Hz between 5.0 and 7.5 mol kg–1 (Figure 3c). Indeed, the basic shear diagrams presented in Figure 3c demonstrate Newtonian behavior at 5.0 mol kg–1, with shear thinning, Bingham plastic behavior (plastic viscosities and yield stresses were determined (73) through the fit of shear stress with shear rate in the range 0.2–4 Hz, to yield plastic viscosity >200 P, increasing with molality) for the liquid crystalline material (m0 > 5.0 mol kg–1), as expected for lamellar (Lα) lyotropic liquid crystals: (74) the shear stress, at high shear rates (>0.2 Hz), increases roughly as a linear function of the shear rate, corresponding to large yield stresses (>30 Pa) which increase with the volume fraction of chloropromazine hydrochloride; this increase gradually tails off at shear rates larger than ca. 4 Hz, as expected. (74) For all three liquid crystal systems examined, there are discontinuities in the flow behavior at low shear rates (<0.2 Hz). This is attributed to “wall slip” where micelles may deplete from the liquid region closest to the surface enabling a thin layer of pure continuous phase to form adjacent to the surface, lowering the viscosity. (75,76) X-ray scattering (Cu Kα radiation at 1.54 Å) was used to characterize the structure of the Lα phase at 10.0 mol kg–1 (Figure 3d), wherein it is seen that, at small angles (3.65° ≤ 2θ ≤ 11.0°), there are three Bragg spacings (strong first- and second-order reflections, with a very weak third-order reflection) in the ratio 1:1/2:1/3, characteristic of the large separations of the Lα arrangement. The fundamental crystal spacing (d) was determined using the Bragg equation: d (Å) = 1.54/(2 sin θ), with the scattering vector (q) estimated through q = 2π/d, so that Bragg ratios q/q0 could be determined, in which q0 is the fundamental repeat distance in the lamellar system (viz. center-to-center separation between surfactant aggregates). We calculated a fundamental repeat distance of 2.42 nm, corresponding to the thickness of the surfactant and the water layers. For this 10.0 mol kg–1 formulation (78 wt %), the thickness of the individual surfactant layers is estimated as 1.88 nm, which, in the light of X-ray crystallographic data for chlorpromazine hydrochloride, suggests the formation of a surfactant bilayer, as expected. The diffuse peak occurring at the wide angle of 2θ = 20.3°, corresponds intra-aggregate spacings (0.44 nm) between the alkyl chains. (54) This tight-packing of the individual monomers suggests that conformational change upon oxidation may disrupt the Lα phase. Indeed, incubation results of the samples in the dark and in the absence of oxygen over a period of four months were observed to be stable and retained their pale yellow coloration; in contrast, samples exposed to both sunlight and oxygen developed a pink-red coloration, which, did not exhibit optical anisotropy when viewed through crossed-polarizers (Figure 3a), indicative of mesomorphism. This is in line with the expectation that flattening the chlorpromazine structure increases the molecular volume of the hydrophobic core, thereby increasing the area of the head group relative to the core through self-distancing of the individual oxidized monomers, and changing the aggregate curvature from zero (Lα) to positive. We did not undertake a chemical analysis of the pink-red material; it is likely that this is a mixture of the cation radical and the sulfoxide. (22,24−30,39,64)

Figure 3

Figure 3. (a) Polarizing microscope images (under crossed-polarizers) of the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol kg–1, freshly prepared (left, magnification × 100) and after 4 months of standing in light and air (middle). Note that in the latter image, a part of the slide outside the cover plate was imaged so as to illustrate the contrast. The image on the right-hand side illustrates the formation of the oxidized material (red-pink) on top of the un-oxidized material (yellow). (b) UV–visible absorption spectrum of the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol  kg–1. (c) Rheological properties of the chlorpromazine hydrochloride/water system at various chlorpromazine hydrochloride molalities (m0): left, viscosity (η) as a function of molality; right, basic shear diagram affording plastic viscosities of 201.2, 306.6, and 499.7  P, and Bingham yields of 30.9, 45.3, and 53.1  Pa for m0  =  7.5, 10.0, and 12.5  mol  kg–1, respectively. (d) X-ray scattering patterns obtained from the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol  kg–1. The primary beam is not shown.

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The apparent fast conformational change in oxidation of chlorpromazine in dilute solution, but slow oxidative breakdown of the long-range order in the 10.0 mol kg–1 anisotropic phase was next investigated through microelectrode voltammetry (Figure 4) so as to quantify the effective relaxation time. Microelectrodes have the multiple advantages of being sufficiently small in size so that only small amounts of material need to be prepared, whilst providing improvements in signal-to-noise ratio, at steady-state, at reduced Ohmic loss. Since the resistance at a disk electrode of radius r0 is ρ/4r0, where ρ is the bulk resistivity of the Lα phase (experimentally determined as 46.4 Ω cm), the Ohmic drop is then ca. 2 mV at the highest scan rates used (corresponding to a maximum current flow of ca. 100 nA). It is clear that a single pair of well-defined Nernstian oxidation and reduction signals is observable at high scan rates (ΔEpp = 74 ± 10 mV), corresponding to the oxidation of chlorpromazine to the corresponding cation radical and its re-reduction, with the reverse peak being considerably thinner than the forward, oxidative peak (cf. half-peak widths of ca. 20 mV with 50 mV for the reverse and forward waves, respectively). At higher potentials, typically around 200 mV more positive (at a scan rate of 100 mV s–1) than those illustrated in Figure 4, a second oxidation wave is observable (data not shown) corresponding to the oxidation of the cation radical to the dication. As for the case in dilute, isotropic solution, this second oxidation wave is chemically irreversible, owing to nucleophilic attack by water on the dication. (64)

Figure 4

Figure 4. Microelectrode voltammetry of the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol  kg–1 at an 11 μm diameter carbon microelectrode. The main image is the variation of the peak potentials with experimental timescale (the error bars correspond to one standard deviation), with peripheral images illustrating four consecutive cycles in the voltammetry at 500, 100, 20, 10, 5, 1, and 0.5  mV  s–1. In these images, the first cycle is shown in red, with the subsequent cycles being first in blue, then green, and finally black.

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The quantitative treatment of the voltammograms requires the effective concentration (in moles per unit volume of the phase) (77,78) to be known. The density of the 10.0 mol kg–1 Lα phase was determined to be 1.30 ± 0.12 g mL–1, leading to an effective concentration, c0 of 2.858 ± 0.263 M. The diffusion coefficient was determined as being (2.0 ± 0.3) × 10–12 m2 s–1 from Randles–Ševčı́k plots using data from the higher scan rates investigated (≥75 mV s–1). Given the liquid crystalline phase is optically anisotropic, it follows that diffusive transport to the electrode might, likewise, be anisotropic. Surprisingly, however, diffusion within the Lα phase was found to be essentially isotropic, viz. the axial diffusion coefficient (Dz) is not significantly different from the tangential diffusion coefficient (Dr): following previous protocols, (78) and using , the first-cycle oxidative peak currents (ipOx) for the high-scan regime were dimensionalized using , where . A nonlinear least-square fit, using the Levenberg–Marquardt algorithm afforded a good correlation using c0 = 2.858 M (coefficient of determination, R2 = 0.9803), with Dr = (2.5 ± 0.4) × 10–12 m2 s–1 and Dz = (1.6 ± 0.7) × 10–12 m2 s–1. We suggest that this apparent transport isotropy arises from the fact that the hydrophobic core is a bilayer of aromatic rings, with the electron lost from the ring nitrogen. (33,64)
The cation radical is less stable in the Lα phase than in aqueous solution—sequential scanning of the voltammetric perturbation reveals the gradual loss of material at higher scan rates. However, on lowering the scan rate, the voltammograms stabilize (cf. the voltammograms at 1 and 500 mV s–1 in Figure 4), and exhibit characteristics corresponding to a switch in diffusion regime (from one- to two-dimensional diffusion) at longer timescales, (79,80) with essentially stable scans on repetitive cycling, indicative of chemical reversibility with fast heterogeneous electron transfer. The variation of the one-electron oxidation peak potentials with scan rate, illustrated in Figure 4 is consistent with a first-order transition corresponding to an electrochemically triggered breakdown of the liquid crystal order (mesomorphism), with the voltammograms at the higher scan rates (≥75 mV s–1) typically exhibiting relatively unperturbed, reversible Nernstian waves (peak potentials being independent of scan rate, half-peak widths of 52 ± 5 mV) based around a formal potential of 0.75 ± 0.1 V vs Ag/AgCl/Cl–, effectively uncomplicated by follow-on kinetics, whilst those at lower scan rates being thinner (40 ± 10 mV), and eventually reversible Nernstian waves centered around a new formal potential 0.71 ± 0.1 V vs Ag/AgCl/Cl–. At these lower scan rates, the oxidation becomes easier, with the peak shifting by 30 ± 7 mV/decade, and eventually become independent of scan rate. This corresponds to the reversible oxidation of chlorpromazine into an equilibrium mixture (lg K = 0.45 ± 0.24) of the radical cation in both the Lα phase and the normal micellar solution, with a first-order rate constant for the phase change of 0.70 ± 0.15 s–1, estimated from the KG to DE transition in the reported kinetic zone diagram. (81)
The phase change results in an apparent paradox at very low scan rates—the voltammograms in Figure 4 take on the shape expected for an electrochemically irreversible system, but do not exhibit decreasing signals upon repetitive cycling. This suggests that, at these slow scan rates (<1.0 mV s–1), there is sufficient time for the electrochemically triggered phase change to be irreversible, giving rise to the observed waveshape. Moreover, under these conditions, the marked increase in peak oxidation current and its shift toward more positive potentials is rationalized as being due to an increase in the local viscosity of the system upon mesomorphism. This analysis assumes that there is negligible volume change during the phase transformation driven by both conformational change and electrostatic interactions. Work on the voltammetry of redox liquid microdroplets, which may generate a phase (due to counterion insertion) starting from the triple phase boundary, suggests that such volume changes, even for immiscible phases, tends to either have little effect on the voltammetry or yield subsequent scans with oxidative peaks shifted negatively. (82) The peak shift between the first scan and the stabilized third/fourth scans in the voltammograms recorded at 0.5 mV s–1 is 10.1 mV. Although this is comparable with the average error in the recording of the first scan of the voltammograms over several experiments (ca. 8 mV), and neglecting reference potential drift, given the voltammgrams at 1 mV s–1 and higher, the peak potential in this region of the EC mechanism is given (83) by , where E0″ is the formal potential for the oxidation of the system to afford an equilibrium mixture and Di (i = Red or Ox) is the diffusion coefficient of the reduced and oxidized species. Thus, we find DRed ∼ 3Dox, indicating that the diffusion coefficient for the cation radical in the disordered, normal micellar solution to be ca. three times smaller than that in the ordered Lα phase. This is roughly in line with expectation, based on the viscosity trends illustrated in Figure 3c, where molecular ordering to form a lamellar phase results in a reduced viscosity than would be expected from the normal isotropic phase. It thus follows that the tightly packed nature of the lyotropic phase enables high rates of electron hopping across bilayer sheets. This is Dahms–Ruff electron hopping, the rate constant for which may be calculated from the diffusion coefficient: (84), where k is the self-exchange rate constant, c0 is the effective homogeneous concentration, and δ is the thickness of the water layer separating the surfactant pseudophase, determined from X-ray scattering to be 0.54 nm. The isotropic diffusion coefficient suggests a rate constant of ca. 1.5 × 107 M–1 s–1, which is reasonably high, whilst the less ordered system is probably limited through translational diffusion through the viscous surfactant system.

Conclusions

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In summary, the amphiphile chlorpromazine hydrochloride (CPZ·HCl) aggregates in dilute solution at concentrations smaller than the cmc; the latter is readily seen through a marked change in the diffusion coefficient with concentration. One-electron oxidation occurs with a conformation change from butterfly to planar shape. Although this unfolding process is electrochemically reversible, it becomes increasingly sluggish with aggregation, indicative of a concerted electron-conformational change. We have discovered that the micelles themselves can aggregate further to form lamellae for the surfactant pseudophase, yielding a lyotropic liquid crystal. Although this phase is optically anisotropic, electron hopping transport within this phase is essentially isotropic. Oxidation breaks down this ordered structure—the oxidized liquid crystal has a half-life of ca. 1.0 s, to yield an isotropic phase (N). This oxidation can be mediated by oxygen and light, or occur heterogeneously at an electrode surface, with fast electrode kinetics consistent with the following mechanism:
The underpinning molecular rationale for this stepwise mesomorphism is either due to increased electrostatic interactions that are poorly supported by the counterions, or, more likely, due to the change in space required by the butterfly-to-planar transition. Such phase transitions may find application of these switchable materials for the development of new types of redox sensors, based on polarizing microscopy or electrochemical techniques.

Experimental Section

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All chemical reagents were purchased from Sigma-Aldrich in the purest commercially available grade and used as received. Water, with a resistivity of not less than 18 MΩ cm, was taken from an Elgastat system (Vivendi). Nitrogen and argon were obtained from Energas, Ltd, U.K..
Viscosities of dilute solutions were measured using an Ubbelohde viscometer mounted within a water bath thermostatted to 298 K. The viscometer was calibrated using pure water. Transmission electron microscopy was undertaken using a JEOL JEM1200EXII instrument equipped with energy-dispersive spectrometry (EDS) analysis (INCA Energy 350, Oxford Instruments). Images were acquired using a Gatan dual view camera.
Concentrated solutions and lyotropic liquid crystals were prepared by mixing the required mass of chlorpromazine hydrochloride with nitrogen- or argon-purged water in the appropriate wt % ratio in screw-capped vials sealed with Parafilm, followed by heating in a water bath, with stirring to approximately 363 K for 60 min, thereby achieving sample homogenization in the normal, isotropic micellar phase. The samples were then allowed to cool to ambient temperature (294 ± 2 K) prior to further experimentation at this temperature. Long-term (four months) exposure of the material to both oxygen and sunlight was undertaken through regular (weekly) opening of the sample vial to enable gas exchange, and keeping the glass vial containing the sample on a south-facing windowsill.
Concentrated samples were examined using an Olympus BX-51 optical polarizing microscope, equipped with a digital camera for image capture. Ultraviolet–visible spectrophotometry was undertaken using a PerkinElmer Lambda-25-Scan-UV–Vis instrument, using a quartz cell of 1.0 cm path length. X-ray scattering measurements were undertaken through filling capillary tubes with the viscous sample, placed into an MAR345 diffractometer with a two-dimensional (2D) image plate detector (Cu Kα radiation, graphite monochromator, λ = 1.54 Å, 130–300 mm detector-sample distance, with an exposure time of 30 min). The samples were heated (between 297 and 363 K) in the presence of a magnetic field using a home-built capillary furnace. The bulk electrical resistivity of the samples was measured using a CDM210 conductivity meter equipped with a four-pole CDC511T conductivity cell (Radiometer) inserted vertically into the sample. Rheological measurements were made using a Bohlin CVO 120 high-resolution rheometer in the controlled rate mode with a truncated cone (4° cone angle, 40 mm cone diameter) in plate geometry (200 μm gap width), at a temperature of 298 K. The lowest shear rate applied was 0.1 s–1. For each step, shear was applied for ca. 10 s, during which the shear stress was measured and the viscosity of the material calculated. Measurements made where the deviation between the achieved and target shear rate was >5% were rejected.
Electrochemical experiments were undertaken using a variety of potentiostats (μAutolab Type III, or Autolab PGSTAT30, or a PalmSens Instrument). Cyclic voltammetry experiments employed a silver/silver chloride reference electrode (BAS), a nickel spiral or nichrome wire counter electrode, and a glassy carbon working electrode (of diameter 3.0 mm, BAS). In the case of dilute solutions, samples were not degassed prior to oxidative electrochemistry, but the working electrode was cleaned and polished using an aqueous 0.3 μm alumina slurry on a wetted, napped polishing cloth before every experiment so that a clean surface was exposed to different locations of the sample for every change in experimental variable. For voltammetric experiments within the redox liquid crystal, to overcome any effects due to wall slip, the phase was allowed to melt into the normal, isotropic micellar phase under argon, prior to insertion of the cleaned and polished 11.0 μm carbon microelectrode, together with the reference and counter electrodes. This system was then cooled to ambient temperature so that the insertion of the electrodes would not shear the liquid crystal. This procedure was repeated for every scan rate examined. For channel electrode measurements of dilute aqueous solutions, a bespoke, rectangular channel flow base plate (of length, L = 7 cm; width, d = 0.6 cm) was machined in PTFE using a CNC, covered with an optically pure silica cover plate (Optiglass, Ltd., Hainault, Essex, U.K.), and sealed with adhesive (Stick 2, Ever Build) so that the channel depth is 2h = 0.08 cm, where h is the half-cell depth. A platinum foil working electrode (of length, xe = 0.55 cm, and width, w = 0.45 cm, measured accurately within a traveling microscope) was positioned so that its upstream edge was located two-thirds of the channel length downstream from the flow entrance. The platinum foil was connected via contact through the verso face with conductive epoxy through a hole at the bottom of the channel, and was polished using a cotton swab impregnated with 0.3 μm alumina slurry prior to sealing the channel flow cell. The long entry length (le) enabled the establishment of a laminar, Hagen–Poiseuille flow (85) (le > 0.034hRe, where Re is the Reynolds number, defined as Re = deû/ν, in which de is the hydraulic diameter, de = 4hd/(2h + d), û is the free stream and average velocity, and ν is the kinematic viscosity), using a syringe pump (Fusion 200, CHEMYX) to drive the solution to flow between 5 and 50 μL s–1, corresponding to 1.5 ≤ Re ≤ 15. A saturated calomel reference (Radiometer) was positioned upstream to the channel flow cell, with a platinum mesh counter electrode placed downstream of the flow cell, so that the products formed on the counter electrode would not interfere with the process occurring on the working electrode during the recording of steady-state currents.

Author Information

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  • Corresponding Author
    • Jay D. Wadhawan - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom;  Present Address: Department of Chemical Engineering, The University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom;  Present Address: G. W. Gray Centre for Advanced Materials, The University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom;  Orcidhttp://orcid.org/0000-0002-1691-7169;  Email: [email protected]
  • Authors
    • Robert D. Crapnell - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
    • Huda S. Alhasan - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom;  Present Address: Environmental Research Studies Centre, University of Babylon, Babylon, Iraq
    • Lee I. Partington - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
    • Yan Zhou - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom;  Present Address: China University of Petroleum (East China), Qingdao City, Shandong, China
    • Ziauddin Ahmed - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
    • Amal A. Altalhi - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom;  Present Address: Department of Chemistry, Faculty of Science, Taif University, Airport Road, Al Hawiyah, Taif, Saudi Arabia
    • Thomas S. Varley - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom
    • Nadiyah Alahmadi - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom;  Present Address: The University of Jeddah, College of Science, Department of Chemistry, Jeddah, Saudi Arabia
    • Georg H. Mehl - Department of Chemistry, University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom;  Present Address: G. W. Gray Centre for Advanced Materials, The University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom;  Orcidhttp://orcid.org/0000-0002-2421-4869
    • Stephen M. Kelly - Organic and Materials Chemistry, Department of Chemistry, Liquid Crystals and Organophotonics Research Group, University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom;  Present Address: G. W. Gray Centre for Advanced Materials, The University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom;  Orcidhttp://orcid.org/0000-0003-0668-6253
    • Nathan S. Lawrence - Department of Physical Sciences (Chemistry), University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, Humberside, United Kingdom;  Present Address: Department of Chemical Engineering, The University of Hull, Cottingham Road, Kingston-upon-Hull HU6 7RX, United Kingdom
    • Frank Marken - Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom;  Orcidhttp://orcid.org/0000-0003-3177-4562
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The authors thank EPSRC (GR/N EP/G020833/1) and The University of Hull for financing this work. G.H.M. thanks EPSRC (GR/N EP/M015726/1) for funding. H.S.A. thanks the Iraqi Cultural Attache for financing her Ph.D. and The University of Babylon for further support. Y.Z. thanks China University of Petroleum for further funding. A.A.A. thanks the Royal Kingdom of Saudi Arabia for funding her Ph.D. and Taif University for further support. N.A. thanks The University of Jeddah for financial support. F.M. and J.D.W. thank Jon Mitchell (University of Bath) for undertaking TEM measurements. H.S.A. and J.D.W. thank Tim Dunstan (University of Hull) for undertaking rheological measurements. The contribution of Laurence Boulder, James Shellbourne, Laetita Testut, Håvard Eide, Haydn Ward, Adam Gregory, and Akalya Raviraj in repeating various aspects of this work is also acknowledged.

References

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    Kinetics of chlorpromazine cation radical decomposition in aqueous buffers
    Cheng, Hung Yuan; Sackett, Patricia Holt; McCreery, Richard L.
    Journal of the American Chemical Society (1978), 100 (3), 962-7CODEN: JACSAT; ISSN:0002-7863.
    The stoichiometry and kinetics of the reactions of chlorpromazine cation radical perchlorate salt (I) [61866-46-4] in aq. buffers were examd. at pH 2-7 using electrochem. and spectrophotometry. In phosphate and citrate media, 1 mol of radical produced 0.5 mol each of chlorpromazine (II) [50-53-3] and chlorpromazine sulfoxide (III) [969-99-3], whereas in amine buffers or unbuffered soln., other products were formed. For phosphate and citrate buffers, the decay of I was 2nd order in I, 1st order in buffer anion concn., inverse 1st order in [H+], and inverse 1st order in neutral II concn. The kinetic data indicate the formation of a cation radical/buffer adduct which is oxidized by another mol. of I, followed by rearrangement to III. The results are inconsistent with a mechanism involving disproportionation of the radical, but rather indicate a direct reaction of cation radical with buffer components and water.
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    Cheng, H. Y.; Sackett, P. H.; McCreery, R. L. Reactions of chlorpromazine cation radical with physiologically occurring nucleophiles. J. Med. Chem. 1978, 21, 948,  DOI: 10.1021/jm00207a019
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    19
    Reactions of chlorpromazine cation radical with physiologically occurring nucleophiles
    Cheng, Hung-Yuan; Sackett, Patricia Holt; McCreery, Richard L.
    Journal of Medicinal Chemistry (1978), 21 (9), 948-52CODEN: JMCMAR; ISSN:0022-2623.
    The chlorpromazine cation radical [34468-21-8] reacts with physiol. nucleophiles, such as citrate, maleate, phosphate, glycine, and H2O, to give N or O adducts, which decomp. to chlorpromazine S-oxide [969-99-3] or hydroxylated derivs. The kinetics of the reaction depends on the nature of nucleophile, the reaction being fastest with SH- and slowest with H2O.
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    Deputy, A.; Wu, H.-P.; McCreery, R. L. Spatially resolved spectroelectrochemical examination of the oxidation of dopamine by chlorpromazine cation radical. J. Phys. Chem. A 1990, 94, 3620,  DOI: 10.1021/j100372a047
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    Spatially resolved spectroelectrochemical examination of the oxidation of dopamine by chlorpromazine cation radical
    Deputy, Andrew; Wu, Huan Ping; McCreery, Richard L.
    Journal of Physical Chemistry (1990), 94 (9), 3620-4CODEN: JPCHAX; ISSN:0022-3654.
    Spatially resolved absorption measurements of electrogenerated chlorpromazine cation radical (CPZ•+) were used to monitor the kinetics of the homogeneous oxidn. of dopamine (DA) in the soln. near planar and cylindrical electrodes. Complete concn. vs distance profiles for CPZ•+ were obtained for both planar and convergent diffusion and were used to det. the reaction mechanism and rate consts. The oxidn. of DA by CPZ•+ to dopamine orthoquinone involves successive one-electron transfers, and the results are inconsistent with disproportionation of the DA semiquinone. The obsd. kinetics and rate-limiting step were dependent on the position within the diffusion layer. Near the electrode surface the rate law is 1st order in CPZ•+ and DA, and a 2nd order rate const. of 2.1 × 10-5 M-1 s-1 was obtained. Further away from the electrode the reaction is 2nd order in CPZ•+ due to the involvement of the 2nd step, and several kinetic parameters for the 2nd electron transfer were obtained. A change in diffusion geometry which occurs at a microwire electrode further perturbs local concn. distributions, and the reaction reaches equil. under certain conditions. In all cases, the obsd. rate laws were consistent with a general expression for the stepwise electron transfer. This report represents the first application of spatially resolved spectroelectrochem. to a kinetic system and provides unprecedented detail about the CPZ•+/DA reaction.
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  21. 21
    Sackett, P. H.; Mayausky, J. S.; Smith, T.; Kalus, S.; McCreery, R. L. Side-chain effects on phenothiazine cation radical reactions. J. Med. Chem. 1981, 24, 1342,  DOI: 10.1021/jm00143a016
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    Side-chain effects on phenothiazine cation radical reactions
    Sackett, Patricia Holt; Mayausky, J. S.; Smith, Theresa; Kalus, Susan; McCreery, Richard L.
    Journal of Medicinal Chemistry (1981), 24 (11), 1342-7CODEN: JMCMAR; ISSN:0022-2623.
    The effect of cation radical structure on the formation of sulfoxide and hydroxylated metabolites in vitro phenothiazine tranquilizers was studied. Cyclic voltammetry, spectrophotometry, and liq. chromatog. were used to examine reactions of various phenothiazine radicals in aq. buffers. A radical with a 3-carbon aliph. side chain [e.g., chlorpromazine (I) [50-53-3]] forms solely sulfoxide and parent unless amine nucleophiles are present, in which case hydroxylation occurs. A shorter side chain [e.g., promethazine (II) [60-87-7]] causes radical dimerization and pronounced hydroxylation, regardless of external nucleophiles. A piperazine side chain [e.g., fluphenazine (III) [69-23-8]] promotes hydroxylation, with some sulfoxide obsd. Apparently, a deprotonated amine is necessary for hydroxylation and the amine may be present in the original drug rather than an external nucleophile. In addn. to information about cation radical reactions, the redox properties of several different phenothiazines are presented.
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  22. 22
    Bosch, E.; Kochi, J. K. Catalytic oxidation of chlorpromazine and related phenothiazines: cation radicals as the reactive intermediates in sulfoxide formation. J. Chem. Soc., Perkin Trans. 1 1995, 1057,  DOI: 10.1039/p19950001057
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    Catalytic oxidation of chlorpromazine and related phenothiazines. Cation radicals as the reactive intermediates in sulfoxide formation
    Bosch, Eric; Kochi, Jay K.
    Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1995), (8), 1057-64CODEN: JCPRB4; ISSN:0300-922X. (Royal Society of Chemistry)
    The aerial oxidn. of various phenothiazines to the corresponding sulfoxides is catalyzed by nitric oxide and related nitrogen oxides. The reactive intermediate in the catalytic autoxidn. is the phenothiazine cation radical which is subsequently transformed to the sulfoxide by nitrate present in the reaction medium. These results are pertinent to any further discussion of the activity and/or metab. of phenothiazine-based drugs.
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  23. 23
    Ximenes, V. F.; Quaggio, G. B.; Graciani, F. S.; de Menezes, M. L. Oxidation of amino acids by chlorpromazine cation radical and co-catalysis by chlorpromazine. Pharmacol. Pharm. 2012, 3, 29,  DOI: 10.4236/pp.2012.31005
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    23
    Oxidation of amino acids by chlorpromazine cation radical and co-catalysis by chlorpromazine
    Ximenes, Valdecir F.; Quaggio, Giovana B.; Graciani, Fernanda S.; de Menezes, Manoel L.
    Pharmacology & Pharmacy (2012), 3 (1), 29-36CODEN: PPHHBN; ISSN:2157-9423. (Scientific Research Publishing, Inc.)
    The long-term use of chlorpromazine (CPZ) may cause severe side effects. This property of CPZ might be related to pro-oxidant effects of the chlorpromazine cation radical (CPZ·+), which can be easily generated by catalytic action of peroxidases, including the neutrophil myeloperoxidase (MPO) and by metHb. Aiming the comprehension of a putative physiol. effect of CPZ·+ upon biomols., in this work we studied the reactivity of CPZ·+ with amino acids and the co-catalytic effect of CPZ during the oxidn. of amino acids by horseradish peroxidase (HRP)/H2O2 system. We also studied whether natural blood plasma components as ascorbic acid, uric acid and nitrite could inhibit the oxidative effect of CPZ·+. We found that tryptophan, tyrosine and cysteine were easily oxidized by pure CPZ·+. Other amino acids as methionine, glycine, phenylalanine, aspartic acid and lysine were unreactive. The decompn. of CPZ·+ was exacerbated by uric acid, ascorbic acid and nitrite, provoking inhibition in the amino acids oxidn. In expts. with HRP/H2O2, and using CPZ as a co-catalyst, a strong effect upon oxidn. of tryptophan, tyrosine and cysteine was obtained. It was also found that tryptophan was more reactive than tyrosine with CPZ·+, a feature that could be related to the recently described favorable interaction between tryptophan and CPZ. The use of CPZ as a co-catalyst is discussed regarding its role in the efficient oxidn. of tryptophan.
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  24. 24
    Rodrigues, T.; dos Santos, C. G.; Riposati, A.; Barbosa, L. R. S.; di Mascio, P.; Itri, R.; Baptista, M. S.; Nascimento, O. R.; Nantes, I. L. Photochemically generated stable cation radical of phenothiazine aggregates in mildly acid buffered solution. J. Phys. Chem. B 2006, 110, 12257,  DOI: 10.1021/jp0605404
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    Photochemically Generated Stable Cation Radical of Phenothiazine Aggregates in Mildly Acid Buffered Solutions
    Rodrigues, Tiago; dos Santos, Carolina G.; Riposati, Alessandra; Barbosa, Leandro R. S.; Di Mascio, Paolo; Itri, Rosangela; Baptista, Mauricio S.; Nascimento, Otaciro R.; Nantes, Iseli L.
    Journal of Physical Chemistry B (2006), 110 (25), 12257-12265CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
    This work characterizes, for the first time, the photochem. behavior of the antipsychotic drugs thioridazine (TR), trifluoperazine (TFP), and fluphenazine (FP) influenced by the aggregation state of the mols. Samples of monomeric and aggregated forms of phenothiazines were submitted to 20 min of irradn. at 254 nm for intervals of 1, 5, 10, 15, 20, or 25 days. In high phenothiazine concns., the irradn. led to the appearance of absorbance bands in the visible region peaking at 633 nm for TR and 509 nm for FP and TFP. In the dark, at room temp. and at 4° C, these bands disappeared, after ∼15 and ∼60 min, resp., but reappeared after a new irradn. session. These visible bands were assigned to stable cation radicals that were characterized by direct EPR measurements and by flash photolysis. Photogenerated stable cation radicals in the phenothiazine aggregates at room temp. are formed probably due to the stacking of the thiazine Ph moieties. For the monomeric forms of phenothiazines, the spectral changes obsd. during the irradn. suggested the formation of sulfoxide and hydroxylated derivates. Oxidized derivates were detected by mass spectrometry of the aggregated forms of phenothiazines (>100 μM) only in the samples irradiated for more than 20 days. In contrast, monomeric phenothiazines were totally converted to the oxidized forms after 20 min of irradn. Surface tension measurements of phenothiazines revealed that, in concns. above 100 μM, the drugs formed aggregates. In the case of TR, small-angle x-ray scattering measurements indicated that this compd. forms large lamellar-like aggregates in aq. solns.
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    Ateş, S.; Somer, G. Photodegradation of chlorpromazine in aqueous solutions as studied by ultraviolet-visible spectrophotometry and voltammetry. J. Chem. Soc., Faraday Trans. 1 1981, 77, 859,  DOI: 10.1039/f19817700859
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    Photodegradation of chlorpromazine in aqueous solutions as studied by ultraviolet-visible spectrophotometry and voltammetry
    Ates, Serdar; Somer, G.
    Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases (1981), 77 (4), 859-67CODEN: JCFTAR; ISSN:0300-9599.
    Photodegrdn. of chlorpromazine (I) [50-53-3] under near-UV radiation was monitored by following its π-π* absorption band at 256 nm and by voltammetric oxidn. peak current measurements. Both techniques gave results which were consistent with the same mechanism for photodegrdn. in aq. solns. of pH 1.5-6.5 at 22-24°. The photooxidn. reaction obeyed zero-order kinetics. Evidence for chlorpromazine phenazathionium ion [78036-25-6] formation was obsd. in spectra of 6 mol/dm3 H2SO4 solns. of the irradiated drug.
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    Garcia, C.; Smith, G. A.; McGimpsey, W. G.; Kochevar, I. E.; Redmond, R. W. Mechanism and solvent dependence for photoionisation of promazine and chlorpromazine. J. Am. Chem. Soc. 1995, 117, 10871,  DOI: 10.1021/ja00149a010
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    26
    Mechanism and Solvent Dependence for Photoionization of Promazine and Chlorpromazine
    Garcia, Carmelo; Smith, Glenn A.; McGimpsey, W. Grant; Kochevar, Irene E.; Redmond, Robert W.
    Journal of the American Chemical Society (1995), 117 (44), 10871-8CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
    The mechanism for photoionization of the phenothiazine derivs., promazine and chlorpromazine, has been studied as a function of solvent and excitation conditions. Sequential biphotonic absorption is responsible for photoionization induced by pulsed laser irradn. at 308 or 355 nm. In order to det. the excited states involved excitation was carried out under conditions where the second photon was exclusively absorbed by the lowest excited singlet state (using picosecond excitation pulses where the pulse duration is « singlet lifetime) or by the lowest triplet state using a two-color, two-pulse excitation protocol. Photoionization occurs upon two-photon excitation within the singlet manifold in aq. solns. and methanol. In addn., photoionization is solvent dependent upon excitation of the triplet state at 355 nm or near its absorption max. of 460 nm. In water the triplet absorption was bleached concomitant with the generation of absorption from the radical cation and hydrated electron. Quantum yields of photoionization of promazine were 0.02 and 0.03 in acetonitrile and water, resp. In methanol or other alcs., photoionization was not obsd. under the same excitation conditions. Triplet lifetimes, molar absorption coeffs., and quantum yields of intersystem crossing were detd. in various solvents. The exptl. results indicate that during single wavelength pulsed irradn. of these compds., the second photon is absorbed predominantly by the lowest excited singlet state rather than the lowest excited triplet state. The energetics of the photoionization of promazine and chlorpromazine were estd. as a function of solvent.
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    Sarata, G.; Noda, Y.; Sakai, M.; Takahashi, H. Structure and dynamics of the lowest excited triplet states and cation radicals of phenothiazine and 2-chlorophenothiazine: transient resonance Raman and absorption study. J. Mol. Struct. 1997, 413–414, 49,  DOI: 10.1016/S0022-2860(97)00060-4
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    27
    Structures and dynamics of the lowest excited triplet states and cation radicals of phenothiazine and 2-chlorophenothiazine: transient resonance Raman and absorption study
    Sarata, Gaku; Noda, Yoshihiro; Sakai, Makoto; Takahashi, Hiroaki
    Journal of Molecular Structure (1997), 413-414 (), 49-59CODEN: JMOSB4; ISSN:0022-2860. (Elsevier)
    Transient resonance-Raman and absorption spectra of the lowest excited triplet states T1 and the cation radicals of phenothiazine (I) and 2-chlorophenothiazine (II) were measured. In the photoreaction of II, a transient exhibiting an absorption band at 556 nm was generated from the cation radical. The corresponding transient was not obsd. in the absorption spectrum of I, a fact which suggests the possibility of phenothiazinyl radical generation from II via photoinduced dechlorination. Vibrational assignments of the T1 states and the cation radicals of both compds. were made based on the frequency shifts on isotopic substitutions. Unusually large low-frequency shifts of the Ph 8a and 8b modes were obsd. in the T1 state but no appreciable shifts were detected in the cation radical, indicating that the Ph rings are drastically weakened, and therefore, the Ph C-C bonds are very much lengthened in the T1 state. This implies that the excitation is strongly localized on the Ph rings and the T1 state has an n-.vpi.* character.
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  28. 28
    Maruthamuthu, P.; Sharma, D. K.; Serpone, N. Sub-nanosecond relaxation dynamics of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) and chlorpromazine: assessment of photosensitisation of a wide band gap metal oxide semiconductor TiO2. J. Phys. Chem. B 1995, 99, 3636,  DOI: 10.1021/j100011a034
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    Subnanosecond Relaxation Dynamics of 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonate) and Chlorpromazine. Assessment of Photosensitization of a Wide Band Gap Metal Oxide Semiconductor TiO2
    Maruthamuthu, P.; Sharma, D. K.; Serpone, N.
    Journal of Physical Chemistry (1995), 99 (11), 3636-42CODEN: JPCHAX; ISSN:0022-3654. (American Chemical Society)
    Subnanosecond relaxation dynamics of the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) monoanion, ABTSH(-H+) and the dianion, ABTS(-2H+), together with the chlorpromazine cation ClPMZ(+H+) were examd. by picosecond laser spectroscopic techniques (excitation wavelength, 355 nm) in the presence and absence of TiO2 colloids to assess their photosensitization of wide band gap metal oxide semiconductors. Fluorescence emissions from ABTSH(-H+) and ABTS(-2H+) by excitation with 370-nm light and from ClPMZ(+H+) by excitation at 360 nm are quenched by TiO2 by an interfacial electron transfer process implicating the singlet excited states of the dyes and the conduction band and/or band gap surface states of TiO2 (electron injection). Subnanosecond change-in-absorbance spectra of the substrates showed formation of singlet excited states followed by electron ejection and formation of the corresponding radical cations (zwitterion radicals). Photolysis in the presence of an electron scavenger (e.g., NO3-) at different delay times confirmed these observations. The lifetime of free ABTS(-2H+)* (S1) is about 80 ps, and that of ClPMZ(+H+)* (S1) is pulse-width limited, that is less than 30 ps. The presence of TiO2 colloids in the photolytic system decreased the rate of loss of the radical cation ABTS•+(-2H+) owing to surface trapping of photoejected electrons from the singlet excited states of the substrates. Formation of the ABTS2+(-2H+) dication is obsd. on photolysis of ABTS•+(-2H+) in the presence of TiO2 colloids and dissolved oxygen; in the absence of either TiO2 and/or O2, formation of the dication is quenched, consistent with the notion that ABTS•+(-2H+) is oxidized by surface trapped holes on the TiO2 particle.
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    Chignell, C. F.; Motten, A. G.; Buettner, G. R. Photoinduced free radicals from chlorpromazine and related phenothiazines: relationship to phenothiazine-induced photosensitisation. Environ. Health Perspect. 1985, 64, 103,  DOI: 10.1289/ehp.8564103
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    Photoinduced free radicals from chlorpromazine and related phenothiazines: relationship to phenothiazine-induced photosensitization
    Chignell, Colin F.; Motten, Ann G.; Buettner, Garry R.
    Environmental Health Perspectives (1985), 64 (), 103-10CODEN: EVHPAZ; ISSN:0091-6765.
    A review, with 54 refs., of the free-radical photochem. of chlorpromazine [50-53-3] and related phenothiazines and the involvement of photoinduced free radicals in photosensitization.
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    Buettner, G. R.; Hall, R. D.; Chignell, C. F.; Motten, A. G. The stepwise biphotonic photoionisation of chlorpromazine as seen by laser flash photolysis. Photochem. Photobiol. 1989, 49, 249,  DOI: 10.1111/j.1751-1097.1989.tb04103.x
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    The stepwise biphotonic photoionization of chlorpromazine as seen by laser flash photolysis
    Buettner, Garry R.; Hall, Robert D.; Chignell, Colin F.; Motten, Ann G.
    Photochemistry and Photobiology (1989), 49 (3), 249-56CODEN: PHCBAP; ISSN:0031-8655.
    It is generally accepted that both promazine (PZ) and chlorpromazine (CPZ) photoionize monophotonically to their resp. cation radicals and the corresponding hydrated electrons. It is also supposed that this photoionization has a role in the phototoxic effects of these drugs. However, using laser flash photolysis, it has been obsd. that photoionization of CPZ during S1 excitation (λ >300 nm) is a stepwise biphotonic process. In the case of PZ, the flash photolysis results are less clear-cut, but are consistent with stepwise biphotonic photoionization for S1 excitation. Using computer simulation of the intramol. kinetics, it is demonstrated that the estd. triplet state lifetime of CPZ is sufficient long (23 ns at room temp.) to account for the apparent monophotonic photoionization that has been obsd. by others at high light intensities and short pulse times. The laser flash photolysis results also suggest that the photoionization mechanism of PZ and CPZ is wavelength-dependent. Both drugs exhibit apparent monophotonic photoionization when they are excited at 266 nm under conditions of laser pulse width and intensity similar to those at 355 nm. It is suggested that photoionization is not an important mechanism in the obsd. phototoxic and photoallergic effects of PZ and CPZ in sunlight.
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    Fenner, H.; Möckel, H. EPR spekten von radikalkationen aus promazin und chlorpomazin. Tetrahedron Lett. 1969, 2815,  DOI: 10.1016/S0040-4039(01)88279-4
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    E.P.R. spectra of radical cations of promazine and chlorpromazine
    Fenner, Helmut; Moeckel, Hermann
    Tetrahedron Letters (1969), (33), 2815-18CODEN: TELEAY; ISSN:0040-4039.
    The E.P.R. spectra of promazine and chlorpromazine radicals were taken at room temp. on samples contg. 0.0001M base and 0.1% Bz2O2 in C6H6 degassed with Ar 30 min. Coupling for ring protons around 0.5 G merged into the line widths or were only detectable as shoulders. Analysis of the hyperfine structure gave in addn. to a large N-coupling (6.95 and 7.0 G) 5 sets of equiv. proton pairs for the promazine radical (I) and 4 for the chlorpromazine radical (II). The assignment of coupling parameters was based on those of the phenothiazine radical cation (III) (CA 64: 18742b) based on M.O. calcns. The coupling consts. for III permitted assignment of the largest proton couplings to the N-CH2 group. On the basis of the E.P.R. spectra the radical cations of I and II were assigned to the polymethine type with alternating charge ds., longwave absorption, and planarity of the system.
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    Pan, D.; Shoute, L. C. T.; Phillips, D. L. Time-resolved resonance Raman and density functional study of the radical cation of chlorpromazine. J. Phys. Chem. A 2000, 104, 4140,  DOI: 10.1021/jp992196z
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    Time-Resolved Resonance Raman and Density Functional Study of the Radical Cation of Chlorpromazine
    Pan, Duohai; Shoute, Lian C. T.; Phillips, David Lee
    Journal of Physical Chemistry A (2000), 104 (18), 4140-4148CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    A resonance Raman spectrum was obtained of the radical cation of promazine. The authors have also carried out d. functional theory calcns. to find the structures, hyperfine coupling consts. (hfcc.'s), spin densities, and vibrational frequencies for the ground electronic states of the neutral chlorpromazine mol. and its radical cation. Preliminary vibrational assignments were made for all of the obsd. bands in the resonance Raman spectrum of the radical cation of chlorpromazine and in the FT-Raman spectrum of the neutral chlorpromazine mol. The radical cation of chlorpromazine has a nonplanar structure similar to that of the radical cation of promazine. The Cl atom at the 2 position in chlorpromazine appears to noticeably change the hfcc.'s and spin densities of the radical cation compared to the radical cation of promazine. This is possibly due to conjugation and/or through-bond interactions of the Cl atom with the central-ring heterocycle.
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    Rupérez, F. L.; Conesa, J. C.; Soria, J.; Apreda, M. C.; Cano, F. H.; Foces-Foces, C. X-ray diffraction and electron paramagnetic resonance study of the chlorpromazine cation radical. J. Phys. Chem. C 1985, 89, 1178,  DOI: 10.1021/j100253a025
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    Pan, D.; Phillips, D. L. Raman and density functional study of the S0 state of phenothiazine and the radical cation of phenothiazine. J. Phys. Chem. A 1999, 103, 4737,  DOI: 10.1021/jp990399h
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    Raman and Density Functional Study of the S0 State of Phenothiazine and the Radical Cation of Phenothiazine
    Pan, Duohai; Phillips, David Lee
    Journal of Physical Chemistry A (1999), 103 (24), 4737-4743CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Raman spectra of phenothiazine and its radical cation were obtained. Hartree-Fock (HF) and d. functional theory (DFT) ab initio calcns. were performed to find optimized structures and computed vibrational frequencies. The ab initio structures are compared to previously reported X-ray diffraction exptl. results, and the vibrational frequencies are compared to Raman spectra given here as well as previously reported Raman spectra. We have made vibrational assignments for the obsd. Raman bands, based on the computed potential energy distribution (PED) and isotopic shifts. Our results indicate that the neutral phenothiazine mol. has a nonplanar structure with ∼153° dihedral angle and the radical cation has a planar (or near planar) structure with ∼180° dihedral angle.
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    Molecular motion in chlorpromazine and chlorpromazine hydrochloride
    Soltz, Barbara A.; Corey, Joyce Y.; Larsen, David W.
    Journal of Physical Chemistry (1979), 83 (16), 2162-6CODEN: JPCHAX; ISSN:0022-3654.
    Chlorpromazine (I) and I.HCl were studied in the solid state with pulsed NMR techniques. The relaxation times, T1, T1ρ, and T1D, and second moments, M2, were measured from 98 K to the m.p. of the solid. Me reorientation was obsd. in I and I.HCl with activation barriers of 2.5 and 2.0 kcal/mol, resp. The onset of a second motion in I is obsd. in the high temp. region with an activation barrier of 3.9 kcal/mol. The M2 transition assocd. with this motion is very large, which suggests that it involves motion of the aminopropyl chain. The motion is attributed to the fact that the chain configuration is trans-gauche, and a model for the motion is discussed. A phase transition occurs for I.HCl in the high temp. region.
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    Crystal and molecular structure of chlorpromazine
    McDowell, J. J. H.
    Acta Crystallographica, Section B: Structural Crystallography and Crystal Chemistry (1969), 25 (Pt. 11), 2175-81CODEN: ACBCAR; ISSN:0567-7408.
    The crystal structure of chlorpromazine (I) has been detd. from 3-dimensioal x-ray diffraction data and refined by least-squarse methods, with individual anisotropic temp. factors. The space group is Pbca with a = 23.50 ± 0.04, b = 15.20 ± 0.02, and c = 9.23 ± 0.01 Å. The mol. is folded about the S-N axis and the angle between the best planes for the 2 benzene rings was found to be 139.4°. The C-S-C angle is 97.3 ± 0.3°, the C-S bonds are 1.75 ± 0.01 Å and C-Cl is 1.74 ± 0.01 Å. The contraction of the C-S bond, the size of the C-S-C angle, and the folding of the mol. are characteristic of a no. of related compds., and can be explained by assuming the participation of d orbitals in the bonding of S.
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    Spectra of radical cations of phenothiazine derivatives in solution and solid state
    Ortiz, A.; Pardo, A.; Fernandez-Alonso, J. I.
    Journal of Pharmaceutical Sciences (1980), 69 (4), 378-80CODEN: JPMSAE; ISSN:0022-3549.
    UV and visible spectra of radical cations of 17 psychotropic phenothiazine derivs. were studied using different solvents. The characteristic charge transfer band was obsd. in the solid state using diffuse reflectance spectroscopy. C(2)-substituents do not affect the band, while substituents at N affected the band considerably, probably owing to steric effects.
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    Bahnemann, D.; Asmus, K.-D.; Wilson, R. L. Free radical induced one-electron oxidation of the phenothiazines chlorpromazine and promethazine. J. Chem. Soc., Perkin Trans 2 1983, 1661,  DOI: 10.1039/p29830001661
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    Free radical induced one-electron oxidation of the phenothiazines chlorpromazine and promethazine
    Bahnemann, Detlef; Asmus, Klaus Dieter; Willson, Robin L.
    Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999) (1983), (11), 1661-8CODEN: JCPKBH; ISSN:0300-9580.
    Abs. rate consts. were detd. for the oxidn. of protonated chlorpromazine and promethazine by HO•, Br2•-, (SCN)2•-, I2•-, N3•, Tl2+, Tl(OH)+, (Me3C)2S•+, (MeS)2•+, and lipoate radical cation at pH 2-8. The k values were 3.1 × 108 to 5.5 × 109 mol-1 dm3 s-1 and the yields of dication radical oxidn. products were 28-97%. The reaction with HO• gives a transient adduct. The mechanism of HO•-induced oxidn. of phenothiazines is discussed.
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    Zhang, H.-M.; Ruan, X.-Q.; Guo, Q.-X.; Liu, Y.-C. A study on one-electron oxidation of phenothiazine derivatives by piperidine oxoammonium ion in SDS micelle. Res. Chem. Intermed. 1998, 24, 687,  DOI: 10.1163/156856798X00582
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    A study on one-electron oxidation of phenothiazine derivatives by piperidine oxoammonium ion in SDS micelle
    Zhang, Hai-Ming; Ruan, Xiu-Qin; Guo, Qing-Xiang; Liu, You-Cheng
    Research on Chemical Intermediates (1998), 24 (6), 687-693CODEN: RCINEE; ISSN:0922-6168. (VSP BV)
    N-Substituted phenothiazines were oxidized by 2,2,6,6-tetramethy-4-acetyloxypiperidine oxoammonium hexachloroantimonate (TAPO) to the corresponding radical cations in sodium dodecyl sulfate (SDS) micellar soln. The radical cations of phenothiazine derivs. were generated and stabilized by the anionic micelle in aq. soln. An electron transfer mechanism has been proposed.
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    Domańska, U.; Pelczarska, A.; Pobudkowska, A. Solubility and pKa determination of six structurally related phenothiazines. Int. J. Pharm. 2011, 421, 135,  DOI: 10.1016/j.ijpharm.2011.09.040
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    Solubility and pKa determination of six structurally related phenothiazines
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    International Journal of Pharmaceutics (Amsterdam, Netherlands) (2011), 421 (1), 135-144CODEN: IJPHDE; ISSN:0378-5173. (Elsevier B.V.)
    Solubilities of six structurally related phenothiazines, namely chlorpromazine hydrochloride, fluphenazine dihydrochloride, promazine hydrochloride, thioridazine hydrochloride, trifluoperazine dihydrochloride, and triflupromazine hydrochloride at const. pH were measured at from 290 K to 350 K in three important drugs solvents: water, ethanol and 1-octanol using the dynamic method and UV-vis method. Dissocn. consts. and corresponding pK a values of drugs were obtained with Bates-Schwarzenbach method at temp. 298.15 K in the buffer solns. Our exptl. pK a values for chlorpromazine hydrochloride, fluphenazine dihydrochloride, promazine hydrochloride, thioridazine hydrochloride, trifluoperazine dihydrochloride, and triflupromazine hydrochloride are 9.15, 10.01, 9.37, 8.89, 8.97, and 9.03, resp. The basic thermal properties of pure drugs i.e. melting and solid-solid phase transition as well as glass-transition temps., the enthalpy of melting and phase transitions and the molar heat capacity at glass transition (at const. pressure) were measured with differential scanning microcalorimetry (DSC) technique. Molar volumes were calcd. with Barton group contribution method. The exptl. soly. data were correlated by means of three commonly known G E equations: the Wilson, NRTL and UNIQUAC with the assumption that the systems studied here have revealed simple eutectic mixts. The root-mean-square deviations of temp. were used for the precision of the correlation. The activity coeffs. of drugs at satd. solns. in each correlated binary mixt. were calcd. from the exptl. data. These new data will help in all prediction-methods and their precision.
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    Attwood, D.; Boitard, E.; Dubès, J.-P.; Tachoire, H. Calorimetric study of the influence of electrolyte on the micellisation of phenothiazine drugs in aqueous solution. J. Phys. Chem. B 1997, 101, 9586,  DOI: 10.1021/jp9721863
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    Calorimetric Study of the Influence of Electrolyte on the Micellization of Phenothiazine Drugs in Aqueous Solution
    Attwood, D.; Boitard, E.; Dubes, J.-P.; Tachoire, H.
    Journal of Physical Chemistry B (1997), 101 (46), 9586-9592CODEN: JPCBFK; ISSN:1089-5647. (American Chemical Society)
    Apparent molar enthalpies were detd. as a function of concn. by heat conduction calorimetry for aq. solns. of the phenothiazine drugs chlorpromazine-HCl, promethazine-HCl, and promazine-HCl in the presence of added electrolyte (0.025-0.10 mol dm-3 NaCl). The concn. dependence of the apparent molar enthalpy was quant. described using a mass action model of assocn. based on the Guggenheim equations for the activity coeffs. for mixed electrolytes. Derived values of the monomer-counterion interaction coeff. became increasingly neg. with increase of salt concn., suggesting that electrolyte addn. promoted assocn. at concns. below the crit. micelle concn. (cmc). Calcns. of the fraction of each drug in the form of micelles as a function of concn. further confirmed the tendency for premicellar assocn. Significant differences in properties were obsd. between promethazine and the other two drugs. The micellization of this drug became increasingly exothermic with increase of electrolyte concn., whereas the micellization of both chlorpromazine and promazine became increasingly endothermic. Moreover, the premicellar assocn. of promethazine was more pronounced, the predicted fraction of drug in micellar form at the cmc increasing from 2.6% in water to 65% in 0.1 mol dm-3 NaCl.
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    Attwood, D.; Natarjan, R. Micellar properties of chlorpromazine hydrochloride in concentrated electrolyte solutions. J. Pharm. Pharmacol. 1983, 35, 317,  DOI: 10.1111/j.2042-7158.1983.tb02941.x
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    Micellar properties of chlorpromazine hydrochloride in concentrated electrolyte solutions
    Attwood, D.; Natarajan, R.
    Journal of Pharmacy and Pharmacology (1983), 35 (5), 317-19CODEN: JPPMAB; ISSN:0022-3573.
    The assocn. of chlorpromazine-HCl (I-HCl) [69-09-0] in aq. NaCl solns. (up to 0.6 mol/dm3) was investigated by light scattering techniques. Measurements were made at 303K with a photogoniodiffusometer at 546 nm. At low electrolyte concns., plots of m2/ΔS90 (S = light scattering intensity) against the molality of the micellar species m (where ΔS90 = S90-S90cmc, and cmc = crit. micellar concn.) were linear with pos. slopes. For higher electrolyte concns., such plots are anomolous, with a pronounced increase in the mean size of aggregates with increasing soln. concn. above the cmc. The std. free energy of micellization was calcd. to be 34.4 kJ/mol. Thus, a very pronounced increase in micellar size and polydispersity in high electrolyte concn. was obsd.
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    Attwood, D.; Mosquera, V.; Villar, V. P. Thermodynamic properties of amphiphilic drugs in aqueous solution. J. Chem. Soc., Faraday Trans 1 1989, 85, 3011,  DOI: 10.1039/f19898503011
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    Thermodynamic properties of amphiphilic drugs in aqueous solution
    Attwood, David; Mosquera, Victor; Villar, Vicente Perez
    Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases (1989), 85 (9), 3011-17CODEN: JCFTAR; ISSN:0300-9599.
    Osmotic and activity coeffs. and excess free energies have been derived as functions of concn. from vapor pressure measurements on aq. solns. of the amphiphilic drugs chlorpromazine, promethazine, and imipramine at 308 and 313 K. The concn. dependence of the osmotic coeff. could be described using a mass-action model of assocn. Aggregation nos. and the degree of micellar ionisation have been predicted from the osmotic data and compared with the values derived by time-averaged light-scattering methods. Temp. increased the crit. micelle concn. but had no measurable influence on the aggregation no.
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    Attwood, D.; Waigh, R.; Blundell, R.; Bloor, D.; Thévand, A.; Boitard, E.; Dubès, J.-P.; Tachoire, H. 1H and 13C NMR studies of the self-association of chlorpromazine hydrochloride in aqueous solution. Magn. Reson. Chem. 1994, 32, 468,  DOI: 10.1002/mrc.1260320807
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    1H and 13C NMR studies of the self-association of chlorpromazine hydrochloride in aqueous solution
    Attwood, David; Waigh, Roger; Blundell, Ross; Bloor, Debra; Thevand, Andre; Boitard, Elizabeth; Dubes, Jean-Paul; Tachoire, Henri
    Magnetic Resonance in Chemistry (1994), 32 (8), 468-72CODEN: MRCHEG; ISSN:0749-1581.
    The 1H NMR spectrum of chlorpromazine hydrochloride was fully assigned at 400 MHz. Similarly, the 13C NMR spectrum was assigned unambiguously using two-dimensional NMR. Measurements of chem. shift as a function of concn. in D2O showed appreciable changes of shift of both protons and carbons which were apparent even at soln. concns. two orders of magnitude lower than the crit. micelle concn. (CMC). The relative magnitude of the shifts of the arom. protons and carbons on diln. below the CMC were compatible with vertical stacking of the mols. in an off-set manner such that max. overlap of the chlorinated rings occurred. Proton chem. shift data were interpreted using a stepwise assocn. model to quantify the extent of assocn. in the pre-CMC region.
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    Pérez-Rodríguez, M.; Varela, L. M.; Taboada, P.; Attwood, D.; Mosquera, V. The temperature dependence of the micellisation of chlorpromazine hydrochloride in aqueous solution. Colloid Polym. Sci. 2000, 278, 706,  DOI: 10.1007/s003960000331
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    The temperature dependence of the micellization of chlorpromazine hydrochloride in aqueous solution
    Perez-Rodriguez, M.; Varela, L. M.; Taboada, P.; Attwood, D.; Mosquera, V.
    Colloid and Polymer Science (2000), 278 (7), 706-709CODEN: CPMSB6; ISSN:0303-402X. (Springer-Verlag)
    The assocn. characteristics of the weakly assocg. drug chlorpromazine-HCl were examd. over the temp. range 10-35° by means of conductometric measurements. Crit. micelle concns. (cmc) have been detd. by the application of a recently developed numerical method esp. designed for the anal. of the assocn. pattern in highly polydisperse systems of low aggregation no. The cmcs detd. in this manner are used in combination with the mass-action model to obtain the thermodn. parameters of the micellization process, in particular the surface and hydrophobic contributions to the free energy. The use of exact forms of equations for the thermodn. of micellization applicable to systems of low aggregation no. leads to values of the enthalpy of micellization in reasonable agreement with exptl. detd. values.
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    Attwood, D.; Mosquera, V.; Novas, L.; Sarmiento, F. Micellisation in binary mixtures of amphiphilic drugs. J. Colloid Interface Sci. 1996, 179, 478,  DOI: 10.1006/jcis.1996.0240
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    Micellization in binary mixtures of amphiphilic drugs
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    Journal of Colloid and Interface Science (1996), 179 (2), 478-481CODEN: JCISA5; ISSN:0021-9797. (Academic)
    The compn. of the micelles in binary mixts. of the cationic amphiphilic drugs (a) chloropromazine and promethazine and (b) chloropromazine and adiphenine has been detd. from an anal. of the variation of the crit. micelle concn., as measured by cond. techniques, as a function of soln. compn. Evaluation of the nonideality of mixing of the components of the mixed micelles using a regular soln. approxn. revealed ideality of mixing in the chlorpromazine/promethazine system. Mixing in the chlorpromazine/adiphenine system did not deviate significantly from ideality despite differences in the structure and packing characteristics of these two drugs.
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    Attwood, D.; Florence, A. T.; Gillan, J. M. N. Micellar properties of drugs: properties of micellar aggregates of phenothiazines and their aqueous solutions. J. Pharm. Sci. 1974, 63, 988,  DOI: 10.1002/jps.2600630649
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    Attwood, D.; Florence, A. T.; Gilla, J. M. N.
    Journal of Pharmaceutical Sciences (1974), 63 (6), 988-93CODEN: JPMSAE; ISSN:0022-3549.
    The soln. properties of a series of phenothiazine hydrochlorides were studied using light-scattering, viscosity, conductivity, dialysis, and NMR techniques. The aggregates formed are considered to be true micelles, which in water are probably composed of about 10 monomers vertically stacked, with the alkyl side chain and nitrogen group alternating to form an approx. spherical unit in soln. In the presence of NaCl the micelles grow and it is thought that the conformation of the aggregate also changes. Calcns. of the monomer concn. as a function of total drug concn. above the CMC's give good agreement with data obtained previously from NMR shift data. The free energy of inserting a monomer into a micelle was calcd.and the values obtained are discussed in the light of free energies of soln. of the hydrophobic bases. The significance of aggregation, mixed micelle formation, and complexation in biol. and pharmaceutical systems contg. phenothiazines is discussed.
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    Attwood, D.; Mosquera, V.; Rey, C.; Vasquez, E. Self-association of amphiphilic phenothiazine drugs in aqueous solutions of low ionic strength. J. Chem. Soc., Faraday Trans. 1991, 87, 2971,  DOI: 10.1039/ft9918702971
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    Self-association of amphiphilic phenothiazine drugs in aqueous solutions of low ionic strength
    Attwood, David; Mosquera, Victor; Rey, Carlos; Vasquez, Esperanza
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    Osmotic coeffs. have been derived from freezing pont detns. on aq. solns. of the amphiphilic drugs, chlorpromazine and promethazine-HCl, in the presence of low concns. of added electrolyte (0.01-0.05 mol kg-1 NaCl). Aggregation nos. predicted by the application of a mass action theory to the osmotic data were in agreement with exptl. values detd. by time-averaged light scattering methods.
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    Attwood, D.; Dickinson, N. A.; Mosquera, V.; Villar, V. P. Osmotic and activity coefficients of amphiphilic drugs in aqueous solution. J. Phys. Chem. E 1987, 91, 4203,  DOI: 10.1021/j100299a050
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    Osmotic and activity coefficients of amphiphilic drugs in aqueous solution
    Attwood, D.; Dickinson, N. A.; Mosquera, V.; Villar, V. Perez
    Journal of Physical Chemistry (1987), 91 (15), 4203-6CODEN: JPCHAX; ISSN:0022-3654.
    Osmotic and activity coeffs. were derived from vapor-pressure measurements on aq. solns. of the amphiphilic drugs promethazine-HCl, chlorpromazine-HCl, clomipramine-HCl, and imipramine-HCl. A mass action model of assocn., based on the Guggenheim equations for the activity coeffs. of mixed electrolyte solns. as proposed by Burchfield and Wooley (1984), quant. described the concn. dependence of the osmotic coeff. for molalities up to 0.25 mol kg-1.
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    Ruso, J. M.; Attwood, D.; Taboada, P.; Suárez, M. J.; Sarmiento, F.; Mosquera, V. Activity and osmotic coefficients of promethazine and chlorpromazine hydrochlorides in aqueous solutions of low ionic strength. J. Chem. Eng. Data 1999, 44, 941,  DOI: 10.1021/je990001a
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    Activity and Osmotic Coefficients of Promethazine and Chlorpromazine Hydrochlorides in Aqueous Solutions of Low Ionic Strength
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    Journal of Chemical and Engineering Data (1999), 44 (5), 941-943CODEN: JCEAAX; ISSN:0021-9568. (American Chemical Society)
    Osmotic and activity coeffs. of amphiphilic drugs chlorpromazine hydrochloride and promethazine hydrochloride in aq. solns. have been derived from vapor pressure measurements, in the presence of low concns. of added electrolyte (0.000, 0.010, 0.025, and 0.050 mol kg-1 NaCl) at the temp. 303.15 K. From these results an inflection point was detected for both phenothiazine drugs identified as a crit. concn.
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    Perez-Villar, V.; Vazquez-Iglesias, M. E.; de Geyer, A. Small-angle neutron scattering studies of chlorpromazine micelles in aqueous solutions. J. Phys. Chem. F 1993, 97, 5149,  DOI: 10.1021/j100121a050
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    Small-angle neutron scattering studies of chlorpromazine micelles in aqueous solutions
    Perez-Villar, V.; Vazquez-Iglesias, M. E.; de Geyer, A.
    Journal of Physical Chemistry (1993), 97 (19), 5149-54CODEN: JPCHAX; ISSN:0022-3654.
    Small-angle neutron scattering (SANS) data for aq. (D2O) solns. of chlorpromazine hydrochloride (with and without added 0.025 m NaCl) are analyzed. This tranquilizing drug (based on the phenothiazine ring system) gives ionic micellar solns. characterized by pronounced interparticle correlations which result from a strong electrostatic interaction between the macroions. The model for fitting SANS data takes into account the effect of size polydispersity on the intensity distribution function I(Q) and computes the intermicellar structure factor by using the generalized 1-component macroion theory, solving the Orstein-Zernike equation in the rescaled mean spherical approxn., and considering a screened Coulomb interparticle interaction potential between micelles, following the procedure of J. Hayter and J. Penfold (1981). The SANS data fittings for different concns. allow one to obtain some structural and thermodynamical parameters (e.g., free energies of formation and growth, min. aggregation nos., polydispersity index).
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    Study of the Cloud Point of the Phenothiazine Drug Chlorpromazine Hydrochloride: Effect of Surfactants and Polymers
    Alam, Md. Sayem; Naqvi, Andleeb Z.; Kabir-ud-Din
    Journal of Dispersion Science and Technology (2008), 29 (2), 274-279CODEN: JDTEDS; ISSN:0193-2691. (Taylor & Francis, Inc.)
    Surfactants/polymers are used extensively in drug delivery as drug carriers. The authors herein report the effect of surfactants and polymers on the cloud point (CP) of amphiphilic drug chlorpromazine hydrochloride. At fixed drug concn. (50 mM) and pH (6.7) these additives affect the CP in accordance to their nature and structure: anionic surfactants show an increase followed by a decrease, whereas cationic (conventional as well as gemini) and nonionic surfactants show continuous increase. The behavior with polymers is dictated by the no. of units present in a particular polymer. Increase in drug concn. and pH, in presence of fixed amts. of CTAB, increases and decreases the CP, resp. Variation of CP with pH at various fixed gemini concns. shows that gemini surfactants are better candidates for drug delivery.
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  54. 54
    Dea, P. K.; Keyzer, H. Conformation and Electronic Aspects of Chlorpromazine in Solution. In Modern Bioelectrochemistry; Gutman, F.; Keyzer, H., Eds.; Plenum Press: New York, 1986; p 481.
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    Atherton, A. D.; Barry, B. W. Micellar properties of phenothiazine drugs: a laser light scattering study. J. Colloid Interface Sci. 1985, 106, 479,  DOI: 10.1016/S0021-9797(85)80023-0
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    Micellar properties of phenothiazine drugs: a laser light scattering study
    Atherton, A. Dianne; Barry, Brian W.
    Journal of Colloid and Interface Science (1985), 106 (2), 479-89CODEN: JCISA5; ISSN:0021-9797.
    Photon-correlation spectroscopy was used to examine the effects of drug and electrolyte concn. and 0.154M Na halide, sulfate, and phosphate upon phenothiazine-HCl salts crit. micelle concns. (CMCs) and micellar sizes, Rh, for promazine-HCl [53-60-1], chlorpromazine-HCl [69-09-0], promethazine-HCl [58-33-3], triflupromazine-HCl [1098-60-8], and thioridazine-HCl [130-61-0]. Rh Values were sensitive to drug and electrolyte concn. Interpretation of the data at low electrolyte concn. was complicated by micellar interactions. In increasing NaCl concns. CMCs decreased and micellar sizes increased markedly leading to phase sepn. in triflupromazine and chlorpromazine solns. Micellar size increased in electrolyte solns. in the order F < Cl < Br < SO4. Complexes formed in iodide and phosphate solns. A mode of aggregation by stacking is proposed, with sizes increasing by addn. of single monomers to the stacks and by addn. of more stacks until phase sepn. occurs.
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    Barbosa, L. R. S.; Caetano, W.; Itri, R.; de Mello, P. H.; Santiago, P. S.; Tabak, M. Interaction of phenothiazine compounds with zwitterionic lysophosphatidylcholine micelles: small angle X-ray scattering, electronic absorption spectroscopy and theoretical calculations. J. Phys. Chem. B 2006, 110, 13086,  DOI: 10.1021/jp056486t
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    56
    Interaction of Phenothiazine Compounds with Zwitterionic Lysophosphatidylcholine Micelles: Small Angle X-ray Scattering, Electronic Absorption Spectroscopy, and Theoretical Calculations
    Barbosa, Leandro R. S.; Caetano, Wilker; Itri, Rosangela; Homem-de-Mello, Paula; Santiago, Patricia S.; Tabak, Marcel
    Journal of Physical Chemistry B (2006), 110 (26), 13086-13093CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
    Small-angle x-ray scattering (SAXS) studies on the interaction of the phenothiazine cationic compds. trifluoperazine (TFP, 2-10 mM) and chlorpromazine (CPZ, 2-10 mM) with micelles of the zwitterionic surfactant L-α-lysophosphatidylcholine (LPC, 30 mM), at pHs 4.0 and 7.0, are reported. The SAXS results demonstrate that, upon addn. of both phenothiazines, the LPC micelle of prolate ellipsoidal shape changes into a cylindrically shaped micelle, increasing its axial ratio from 1.6 ± 0.1 (in the absence of drug) to 2.5 ± 0.1 (for 5 and 10 mM of phenothiazine). Such an effect is accompanied by a shrinking of the paraffinic shortest semiaxis from 22.5 ± 0.3 to 20.0 ± 0.5 Å. Besides, a significant increase in polar shell electron d. from 0.39(1) to 0.45(1) e/Å3 is obsd., consistent with cylinder-like aggregate geometry. Also, an increase of the phenothiazine concn. induces the appearance of a repulsive interference function over the SAXS curve of zwitterionic micelles, which is typical of interaction between surface-charged micelles. Such a finding provides evidence that the pos. charged phenothiazine mol. must be accommodated near the hydrophobic/hydrophilic inner micellar interface in such a way that a net surface charge is altered with respect to the original overall neutral zwitterionic micelle. Such phenothiazine location is favored by both electrostatic and hydrophobic contributions, giving rise to binding const. values, obtained from electronic absorption results, that are quite larger compared to their binding to another zwitterionic surfactant, 3-(N-hexadecyl-N,N-dimethylammonio)propanesulfonate (HPS) (Caetano, W., et al. J. Colloid Int. Sci. 2003, 260, 414-422). Comparisons are made by theor. calcns. of the surfactant headgroup dipole moments for monomers of LPC and HPS. The theor. results show that the dipole moment in LPC is almost perpendicular to the methylene chain, while a significant contribution along the methylene chain occurs for HPS. Besides, evidence is presented for extensive delocalization of the charges in the headgroups, which could be also relevant for the binding of the drugs.
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    Numerous studies have reported the voltammetry or redox transformation of N-substituted phenothiazine derivatives, as given in references 58-67.
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    Horn, J. J.; McCreedy, T.; Wadhawan, J. Amperometric measurement of gaseous hydrogen sulphide via a Clark-type approach. Anal. Methods 2010, 2, 1346,  DOI: 10.1039/c0ay00338g
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    Amperometric measurement of gaseous hydrogen sulfide via a Clark-type approach
    Horn, Jason J.; McCreedy, Tom; Wadhawan, Jay
    Analytical Methods (2010), 2 (9), 1346-1354CODEN: AMNEGX; ISSN:1759-9679. (Royal Society of Chemistry)
    The direct oxidn. of hydrogen sulfide in the range 2.0-20 ppm by vol. (ppmv) using a Clark-type amperometric gas sensing methodol. is investigated via amperometric transients at 298 K. The diluent gas employed is air (20.9% O2 in N2), and it is shown that the obsd. current transients are limited by transport through the membrane covering, reaching a steady-state value within at least 200 s for one of the manifestations described. The measurement system presented is shown to be operational over a long time (tens of hours), provided certain quantification protocols are employed; the latter are suggested as pragmatic guidelines for the deployment of this detection methodol. Importantly and notably, it is shown that readily-oxidizable gases such as carbon monoxide and mol. hydrogen are obsd. not to interfere with the measurement quantification.
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    Huie, R. E.; Neta, P. Reaction of the vanadate ion with chlorpromazine and the chlorpromazine free radical with the vanadyl ion. Inorg. Chim. Acta 1984, 93, L27,  DOI: 10.1016/S0020-1693(00)87887-1
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    Reaction of the vanadate ion with chlorpromazine and the chlorpromazine free radical with the vanadyl ion
    Huie, Robert E.; Neta, P.
    Inorganica Chimica Acta (1984), 93 (2), L27-L28CODEN: ICHAA3; ISSN:0020-1693.
    The reaction V(V) + ClPz ↹ V(IV) + ClPz+· (ClPz = chlorpromazine) was studied by stopped-flow spectrometry and pulsed radiolysis methods. Oxidn. occurs at pH > 4. The forward and reverse rate consts. are given.
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    Roseboom, H.; Perrin, J. H. Oxidation kinetics of phenothiazine and 10-methylphenothiazine in acidic medium. J. Pharm. Sci. 1977, 66, 1392,  DOI: 10.1002/jps.2600661010
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    Oxidation kinetics of phenothiazine and 10-methylphenothiazine in acidic medium
    Roseboom, H.; Perrin, J. H.
    Journal of Pharmaceutical Sciences (1977), 66 (10), 1392-5CODEN: JPMSAE; ISSN:0022-3549.
    The rate of phenothiazine degrdn. in an acidic oxygen-satd. medium was studied. 3H-phenothiazin-3-one and phenothiazine 5-oxide are produced by parallel reactions, and 7-(10'-phenothiazinyl)-3H-phenothiazine-3-one is produced in a more complex manner. The overall phenothiazine degrdn. rate appears to be pH independent up to pH 7.0. The degrdn. kinetics of 10-methylphenothiazine were studied after isolation and identification of its degrdn. products, 10-methylphenothiazine 5-oxide and 3H-phenothiazine-3-one. The main degrdn. product is 10-methylphenothiazine 5-oxide; but at low pH values and high temps., more 3H-phenothiazine-3-one is formed. The degrdn. rate of 10-methylphenothiazine is pH independent up to pH 7.
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    Karpińska, J.; Starczewska, B.; Puzanowska-Tarasiewicz, H. Analytical properties of 2- and 10-disubsituted phenothiazine derivatives. Anal. Sci. 1996, 12, 161,  DOI: 10.2116/analsci.12.161
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    Analytical properties of 2- and 10-disubstituted phenothiazine derivatives
    Karpinska, J.; Starczewska, B.; Puzanowska-Tarasiewicz, H.
    Analytical Sciences (1996), 12 (2), 161-70CODEN: ANSCEN; ISSN:0910-6340. (Japan Society for Analytical Chemistry)
    A review with 74 refs. Phenothiazine derivs. substituted in the 2 and 10 positions belong to a big group of tricyclic arom. compds. They are in extensive use in psychiatry as tranquilizers and neuroleptics. Due to their characteristic structure they exhibit many valuable anal. properties. They are easily oxidized in an acidic medium while generating color products. They also react with some thiocyanate and halide complexes of metals as well as some org. compds., and form well-defined ion-assocn. complexes. The properties mentioned above are the basis for using the phenothiazine derivs. as reagents for chem. anal. The phys. and chem. properties of 2,10-disubstituted phenothiazine derivs. are described in the presented paper. The paper is divided into seven parts. The 1st chapter presents the phys. properties of the phenothiazine derivs., such as their phys. state, thermal stability and soly. The next part of the paper is devoted to the spectral properties of 2,10-disubstituted phenothiazine derivs. The influence of the type of substituents on the intensity and shape of the UV and fluorescence spectra of phenothiazine derivs. are discussed. Chapters 4 and 5 show the run and the mechanism of phenothiazine derivs. oxidn., their electrochem. properties and the anal. aspects of the described processes. Chapter 6 of the present paper is devoted to the complexing abilities of the phenothiazine derivs. The paper is based on a review of the chem. literature up to 1995. A short specification of the anal. methods using the phys. and chem. properties of the phenothiazine derivs. is also included.
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    Cauquis, G.; Deronzier, A.; Lepage, J.-L.; Serve, D. Une nouvelle étude de l′oxydation électrochimique dy noyau phénothiazinique I: cas de la phénothiazine et de ses derives disubstitués en 3 et 7. Bull. Soc. Chim. Fr. 1977, 295
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    A new study of the electrochemical oxidation of the phenothiazine ring. I. The case of phenothiazine and its 3 and 7 disubstituted derivatives
    Cauquis, Georges; Deronzier, Alain; Lepage, Jean Luc; Serve, Denis
    Bulletin de la Societe Chimique de France (1977), (3-4, Pt. 2), 295-302CODEN: BSCFAS; ISSN:0037-8968.
    The anodic processes of some 3,7-disubstituted phenothiazines and of N-methylphenothiazine [1207-72-3] in various acidic and alk. media in MeCN were studied. Depending on the medium, the oxidn. of the N-unsubstituted phenothiazines, which enclose the NH group, allows one to observe as a rule 6 species. In alk. medium, a 1-electron transfer results in the neutral free radical which, in some cases, dimerizes to give just the 1,10'- and 3,10'-biphenothiazinyls. The other species produced in acidic media are sufficiently stable to be unambiguously characterized. The oxidn. mechanism which is an EEC one in acidic media becomes progressively an ECE and a CEE one when increasing the basicity. The N-methylphenothiazine gives the sulfoxide through the radical cation. This sulfoxide is also oxidized to give the disulfoxide of a biphenothiazinyl.
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    Cauquis, G.; Deronzier, A.; Lepage, J.-L.; Serve, D. Une nouvelle étude de l′oxydation électrochimique dy noyau phénothiazinique II: cas de quelques biphénothiazinyles-1,10′ et −3,10′. Bull. Soc. Chim. Fr. 1977, 303
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    A new study of the electrochemical oxidation of the phenothiazine ring. II. The case of some 1,10- and 3,10'-biphenothiazinyls
    Cauquis, Georges; Deronzier, Alain; Lepage, Jean Luc; Serve, Denis
    Bulletin de la Societe Chimique de France (1977), (3-4, Pt. 2), 303-9CODEN: BSCFAS; ISSN:0037-8968.
    Neutral radicals produced from the anodic oxidn. of various phenothiazines dimerize into 3,10'- and 1,10'-biphenothiazinyls. These compds. are models of mols. with 2 electroactive centers included in resonant systems which have various levels of conjugation. Their anodic oxidn. in MeCN allows one to characterize the diverse cationic and/or new radical species and also to show the influence that conjugation of the 2 phenothiazine entities has on the spectroscopic properties of these species and on the electrochem. processes. The various mechanisms leading to these species are described.
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    Billon, J.-P. Etude électrochimique des propriétés oxydo-réductrices des phénothiazines dans l′acétonitrile. Ann. Chim. 1962, 7, 183
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    Electrochemistry of the oxidation-reduction properties of phenothiazines in acetonitrile
    Billon, Jean Pierre
    (1962), 7 (), 183-206 ISSN:.
    cf. CA 55, 15183f. Potentiometric curves of phenothiazine (I) and some of its derivs. in MeCN (generally contg. 0.1M HClO4) were detd. by using a rotating bright Pt electrode and LiClO4 as inert electrolyte. In general, oxidn. occurred more readily at high pH. I was reversibly oxidized in 2 steps to give the free radical II (unstable in alk. media; perchlorate obtained from 0.24 g. I, 0.26 g. S-hydroxyphenothiazine, and 10 ml. 65% HClO4, green crystals, orange in MeCN, decomp. 175°) and the phenazothionium salt (III) [red-violet crystals, obtained also from 0.5 g. 9-hydroxyphenothiazine (IV) and 10 cc. 65% HClO4]. NaOH and III gave IV. On addn. of 0.4-6% H2O to the solvent during the electrochem. oxidn. of I, the 2nd step occurred at a lower potential. H2O reacted with III to give a green compd. (V) (λ 650, 625, 455 mμ). On addn. of 7% H2O, the electrochem. oxidn. of I gave V only. A soln. of II in neutral media gave V and I on addn. of H2O. Addn. of H2O to III gave V. Attempted purification of V by chromatography on Al2O3 gave 2-phenothiazone (VI) and a blue product (λ 660 mμ). On increasing the HClO4 concn. in the electrochem. oxidn. of I from 10-2 to 10-1M, the 2nd stage occurred at a lower potential. Addn. of a base (diphenylguanidine) in the electrochem. oxidn. of I facilitated oxidn. of II to III, but a no. of side reactions occurred. The presence of a Me in the lateral rings of I facilitated the electrochem. oxidn. II could oxidize chem. all these derivs. (free radicals and phenazothionium salts). The phenazothionium cations of the 2- and 3-Me derivs. gave with H2O green products; the disubstituted cation was stable to H2O, but with strong bases gave a colorless sulfoxide deriv. 10-Methylphenothiazine and 2,7,10-trimethylphenothiazine (VII) were more difficultly oxidized electrochem. than the corresponding compds. not contg. the N-Me group. An electrochem. study of oxidn. of the N-Me compds. (or of chlorpromazine) showed that the 1st step gave the colored free radical, but the 2nd step gave the sulfoxide deriv. (VIII). The expected orthoquinone bivalent cation (IX) was formed, in the electrochem. oxidn. of VII in the presence of only 0.002% H2O, as an intermediate that later reacted with H2O to give the sulfoxide. The influence of substituents on the oxidn. potential of X was studied for the following compds. [R, R1, and R2 given, where A = (CH2)3NMe2, B = CH2CHMeCH2NMe2, and C = 3-(4-methyl-1-piperazinyl)propyl]: OEt, H, A; OMe, H, B; OMe, H, A; H, OMe, A; Me, H, A; Et, H, A; H, H, A; SMe, H, B; H, Cl, A; Cl, H, A; Cl, H, C; COMe, H, A; CHO, H, C; COPr, H, C; CF3, H, A; SO2NMe2, H, A; SO2NMe2, H, C; CN, H, A; SO2Me, H, C; and NO2, H, A. VI in acid media in MeCN gave 1st a purple free radical and then 2-hydroxyphenothiazine (XI). Addn. of acid caused a color change from red to purple; this was due to the formation of a 2-hydroxyphenazothionium ion. This change was reversible. In acid or neutral media XI was directly oxidized to the phenazothionium salt, which was converted to VI by action of a base. In many cases the results were confirmed by studies of the ultraviolet and visible spectra and of electron paramagnetic resonance.
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    Humphry-Baker, R.; Braun, A. M.; Grätzel, M. Effect of self-assembly of amphiphilic redox chromophores on photoionisation processes. Helv. Chim. Acta 1981, 64, 2036,  DOI: 10.1002/hlca.19810640708
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    Effect of self-assembly of amphiphilic redox-chromophores on photoionization processes
    Humphry-Baker, Robin; Braun, Andre M.; Graetzel, Michael
    Helvetica Chimica Acta (1981), 64 (7), 2036-47CODEN: HCACAV; ISSN:0018-019X.
    The photochem. behavior of Na 12-(10-phenothiazinyl)dodecyl-1-sulfonate underwent change upon micellization. In particular, monophotonic photoionization was obsd. only above the crit. micelle concn. The net effect of micelle formation was to enhance the cation yield and to decrease the yield of triplets obsd. The results were explained in terms of local electrostatic barriers within the micelle.
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    Grätzel, M. Interfacial Charge Transfer Reactions in Colloidal Dispersions and Their Application to Water Cleavage by Visible Light. In Modern Aspects of Electrochemistry; Plenum Press: New York, 1983; Vol. 15, p 83.
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    Krieg, M.; Pileni, M.-P.; Braun, A. M.; Grätzel, M. Micelle formation and surface activity of functional redox relays: viologens substituted by a long alkyl chain. J. Colloid Interface Sci. 1981, 83, 209,  DOI: 10.1016/0021-9797(81)90025-4
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    Micelle formation and surface activity of functional redox relays: viologens substituted by a long alkyl chain
    Krieg, Marianne; Pileni, Marie Paule; Braun, Andre M.; Graetzel, Michael
    Journal of Colloid and Interface Science (1981), 83 (1), 209-13CODEN: JCISA5; ISSN:0021-9797.
    Suitable mol. organizates are being developed for efficient and simultaneous prodn. of H and O from H2O under illumination with visible light. The crit. micelle concn. of surface-active asym. substituted alkyl viologens was detd. by surface-tension measurements and spectroscopic investigations.
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    Rusling, J. F. Electrochemistry in Micelles and Microemulsions. In Interfacial Kinetics and Mass Transport; Calvo, E. J., Ed.; Wiley: Weinheim, 2003; Vol. 2, p 418.
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    Gooding, J. J.; Compton, R. G.; Brennan, C. M.; Atherton, J. H. A new electrochemical method for the investigation of the aggregation of dyes in solution. Electroanalysis 1997, 9, 759,  DOI: 10.1002/elan.1140091006
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    A new electrochemical method for the investigation of the aggregation of dyes in solution
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    Electroanalysis (1997), 9 (10), 759-764CODEN: ELANEU; ISSN:1040-0397. (Wiley-VCH)
    A new electrochem. technique is presented for the investigation of aggregation phenomena in soln. over a wide range of soln. conditions. Developed nominally for dyes, the method is, in principle, applicable to any electroactive compd. The method employs microelectrodes to measure the change in the diffusion-limited current, with concn., of the aggregating species of interest. At the onset of aggregation, the relationship between this limiting current and concn. deviates from linearity. This deviation, due to the slower rate of diffusion of aggregates, is related to the degree of assocn. of the mol., assuming a mol. wt. distribution of aggregates and using an established relationship between the effective diffusion coeff. and mol. wt. The technique is contrasted with an existing spectroscopic method.
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    Anicet, N.; Bourdillon, C.; Demaille, C.; Moiroux, J.; Savéant, J.-M. Catalysis of the electrochemical oxidation of glucose by glucose oxidase and a single electron co-substrate: kinetics in viscous solutions. J. Electroanal. Chem. 1996, 410, 199,  DOI: 10.1016/0022-0728(96)04558-5
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    Catalysis of the electrochemical oxidation of glucose by glucose oxidase and a single electron cosubstrate: kinetics in viscous solutions
    Anicet, Nathalie; Bourdillon, Christian; Demaille, Christophe; Moiroux, Jacques; Saveant, Jean-Michel
    Journal of Electroanalytical Chemistry (1996), 410 (2), 199-202CODEN: JECHES ISSN:. (Elsevier)
    Catalysis of the electrochem. oxidn. of glucose by glucose oxidase with a single electron mediator (cosubstrate) may be used to transform mixts. of concd. industrial sugars. How the high viscosity of such media may affect the enzymic reaction and the transport of the mediator can be mimicked by addn. of large concns. of sucrose to glucose solns. Cyclic voltammetry then provides a simple means of investigating the effect of an increased viscosity on the kinetics of the enzymic reaction and the diffusion of the mediator. The diffusion coeff. of the mediator is decreased 10 times by addn. of 1.6 M sucrose. At pH 8, in the presence of the same concn. of sucrose, the catalytic activity of the enzyme towards its substrate is only slightly affected. A 35% decrease of the glucose Michaelis const. is obsd. The reaction of the reduced enzyme with the cosubstrate is six times slower and the mediator Michaelis const. undergoes a three-fold increase. It follows that glucose oxidase remains an efficient catalyst in such viscous media.
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    Halls, J. E.; Wadhawan, J. D. Photogalvanic cells based on lyotropic nanosystems: towards the use of liquid nanotechnology for personalised energy sources. Energy Environ. Sci. 2012, 5, 6541,  DOI: 10.1039/c2ee03169h
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    Photogalvanic cells based on lyotropic nanosystems: towards the use of liquid nanotechnology for personalised energy sources
    Halls, Jonathan E.; Wadhawan, Jay D.
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    A lightwt., autonomous and practical, proof-of-concept elec. power source is developed within this work. It comprises a photoredox-active material embedded within the non-ionic surfactant subphase, with a second redox reagent present within the aq. pseudophase of a lamellar (Lα) lyotropic liq. crystal framework, which is sandwiched between two electrodes, one of which acts in a sacrificial manner. This quasi-biphasic, entirely new-concept, electrochem. cell, based on electron transfer, rather than ion transfer, is shown to act as a photogalvanic device which, under violet light, is demonstrated to exhibit max. light-to-elec. power conversion efficiency of ca. 2% (fill factor of 15%), with addnl. ability to act as an elec.-rechargeable electrochem. capacitor of voltage efficiency ∼85% and power efficiency ∼80%, and with estd. max. energy d. of ∼1 W h kg-1 at a power d. of ∼1 kW kg-1.
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  1. David L. O. Ramos, Robert D. Crapnell, Ridho Asra, Elena Bernalte, Ana C. M. Oliveira, Rodrigo A. A. Muñoz, Eduardo M. Richter, Alan M. Jones, Craig E. Banks. Conductive Polypropylene Additive Manufacturing Feedstock: Application to Aqueous Electroanalysis and Unlocking Nonaqueous Electrochemistry and Electrosynthesis. ACS Applied Materials & Interfaces 2024, 16 (41) , 56006-56018. https://doi.org/10.1021/acsami.4c12967
  2. Francisco Martinez-Rojas, Christian Espinosa-Bustos, Galo Ramirez, Francisco Armijo. Electrochemical oxidation of chlorpromazine, characterisation of products by mass spectroscopy and determination in pharmaceutical samples. Electrochimica Acta 2023, 443 , 141873. https://doi.org/10.1016/j.electacta.2023.141873
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  • Abstract

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    Figure 1

    Figure 1. (a) Structure of chlorpromazine hydrochloride in planar (left) and quasi-equatorial (right) conformations. The latter has been drawn to emphasize the boat conformation of the central six-ring. (b) Transmission electron micrograph of chlorpromazine hydrochloride aggregates obtained in an aqueous solution comprising 13.1 mM chlorpromazine hydrochloride and 36.0 mM zinc chloride. The scale bar corresponds to 50 nm.

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    Figure 2

    Figure 2. (a) Cyclic voltammograms (fourth scan from a series of four cycles illustrated) for the oxidation of 1.0  mM chlorpromazine hydrochloride in aqueous 0.1  M aqueous potassium chloride solution, recorded using a 3.0  mm diameter glassy carbon working electrode swept at a rate of 0.1 V  s–1  (green), 0.5  V  s–1 (black), 1.0  V  s–1 (blue), and 2.0 V  s–1  (red) . (b) Variation of the voltammetric peak potentials (from the first scan) with experimental timescale at various concentrations of chlorpromazine hydrochloride: 1.0  mM (red circles), 10  mM (blue squares), 100  mM (black diamonds); open symbols refer to the oxidative peak, with filled symbols corresponding to the re-reductive peak. Data points are plotted as the average over two measurements, with error bars indicating one standard deviation. (c) Variation of the diffusion coefficient, D, (left) and aqueous solution (0.1  M KCl) viscosity, η (right), with chlorpromazine hydrochloride concentration (c0). For the left panel, the aqueous solution was 0.1  M KCl (green diamonds and blue squares as an internal laboratory repeat), pH  4 acetate buffer with 0.1  M KCl (magenta triangles), from cyclic voltammetric measurements at a 3.0  mm glassy carbon electrode, and 0.1  M KCl using steady-state currents at a 5.5  mm ×  4.5  mm platinum channel flow electrode (red circles). The black line is the average of all of the data illustrated, with the error bar representing one standard deviation.

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    Figure 3

    Figure 3. (a) Polarizing microscope images (under crossed-polarizers) of the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol kg–1, freshly prepared (left, magnification × 100) and after 4 months of standing in light and air (middle). Note that in the latter image, a part of the slide outside the cover plate was imaged so as to illustrate the contrast. The image on the right-hand side illustrates the formation of the oxidized material (red-pink) on top of the un-oxidized material (yellow). (b) UV–visible absorption spectrum of the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol  kg–1. (c) Rheological properties of the chlorpromazine hydrochloride/water system at various chlorpromazine hydrochloride molalities (m0): left, viscosity (η) as a function of molality; right, basic shear diagram affording plastic viscosities of 201.2, 306.6, and 499.7  P, and Bingham yields of 30.9, 45.3, and 53.1  Pa for m0  =  7.5, 10.0, and 12.5  mol  kg–1, respectively. (d) X-ray scattering patterns obtained from the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol  kg–1. The primary beam is not shown.

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    Figure 4

    Figure 4. Microelectrode voltammetry of the Lα phase of chlorpromazine hydrochloride in water at 10.0  mol  kg–1 at an 11 μm diameter carbon microelectrode. The main image is the variation of the peak potentials with experimental timescale (the error bars correspond to one standard deviation), with peripheral images illustrating four consecutive cycles in the voltammetry at 500, 100, 20, 10, 5, 1, and 0.5  mV  s–1. In these images, the first cycle is shown in red, with the subsequent cycles being first in blue, then green, and finally black.

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  • References

    This article references 85 other publications.

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      Evans, D. H.; O’Connell, K. M. Conformational Change and Isomerisation Associated with Electrode Reactions. In Electroanalytical Chemistry; Bard, A. J., Ed.; Marcel Dekker: New York, 1986; Vol. 14, p 113.
      There is no corresponding record for this reference.
    2. 2

      See, for example

      Pombeiro, A. J. L.; da Silva, M. F. C. G. Bond and Structure Activation by Anodic Electron Transfer: Metal-Hydrogen Bond Cleavage and cis/trans Isomerisation in Co-ordination Compounds. In Trends in Molecular Electrochemistry; Pombeiro, A. J. L.; Amatore, C., Eds.; Marcel Dekker: New York, 2004; p 153.
      There is no corresponding record for this reference.
    3. 3
      Hale, J. M. The Rates of Reactions Involving Only Electron Transfer, at Metal Electrodes. In Reactions of Molecules at Electrodes; Hush, N. S., Ed.; John Wiley: London, 1971; p 229.
      There is no corresponding record for this reference.
    4. 4
      Allendoerfer, R. D.; Reiger, P. H. Electrolytic reduction of cyclooctatetraene. J. Am. Chem. Soc. 1965, 87, 2336,  DOI: 10.1021/ja01089a006
      4
      Electrolytic reduction of cyclooctatetraene
      Allendoerfer, Robert D.; Rieger, Philip H.
      Journal of the American Chemical Society (1965), 87 (11), 2336-44CODEN: JACSAT; ISSN:0002-7863.
      The redn. of cyclooctatetraene was studied in HCONMe2 and Me2SO by d.c. polarography, triangular wave oscillopolarography, and a.c. polarography. Cyclooctatetraene is reduced in 2 1-electron steps. Previous expts. (Hoijtink, et al., CA 50, 14412h) in which the anion radical was found to disproportionate were explained on the basis of reactions of the cyclooctatetraene dianion with alkali metal ions to form tightly bound complexes or with H2O to form cyclooctatrienes. The E.S.P. spectrum of cyclooctatetraene anion radicals, produced by controlled-potential electrolysis in HCONMe2, was virtually identical with previous results. The 1st electron transfer to cyclooctatetraene was slow and proceeded through a transition state which resembles planar cyclooctatetraene. The cathodic transfer coeff. was found to be significantly <0.5, and a suggestion is made regarding its interpretation. Rapid electron transfer to the anion radical was observed, and the significance discussed. The difference between the 2 half-wave potentials of the hypothetical planar conformer was estd. to be about 0.80 v.
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    5. 5
      Anderson, L. B.; Hansen, J. F.; Kakihana, T.; Paquette, L. A. Unsaturated heterocyclic systems part 74: electrochemical studies of reduction of 2-methoxyazocines in aprotic solvents – comparison with cyclooctatetraene system. J. Am. Chem. Soc. 1971, 93, 161,  DOI: 10.1021/ja00730a028
      5
      Unsaturated heterocyclic systems. LXXIV. Electrochemical studies of the reduction of 2-methoxyazocines in aprotic solvents. Comparison with the cyclooctatetraene system
      Paquette, Leo A.; Anderson, Larry Bernard; Hansen, John F.; Kakihana, Tsuyoshi
      Journal of the American Chemical Society (1971), 93 (1), 161-7CODEN: JACSAT; ISSN:0002-7863.
      The polarog. redn. of each of the 5 different 2-methoxyazocines studied was non-Nernstian. In THF or DMF solns. contg. 0.1M Bu4NClO4 background electrolyte, the redn. occurs by the addn. of 2 electrons to the parent azocine to form directly the dianion product. Cyclic voltammetry of the azocines indicates that the dianion product is not reoxidized at the Hg drop electrode until the potential is scanned nearly 1 V anodic of the initial redn. wave. This behavior is in strong contrast to the previously reported mechanism for the redn. of cyclooctatetraene (COT), the hydrocarbon analog. COT and its derivs. undergo 2 nearly Nernstian 1-electron redns. sepd. by ∼0.24 V. A mechanism is proposed for the azocine redn. process. Addn. of the 1st electron is thought to be accompanied by considerable ring flattening, producing a planar or nearly planar anion radical. This radical is more easily reduced than the parent heterocycle, resulting in the immediate introduction of a 2nd electron to form the stable dianion. The reason for the spontaneous addn. of a 2nd electron at the same potential as the addn. of the 1st is thought to be the favorable energy gain upon formation of a 10 π-electron aromatic dianion. The significance of these results in interpreting the previously reported behavior of cyclooctatetraene and its derivs. is discussed.
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    6. 6

      See, for example

      Savéant, J.-M. Elements of Molecular and Biomolecular Electrochemistry; John Wiley: Hoboken, NJ, USA, 2006.
      There is no corresponding record for this reference.
    7. 7
      Amatore, C.; Maisonhaute, E.; Simonneau, G. Ohmic drop compensation in cyclic voltammetry at scan rates in the megavolt per second range: access to nanometric diffusion layers via transient electrochemistry. J. Electroanal. Chem. 2000, 486, 141,  DOI: 10.1016/S0022-0728(00)00131-5
      7
      Ohmic drop compensation in cyclic voltammetry at scan rates in the megavolt per second range: access to nanometric diffusion layers via transient electrochemistry
      Amatore, Christian; Maisonhaute, Emmanuel; Simonneau, Gerard
      Journal of Electroanalytical Chemistry (2000), 486 (2), 141-155CODEN: JECHES ISSN:. (Elsevier Science S.A.)
      A new concept of a three-electrode potentiostat involving pos. feedback compensation of ohmic drop is discussed. This potentiostat allows the electrochem. investigation of nanosecond time scales by allowing the recording of ohmic drop-free voltammograms at scan rates in the megavolt per s range. This range of scan rate corresponds to the development of diffusion layers having only a few nanometers thickness. The principle and properties of the potentiostat are first demonstrated anal. based on a simplified equiv. circuit for the conditions used in this study (v < 5 MV s-1). The validity of this simplified anal. approach is then tested and further investigated by precise simulations of the electronic properties of the real circuit, and then by exptl. tests on RC dummy cells or on dummy cells equipped with a pseudo-faradaic impedance. These tests establish that the potentiostat behaves excellently up to slightly above 2 MV s-1. These results were then confirmed by examn. of the redn. voltammetry of anthracene in highly concd. (0.9 M) supporting electrolyte to avoid interference with transport in the double layer, since usual supporting electrolyte concns. would produce double layers of the same thicknesses as the diffusion layers that are created in this range of scan rates. These tests confirmed the results of the above investigations and finally demonstrated that this potentiostat allows the recording of undistorted voltammograms up to 2.25 MV s-1.
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    8. 8
      Amatore, C.; Maisonhaute, E.; Schöllhorn, B.; Wadhawan, J. Ultrafast voltammetry for probing interfacial electron transfer in molecular wires. ChemPhysChem 2007, 8, 1321,  DOI: 10.1002/cphc.200600774
      8
      Ultrafast voltammetry for probing interfacial electron transfer in molecular wires
      Amatore, Christian; Maisonhaute, Emmanuel; Schollhorn, Bernd; Wadhawan, Jay
      ChemPhysChem (2007), 8 (9), 1321-1329CODEN: CPCHFT; ISSN:1439-4235. (Wiley-VCH Verlag GmbH & Co. KGaA)
      Electron transfer inside self-assembled monolayers made from complex redox-active oligophenylenevinylene mol. wires is examd. by ultrafast cyclic voltammetry. Rate consts. >106 s1 are measured when the electroactive moieties are easily accessible to counterions from the electrolyte. These counterion movements are necessary to compensate the local charge created upon electron transfer. Conversely, if the redox center is buried within long hydrophobic diluents, the counterion movement towards the redox entity becomes rate limiting, thus drastically altering the rate magnitude and its phys. meaning. This change in the mechanism is examd. both for superexchange or when one electron-hopping step is involved.
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    9. 9
      Moraczewski, J.; Geiger, W. E. Electrochemical properties of bis(cyclopentadienylcobalt)cyclooctatetraene: formation of 34-electron triple decker compound. J. Am. Chem. Soc. 1978, 100, 7429,  DOI: 10.1021/ja00491a059
      9
      Electrochemical properties of bis(cyclopentadienylcobalt)cyclooctatetraene. Formation of a 34-electron triple-decker compound
      Moraczewski, Jerry; Geiger, William E., Jr.
      Journal of the American Chemical Society (1978), 100 (23), 7429-31CODEN: JACSAT; ISSN:0002-7863.
      Electrochem. redn. and oxidn. of bis(cyclopentadienylcobalt)cyclooctatetraene [68865-94-1] was effected in nonaq. electrolytes and studied by polarog., cyclic voltammetry, and bulk coulometry. The mol. was reduced in 2 well sepd. 1-electron processes, the 1st of which was highly reversible. In contrast, the oxidn. proceeded by a 2-electron reversible process to a dication having 34 metal valence electrons, isoelectronic with the triple-decker cation (η5-C5H5)3Ni2+. This is believed to be the 1st report wherein electrochem. has been used to generate a triple-decker sandwich compd.
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    10. 10
      Deschenaux, R.; Schweissguth, M.; Levelut, A.-M. Electron-transfer induced mesomorphism in the ferrocene-ferricenium redox system: the first ferricenium-containing thermotropic liquid crystal. Chem. Commun. 1996, 1275,  DOI: 10.1039/CC9960001275
      10
      Electron-transfer induced mesomorphism in the ferrocene-ferrocenium redox system: first ferrocenium-containing thermotropic liquid crystal
      Deschenaux, Robert; Schweissguth, Martin; Levelut, Anne-Marie
      Chemical Communications (Cambridge) (1996), (11), 1275-1276CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
      Chem. oxidn. (Ag tosylate, acetone, room temp.) of a nonmesomorphic persubstituted ferrocene deriv. leads to the corresponding ferrocenium species which exhibits a smectic A phase (polarized optical microscopy, DSC, x-ray diffraction).
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    11. 11
      Deschenaux, R.; Schweissguth, M.; Vilches, M.-T.; Levelut, A.-M.; Hautot, D.; Long, G. J.; Luneau, D. Switchable mesomorphic materials based on the ferrocene-ferricenium redox system: electron transfer generated columnar liquid crystalline phases. Organometallics 1999, 18, 5553,  DOI: 10.1021/om9905308
      11
      Switchable Mesomorphic Materials Based on the Ferrocene-Ferrocenium Redox System: Electron-Transfer-Generated Columnar Liquid-Crystalline Phases
      Deschenaux, Robert; Schweissguth, Martin; Vilches, Maria-Teresa; Levelut, Anne-Marie; Hautot, Dimitri; Long, Gary J.; Luneau, Dominique
      Organometallics (1999), 18 (26), 5553-5559CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
      Oxidn. of the nonmesomorphic ferrocene deriv. 1 with Ag toluene-4-sulfonate gave the ferrocenium deriv. 2, which showed a monotropic columnar phase. The latter two-dimensional phase is composed of ribbons, in which deriv. 2 is organized into bilayers, and has a centered rectangular symmetry with a 318.3 and c 94.9 Å. The Mossbauer spectra of the ferrocene deriv. 1 yields hyperfine parameters that are typical of these derivs. and are, as expected, virtually independent of temp. In a similar fashion, the hyperfine parameters of the ferrocenium deriv. 2 are typical of these derivs., but in this case at both 78 and 4.2 K slow paramagnetic relaxation of the magnetic moment assocd. with the rather well isolated paramagnetic ferrocenium ion is obsd. The temp.-dependent magnetic susceptibilities of 2 are in agreement with those expected for weakly interacting ferrocenium cores. No magnetic-field-induced orientation was obsd. upon cooling the sample from the isotropic phase down to the columnar phase. Ferrocene and ferrocenium are valuable units for the design of liq.-cryst. switches.
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    12. 12
      Donnio, B.; Seddon, J. M.; Deschenaux, R. A ferrocene containing carbohydrate surfactant: thermotropic and lyotropic phase behaviour. Organometallics 2000, 19, 3077,  DOI: 10.1021/om0001568
      12
      A Ferrocene-Containing Carbohydrate Surfactant: Thermotropic and Lyotropic Phase Behavior
      Donnio, Bertrand; Seddon, John M.; Deschenaux, Robert
      Organometallics (2000), 19 (16), 3077-3081CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
      A ferrocene-contg. carbohydrate surfactant has been synthesized and shown by polarized optical microscopy, differential scanning calorimetry, and x-ray diffraction to exhibit both thermotropic and lyotropic liq.-cryst. phase behavior. This new class of materials should prove useful for the design of redox-active lyotropic liq. crystals, allowing fine electrochem. control of the phase structure and symmetry.
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    13. 13
      Nakamura, Y.; Matsumoto, T.; Sakazume, Y.; Murata, J.; Chang, H.-C. Tuning the mesomorphism and redox response of anionic ligand-based mixed-valent nickel(II) complexes by alkyl-substituted quaternary ammonium cations. Chem. - Eur. J. 2018, 24, 7398,  DOI: 10.1002/chem.201706006
      13
      Tuning the Mesomorphism and Redox Response of Anionic-Ligand-Based Mixed-Valent Nickel(II) Complexes by Alkyl-Substituted Quaternary Ammonium Cations
      Nakamura, Yuichi; Matsumoto, Takeshi; Sakazume, Yasutaka; Murata, Junnosuke; Chang, Ho-Chol
      Chemistry - A European Journal (2018), 24 (29), 7398-7409CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
      The combination of the redox-active mesogenic anion [NiII(Bdt)(BdtSQ)]- (Bdt = 1,2-benzenedithiolato; BdtSQ = 1,2-dithia-semi-benzoquinonato) with alkyl-substituted ammonium cations afforded a series of redox-active ionic complexes of the type [NR4][NiII(Bdt)(BdtSQ)] [R = nC16H33 (NC164Ni) and C8,10 (NC8,104Ni); C8,10 = 6-octylhexadecyl] or [NMe2R2][NiII(Bdt)(BdtSQ)] [R = nC16H33 (NMe2C162Ni) and C8,10 (NMe2C8,102Ni)]. X-ray crystallog. analyses of NMe2C162Ni and NC164Ni revealed the formation of cation-dependent integrated ionic layers sepd. by interdigittated alkyl chains. Complexes NMe2C162Ni and NC164Ni commonly form cryst. phases at room temp., whereas complexes NMe2C8,102Ni and NC8,104Ni, which contain branched alkyl chains, form a metastable mesophase and an amorphous phase at the same temp., resp. Furthermore, complexes NMe2C162Ni, NMe2C8,102Ni, and NC164Ni commonly form a smectic A phase (SmA) at 375, 317, and 342 K, resp. For the four complexes, well-defined cyclic voltammetry responses, derived from ligand-based oxidn. and redn., were obsd. in soln. and the condensed phases, i.e., upon casting these complexes on an indium-doped tin oxide working electrode. The present study demonstrates the tunability of the mesomorphism of ionic mol. assemblies composed of alkyl-substituted quaternary ammonium cations, while maintaining the well-defined redox responses of the anions even in the condensed phases.
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    14. 14
      Bourdillon, C.; Demaille, C.; Moiroux, J.; Savéant, J.-M. New insights into the enzymatic catalysis of the oxidation of glucose by native and recombinant glucose oxidase mediated by electrochemically generated one-electron redox co-substrates. J. Am. Chem. Soc. 1993, 115, 1,  DOI: 10.1021/ja00054a001
      There is no corresponding record for this reference.
    15. 15
      Ban, T. A. Fifty years chlorpromazine: an historical perspective. Neuropsychiatr. Dis. Treat. 2007, 3, 495
      15
      Fifty years chlorpromazine: a historical perspective
      Ban, Thomas A.
      Neuropsychiatric Disease and Treatment (2007), 3 (4), 495-500CODEN: NDTEAZ; ISSN:1176-6328. (Dove Medical Press (NZ) Ltd.)
      A review. Chlorpromazine was synthesized in Dec. 1951 in the labs. of Rhone-Poiulenc, and became available on prescription in France in Nov. 1952. Its effectiveness was reflected in the transformation of disturbed wards; its com. success stimulated the development of other psychotropic drugs. Recognition of chem. mediation at the site of the synapse, followed by the introduction of the spectrophotofluorimeter first, and receptor assays subsequently, led to the demonstration that chlorpromazine blocks dopamine receptors. Treatment with chlorpromazine focused attention on the heterogeneity of schizophrenia in terms of responsiveness to treatment. By the mid-1980s there was sufficient evidence to believe that resolving this heterogeneity is a prerequisite for developing more effective treatments. Chlorpromazine was instrumental in the development of neuropsychopharmacol., a new discipline dedicated to the study of mental pathol. with the employment of centrally acting drugs.
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    16. 16

      See, for example

      Eckert, G. M.; Gutmann, F.; Keyzer, H. Electrochemistry of Drug Interactions and Incompatibilities. In Modern Bioelectrochemistry; Gutman, F.; Keyzer, H., Eds.; Plenum Press: New York, 1986; p 503.
      There is no corresponding record for this reference.
    17. 17
      Dryhurst, G.; Kadish, K. M.; Scheller, F.; Renneberg, R. Phenothiazines. In Biological Electrochemistry; Academic Press: New York, 1982; Vol. 1, p 180.
      There is no corresponding record for this reference.
    18. 18
      Cheng, H. Y.; Sackett, P. H.; McCreery, R. L. Kinetics of chlorpromazine cation radical decomposition in aqueous buffers. J. Am. Chem. Soc. 1978, 100, 962,  DOI: 10.1021/ja00471a051
      18
      Kinetics of chlorpromazine cation radical decomposition in aqueous buffers
      Cheng, Hung Yuan; Sackett, Patricia Holt; McCreery, Richard L.
      Journal of the American Chemical Society (1978), 100 (3), 962-7CODEN: JACSAT; ISSN:0002-7863.
      The stoichiometry and kinetics of the reactions of chlorpromazine cation radical perchlorate salt (I) [61866-46-4] in aq. buffers were examd. at pH 2-7 using electrochem. and spectrophotometry. In phosphate and citrate media, 1 mol of radical produced 0.5 mol each of chlorpromazine (II) [50-53-3] and chlorpromazine sulfoxide (III) [969-99-3], whereas in amine buffers or unbuffered soln., other products were formed. For phosphate and citrate buffers, the decay of I was 2nd order in I, 1st order in buffer anion concn., inverse 1st order in [H+], and inverse 1st order in neutral II concn. The kinetic data indicate the formation of a cation radical/buffer adduct which is oxidized by another mol. of I, followed by rearrangement to III. The results are inconsistent with a mechanism involving disproportionation of the radical, but rather indicate a direct reaction of cation radical with buffer components and water.
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    19. 19
      Cheng, H. Y.; Sackett, P. H.; McCreery, R. L. Reactions of chlorpromazine cation radical with physiologically occurring nucleophiles. J. Med. Chem. 1978, 21, 948,  DOI: 10.1021/jm00207a019
      19
      Reactions of chlorpromazine cation radical with physiologically occurring nucleophiles
      Cheng, Hung-Yuan; Sackett, Patricia Holt; McCreery, Richard L.
      Journal of Medicinal Chemistry (1978), 21 (9), 948-52CODEN: JMCMAR; ISSN:0022-2623.
      The chlorpromazine cation radical [34468-21-8] reacts with physiol. nucleophiles, such as citrate, maleate, phosphate, glycine, and H2O, to give N or O adducts, which decomp. to chlorpromazine S-oxide [969-99-3] or hydroxylated derivs. The kinetics of the reaction depends on the nature of nucleophile, the reaction being fastest with SH- and slowest with H2O.
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    20. 20
      Deputy, A.; Wu, H.-P.; McCreery, R. L. Spatially resolved spectroelectrochemical examination of the oxidation of dopamine by chlorpromazine cation radical. J. Phys. Chem. A 1990, 94, 3620,  DOI: 10.1021/j100372a047
      20
      Spatially resolved spectroelectrochemical examination of the oxidation of dopamine by chlorpromazine cation radical
      Deputy, Andrew; Wu, Huan Ping; McCreery, Richard L.
      Journal of Physical Chemistry (1990), 94 (9), 3620-4CODEN: JPCHAX; ISSN:0022-3654.
      Spatially resolved absorption measurements of electrogenerated chlorpromazine cation radical (CPZ•+) were used to monitor the kinetics of the homogeneous oxidn. of dopamine (DA) in the soln. near planar and cylindrical electrodes. Complete concn. vs distance profiles for CPZ•+ were obtained for both planar and convergent diffusion and were used to det. the reaction mechanism and rate consts. The oxidn. of DA by CPZ•+ to dopamine orthoquinone involves successive one-electron transfers, and the results are inconsistent with disproportionation of the DA semiquinone. The obsd. kinetics and rate-limiting step were dependent on the position within the diffusion layer. Near the electrode surface the rate law is 1st order in CPZ•+ and DA, and a 2nd order rate const. of 2.1 × 10-5 M-1 s-1 was obtained. Further away from the electrode the reaction is 2nd order in CPZ•+ due to the involvement of the 2nd step, and several kinetic parameters for the 2nd electron transfer were obtained. A change in diffusion geometry which occurs at a microwire electrode further perturbs local concn. distributions, and the reaction reaches equil. under certain conditions. In all cases, the obsd. rate laws were consistent with a general expression for the stepwise electron transfer. This report represents the first application of spatially resolved spectroelectrochem. to a kinetic system and provides unprecedented detail about the CPZ•+/DA reaction.
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    21. 21
      Sackett, P. H.; Mayausky, J. S.; Smith, T.; Kalus, S.; McCreery, R. L. Side-chain effects on phenothiazine cation radical reactions. J. Med. Chem. 1981, 24, 1342,  DOI: 10.1021/jm00143a016
      21
      Side-chain effects on phenothiazine cation radical reactions
      Sackett, Patricia Holt; Mayausky, J. S.; Smith, Theresa; Kalus, Susan; McCreery, Richard L.
      Journal of Medicinal Chemistry (1981), 24 (11), 1342-7CODEN: JMCMAR; ISSN:0022-2623.
      The effect of cation radical structure on the formation of sulfoxide and hydroxylated metabolites in vitro phenothiazine tranquilizers was studied. Cyclic voltammetry, spectrophotometry, and liq. chromatog. were used to examine reactions of various phenothiazine radicals in aq. buffers. A radical with a 3-carbon aliph. side chain [e.g., chlorpromazine (I) [50-53-3]] forms solely sulfoxide and parent unless amine nucleophiles are present, in which case hydroxylation occurs. A shorter side chain [e.g., promethazine (II) [60-87-7]] causes radical dimerization and pronounced hydroxylation, regardless of external nucleophiles. A piperazine side chain [e.g., fluphenazine (III) [69-23-8]] promotes hydroxylation, with some sulfoxide obsd. Apparently, a deprotonated amine is necessary for hydroxylation and the amine may be present in the original drug rather than an external nucleophile. In addn. to information about cation radical reactions, the redox properties of several different phenothiazines are presented.
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    22. 22
      Bosch, E.; Kochi, J. K. Catalytic oxidation of chlorpromazine and related phenothiazines: cation radicals as the reactive intermediates in sulfoxide formation. J. Chem. Soc., Perkin Trans. 1 1995, 1057,  DOI: 10.1039/p19950001057
      22
      Catalytic oxidation of chlorpromazine and related phenothiazines. Cation radicals as the reactive intermediates in sulfoxide formation
      Bosch, Eric; Kochi, Jay K.
      Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1995), (8), 1057-64CODEN: JCPRB4; ISSN:0300-922X. (Royal Society of Chemistry)
      The aerial oxidn. of various phenothiazines to the corresponding sulfoxides is catalyzed by nitric oxide and related nitrogen oxides. The reactive intermediate in the catalytic autoxidn. is the phenothiazine cation radical which is subsequently transformed to the sulfoxide by nitrate present in the reaction medium. These results are pertinent to any further discussion of the activity and/or metab. of phenothiazine-based drugs.
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    23. 23
      Ximenes, V. F.; Quaggio, G. B.; Graciani, F. S.; de Menezes, M. L. Oxidation of amino acids by chlorpromazine cation radical and co-catalysis by chlorpromazine. Pharmacol. Pharm. 2012, 3, 29,  DOI: 10.4236/pp.2012.31005
      23
      Oxidation of amino acids by chlorpromazine cation radical and co-catalysis by chlorpromazine
      Ximenes, Valdecir F.; Quaggio, Giovana B.; Graciani, Fernanda S.; de Menezes, Manoel L.
      Pharmacology & Pharmacy (2012), 3 (1), 29-36CODEN: PPHHBN; ISSN:2157-9423. (Scientific Research Publishing, Inc.)
      The long-term use of chlorpromazine (CPZ) may cause severe side effects. This property of CPZ might be related to pro-oxidant effects of the chlorpromazine cation radical (CPZ·+), which can be easily generated by catalytic action of peroxidases, including the neutrophil myeloperoxidase (MPO) and by metHb. Aiming the comprehension of a putative physiol. effect of CPZ·+ upon biomols., in this work we studied the reactivity of CPZ·+ with amino acids and the co-catalytic effect of CPZ during the oxidn. of amino acids by horseradish peroxidase (HRP)/H2O2 system. We also studied whether natural blood plasma components as ascorbic acid, uric acid and nitrite could inhibit the oxidative effect of CPZ·+. We found that tryptophan, tyrosine and cysteine were easily oxidized by pure CPZ·+. Other amino acids as methionine, glycine, phenylalanine, aspartic acid and lysine were unreactive. The decompn. of CPZ·+ was exacerbated by uric acid, ascorbic acid and nitrite, provoking inhibition in the amino acids oxidn. In expts. with HRP/H2O2, and using CPZ as a co-catalyst, a strong effect upon oxidn. of tryptophan, tyrosine and cysteine was obtained. It was also found that tryptophan was more reactive than tyrosine with CPZ·+, a feature that could be related to the recently described favorable interaction between tryptophan and CPZ. The use of CPZ as a co-catalyst is discussed regarding its role in the efficient oxidn. of tryptophan.
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    24. 24
      Rodrigues, T.; dos Santos, C. G.; Riposati, A.; Barbosa, L. R. S.; di Mascio, P.; Itri, R.; Baptista, M. S.; Nascimento, O. R.; Nantes, I. L. Photochemically generated stable cation radical of phenothiazine aggregates in mildly acid buffered solution. J. Phys. Chem. B 2006, 110, 12257,  DOI: 10.1021/jp0605404
      24
      Photochemically Generated Stable Cation Radical of Phenothiazine Aggregates in Mildly Acid Buffered Solutions
      Rodrigues, Tiago; dos Santos, Carolina G.; Riposati, Alessandra; Barbosa, Leandro R. S.; Di Mascio, Paolo; Itri, Rosangela; Baptista, Mauricio S.; Nascimento, Otaciro R.; Nantes, Iseli L.
      Journal of Physical Chemistry B (2006), 110 (25), 12257-12265CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
      This work characterizes, for the first time, the photochem. behavior of the antipsychotic drugs thioridazine (TR), trifluoperazine (TFP), and fluphenazine (FP) influenced by the aggregation state of the mols. Samples of monomeric and aggregated forms of phenothiazines were submitted to 20 min of irradn. at 254 nm for intervals of 1, 5, 10, 15, 20, or 25 days. In high phenothiazine concns., the irradn. led to the appearance of absorbance bands in the visible region peaking at 633 nm for TR and 509 nm for FP and TFP. In the dark, at room temp. and at 4° C, these bands disappeared, after ∼15 and ∼60 min, resp., but reappeared after a new irradn. session. These visible bands were assigned to stable cation radicals that were characterized by direct EPR measurements and by flash photolysis. Photogenerated stable cation radicals in the phenothiazine aggregates at room temp. are formed probably due to the stacking of the thiazine Ph moieties. For the monomeric forms of phenothiazines, the spectral changes obsd. during the irradn. suggested the formation of sulfoxide and hydroxylated derivates. Oxidized derivates were detected by mass spectrometry of the aggregated forms of phenothiazines (>100 μM) only in the samples irradiated for more than 20 days. In contrast, monomeric phenothiazines were totally converted to the oxidized forms after 20 min of irradn. Surface tension measurements of phenothiazines revealed that, in concns. above 100 μM, the drugs formed aggregates. In the case of TR, small-angle x-ray scattering measurements indicated that this compd. forms large lamellar-like aggregates in aq. solns.
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    25. 25
      Ateş, S.; Somer, G. Photodegradation of chlorpromazine in aqueous solutions as studied by ultraviolet-visible spectrophotometry and voltammetry. J. Chem. Soc., Faraday Trans. 1 1981, 77, 859,  DOI: 10.1039/f19817700859
      25
      Photodegradation of chlorpromazine in aqueous solutions as studied by ultraviolet-visible spectrophotometry and voltammetry
      Ates, Serdar; Somer, G.
      Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases (1981), 77 (4), 859-67CODEN: JCFTAR; ISSN:0300-9599.
      Photodegrdn. of chlorpromazine (I) [50-53-3] under near-UV radiation was monitored by following its π-π* absorption band at 256 nm and by voltammetric oxidn. peak current measurements. Both techniques gave results which were consistent with the same mechanism for photodegrdn. in aq. solns. of pH 1.5-6.5 at 22-24°. The photooxidn. reaction obeyed zero-order kinetics. Evidence for chlorpromazine phenazathionium ion [78036-25-6] formation was obsd. in spectra of 6 mol/dm3 H2SO4 solns. of the irradiated drug.
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    26. 26
      Garcia, C.; Smith, G. A.; McGimpsey, W. G.; Kochevar, I. E.; Redmond, R. W. Mechanism and solvent dependence for photoionisation of promazine and chlorpromazine. J. Am. Chem. Soc. 1995, 117, 10871,  DOI: 10.1021/ja00149a010
      26
      Mechanism and Solvent Dependence for Photoionization of Promazine and Chlorpromazine
      Garcia, Carmelo; Smith, Glenn A.; McGimpsey, W. Grant; Kochevar, Irene E.; Redmond, Robert W.
      Journal of the American Chemical Society (1995), 117 (44), 10871-8CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
      The mechanism for photoionization of the phenothiazine derivs., promazine and chlorpromazine, has been studied as a function of solvent and excitation conditions. Sequential biphotonic absorption is responsible for photoionization induced by pulsed laser irradn. at 308 or 355 nm. In order to det. the excited states involved excitation was carried out under conditions where the second photon was exclusively absorbed by the lowest excited singlet state (using picosecond excitation pulses where the pulse duration is « singlet lifetime) or by the lowest triplet state using a two-color, two-pulse excitation protocol. Photoionization occurs upon two-photon excitation within the singlet manifold in aq. solns. and methanol. In addn., photoionization is solvent dependent upon excitation of the triplet state at 355 nm or near its absorption max. of 460 nm. In water the triplet absorption was bleached concomitant with the generation of absorption from the radical cation and hydrated electron. Quantum yields of photoionization of promazine were 0.02 and 0.03 in acetonitrile and water, resp. In methanol or other alcs., photoionization was not obsd. under the same excitation conditions. Triplet lifetimes, molar absorption coeffs., and quantum yields of intersystem crossing were detd. in various solvents. The exptl. results indicate that during single wavelength pulsed irradn. of these compds., the second photon is absorbed predominantly by the lowest excited singlet state rather than the lowest excited triplet state. The energetics of the photoionization of promazine and chlorpromazine were estd. as a function of solvent.
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    27. 27
      Sarata, G.; Noda, Y.; Sakai, M.; Takahashi, H. Structure and dynamics of the lowest excited triplet states and cation radicals of phenothiazine and 2-chlorophenothiazine: transient resonance Raman and absorption study. J. Mol. Struct. 1997, 413–414, 49,  DOI: 10.1016/S0022-2860(97)00060-4
      27
      Structures and dynamics of the lowest excited triplet states and cation radicals of phenothiazine and 2-chlorophenothiazine: transient resonance Raman and absorption study
      Sarata, Gaku; Noda, Yoshihiro; Sakai, Makoto; Takahashi, Hiroaki
      Journal of Molecular Structure (1997), 413-414 (), 49-59CODEN: JMOSB4; ISSN:0022-2860. (Elsevier)
      Transient resonance-Raman and absorption spectra of the lowest excited triplet states T1 and the cation radicals of phenothiazine (I) and 2-chlorophenothiazine (II) were measured. In the photoreaction of II, a transient exhibiting an absorption band at 556 nm was generated from the cation radical. The corresponding transient was not obsd. in the absorption spectrum of I, a fact which suggests the possibility of phenothiazinyl radical generation from II via photoinduced dechlorination. Vibrational assignments of the T1 states and the cation radicals of both compds. were made based on the frequency shifts on isotopic substitutions. Unusually large low-frequency shifts of the Ph 8a and 8b modes were obsd. in the T1 state but no appreciable shifts were detected in the cation radical, indicating that the Ph rings are drastically weakened, and therefore, the Ph C-C bonds are very much lengthened in the T1 state. This implies that the excitation is strongly localized on the Ph rings and the T1 state has an n-.vpi.* character.
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    28. 28
      Maruthamuthu, P.; Sharma, D. K.; Serpone, N. Sub-nanosecond relaxation dynamics of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) and chlorpromazine: assessment of photosensitisation of a wide band gap metal oxide semiconductor TiO2. J. Phys. Chem. B 1995, 99, 3636,  DOI: 10.1021/j100011a034
      28
      Subnanosecond Relaxation Dynamics of 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonate) and Chlorpromazine. Assessment of Photosensitization of a Wide Band Gap Metal Oxide Semiconductor TiO2
      Maruthamuthu, P.; Sharma, D. K.; Serpone, N.
      Journal of Physical Chemistry (1995), 99 (11), 3636-42CODEN: JPCHAX; ISSN:0022-3654. (American Chemical Society)
      Subnanosecond relaxation dynamics of the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) monoanion, ABTSH(-H+) and the dianion, ABTS(-2H+), together with the chlorpromazine cation ClPMZ(+H+) were examd. by picosecond laser spectroscopic techniques (excitation wavelength, 355 nm) in the presence and absence of TiO2 colloids to assess their photosensitization of wide band gap metal oxide semiconductors. Fluorescence emissions from ABTSH(-H+) and ABTS(-2H+) by excitation with 370-nm light and from ClPMZ(+H+) by excitation at 360 nm are quenched by TiO2 by an interfacial electron transfer process implicating the singlet excited states of the dyes and the conduction band and/or band gap surface states of TiO2 (electron injection). Subnanosecond change-in-absorbance spectra of the substrates showed formation of singlet excited states followed by electron ejection and formation of the corresponding radical cations (zwitterion radicals). Photolysis in the presence of an electron scavenger (e.g., NO3-) at different delay times confirmed these observations. The lifetime of free ABTS(-2H+)* (S1) is about 80 ps, and that of ClPMZ(+H+)* (S1) is pulse-width limited, that is less than 30 ps. The presence of TiO2 colloids in the photolytic system decreased the rate of loss of the radical cation ABTS•+(-2H+) owing to surface trapping of photoejected electrons from the singlet excited states of the substrates. Formation of the ABTS2+(-2H+) dication is obsd. on photolysis of ABTS•+(-2H+) in the presence of TiO2 colloids and dissolved oxygen; in the absence of either TiO2 and/or O2, formation of the dication is quenched, consistent with the notion that ABTS•+(-2H+) is oxidized by surface trapped holes on the TiO2 particle.
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    29. 29
      Chignell, C. F.; Motten, A. G.; Buettner, G. R. Photoinduced free radicals from chlorpromazine and related phenothiazines: relationship to phenothiazine-induced photosensitisation. Environ. Health Perspect. 1985, 64, 103,  DOI: 10.1289/ehp.8564103
      29
      Photoinduced free radicals from chlorpromazine and related phenothiazines: relationship to phenothiazine-induced photosensitization
      Chignell, Colin F.; Motten, Ann G.; Buettner, Garry R.
      Environmental Health Perspectives (1985), 64 (), 103-10CODEN: EVHPAZ; ISSN:0091-6765.
      A review, with 54 refs., of the free-radical photochem. of chlorpromazine [50-53-3] and related phenothiazines and the involvement of photoinduced free radicals in photosensitization.
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    30. 30
      Buettner, G. R.; Hall, R. D.; Chignell, C. F.; Motten, A. G. The stepwise biphotonic photoionisation of chlorpromazine as seen by laser flash photolysis. Photochem. Photobiol. 1989, 49, 249,  DOI: 10.1111/j.1751-1097.1989.tb04103.x
      30
      The stepwise biphotonic photoionization of chlorpromazine as seen by laser flash photolysis
      Buettner, Garry R.; Hall, Robert D.; Chignell, Colin F.; Motten, Ann G.
      Photochemistry and Photobiology (1989), 49 (3), 249-56CODEN: PHCBAP; ISSN:0031-8655.
      It is generally accepted that both promazine (PZ) and chlorpromazine (CPZ) photoionize monophotonically to their resp. cation radicals and the corresponding hydrated electrons. It is also supposed that this photoionization has a role in the phototoxic effects of these drugs. However, using laser flash photolysis, it has been obsd. that photoionization of CPZ during S1 excitation (λ >300 nm) is a stepwise biphotonic process. In the case of PZ, the flash photolysis results are less clear-cut, but are consistent with stepwise biphotonic photoionization for S1 excitation. Using computer simulation of the intramol. kinetics, it is demonstrated that the estd. triplet state lifetime of CPZ is sufficient long (23 ns at room temp.) to account for the apparent monophotonic photoionization that has been obsd. by others at high light intensities and short pulse times. The laser flash photolysis results also suggest that the photoionization mechanism of PZ and CPZ is wavelength-dependent. Both drugs exhibit apparent monophotonic photoionization when they are excited at 266 nm under conditions of laser pulse width and intensity similar to those at 355 nm. It is suggested that photoionization is not an important mechanism in the obsd. phototoxic and photoallergic effects of PZ and CPZ in sunlight.
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    31. 31
      Fenner, H.; Möckel, H. EPR spekten von radikalkationen aus promazin und chlorpomazin. Tetrahedron Lett. 1969, 2815,  DOI: 10.1016/S0040-4039(01)88279-4
      31
      E.P.R. spectra of radical cations of promazine and chlorpromazine
      Fenner, Helmut; Moeckel, Hermann
      Tetrahedron Letters (1969), (33), 2815-18CODEN: TELEAY; ISSN:0040-4039.
      The E.P.R. spectra of promazine and chlorpromazine radicals were taken at room temp. on samples contg. 0.0001M base and 0.1% Bz2O2 in C6H6 degassed with Ar 30 min. Coupling for ring protons around 0.5 G merged into the line widths or were only detectable as shoulders. Analysis of the hyperfine structure gave in addn. to a large N-coupling (6.95 and 7.0 G) 5 sets of equiv. proton pairs for the promazine radical (I) and 4 for the chlorpromazine radical (II). The assignment of coupling parameters was based on those of the phenothiazine radical cation (III) (CA 64: 18742b) based on M.O. calcns. The coupling consts. for III permitted assignment of the largest proton couplings to the N-CH2 group. On the basis of the E.P.R. spectra the radical cations of I and II were assigned to the polymethine type with alternating charge ds., longwave absorption, and planarity of the system.
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    32. 32
      Pan, D.; Shoute, L. C. T.; Phillips, D. L. Time-resolved resonance Raman and density functional study of the radical cation of chlorpromazine. J. Phys. Chem. A 2000, 104, 4140,  DOI: 10.1021/jp992196z
      32
      Time-Resolved Resonance Raman and Density Functional Study of the Radical Cation of Chlorpromazine
      Pan, Duohai; Shoute, Lian C. T.; Phillips, David Lee
      Journal of Physical Chemistry A (2000), 104 (18), 4140-4148CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      A resonance Raman spectrum was obtained of the radical cation of promazine. The authors have also carried out d. functional theory calcns. to find the structures, hyperfine coupling consts. (hfcc.'s), spin densities, and vibrational frequencies for the ground electronic states of the neutral chlorpromazine mol. and its radical cation. Preliminary vibrational assignments were made for all of the obsd. bands in the resonance Raman spectrum of the radical cation of chlorpromazine and in the FT-Raman spectrum of the neutral chlorpromazine mol. The radical cation of chlorpromazine has a nonplanar structure similar to that of the radical cation of promazine. The Cl atom at the 2 position in chlorpromazine appears to noticeably change the hfcc.'s and spin densities of the radical cation compared to the radical cation of promazine. This is possibly due to conjugation and/or through-bond interactions of the Cl atom with the central-ring heterocycle.
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    33. 33
      Rupérez, F. L.; Conesa, J. C.; Soria, J.; Apreda, M. C.; Cano, F. H.; Foces-Foces, C. X-ray diffraction and electron paramagnetic resonance study of the chlorpromazine cation radical. J. Phys. Chem. C 1985, 89, 1178,  DOI: 10.1021/j100253a025
      There is no corresponding record for this reference.
    34. 34
      Pan, D.; Phillips, D. L. Raman and density functional study of the S0 state of phenothiazine and the radical cation of phenothiazine. J. Phys. Chem. A 1999, 103, 4737,  DOI: 10.1021/jp990399h
      34
      Raman and Density Functional Study of the S0 State of Phenothiazine and the Radical Cation of Phenothiazine
      Pan, Duohai; Phillips, David Lee
      Journal of Physical Chemistry A (1999), 103 (24), 4737-4743CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Raman spectra of phenothiazine and its radical cation were obtained. Hartree-Fock (HF) and d. functional theory (DFT) ab initio calcns. were performed to find optimized structures and computed vibrational frequencies. The ab initio structures are compared to previously reported X-ray diffraction exptl. results, and the vibrational frequencies are compared to Raman spectra given here as well as previously reported Raman spectra. We have made vibrational assignments for the obsd. Raman bands, based on the computed potential energy distribution (PED) and isotopic shifts. Our results indicate that the neutral phenothiazine mol. has a nonplanar structure with ∼153° dihedral angle and the radical cation has a planar (or near planar) structure with ∼180° dihedral angle.
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    35. 35
      Soltz, B. A.; Corey, J. Y.; Larsen, D. W. Molecular motion in chlorpromazine and chlorpromazine hydrochloride. J. Phys. Chem. D 1979, 83, 2162,  DOI: 10.1021/j100479a024
      35
      Molecular motion in chlorpromazine and chlorpromazine hydrochloride
      Soltz, Barbara A.; Corey, Joyce Y.; Larsen, David W.
      Journal of Physical Chemistry (1979), 83 (16), 2162-6CODEN: JPCHAX; ISSN:0022-3654.
      Chlorpromazine (I) and I.HCl were studied in the solid state with pulsed NMR techniques. The relaxation times, T1, T1ρ, and T1D, and second moments, M2, were measured from 98 K to the m.p. of the solid. Me reorientation was obsd. in I and I.HCl with activation barriers of 2.5 and 2.0 kcal/mol, resp. The onset of a second motion in I is obsd. in the high temp. region with an activation barrier of 3.9 kcal/mol. The M2 transition assocd. with this motion is very large, which suggests that it involves motion of the aminopropyl chain. The motion is attributed to the fact that the chain configuration is trans-gauche, and a model for the motion is discussed. A phase transition occurs for I.HCl in the high temp. region.
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    36. 36
      Hough, E.; Hjorth, M.; Dahl, S. G. The structures of (dimethylaminopropyl)phenothiazine drugs and their metabolites, part II: chlorpromazine sulphoxide, C17H19ClN2OS, at 120 K. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1985, 41, 383,  DOI: 10.1107/s0108270185003997
      There is no corresponding record for this reference.
    37. 37
      McDowell, J. J. H. The crystal and molecular structure of chlorpromazine. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1969, 25, 2175,  DOI: 10.1107/S0567740869005437
      37
      Crystal and molecular structure of chlorpromazine
      McDowell, J. J. H.
      Acta Crystallographica, Section B: Structural Crystallography and Crystal Chemistry (1969), 25 (Pt. 11), 2175-81CODEN: ACBCAR; ISSN:0567-7408.
      The crystal structure of chlorpromazine (I) has been detd. from 3-dimensioal x-ray diffraction data and refined by least-squarse methods, with individual anisotropic temp. factors. The space group is Pbca with a = 23.50 ± 0.04, b = 15.20 ± 0.02, and c = 9.23 ± 0.01 Å. The mol. is folded about the S-N axis and the angle between the best planes for the 2 benzene rings was found to be 139.4°. The C-S-C angle is 97.3 ± 0.3°, the C-S bonds are 1.75 ± 0.01 Å and C-Cl is 1.74 ± 0.01 Å. The contraction of the C-S bond, the size of the C-S-C angle, and the folding of the mol. are characteristic of a no. of related compds., and can be explained by assuming the participation of d orbitals in the bonding of S.
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    38. 38
      Ortiz, A.; Pardo, A.; Fernández-Alonso, J. I. Spectra of radical cations of phenothiazine derivatives in solution and solid state. J. Pharm. Sci. 1980, 69, 378,  DOI: 10.1002/jps.2600690403
      38
      Spectra of radical cations of phenothiazine derivatives in solution and solid state
      Ortiz, A.; Pardo, A.; Fernandez-Alonso, J. I.
      Journal of Pharmaceutical Sciences (1980), 69 (4), 378-80CODEN: JPMSAE; ISSN:0022-3549.
      UV and visible spectra of radical cations of 17 psychotropic phenothiazine derivs. were studied using different solvents. The characteristic charge transfer band was obsd. in the solid state using diffuse reflectance spectroscopy. C(2)-substituents do not affect the band, while substituents at N affected the band considerably, probably owing to steric effects.
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    39. 39
      Bahnemann, D.; Asmus, K.-D.; Wilson, R. L. Free radical induced one-electron oxidation of the phenothiazines chlorpromazine and promethazine. J. Chem. Soc., Perkin Trans 2 1983, 1661,  DOI: 10.1039/p29830001661
      39
      Free radical induced one-electron oxidation of the phenothiazines chlorpromazine and promethazine
      Bahnemann, Detlef; Asmus, Klaus Dieter; Willson, Robin L.
      Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999) (1983), (11), 1661-8CODEN: JCPKBH; ISSN:0300-9580.
      Abs. rate consts. were detd. for the oxidn. of protonated chlorpromazine and promethazine by HO•, Br2•-, (SCN)2•-, I2•-, N3•, Tl2+, Tl(OH)+, (Me3C)2S•+, (MeS)2•+, and lipoate radical cation at pH 2-8. The k values were 3.1 × 108 to 5.5 × 109 mol-1 dm3 s-1 and the yields of dication radical oxidn. products were 28-97%. The reaction with HO• gives a transient adduct. The mechanism of HO•-induced oxidn. of phenothiazines is discussed.
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    40. 40
      Zhang, H.-M.; Ruan, X.-Q.; Guo, Q.-X.; Liu, Y.-C. A study on one-electron oxidation of phenothiazine derivatives by piperidine oxoammonium ion in SDS micelle. Res. Chem. Intermed. 1998, 24, 687,  DOI: 10.1163/156856798X00582
      40
      A study on one-electron oxidation of phenothiazine derivatives by piperidine oxoammonium ion in SDS micelle
      Zhang, Hai-Ming; Ruan, Xiu-Qin; Guo, Qing-Xiang; Liu, You-Cheng
      Research on Chemical Intermediates (1998), 24 (6), 687-693CODEN: RCINEE; ISSN:0922-6168. (VSP BV)
      N-Substituted phenothiazines were oxidized by 2,2,6,6-tetramethy-4-acetyloxypiperidine oxoammonium hexachloroantimonate (TAPO) to the corresponding radical cations in sodium dodecyl sulfate (SDS) micellar soln. The radical cations of phenothiazine derivs. were generated and stabilized by the anionic micelle in aq. soln. An electron transfer mechanism has been proposed.
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    41. 41
      Domańska, U.; Pelczarska, A.; Pobudkowska, A. Solubility and pKa determination of six structurally related phenothiazines. Int. J. Pharm. 2011, 421, 135,  DOI: 10.1016/j.ijpharm.2011.09.040
      41
      Solubility and pKa determination of six structurally related phenothiazines
      Domanska, Urszula; Pelczarska, Aleksandra; Pobudkowska, Aneta
      International Journal of Pharmaceutics (Amsterdam, Netherlands) (2011), 421 (1), 135-144CODEN: IJPHDE; ISSN:0378-5173. (Elsevier B.V.)
      Solubilities of six structurally related phenothiazines, namely chlorpromazine hydrochloride, fluphenazine dihydrochloride, promazine hydrochloride, thioridazine hydrochloride, trifluoperazine dihydrochloride, and triflupromazine hydrochloride at const. pH were measured at from 290 K to 350 K in three important drugs solvents: water, ethanol and 1-octanol using the dynamic method and UV-vis method. Dissocn. consts. and corresponding pK a values of drugs were obtained with Bates-Schwarzenbach method at temp. 298.15 K in the buffer solns. Our exptl. pK a values for chlorpromazine hydrochloride, fluphenazine dihydrochloride, promazine hydrochloride, thioridazine hydrochloride, trifluoperazine dihydrochloride, and triflupromazine hydrochloride are 9.15, 10.01, 9.37, 8.89, 8.97, and 9.03, resp. The basic thermal properties of pure drugs i.e. melting and solid-solid phase transition as well as glass-transition temps., the enthalpy of melting and phase transitions and the molar heat capacity at glass transition (at const. pressure) were measured with differential scanning microcalorimetry (DSC) technique. Molar volumes were calcd. with Barton group contribution method. The exptl. soly. data were correlated by means of three commonly known G E equations: the Wilson, NRTL and UNIQUAC with the assumption that the systems studied here have revealed simple eutectic mixts. The root-mean-square deviations of temp. were used for the precision of the correlation. The activity coeffs. of drugs at satd. solns. in each correlated binary mixt. were calcd. from the exptl. data. These new data will help in all prediction-methods and their precision.
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    42. 42
      Attwood, D.; Boitard, E.; Dubès, J.-P.; Tachoire, H. Calorimetric study of the influence of electrolyte on the micellisation of phenothiazine drugs in aqueous solution. J. Phys. Chem. B 1997, 101, 9586,  DOI: 10.1021/jp9721863
      42
      Calorimetric Study of the Influence of Electrolyte on the Micellization of Phenothiazine Drugs in Aqueous Solution
      Attwood, D.; Boitard, E.; Dubes, J.-P.; Tachoire, H.
      Journal of Physical Chemistry B (1997), 101 (46), 9586-9592CODEN: JPCBFK; ISSN:1089-5647. (American Chemical Society)
      Apparent molar enthalpies were detd. as a function of concn. by heat conduction calorimetry for aq. solns. of the phenothiazine drugs chlorpromazine-HCl, promethazine-HCl, and promazine-HCl in the presence of added electrolyte (0.025-0.10 mol dm-3 NaCl). The concn. dependence of the apparent molar enthalpy was quant. described using a mass action model of assocn. based on the Guggenheim equations for the activity coeffs. for mixed electrolytes. Derived values of the monomer-counterion interaction coeff. became increasingly neg. with increase of salt concn., suggesting that electrolyte addn. promoted assocn. at concns. below the crit. micelle concn. (cmc). Calcns. of the fraction of each drug in the form of micelles as a function of concn. further confirmed the tendency for premicellar assocn. Significant differences in properties were obsd. between promethazine and the other two drugs. The micellization of this drug became increasingly exothermic with increase of electrolyte concn., whereas the micellization of both chlorpromazine and promazine became increasingly endothermic. Moreover, the premicellar assocn. of promethazine was more pronounced, the predicted fraction of drug in micellar form at the cmc increasing from 2.6% in water to 65% in 0.1 mol dm-3 NaCl.
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    43. 43
      Attwood, D.; Natarjan, R. Micellar properties of chlorpromazine hydrochloride in concentrated electrolyte solutions. J. Pharm. Pharmacol. 1983, 35, 317,  DOI: 10.1111/j.2042-7158.1983.tb02941.x
      43
      Micellar properties of chlorpromazine hydrochloride in concentrated electrolyte solutions
      Attwood, D.; Natarajan, R.
      Journal of Pharmacy and Pharmacology (1983), 35 (5), 317-19CODEN: JPPMAB; ISSN:0022-3573.
      The assocn. of chlorpromazine-HCl (I-HCl) [69-09-0] in aq. NaCl solns. (up to 0.6 mol/dm3) was investigated by light scattering techniques. Measurements were made at 303K with a photogoniodiffusometer at 546 nm. At low electrolyte concns., plots of m2/ΔS90 (S = light scattering intensity) against the molality of the micellar species m (where ΔS90 = S90-S90cmc, and cmc = crit. micellar concn.) were linear with pos. slopes. For higher electrolyte concns., such plots are anomolous, with a pronounced increase in the mean size of aggregates with increasing soln. concn. above the cmc. The std. free energy of micellization was calcd. to be 34.4 kJ/mol. Thus, a very pronounced increase in micellar size and polydispersity in high electrolyte concn. was obsd.
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    44. 44
      Attwood, D.; Mosquera, V.; Villar, V. P. Thermodynamic properties of amphiphilic drugs in aqueous solution. J. Chem. Soc., Faraday Trans 1 1989, 85, 3011,  DOI: 10.1039/f19898503011
      44
      Thermodynamic properties of amphiphilic drugs in aqueous solution
      Attwood, David; Mosquera, Victor; Villar, Vicente Perez
      Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases (1989), 85 (9), 3011-17CODEN: JCFTAR; ISSN:0300-9599.
      Osmotic and activity coeffs. and excess free energies have been derived as functions of concn. from vapor pressure measurements on aq. solns. of the amphiphilic drugs chlorpromazine, promethazine, and imipramine at 308 and 313 K. The concn. dependence of the osmotic coeff. could be described using a mass-action model of assocn. Aggregation nos. and the degree of micellar ionisation have been predicted from the osmotic data and compared with the values derived by time-averaged light-scattering methods. Temp. increased the crit. micelle concn. but had no measurable influence on the aggregation no.
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    45. 45
      Attwood, D.; Waigh, R.; Blundell, R.; Bloor, D.; Thévand, A.; Boitard, E.; Dubès, J.-P.; Tachoire, H. 1H and 13C NMR studies of the self-association of chlorpromazine hydrochloride in aqueous solution. Magn. Reson. Chem. 1994, 32, 468,  DOI: 10.1002/mrc.1260320807
      45
      1H and 13C NMR studies of the self-association of chlorpromazine hydrochloride in aqueous solution
      Attwood, David; Waigh, Roger; Blundell, Ross; Bloor, Debra; Thevand, Andre; Boitard, Elizabeth; Dubes, Jean-Paul; Tachoire, Henri
      Magnetic Resonance in Chemistry (1994), 32 (8), 468-72CODEN: MRCHEG; ISSN:0749-1581.
      The 1H NMR spectrum of chlorpromazine hydrochloride was fully assigned at 400 MHz. Similarly, the 13C NMR spectrum was assigned unambiguously using two-dimensional NMR. Measurements of chem. shift as a function of concn. in D2O showed appreciable changes of shift of both protons and carbons which were apparent even at soln. concns. two orders of magnitude lower than the crit. micelle concn. (CMC). The relative magnitude of the shifts of the arom. protons and carbons on diln. below the CMC were compatible with vertical stacking of the mols. in an off-set manner such that max. overlap of the chlorinated rings occurred. Proton chem. shift data were interpreted using a stepwise assocn. model to quantify the extent of assocn. in the pre-CMC region.
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    46. 46
      Pérez-Rodríguez, M.; Varela, L. M.; Taboada, P.; Attwood, D.; Mosquera, V. The temperature dependence of the micellisation of chlorpromazine hydrochloride in aqueous solution. Colloid Polym. Sci. 2000, 278, 706,  DOI: 10.1007/s003960000331
      46
      The temperature dependence of the micellization of chlorpromazine hydrochloride in aqueous solution
      Perez-Rodriguez, M.; Varela, L. M.; Taboada, P.; Attwood, D.; Mosquera, V.
      Colloid and Polymer Science (2000), 278 (7), 706-709CODEN: CPMSB6; ISSN:0303-402X. (Springer-Verlag)
      The assocn. characteristics of the weakly assocg. drug chlorpromazine-HCl were examd. over the temp. range 10-35° by means of conductometric measurements. Crit. micelle concns. (cmc) have been detd. by the application of a recently developed numerical method esp. designed for the anal. of the assocn. pattern in highly polydisperse systems of low aggregation no. The cmcs detd. in this manner are used in combination with the mass-action model to obtain the thermodn. parameters of the micellization process, in particular the surface and hydrophobic contributions to the free energy. The use of exact forms of equations for the thermodn. of micellization applicable to systems of low aggregation no. leads to values of the enthalpy of micellization in reasonable agreement with exptl. detd. values.
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    47. 47
      Attwood, D.; Mosquera, V.; Novas, L.; Sarmiento, F. Micellisation in binary mixtures of amphiphilic drugs. J. Colloid Interface Sci. 1996, 179, 478,  DOI: 10.1006/jcis.1996.0240
      47
      Micellization in binary mixtures of amphiphilic drugs
      Attwood, David; Mosquera, Victor; Novas, Laura; Sarmiento, Felix
      Journal of Colloid and Interface Science (1996), 179 (2), 478-481CODEN: JCISA5; ISSN:0021-9797. (Academic)
      The compn. of the micelles in binary mixts. of the cationic amphiphilic drugs (a) chloropromazine and promethazine and (b) chloropromazine and adiphenine has been detd. from an anal. of the variation of the crit. micelle concn., as measured by cond. techniques, as a function of soln. compn. Evaluation of the nonideality of mixing of the components of the mixed micelles using a regular soln. approxn. revealed ideality of mixing in the chlorpromazine/promethazine system. Mixing in the chlorpromazine/adiphenine system did not deviate significantly from ideality despite differences in the structure and packing characteristics of these two drugs.
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    48. 48
      Attwood, D.; Florence, A. T.; Gillan, J. M. N. Micellar properties of drugs: properties of micellar aggregates of phenothiazines and their aqueous solutions. J. Pharm. Sci. 1974, 63, 988,  DOI: 10.1002/jps.2600630649
      48
      Micellar properties of drugs. Properties of micellar aggregates of phenothiazines and their aqueous solutions
      Attwood, D.; Florence, A. T.; Gilla, J. M. N.
      Journal of Pharmaceutical Sciences (1974), 63 (6), 988-93CODEN: JPMSAE; ISSN:0022-3549.
      The soln. properties of a series of phenothiazine hydrochlorides were studied using light-scattering, viscosity, conductivity, dialysis, and NMR techniques. The aggregates formed are considered to be true micelles, which in water are probably composed of about 10 monomers vertically stacked, with the alkyl side chain and nitrogen group alternating to form an approx. spherical unit in soln. In the presence of NaCl the micelles grow and it is thought that the conformation of the aggregate also changes. Calcns. of the monomer concn. as a function of total drug concn. above the CMC's give good agreement with data obtained previously from NMR shift data. The free energy of inserting a monomer into a micelle was calcd.and the values obtained are discussed in the light of free energies of soln. of the hydrophobic bases. The significance of aggregation, mixed micelle formation, and complexation in biol. and pharmaceutical systems contg. phenothiazines is discussed.
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    49. 49
      Attwood, D.; Mosquera, V.; Rey, C.; Vasquez, E. Self-association of amphiphilic phenothiazine drugs in aqueous solutions of low ionic strength. J. Chem. Soc., Faraday Trans. 1991, 87, 2971,  DOI: 10.1039/ft9918702971
      49
      Self-association of amphiphilic phenothiazine drugs in aqueous solutions of low ionic strength
      Attwood, David; Mosquera, Victor; Rey, Carlos; Vasquez, Esperanza
      Journal of the Chemical Society, Faraday Transactions (1991), 87 (18), 2971-3CODEN: JCFTEV; ISSN:0956-5000.
      Osmotic coeffs. have been derived from freezing pont detns. on aq. solns. of the amphiphilic drugs, chlorpromazine and promethazine-HCl, in the presence of low concns. of added electrolyte (0.01-0.05 mol kg-1 NaCl). Aggregation nos. predicted by the application of a mass action theory to the osmotic data were in agreement with exptl. values detd. by time-averaged light scattering methods.
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    50. 50
      Attwood, D.; Dickinson, N. A.; Mosquera, V.; Villar, V. P. Osmotic and activity coefficients of amphiphilic drugs in aqueous solution. J. Phys. Chem. E 1987, 91, 4203,  DOI: 10.1021/j100299a050
      50
      Osmotic and activity coefficients of amphiphilic drugs in aqueous solution
      Attwood, D.; Dickinson, N. A.; Mosquera, V.; Villar, V. Perez
      Journal of Physical Chemistry (1987), 91 (15), 4203-6CODEN: JPCHAX; ISSN:0022-3654.
      Osmotic and activity coeffs. were derived from vapor-pressure measurements on aq. solns. of the amphiphilic drugs promethazine-HCl, chlorpromazine-HCl, clomipramine-HCl, and imipramine-HCl. A mass action model of assocn., based on the Guggenheim equations for the activity coeffs. of mixed electrolyte solns. as proposed by Burchfield and Wooley (1984), quant. described the concn. dependence of the osmotic coeff. for molalities up to 0.25 mol kg-1.
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    51. 51
      Ruso, J. M.; Attwood, D.; Taboada, P.; Suárez, M. J.; Sarmiento, F.; Mosquera, V. Activity and osmotic coefficients of promethazine and chlorpromazine hydrochlorides in aqueous solutions of low ionic strength. J. Chem. Eng. Data 1999, 44, 941,  DOI: 10.1021/je990001a
      51
      Activity and Osmotic Coefficients of Promethazine and Chlorpromazine Hydrochlorides in Aqueous Solutions of Low Ionic Strength
      Ruso, Juan M.; Attwood, David; Taboada, Pablo; Suarez, Maria J.; Sarmiento, Felix; Mosquera, Victor
      Journal of Chemical and Engineering Data (1999), 44 (5), 941-943CODEN: JCEAAX; ISSN:0021-9568. (American Chemical Society)
      Osmotic and activity coeffs. of amphiphilic drugs chlorpromazine hydrochloride and promethazine hydrochloride in aq. solns. have been derived from vapor pressure measurements, in the presence of low concns. of added electrolyte (0.000, 0.010, 0.025, and 0.050 mol kg-1 NaCl) at the temp. 303.15 K. From these results an inflection point was detected for both phenothiazine drugs identified as a crit. concn.
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    52. 52
      Perez-Villar, V.; Vazquez-Iglesias, M. E.; de Geyer, A. Small-angle neutron scattering studies of chlorpromazine micelles in aqueous solutions. J. Phys. Chem. F 1993, 97, 5149,  DOI: 10.1021/j100121a050
      52
      Small-angle neutron scattering studies of chlorpromazine micelles in aqueous solutions
      Perez-Villar, V.; Vazquez-Iglesias, M. E.; de Geyer, A.
      Journal of Physical Chemistry (1993), 97 (19), 5149-54CODEN: JPCHAX; ISSN:0022-3654.
      Small-angle neutron scattering (SANS) data for aq. (D2O) solns. of chlorpromazine hydrochloride (with and without added 0.025 m NaCl) are analyzed. This tranquilizing drug (based on the phenothiazine ring system) gives ionic micellar solns. characterized by pronounced interparticle correlations which result from a strong electrostatic interaction between the macroions. The model for fitting SANS data takes into account the effect of size polydispersity on the intensity distribution function I(Q) and computes the intermicellar structure factor by using the generalized 1-component macroion theory, solving the Orstein-Zernike equation in the rescaled mean spherical approxn., and considering a screened Coulomb interparticle interaction potential between micelles, following the procedure of J. Hayter and J. Penfold (1981). The SANS data fittings for different concns. allow one to obtain some structural and thermodynamical parameters (e.g., free energies of formation and growth, min. aggregation nos., polydispersity index).
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    53. 53
      Alam, M. S.; Naqvi, A. Z.; ud Din, K. Study of the cloud point of the phenothiazine drug chlorpromazine hydrochloride: effect of surfactants and polymers. J. Dispersion Sci. Technol. 2008, 29, 274,  DOI: 10.1080/01932690701707597
      53
      Study of the Cloud Point of the Phenothiazine Drug Chlorpromazine Hydrochloride: Effect of Surfactants and Polymers
      Alam, Md. Sayem; Naqvi, Andleeb Z.; Kabir-ud-Din
      Journal of Dispersion Science and Technology (2008), 29 (2), 274-279CODEN: JDTEDS; ISSN:0193-2691. (Taylor & Francis, Inc.)
      Surfactants/polymers are used extensively in drug delivery as drug carriers. The authors herein report the effect of surfactants and polymers on the cloud point (CP) of amphiphilic drug chlorpromazine hydrochloride. At fixed drug concn. (50 mM) and pH (6.7) these additives affect the CP in accordance to their nature and structure: anionic surfactants show an increase followed by a decrease, whereas cationic (conventional as well as gemini) and nonionic surfactants show continuous increase. The behavior with polymers is dictated by the no. of units present in a particular polymer. Increase in drug concn. and pH, in presence of fixed amts. of CTAB, increases and decreases the CP, resp. Variation of CP with pH at various fixed gemini concns. shows that gemini surfactants are better candidates for drug delivery.
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    54. 54
      Dea, P. K.; Keyzer, H. Conformation and Electronic Aspects of Chlorpromazine in Solution. In Modern Bioelectrochemistry; Gutman, F.; Keyzer, H., Eds.; Plenum Press: New York, 1986; p 481.
      There is no corresponding record for this reference.
    55. 55
      Atherton, A. D.; Barry, B. W. Micellar properties of phenothiazine drugs: a laser light scattering study. J. Colloid Interface Sci. 1985, 106, 479,  DOI: 10.1016/S0021-9797(85)80023-0
      55
      Micellar properties of phenothiazine drugs: a laser light scattering study
      Atherton, A. Dianne; Barry, Brian W.
      Journal of Colloid and Interface Science (1985), 106 (2), 479-89CODEN: JCISA5; ISSN:0021-9797.
      Photon-correlation spectroscopy was used to examine the effects of drug and electrolyte concn. and 0.154M Na halide, sulfate, and phosphate upon phenothiazine-HCl salts crit. micelle concns. (CMCs) and micellar sizes, Rh, for promazine-HCl [53-60-1], chlorpromazine-HCl [69-09-0], promethazine-HCl [58-33-3], triflupromazine-HCl [1098-60-8], and thioridazine-HCl [130-61-0]. Rh Values were sensitive to drug and electrolyte concn. Interpretation of the data at low electrolyte concn. was complicated by micellar interactions. In increasing NaCl concns. CMCs decreased and micellar sizes increased markedly leading to phase sepn. in triflupromazine and chlorpromazine solns. Micellar size increased in electrolyte solns. in the order F < Cl < Br < SO4. Complexes formed in iodide and phosphate solns. A mode of aggregation by stacking is proposed, with sizes increasing by addn. of single monomers to the stacks and by addn. of more stacks until phase sepn. occurs.
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    56. 56
      Barbosa, L. R. S.; Caetano, W.; Itri, R.; de Mello, P. H.; Santiago, P. S.; Tabak, M. Interaction of phenothiazine compounds with zwitterionic lysophosphatidylcholine micelles: small angle X-ray scattering, electronic absorption spectroscopy and theoretical calculations. J. Phys. Chem. B 2006, 110, 13086,  DOI: 10.1021/jp056486t
      56
      Interaction of Phenothiazine Compounds with Zwitterionic Lysophosphatidylcholine Micelles: Small Angle X-ray Scattering, Electronic Absorption Spectroscopy, and Theoretical Calculations
      Barbosa, Leandro R. S.; Caetano, Wilker; Itri, Rosangela; Homem-de-Mello, Paula; Santiago, Patricia S.; Tabak, Marcel
      Journal of Physical Chemistry B (2006), 110 (26), 13086-13093CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
      Small-angle x-ray scattering (SAXS) studies on the interaction of the phenothiazine cationic compds. trifluoperazine (TFP, 2-10 mM) and chlorpromazine (CPZ, 2-10 mM) with micelles of the zwitterionic surfactant L-α-lysophosphatidylcholine (LPC, 30 mM), at pHs 4.0 and 7.0, are reported. The SAXS results demonstrate that, upon addn. of both phenothiazines, the LPC micelle of prolate ellipsoidal shape changes into a cylindrically shaped micelle, increasing its axial ratio from 1.6 ± 0.1 (in the absence of drug) to 2.5 ± 0.1 (for 5 and 10 mM of phenothiazine). Such an effect is accompanied by a shrinking of the paraffinic shortest semiaxis from 22.5 ± 0.3 to 20.0 ± 0.5 Å. Besides, a significant increase in polar shell electron d. from 0.39(1) to 0.45(1) e/Å3 is obsd., consistent with cylinder-like aggregate geometry. Also, an increase of the phenothiazine concn. induces the appearance of a repulsive interference function over the SAXS curve of zwitterionic micelles, which is typical of interaction between surface-charged micelles. Such a finding provides evidence that the pos. charged phenothiazine mol. must be accommodated near the hydrophobic/hydrophilic inner micellar interface in such a way that a net surface charge is altered with respect to the original overall neutral zwitterionic micelle. Such phenothiazine location is favored by both electrostatic and hydrophobic contributions, giving rise to binding const. values, obtained from electronic absorption results, that are quite larger compared to their binding to another zwitterionic surfactant, 3-(N-hexadecyl-N,N-dimethylammonio)propanesulfonate (HPS) (Caetano, W., et al. J. Colloid Int. Sci. 2003, 260, 414-422). Comparisons are made by theor. calcns. of the surfactant headgroup dipole moments for monomers of LPC and HPS. The theor. results show that the dipole moment in LPC is almost perpendicular to the methylene chain, while a significant contribution along the methylene chain occurs for HPS. Besides, evidence is presented for extensive delocalization of the charges in the headgroups, which could be also relevant for the binding of the drugs.
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    57. 57
      Numerous studies have reported the voltammetry or redox transformation of N-substituted phenothiazine derivatives, as given in references 58-67.
      There is no corresponding record for this reference.
    58. 58
      Horn, J. J.; McCreedy, T.; Wadhawan, J. Amperometric measurement of gaseous hydrogen sulphide via a Clark-type approach. Anal. Methods 2010, 2, 1346,  DOI: 10.1039/c0ay00338g
      58
      Amperometric measurement of gaseous hydrogen sulfide via a Clark-type approach
      Horn, Jason J.; McCreedy, Tom; Wadhawan, Jay
      Analytical Methods (2010), 2 (9), 1346-1354CODEN: AMNEGX; ISSN:1759-9679. (Royal Society of Chemistry)
      The direct oxidn. of hydrogen sulfide in the range 2.0-20 ppm by vol. (ppmv) using a Clark-type amperometric gas sensing methodol. is investigated via amperometric transients at 298 K. The diluent gas employed is air (20.9% O2 in N2), and it is shown that the obsd. current transients are limited by transport through the membrane covering, reaching a steady-state value within at least 200 s for one of the manifestations described. The measurement system presented is shown to be operational over a long time (tens of hours), provided certain quantification protocols are employed; the latter are suggested as pragmatic guidelines for the deployment of this detection methodol. Importantly and notably, it is shown that readily-oxidizable gases such as carbon monoxide and mol. hydrogen are obsd. not to interfere with the measurement quantification.
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    59. 59
      Huie, R. E.; Neta, P. Reaction of the vanadate ion with chlorpromazine and the chlorpromazine free radical with the vanadyl ion. Inorg. Chim. Acta 1984, 93, L27,  DOI: 10.1016/S0020-1693(00)87887-1
      59
      Reaction of the vanadate ion with chlorpromazine and the chlorpromazine free radical with the vanadyl ion
      Huie, Robert E.; Neta, P.
      Inorganica Chimica Acta (1984), 93 (2), L27-L28CODEN: ICHAA3; ISSN:0020-1693.
      The reaction V(V) + ClPz ↹ V(IV) + ClPz+· (ClPz = chlorpromazine) was studied by stopped-flow spectrometry and pulsed radiolysis methods. Oxidn. occurs at pH > 4. The forward and reverse rate consts. are given.
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    60. 60
      Roseboom, H.; Perrin, J. H. Oxidation kinetics of phenothiazine and 10-methylphenothiazine in acidic medium. J. Pharm. Sci. 1977, 66, 1392,  DOI: 10.1002/jps.2600661010
      60
      Oxidation kinetics of phenothiazine and 10-methylphenothiazine in acidic medium
      Roseboom, H.; Perrin, J. H.
      Journal of Pharmaceutical Sciences (1977), 66 (10), 1392-5CODEN: JPMSAE; ISSN:0022-3549.
      The rate of phenothiazine degrdn. in an acidic oxygen-satd. medium was studied. 3H-phenothiazin-3-one and phenothiazine 5-oxide are produced by parallel reactions, and 7-(10'-phenothiazinyl)-3H-phenothiazine-3-one is produced in a more complex manner. The overall phenothiazine degrdn. rate appears to be pH independent up to pH 7.0. The degrdn. kinetics of 10-methylphenothiazine were studied after isolation and identification of its degrdn. products, 10-methylphenothiazine 5-oxide and 3H-phenothiazine-3-one. The main degrdn. product is 10-methylphenothiazine 5-oxide; but at low pH values and high temps., more 3H-phenothiazine-3-one is formed. The degrdn. rate of 10-methylphenothiazine is pH independent up to pH 7.
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    61. 61
      Karpińska, J.; Starczewska, B.; Puzanowska-Tarasiewicz, H. Analytical properties of 2- and 10-disubsituted phenothiazine derivatives. Anal. Sci. 1996, 12, 161,  DOI: 10.2116/analsci.12.161
      61
      Analytical properties of 2- and 10-disubstituted phenothiazine derivatives
      Karpinska, J.; Starczewska, B.; Puzanowska-Tarasiewicz, H.
      Analytical Sciences (1996), 12 (2), 161-70CODEN: ANSCEN; ISSN:0910-6340. (Japan Society for Analytical Chemistry)
      A review with 74 refs. Phenothiazine derivs. substituted in the 2 and 10 positions belong to a big group of tricyclic arom. compds. They are in extensive use in psychiatry as tranquilizers and neuroleptics. Due to their characteristic structure they exhibit many valuable anal. properties. They are easily oxidized in an acidic medium while generating color products. They also react with some thiocyanate and halide complexes of metals as well as some org. compds., and form well-defined ion-assocn. complexes. The properties mentioned above are the basis for using the phenothiazine derivs. as reagents for chem. anal. The phys. and chem. properties of 2,10-disubstituted phenothiazine derivs. are described in the presented paper. The paper is divided into seven parts. The 1st chapter presents the phys. properties of the phenothiazine derivs., such as their phys. state, thermal stability and soly. The next part of the paper is devoted to the spectral properties of 2,10-disubstituted phenothiazine derivs. The influence of the type of substituents on the intensity and shape of the UV and fluorescence spectra of phenothiazine derivs. are discussed. Chapters 4 and 5 show the run and the mechanism of phenothiazine derivs. oxidn., their electrochem. properties and the anal. aspects of the described processes. Chapter 6 of the present paper is devoted to the complexing abilities of the phenothiazine derivs. The paper is based on a review of the chem. literature up to 1995. A short specification of the anal. methods using the phys. and chem. properties of the phenothiazine derivs. is also included.
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    62. 62
      Cauquis, G.; Deronzier, A.; Lepage, J.-L.; Serve, D. Une nouvelle étude de l′oxydation électrochimique dy noyau phénothiazinique I: cas de la phénothiazine et de ses derives disubstitués en 3 et 7. Bull. Soc. Chim. Fr. 1977, 295
      62
      A new study of the electrochemical oxidation of the phenothiazine ring. I. The case of phenothiazine and its 3 and 7 disubstituted derivatives
      Cauquis, Georges; Deronzier, Alain; Lepage, Jean Luc; Serve, Denis
      Bulletin de la Societe Chimique de France (1977), (3-4, Pt. 2), 295-302CODEN: BSCFAS; ISSN:0037-8968.
      The anodic processes of some 3,7-disubstituted phenothiazines and of N-methylphenothiazine [1207-72-3] in various acidic and alk. media in MeCN were studied. Depending on the medium, the oxidn. of the N-unsubstituted phenothiazines, which enclose the NH group, allows one to observe as a rule 6 species. In alk. medium, a 1-electron transfer results in the neutral free radical which, in some cases, dimerizes to give just the 1,10'- and 3,10'-biphenothiazinyls. The other species produced in acidic media are sufficiently stable to be unambiguously characterized. The oxidn. mechanism which is an EEC one in acidic media becomes progressively an ECE and a CEE one when increasing the basicity. The N-methylphenothiazine gives the sulfoxide through the radical cation. This sulfoxide is also oxidized to give the disulfoxide of a biphenothiazinyl.
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    63. 63
      Cauquis, G.; Deronzier, A.; Lepage, J.-L.; Serve, D. Une nouvelle étude de l′oxydation électrochimique dy noyau phénothiazinique II: cas de quelques biphénothiazinyles-1,10′ et −3,10′. Bull. Soc. Chim. Fr. 1977, 303
      63
      A new study of the electrochemical oxidation of the phenothiazine ring. II. The case of some 1,10- and 3,10'-biphenothiazinyls
      Cauquis, Georges; Deronzier, Alain; Lepage, Jean Luc; Serve, Denis
      Bulletin de la Societe Chimique de France (1977), (3-4, Pt. 2), 303-9CODEN: BSCFAS; ISSN:0037-8968.
      Neutral radicals produced from the anodic oxidn. of various phenothiazines dimerize into 3,10'- and 1,10'-biphenothiazinyls. These compds. are models of mols. with 2 electroactive centers included in resonant systems which have various levels of conjugation. Their anodic oxidn. in MeCN allows one to characterize the diverse cationic and/or new radical species and also to show the influence that conjugation of the 2 phenothiazine entities has on the spectroscopic properties of these species and on the electrochem. processes. The various mechanisms leading to these species are described.
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    64. 64
      Billon, J.-P. Etude électrochimique des propriétés oxydo-réductrices des phénothiazines dans l′acétonitrile. Ann. Chim. 1962, 7, 183
      64
      Electrochemistry of the oxidation-reduction properties of phenothiazines in acetonitrile
      Billon, Jean Pierre
      (1962), 7 (), 183-206 ISSN:.
      cf. CA 55, 15183f. Potentiometric curves of phenothiazine (I) and some of its derivs. in MeCN (generally contg. 0.1M HClO4) were detd. by using a rotating bright Pt electrode and LiClO4 as inert electrolyte. In general, oxidn. occurred more readily at high pH. I was reversibly oxidized in 2 steps to give the free radical II (unstable in alk. media; perchlorate obtained from 0.24 g. I, 0.26 g. S-hydroxyphenothiazine, and 10 ml. 65% HClO4, green crystals, orange in MeCN, decomp. 175°) and the phenazothionium salt (III) [red-violet crystals, obtained also from 0.5 g. 9-hydroxyphenothiazine (IV) and 10 cc. 65% HClO4]. NaOH and III gave IV. On addn. of 0.4-6% H2O to the solvent during the electrochem. oxidn. of I, the 2nd step occurred at a lower potential. H2O reacted with III to give a green compd. (V) (λ 650, 625, 455 mμ). On addn. of 7% H2O, the electrochem. oxidn. of I gave V only. A soln. of II in neutral media gave V and I on addn. of H2O. Addn. of H2O to III gave V. Attempted purification of V by chromatography on Al2O3 gave 2-phenothiazone (VI) and a blue product (λ 660 mμ). On increasing the HClO4 concn. in the electrochem. oxidn. of I from 10-2 to 10-1M, the 2nd stage occurred at a lower potential. Addn. of a base (diphenylguanidine) in the electrochem. oxidn. of I facilitated oxidn. of II to III, but a no. of side reactions occurred. The presence of a Me in the lateral rings of I facilitated the electrochem. oxidn. II could oxidize chem. all these derivs. (free radicals and phenazothionium salts). The phenazothionium cations of the 2- and 3-Me derivs. gave with H2O green products; the disubstituted cation was stable to H2O, but with strong bases gave a colorless sulfoxide deriv. 10-Methylphenothiazine and 2,7,10-trimethylphenothiazine (VII) were more difficultly oxidized electrochem. than the corresponding compds. not contg. the N-Me group. An electrochem. study of oxidn. of the N-Me compds. (or of chlorpromazine) showed that the 1st step gave the colored free radical, but the 2nd step gave the sulfoxide deriv. (VIII). The expected orthoquinone bivalent cation (IX) was formed, in the electrochem. oxidn. of VII in the presence of only 0.002% H2O, as an intermediate that later reacted with H2O to give the sulfoxide. The influence of substituents on the oxidn. potential of X was studied for the following compds. [R, R1, and R2 given, where A = (CH2)3NMe2, B = CH2CHMeCH2NMe2, and C = 3-(4-methyl-1-piperazinyl)propyl]: OEt, H, A; OMe, H, B; OMe, H, A; H, OMe, A; Me, H, A; Et, H, A; H, H, A; SMe, H, B; H, Cl, A; Cl, H, A; Cl, H, C; COMe, H, A; CHO, H, C; COPr, H, C; CF3, H, A; SO2NMe2, H, A; SO2NMe2, H, C; CN, H, A; SO2Me, H, C; and NO2, H, A. VI in acid media in MeCN gave 1st a purple free radical and then 2-hydroxyphenothiazine (XI). Addn. of acid caused a color change from red to purple; this was due to the formation of a 2-hydroxyphenazothionium ion. This change was reversible. In acid or neutral media XI was directly oxidized to the phenazothionium salt, which was converted to VI by action of a base. In many cases the results were confirmed by studies of the ultraviolet and visible spectra and of electron paramagnetic resonance.
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    65. 65
      Humphry-Baker, R.; Braun, A. M.; Grätzel, M. Effect of self-assembly of amphiphilic redox chromophores on photoionisation processes. Helv. Chim. Acta 1981, 64, 2036,  DOI: 10.1002/hlca.19810640708
      65
      Effect of self-assembly of amphiphilic redox-chromophores on photoionization processes
      Humphry-Baker, Robin; Braun, Andre M.; Graetzel, Michael
      Helvetica Chimica Acta (1981), 64 (7), 2036-47CODEN: HCACAV; ISSN:0018-019X.
      The photochem. behavior of Na 12-(10-phenothiazinyl)dodecyl-1-sulfonate underwent change upon micellization. In particular, monophotonic photoionization was obsd. only above the crit. micelle concn. The net effect of micelle formation was to enhance the cation yield and to decrease the yield of triplets obsd. The results were explained in terms of local electrostatic barriers within the micelle.
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    66. 66
      Grätzel, M. Interfacial Charge Transfer Reactions in Colloidal Dispersions and Their Application to Water Cleavage by Visible Light. In Modern Aspects of Electrochemistry; Plenum Press: New York, 1983; Vol. 15, p 83.
      There is no corresponding record for this reference.
    67. 67
      Krieg, M.; Pileni, M.-P.; Braun, A. M.; Grätzel, M. Micelle formation and surface activity of functional redox relays: viologens substituted by a long alkyl chain. J. Colloid Interface Sci. 1981, 83, 209,  DOI: 10.1016/0021-9797(81)90025-4
      67
      Micelle formation and surface activity of functional redox relays: viologens substituted by a long alkyl chain
      Krieg, Marianne; Pileni, Marie Paule; Braun, Andre M.; Graetzel, Michael
      Journal of Colloid and Interface Science (1981), 83 (1), 209-13CODEN: JCISA5; ISSN:0021-9797.
      Suitable mol. organizates are being developed for efficient and simultaneous prodn. of H and O from H2O under illumination with visible light. The crit. micelle concn. of surface-active asym. substituted alkyl viologens was detd. by surface-tension measurements and spectroscopic investigations.
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    68. 68
      Rusling, J. F. Electrochemistry in Micelles and Microemulsions. In Interfacial Kinetics and Mass Transport; Calvo, E. J., Ed.; Wiley: Weinheim, 2003; Vol. 2, p 418.
      There is no corresponding record for this reference.
    69. 69

      See, for example

      Gooding, J. J.; Compton, R. G.; Brennan, C. M.; Atherton, J. H. A new electrochemical method for the investigation of the aggregation of dyes in solution. Electroanalysis 1997, 9, 759,  DOI: 10.1002/elan.1140091006
      69
      A new electrochemical method for the investigation of the aggregation of dyes in solution
      Gooding, Justin J.; Compton, Richard G.; Brennan, Colin M.; Atherton, John H.
      Electroanalysis (1997), 9 (10), 759-764CODEN: ELANEU; ISSN:1040-0397. (Wiley-VCH)
      A new electrochem. technique is presented for the investigation of aggregation phenomena in soln. over a wide range of soln. conditions. Developed nominally for dyes, the method is, in principle, applicable to any electroactive compd. The method employs microelectrodes to measure the change in the diffusion-limited current, with concn., of the aggregating species of interest. At the onset of aggregation, the relationship between this limiting current and concn. deviates from linearity. This deviation, due to the slower rate of diffusion of aggregates, is related to the degree of assocn. of the mol., assuming a mol. wt. distribution of aggregates and using an established relationship between the effective diffusion coeff. and mol. wt. The technique is contrasted with an existing spectroscopic method.
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    70. 70
      Anicet, N.; Bourdillon, C.; Demaille, C.; Moiroux, J.; Savéant, J.-M. Catalysis of the electrochemical oxidation of glucose by glucose oxidase and a single electron co-substrate: kinetics in viscous solutions. J. Electroanal. Chem. 1996, 410, 199,  DOI: 10.1016/0022-0728(96)04558-5
      70
      Catalysis of the electrochemical oxidation of glucose by glucose oxidase and a single electron cosubstrate: kinetics in viscous solutions
      Anicet, Nathalie; Bourdillon, Christian; Demaille, Christophe; Moiroux, Jacques; Saveant, Jean-Michel
      Journal of Electroanalytical Chemistry (1996), 410 (2), 199-202CODEN: JECHES ISSN:. (Elsevier)
      Catalysis of the electrochem. oxidn. of glucose by glucose oxidase with a single electron mediator (cosubstrate) may be used to transform mixts. of concd. industrial sugars. How the high viscosity of such media may affect the enzymic reaction and the transport of the mediator can be mimicked by addn. of large concns. of sucrose to glucose solns. Cyclic voltammetry then provides a simple means of investigating the effect of an increased viscosity on the kinetics of the enzymic reaction and the diffusion of the mediator. The diffusion coeff. of the mediator is decreased 10 times by addn. of 1.6 M sucrose. At pH 8, in the presence of the same concn. of sucrose, the catalytic activity of the enzyme towards its substrate is only slightly affected. A 35% decrease of the glucose Michaelis const. is obsd. The reaction of the reduced enzyme with the cosubstrate is six times slower and the mediator Michaelis const. undergoes a three-fold increase. It follows that glucose oxidase remains an efficient catalyst in such viscous media.
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    71. 71
      Fahidy, T. Z. Principles of Electrochemical Reactor Analysis, Elsevier: Amsterdam, 1985.
      There is no corresponding record for this reference.
    72. 72
      Halls, J. E.; Wadhawan, J. D. Photogalvanic cells based on lyotropic nanosystems: towards the use of liquid nanotechnology for personalised energy sources. Energy Environ. Sci. 2012, 5, 6541,  DOI: 10.1039/c2ee03169h
      72
      Photogalvanic cells based on lyotropic nanosystems: towards the use of liquid nanotechnology for personalised energy sources
      Halls, Jonathan E.; Wadhawan, Jay D.
      Energy & Environmental Science (2012), 5 (4), 6541-6551CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)
      A lightwt., autonomous and practical, proof-of-concept elec. power source is developed within this work. It comprises a photoredox-active material embedded within the non-ionic surfactant subphase, with a second redox reagent present within the aq. pseudophase of a lamellar (Lα) lyotropic liq. crystal framework, which is sandwiched between two electrodes, one of which acts in a sacrificial manner. This quasi-biphasic, entirely new-concept, electrochem. cell, based on electron transfer, rather than ion transfer, is shown to act as a photogalvanic device which, under violet light, is demonstrated to exhibit max. light-to-elec. power conversion efficiency of ca. 2% (fill factor of 15%), with addnl. ability to act as an elec.-rechargeable electrochem. capacitor of voltage efficiency ∼85% and power efficiency ∼80%, and with estd. max. energy d. of ∼1 W h kg-1 at a power d. of ∼1 kW kg-1.
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    73. 73
      Ekdawi, N.; Hunter, R. J. Couette flow behaviour of coagulated colloidal suspensions, part IV: the elastic floc model at low shear rates. J. Colloid Interface Sci. 1983, 94, 355,  DOI: 10.1016/0021-9797(83)90274-6
      73
      Couette flow behavior of coagulated colloidal suspensions. VI. The elastic floc model at low shear rates
      Ekdawi, Nagi; Hunter, Robert J.
      Journal of Colloid and Interface Science (1983), 94 (2), 355-61CODEN: JCISA5; ISSN:0021-9797.
      The elastic floc model was extended from the high shear rate region to low shear rate. The flow behavior of a coagulated sol (monodisperse PMMA latex in water and glycerol/water mixts.) is described very well by using the same concepts as were successful at high shear rates. At low shear the flocs retain their integrity but form aggregates; the suspension medium appears to be able to flow between the flocs with minimal impediment, but not through them. The parameters measured at high shear rate can be carried over unchanged to describe the low shear rate behavior.
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    74. 74
      Bourgoin, D.; Shankland, W. Rheology of the lecithin-water system in its lamellar phase. Rheol. Acta 1980, 19, 226,  DOI: 10.1007/BF01521935
      74
      Rheology of the lecithin-water system in its lamellar phase
      Bourgoin, D.; Shankland, W.
      Rheologica Acta (1980), 19 (2), 226-38CODEN: RHEAAK; ISSN:0035-4511.
      Dispersions of hen egg lecithin with a water content of 5-42.5% were examd. with a Weissenberg Rheogoniometer. Each sample was previously sheared at a low shear rate to produce a steady state and the stresses arising from various mech. deformations were analyzed. The deformations were induced by steady rates of shear, or by a steady rate of shear partly modulated at various frequencies, or by pure oscillatory rates of shear. When subjected to steady rates of shear, the dispersions show a plastic flow behavior with a stress varying only a little as the rate of shear decreases to 0. When a steady rate of shear is brought abruptly to 0, a part of the stress relaxes immediately and the other part much more slowly. When submitted to a modulated rate of shear, these dispersions show the behavior of a quasi-Newtonian liq. When submitted to pure oscillatory rates of shear, they give rise to stresses in a nonlinear relation with deformations. The stresses are higher, the rougher the surfaces and the thinner the samples. A model for the sample under shear composed of a liq. sheet lying at each plate and a viscoelastic body with a high viscosity between them was proposed. In addn., it was shown that the rheol. properties of the lecithin-water system may vary quant. in an abrupt manner for small variations in the water content of the system.
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    75. 75
      Malkin, A. Y.; Patlazhan, S. A. Wall slip for complex liquids – phenomenon and its causes. Adv. Colloid Interface Sci. 2018, 257, 42,  DOI: 10.1016/j.cis.2018.05.008
      75
      Wall slip for complex liquids - Phenomenon and its causes
      Malkin, A. Ya; Patlazhan, S. A.
      Advances in Colloid and Interface Science (2018), 257 (), 42-57CODEN: ACISB9; ISSN:0001-8686. (Elsevier B.V.)
      In this review, we tried to qualify different types and mechanisms of wall slip phenomenon, paying particular attention to the most recent publications and issues. The review covers all type of fluids homogeneous low mol. wt. liqs., polymer soln., multi-component dispersed media, and polymer melts. We focused on two basic concepts fluid-solid wall interaction and shear induced fluid-to-solid transitions which are the dominant mechanisms of wall slip. The influence of nanobubbles and microcavities on the effectiveness of wall slip is illuminated with regard to the bubble dynamics, as well as their stability at smooth and rough interfaces, including superhydrophobic surfaces. Flow of multi-component matter (microgel pastes, concd. suspensions of solid particles, compressed emulsions, and colloidal systems) is accompanied by wall slip in two cases. The second case is related to the transition from fluid to solid states at high deformation rates or large deformations caused by the strain-induced glass transition of concd. dispersions. In the latter case, the wall effects consist of apparent slip due to the formation of a low viscous thin layer of fluid at the wall. The liq.-to-solid transition is also a dominant mechanism in wall slip of polymer melts because liq. polymers are elastic fluids which can be in two relaxation states depending on the strain rate. The realization of these mechanisms is detd. by polymer melt interaction with the solid wall.
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    76. 76
      Binks, B. P.; Clint, J. H.; Whitby, C. P. Rheological behaviour of water-in-oil emulsions stabilised by hydrophobic bentonite particles. Langmuir 2005, 21, 5307,  DOI: 10.1021/la050255w
      76
      Rheological Behavior of Water-in-Oil Emulsions Stabilized by Hydrophobic Bentonite Particles
      Binks, Bernard P.; Clint, John H.; Whitby, Catherine P.
      Langmuir (2005), 21 (12), 5307-5316CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
      A study of the rheol. behavior of water-in-oil emulsions stabilized by hydrophobic bentonite particles is described. Concd. emulsions were prepd. and dild. at const. particle concn. to investigate the effect of drop vol. fraction on the viscosity and viscoelastic response of the emulsions. The influence of the structure of the hydrophobic clay particles in the oil has also been studied by using oils in which the clay swells to very different extents. Emulsions prepd. from iso-Pr myristate, in which the particles do not swell, are increasingly flocculated as the drop vol. fraction increases and the viscosity of the emulsions increases accordingly. The concd. emulsions are viscoelastic and the elastic storage and viscous loss moduli also increase with increasing drop vol. fraction. Emulsions prepd. from toluene, in which the clay particles swell to form tactoids, are highly structured due to the formation of an integrated network of clay tactoids and drops, and the moduli of the emulsions are significantly larger than those of the emulsions prepd. from iso-Pr myristate.
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    77. 77
      Evans, L. A.; Thomasson, M. J.; Kelly, S. M.; Wadhawan, J. Electrochemical determination of diffusion anisotropy in molecularly structured materials. J. Phys. Chem. C 2009, 113, 8901,  DOI: 10.1021/jp806322c
      77
      Electrochemical Determination of Diffusion Anisotropy in Molecularly-Structured Materials
      Evans, Louise A.; Thomasson, Matthew J.; Kelly, Stephen M.; Wadhawan, Jay
      Journal of Physical Chemistry C (2009), 113 (20), 8901-8910CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      Theory is presented for the case of 2-dimensional diffusion anisotropy in axiosym. systems, which, advantageously and indirectly, affords a unified theory of diffusive mass transport at planar, microdisk (or nanodisk) and cylindrical electrodes in isotropic media. A strategy is proposed to det. the extent of diffusion anisotropy in exptl. data; proof-of-concept is considered via a lamellar lyotropic liq. cryst. system.
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    78. 78
      Halls, J. E.; Lawrence, N. S.; Wadhawan, J. D. Electrochemical estimation of diffusion anisotropy of N,N,N′,N′-tetramethyl-para-phenylenediamine within the normal hexagonal lyotropic mesophase of Triton X 100/light water: when can the effects of cross-pseudophase electron transfer be neglected for partitioned reagents?. J. Phys. Chem. B 2011, 115, 6509,  DOI: 10.1021/jp201806f
      78
      Electrochemical Estimation of Diffusion Anisotropy of N,N,N',N'-Tetramethyl-para-phenylenediamine within the Normal Hexagonal Lyotropic Mesophase of Triton X 100/Light Water: When Can the Effects of Cross-Pseudophase Electron Transfer be Neglected for Partitioned Reagents?
      Halls, Jonathan E.; Lawrence, Nathan S.; Wadhawan, Jay D.
      Journal of Physical Chemistry B (2011), 115 (20), 6509-6523CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)
      The H1 lyotropic liq. cryst. phase of Triton X100 with aq. 0.1 M KCl was examd. as a medium in which to det. the axiosym. anisotropy in the diffusion flux of N,N,N',N'-tetramethyl-para-phenylenediamine using electrochem. methods (voltammetry and potential step chronoamperometry) at both planar electrodes and two-dimensional flux microdisk electrodes. Comparison of expt. with theory suggests the ratio of anisotropic diffusion coeffs. in the directions tangential and perpendicular to the electrode surface varies over two orders of magnitude (from 0.04 to 3.3) with increasing concn. of the redox analyte. This is understood through the occurrence of a long-range charge transfer across the pseudophase pseudophase boundary interface, occurring as a result of differential diffusivities of the redox probe within the surfactant and aq. subphases. These data and their dependence on the analyte concn. empower, in a proof-of-concept, the estn. of the partition equil. const. (KP); the value estd. for the small electroactive-drug mimetic considered is log KP = 2.01 ± 0.05 (at 294 ± 2 K) and is in agreement with that envisaged for its partition between n-octanol and H2O. Probably only measurements at low analyte loadings allow for interphase electron transfers to be neglected, since then percolation effects appear to dominate the faradaic current.
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    79. 79
      Michael, A. C.; Wightman, R. M.; Amatore, C. A. Microdisc electrodes, part I: digital simulation with a conformal map. J. Electroanal. Chem. Interfacial Electrochem. 1989, 267, 33,  DOI: 10.1016/0022-0728(89)80235-9
      79
      Microdisk electrodes. Part I. Digital simulation with a conformal map
      Michael, A. C.; Wightman, R. M.; Amatore, C. A.
      Journal of Electroanalytical Chemistry and Interfacial Electrochemistry (1989), 267 (1-2), 33-45CODEN: JEIEBC; ISSN:0022-0728.
      Cyclic voltammetry at microdisk electrodes (i.e. whose radii are less than ≈20 μm) imbedded in infinite coplanar insulators was simulated using a two-dimensional finite differences method. Prior to solving the diffusion equation, a change of variables is used to allow the diffusion and reaction layers surrounding the microdisk to be efficiently divided into discrete elements. The Hopscotch algorithm is used to solve the diffusion equation in the new, conformally mapped spatial coordinates. Simulations were carried out for reversible, irreversible and quasi-reversible charge transfer reactions and the results are shown to agree with available anal. solns. The simulation can also be applied to conditions for which anal. solns. are not available presently. The effect of unequal diffusion coeffs. of the oxidized and reduced form of a redox couple was investigated. To demonstrate the application to coupled chem. steps, the EC mechanism was simulated.
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    80. 80
      Alden, J. A.; Hutchinson, F.; Compton, R. G. Can cyclic voltammetry at microdisc electrodes be approximately described by one-dimensional diffusion?. J. Phys. Chem. B 1997, 101, 949,  DOI: 10.1021/jp962323g
      80
      Can Cyclic Voltammetry at Microdisk Electrodes Be Approximately Described by One-Dimensional Diffusion?
      Alden, John A.; Hutchinson, Francis; Compton, Richard G.
      Journal of Physical Chemistry B (1997), 101 (6), 949-958CODEN: JPCBFK; ISSN:1089-5647. (American Chemical Society)
      Fast scan cyclic voltammetry using microdisk electrodes is now widely employed for the study of the kinetics and mechanism of electrode processes. For convenience, it is common for experimentalists to interpret the results assuming that the disk can be treated as either a planar or a hemispherical electrode. Both approxns. are available in the now widely adopted 1-dimensional simulation package DigiSim which can simulate the cyclic voltammetric response of arbitrarily complex reaction mechanisms. This paper critically addresses the validity of this simplification. To this end, the application of the strongly implicit procedure (SIP) is developed to simulate transient processes at microdisk electrodes. The approach is vindicated by the simulation of chronoamperometric transients resulting from potential steps at microdisk electrodes; excellent agreement was obtained with anal. and other simulation methods. The simulation method is then used to model the cyclic voltammetric response of electrochem. reversible processes at microdisk electrodes. Corresponding simulations are reported for micro-hemisphere electrodes using the backwards implicit in time (BIT) method, allowing comparison between the two electrode geometries so that limitations of treating voltammetry at microdisk electrodes by approxn. to a 1-dimensional (hemispherical) diffusion problem can be quantified. Strong reservations are expressed about the approxn. under transient conditions.
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    81. 81
      Savéant, J.-M.; Vianello, E. Potential-sweep voltammetry: general theory of chemical polarisation. Electrochim. Acta 1967, 12, 629,  DOI: 10.1016/0013-4686(67)85031-X
      81
      Potential-sweep voltammetry: general theory of chemical polarization
      Saveant, Jean M.; Vianello, Elio
      Electrochimica Acta (1967), 12 (6), 629-46CODEN: ELCAAV; ISSN:0013-4686.
      A general theoretical approach is presented for the calcn. of single potential-sweep voltammetric curves in such conditions that a chem. reaction of any order, preceding, following, or parallel to the charge transfer, kinetically influences the overall electrode process. For limiting values of the adimensional parameters defining the interaction between chem. reaction and diffusion kinetics, polarization curves present characteristic behavior corresponding to pure kinetic or diffusion conditions. Some general diagnostic criteria are derived, allowing information on the rate-detg. step of a complex electrode reaction to be acquired, by analyzing the shape of the voltammetric curves and the variations of their characteristic current and potential values as a function of exptl. parameters. The possibilities of evaluating rate and (or) equil. consts. of chem. reactions of any order coupled with the electron-transfer process are discussed.
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    82. 82
      Ball, J. C.; Marken, F.; Fulian, Q.; Wadhawan, J. D.; Blythe, A. N.; Schröder, U.; Compton, R. G.; Bull, S. D.; Davies, S. G. Voltammetry of electroactive oil droplets, part II: comparison of experimental and simulation data for coupled ion and electron insertion processes and evidence for microscale convection. Electroanalysis 2000, 12, 1017,  DOI: 10.1002/1521-4109(200009)12:13<1017::AID-ELAN1017>3.0.CO;2-7
      82
      Voltammetry of electroactive oil droplets. Part II: comparison of experimental and simulation data for coupled ion and electron insertion processes and evidence for microscale convection
      Ball, Jon C.; Marken, Frank; Fulian, Qiu; Wadhawan, Jay D.; Blythe, Alastair N.; Schroder, Uwe; Compton, Richard G.; Bull, Steven D.; Davies, Stephen G.
      Electroanalysis (2000), 12 (13), 1017-1025CODEN: ELANEU; ISSN:1040-0397. (Wiley-VCH Verlag GmbH)
      Modeling electrochem. processes at the three phase junction between electrode-aq. electrolyte-oil droplet presents a considerable challenge due to the complexity of simultaneous electron transfer between electrode and droplet, ion uptake or expulsion between droplet and aq. phase, the interaction of redox centers at high concn., and transport processes accompanying the electrochem. process. For the case of oxidn. of p-tetrahexylphenylenediamine (THPD) microdroplet deposits on basal plane pyrolytic graphite electrodes or random arrays of microelectrodes (RAM) three models may be envisaged which proceed via (A) exchange of ions between droplet and aq. electrolyte with the electrochem. process commencing at the electrode-oil interface, (B) rapid electron transport over the oil-aq. electrolyte interface and the electrochem. process commencing from the oil-aq. electrolyte interface inwards, and (C) slow electron transport across the oil-aq. electrolyte interface and the electrochem. process commencing solely from the triple interface. Numerical simulation procedures for these three models, which allow for interaction of redox centers via a regular soln. theory approach, are compared with exptl. data. A pos. interaction parameter, Z = 1.4, consistent with a dominant ionic liq.-ionic liq. and neutral oil-neutral oil type interaction is detd. from exptl. data recorded at sufficiently slow scan rates. The overall mechanism, which governs the voltammetric characteristics at higher scan rates, is apparently consistent with the triple interface model (C). However, the rate of diffusional transport detd. by comparison of exptl. with simulation data is orders of magnitudes too high. Addnl. convection processes, possibly of the Marangoni type, appear to be responsible for the fast rate obsd. for the redox process. The significance of the models presented in the context of microdroplet deposits for other related electrochem. systems is discussed.
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    83. 83
      Nicholson, R. S.; Shain, I. Theory of stationary electrode polarography: single scan and cyclic methods applied to reversible, irreversible and kinetic systems. Anal. Chem. 1964, 36, 706,  DOI: 10.1021/ac60210a007
      83
      Theory of stationary electrode polarography. Single scan and cyclic methods applied to reversible, irreversible, and kinetic systems
      Nicholson, Richard S.; Shain, Irving
      (1964), 36 (4), 706-23CODEN: ANCHAM; ISSN:0003-2700.
      A numerical method is developed for solving the integral equations obtained from the boundary value problems, and extensive data were calcd. which permit construction of stationary electrode polarograms from theory. Correlations of kinetic and exptl. parameters make it possible to develop diagnostic criteria so that unknown systems can be characterized by studying the variation of peak current, half-peak potential, or ratio of anodic to cathodic peak currents as a function of rate of voltage scan. 51 references.
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    84. 84
      Cummings, C. Y.; Wadhawan, J. D.; Nakabayashi, T.; Haga, M.-A.; Rassaei, L.; Dale, S. E. C.; Bending, S.; Pumera, M.; Parker, S. C.; Marken, F. Electron hopping rate measurements in ITO junctions: charge diffusion in a layer-by-layer deposited ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate-TiO2 film. J. Electroanal. Chem. 2011, 657, 196,  DOI: 10.1016/j.jelechem.2011.04.010
      84
      Electron hopping rate measurements in ITO junctions: Charge diffusion in a layer-by-layer deposited ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate-TiO2 film
      Cummings, Charles Y.; Wadhawan, Jay D.; Nakabayashi, Takuya; Haga, Masa-aki; Rassaei, Liza; Dale, Sara E. C.; Bending, Simon; Pumera, Martin; Parker, Stephen C.; Marken, Frank
      Journal of Electroanalytical Chemistry (2011), 657 (1-2), 196-201CODEN: JECHES; ISSN:1873-2569. (Elsevier B.V.)
      Focused ion beam (FIB) machining allowed a sub-micron trench to be cut through Sn-doped In oxide (ITO) film on glass to give a generator - collector junction electrode with narrow gap (∼600 nm). A layer-by-layer deposited film composed of a dinuclear Ru(II)-bis(benzimidazolyl)pyridine-phosphonate (as the neg. component) and nanoparticulate TiO2 (∼6 nm diam., as the pos. component) was formed and studied 1st on simple ITO electrodes and then on ITO junction electrodes. The charge transport within this film due to Ru(II/III) redox switching (electron hopping) was studied and an apparent diffusion coeff. of ca. D app = 2 (± 1) × 10-15 m2 s-1 was obsd. with minimal contributions from intra-mol. Ru-Ru interactions. The benefits of FIB-cut ITO junctions as a tool in detg. charge hopping rates are highlighted.
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    85. 85
      Wang, Y. L.; Longwell, P. A. Laminar flow in the inlet section of parallel plates. AIChE J. 1964, 10, 323,  DOI: 10.1002/aic.690100310
      There is no corresponding record for this reference.