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C: Plasmonics; Optical, Magnetic, and Hybrid MaterialsNovember 9, 2020

Photoactivated Refractive Index Anisotropy in Fluorescent Thiophene Derivatives
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Adam Szukalski*
Adam Szukalski
NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy
Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
*Email: [email protected]
More by Adam Szukalski
http://orcid.org/0000-0003-1062-0812
Karolina A. Haupa
Karolina A. Haupa
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Daxue Road 1001, 30010 Hsinchu, Taiwan
Institute of Physical Chemistry, Karlsruhe Institute of Technology, Fritz-Haber Weg 2 (Geb. 30.44), D-76131 Karlsruhe, Germany
More by Karolina A. Haupa
http://orcid.org/0000-0002-6604-4730
Alina Adamow
Alina Adamow
NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy
Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
More by Alina Adamow
Yohan Cheret
Yohan Cheret
MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
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Raphael Hue
Raphael Hue
MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
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Abdelkrim El-Ghayoury*
Abdelkrim El-Ghayoury
MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
*Email: [email protected]
More by Abdelkrim El-Ghayoury
http://orcid.org/0000-0003-2787-3859
Bouchta Sahraoui
Bouchta Sahraoui
MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
More by Bouchta Sahraoui
Dario Pisignano
Dario Pisignano
NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy
Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy
More by Dario Pisignano
http://orcid.org/0000-0003-3758-5199
Jaroslaw Mysliwiec
Jaroslaw Mysliwiec
Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
More by Jaroslaw Mysliwiec
Andrea Camposeo*
Andrea Camposeo
NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy
*Email: [email protected]
More by Andrea Camposeo
http://orcid.org/0000-0002-3533-7389

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The Journal of Physical Chemistry C

Cite this: J. Phys. Chem. C 2020, 124, 46, 25465–25472

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https://doi.org/10.1021/acs.jpcc.0c07455

Published November 9, 2020

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Abstract

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The optical control of anisotropy in materials is highly advantageous for many technological applications, including the real-time modulation of another light signal in photonic switches and sensors. Here, we introduce three thiophene derivatives with a donor–acceptor structure, which feature different positions of an electron-acceptor nitrile group, and both photoalignment and luminescence properties. Quantum chemical calculations highlight the presence of trans-forms stable at room temperature and metastable cis-isomers. Besides photoluminescence peaked at 440–460 nm and 0.4 ns lifetime, the three nonlinear optical chromophores exhibit photoinduced anisotropy of the refractive index closely depending on the specific molecular structure, with higher values of birefringence at lower driving signal being obtained for ortho substitution of the nitrile group. All-optical modulation of an external light beam at rates of hundreds of hertz is demonstrated in the fluorescent systems. This finding opens an interesting route to multispectral photonic switches embedded in the active layers of light-emitting devices.

Subjects

Introduction

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The management of light propagation and of light–matter interaction benefits from the availability of materials whose physical properties can be controlled and varied in real time by means of external fields. (1−3) The properties of various optical materials and photonic devices such as absorption and fluorescence, (4) light-scattering, (5) optical gain and lasing, (6,7) and nonlinear optical (NLO) features (8,9) can be effectively modulated through electric and magnetic fields, (10,11) mechanical stretching, (12,13) temperature, (14) chemical interactions, (15,16) pressure, (17) or light. (18) Control achieved by light is especially interesting because the so-enabled, remote modulation of the properties of operating devices can be very fast and pushed at high spatial resolution by employing focused laser beams. For these reasons, light-responsive systems (19−22) are continuously expanding their fields of use, with recent examples including photoswitchable dual-color (23) and white light-emitting (24) nanoparticles, photochromic transparent wood for smart windows, (25) anticounterfeiting systems, (26) and UV sensors. (27) In this framework, achieving simultaneous optical control of light intensity and photon generation by compact, multifunctional systems would be of paramount importance, allowing passive and active light modulation to be potentially combined in super-resolution microscopy, optical computing and communications, multispectral sensing, diagnostics, and analytics. (23,28,29)

Molecules designed to optimize their NLO properties are highly relevant in this respect. (30) For instance, azobenzene derivatives were largely used as building blocks of light-responsive materials and surfaces. (31) Upon photoirradiation, trans-to-cis isomerization is activated in azobenzenes, which might lead to a neat photoalignment of chromophores along a given direction. Such anisotropy, in turn impacting optical absorption and refractive index, can be exploited for the passive modulation of a polarized light beam, (32) but it is not normally accompanied by light emission, that is, by passive/active multifunctionality. Other systems were reported, such as stilbene derivatives, that exhibit photon emission combined with NLO properties. (33,34) Second-harmonic generation (SHG) and light switching have been recently shown by pyrazoline derivatives, that is, push–pull donor–acceptor molecules based on the stilbene fragment. (35,36) Overall, these studies indicate that the SHG signal and photoinduced birefringence can be tailored by specific moieties and by varying the electron-donor and -acceptor units and their position.

Here, we report on three new thiophene derivatives based on stilbene, designed as push–pull molecules with an aromatic electron-donor group and a nitrile acceptor group. The derivatives differ for the position of the acceptor unit with respect to an aromatic ring, close to the electron-acceptor region. Quantum chemical calculations determine the available isomers for each derivative and their structures. In addition to light emission with sub-nanosecond lifetime, the molecules are found to undergo photoisomerization upon optical pumping with a beam resonant with the absorption band, which is associated with molecular alignment and building-up of optical birefringence, allowing the intensity of polarized light to be switched at rates up to many hundreds of hertz. The investigated compounds display different magnitudes of their photoinduced birefringence, which provides a significant design pathway for enhancing optical switching and for combined passive/active light modulation by organic systems.

Experimental Methods

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Materials and Characterization Techniques

Commercially available reagents and solvents of analytical grade are used without any further purification. Diethylcyanobenzylphosophonate precursors (A–C in Scheme 1) are prepared following the Arbuzov reaction, (37) while the thiophene derivatives were obtained by the Horner–Wadsworth–Emmons reaction between phenylthiophenealdehyde and the phosphonate derivatives A–C (Scheme 1). All reactions are carried out under an inert nitrogen atmosphere. Nuclear magnetic resonance (NMR) spectra are measured by using a Bruker Avance DRX 300 spectrometer operating at 300 MHz for ¹H NMR and at 75 MHz for ¹³C NMR. Mass spectra are collected with the Bruker Biflex-III apparatus.

Scheme 1. Scheme of the Synthetic Route of the Th-oCN, Th-mCN, and Th-pCN Derivatives

Synthesis of Thiophene Derivatives and Film Preparation

For the synthesis of (E)-2-(2-(5-phenylthiophen-2-yl)vinyl)benzonitrile (Th-oCN), (E)-3-(2-(5-phenylthiophen-2-yl)vinyl)benzonitrile (Th-mCN), and (E)-4-(2-(5-phenylthiophen-2-yl)vinyl)benzonitrile (Th-pCN), a solution of potassium tert-butoxide (t-BuOK, 297 mg, 2.65 mmol) is added dropwise to a solution of diethylcyanobenzylphosphonate (268 mg, 1.06 mmol) in 20 mL of dry tetrahydrofuran (THF) in a three-necked flask under nitrogen (Scheme 1). The mixture is stirred for few minutes and, subsequently, a THF solution of 5-phenylthiophene-2-carbaldehyde (200 mg, 1.06 mmol) is added. The resulting mixture is stirred for one night and, after evaporation of THF, the resulting product is dissolved in dichloromethane (DCM) and washed with an aqueous NaCl solution. The organic phase is collected, and the solvent was left to evaporate. The resulting product undergoes silica gel chromatography column using petroleum ether/DCM 3:1 (v/v) followed by petroleum ether/DCM 1:1 (v/v) as the eluent to afford the resulting compound. The reaction yield and the results of the NMR characterization of the Th-xCN (x = o, m and p) compounds are reported in the Supporting Information (Figures S1–S4).

Th-xCN-doped poly(methyl methacrylate) (PMMA, Sigma-Aldrich) films are drop-cast on silica glass plates from DCM solutions (2% dry w/w dopant/polymer ratio). After mixing, stirring for 24 h, and drop-casting, films are formed under solvent vapors during the next 24 h, and their thickness (4–5 μm) is measured in different areas of the samples using a DektakXT (Bruker) profilometer.

Computational Analysis

Quantum-chemical calculations are performed using the Gaussian 09 program. (38) Geometrical optimization and harmonic vibrational analysis are carried out by density functional theory with the B3LYP functional. (39) The standard Dunning’s correlation-consistent basis set augmented with diffuse functions (aug-cc-pVDZ) is used. (40) The nature of the stationary points is checked by the calculation of the vibrational frequency, obtained for all minimum energies and found to have no imaginary values. The obtained relative energies include zero-point vibrational energy corrections. The abundances of the found conformers at room temperature are calculated according to the Boltzmann distribution.

Absorption and Time-Resolved Fluorescence

Absorption and fluorescence spectra of Th-xCN in PMMA are measured by the Jasco V-550 UV–vis spectrophotometer and the Varian Cary Eclipse fluorescence spectrometer, respectively. The investigation of the photoluminescence (PL) lifetime is carried out by a femtosecond laser (Legend, Coherent) and a streak-camera (C10910, Hamamatsu) coupled to a spectrograph (Acton SpectraPro SP-2300, Princeton Instruments). More specifically, the second harmonic (λ = 400 nm) of the output beam of the femtosecond laser system (wavelength: 800 nm, pulse duration: 90 fs, repetition rate = 1 kHz) is focused on the sample surface by a lens (focal distance, 100 mm), while the emitted light is collected by the same lens in a backscattering geometry and coupled to the monochromator by a second lens (focal distance, 100 mm). The absolute fluorescence quantum yield (Φ_F) is measured by an integrating sphere (LabSphere). (41) To this aim, the samples are optically pumped by a 375 nm continuous wave (cw) diode laser (L6Cc, OXXIUS).

Optically Induced Birefringence

For the investigation of the optical birefringence property that is induced optically, a cw pump–probe experimental setup is used, similar to the one typically utilized for the investigation of the optical Kerr effect. (42) This method relies on the measurement of the variation of the polarization direction of a probe beam (λ_probe = 638 nm, i.e., in the Th-xCN transparency region), which is induced by a pump laser beam (λ_pump = 405 nm, i.e., in the absorption band of the used molecules), as schematized in Figure S5 in the Supporting Information. To this aim, two diode lasers of the L6Cc system (OXXIUS) are used. To maximize the photoinduced birefringence effect, the pumping beam polarization direction is rotated by 45° with respect to the polarization direction of the incident probe beam by means of a half waveplate. A cross-polarizer configuration is used for the probe beam. More specifically, the probe beam is linearly polarized by a first polarizer placed between the light source and the sample, whereas a second polarizer (analyzer) with the axis perpendicular to the first one is placed on the path of the probe beam that is transmitted by a sample. The intensity of so transmitted light is measured by a Si photodiode located behind the analyzer (Figure S5). In such a configuration, the intensity of the probe beam transmitted by an optically isotropic material placed between the polarizer and the analyzer is zero. In contrast, any anisotropy induced in the refractive index of the Th-xCN samples will cause a rotation of the polarization direction of the probe beam passing through them, namely, a nonzero transmission through the analyzer. The magnitude of the photoinduced optical anisotropy can be calculated by the expression (35,36,43)

(1)

where I_probe⁰ and I_probe^T are the incident and transmitted intensities of the probe beam, respectively, d is the sample thickness, and Δn(I_pump) is the pump intensity (I_pump)-dependent anisotropy of the refractive index, namely, the difference of the refractive index for light polarized parallel and perpendicular to the direction of polarization of the pump. Two temporal regimes can be typically considered in the experiments: one is related to the steady-state photoalignment of molecules upon optical pumping. This can be evaluated by the stationary amplitude of the probe signal detected by the photodiode with the pump beam switched on. Indeed, thanks to the many photoinduced conformational changes of the active molecules (typically trans–cis–trans transformations), it is possible to photoalign a significant population of the initially isotropic molecules, with an associated increase of Δn typically occurring on timescales (τ_on) of seconds or minutes in solid-state systems. (35,36,43) Such optically induced birefringence typically vanishes on timescales (τ_off) comparable to τ_on upon switching off the pumping beam. (44) Another interesting regime is associated with variations of the pump intensity much faster than τ_on, but sufficiently long to observe the effect of conformational changes, which occur typically in sub-millisecond timescale. (35,36,45) This regime, which is appealing for fast light modulation, can be inspected by modulating the pump intensity with a mechanical chopper (Figure S5) and measuring the corresponding variation of the transmitted probe intensity.

Results and Discussion

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Quantum Chemical Calculations

The systematic scan of the potential energy surface allows six minima for Th-oCN and Th-mCN and four minima for Th-pCN to be found. The optimized trans- and cis-conformers of Th-oCN, Th-mCN, and Th-pCN are shown in Figure 1, whereas the structures of conformers with higher energy are shown in Figure S6. The relative energies, Gibbs free enthalpies, and abundance at the room temperature of all the structures found for the three compounds are summarized in Table S1 in the Supporting Information. Trans-isomers are lower in energy and have a planar configuration. Only these isomers are predicted to contribute to the population at ambient temperature. In order to rationalize the structure of the conformers, the energies associated with the torsions along S–C1–C2–C3, H1–C2–C3–H2, and H2–C3–C4–C5 (atom notation shown in Figure 1) bonds are calculated (Figure S7). The estimated energy barrier for trans → cis isomerization is about 80 kcal mol^–1, and it is almost comparable for all the investigated molecules, as can be appreciated by scanning the angle H1–C2–C3–H2 (Figure S7b,e,h). Furthermore, the possibility of rotation along S–C1–C2–C3 and H2–C3–C4–C5 bonds gives conformational flexibility to trans-Th-xCN, leading to syn- and anti-conformers. Scan of the S–C1–C2–C3 bond shows that the rotation of the thiophene ring has a small energy barrier (∼10 kcal mol^–1, Figure S7a,d,g). Rotation of the Ph–CN group along the H2–C3–C4–C5 bond has a significantly higher barrier (∼40 kcal mol^–1, Figure S7c,f,i). Rotation barriers appear to be independent from the position of the −CN group (Figure S7). For Th-oCN, the anti–trans–syn conformer is identified as the global minimum with a calculated abundance of 72%. For Th-mCN, anti–trans–anti and anti–trans–syn isomers are very close in energy, and their abundance at room temperature is comparable, that is, 45 and 42%, respectively. Substitution in the para position in Th-pCN limits the number of conformers to four. The anti–trans conformer was found as the conformer with minimum energy, with 89% contribution to the population at room temperature.

Figure 1. Optimized geometries of the most stable conformers of *trans*- and *cis*-Th-oCN, Th-mCN, and Th-pCN calculated with the B3LYP/aug-cc-pVDZ method. In-plane view (left) and out-of-plane view (right) are shown for each conformer by considering the plane containing the thiophene group.

The calculated values of the dipole moment for all the optimized conformers are also summarized in Table S1. The orientation of dipole moments for the most stable trans- and cis-conformers is shown in Figure 2. The different position of the electron-acceptor unit impacts the spatial orientation of the dipole moment. For the trans-form of Th-mCN and Th-pCN, the dipole moment is in the plane containing the thiophene group, along the direction from the donor to the acceptor unit. trans-Th-oCN displays a significantly different orientation of the dipole moment vector that is almost orthogonal to the donor-to-acceptor unit direction (Figure 2). In addition, the calculated dipole moments reported in Table S1 evidence an impact of the different position of the electron-acceptor unit, the trans-Th-pCN featuring the dipole with the highest magnitude. Overall, these features are expected to determine different properties at the solid state, where both steric and electronic effects (including dipolar interactions) influence the final packing of the molecules, (46,47) with a possibly more closed packed stacking for the para derivative (see also the different color of the powders shown in Figure S1).

Figure 2. Orientation of dipole moment vectors for the most stable conformers of *trans*- and *cis*-Th-oCN, Th-mCN, and Th-pCN. In-plane view (left) and out-of-plane view (right) are shown for each conformer.

In the case of nonplanar cis-conformers, the vector of dipole moment is oriented from the donor to the acceptor, out-of-the-plane containing the thiophene group.

Spectroscopy

The absorption and fluorescence spectra of Th-xCNs in PMMA are shown in Figure 3a. All the systems show a double-band absorption spectrum, with a maximum at ∼360 nm and another one at ∼395 nm (for Th-mCN and Th-pCN) and at ∼410 nm (for Th-oCN), respectively. The PL measurements show broad (full width at half-maximum, in the range 65–70 nm) and featureless bands peaked at 440 nm (for Th-pCN) and at 457–460 nm (for Th-oCN and Th-mCN), respectively. All the Th-xCNs in PMMA show PL quantum yields stable at 5–6%, and monoexponential temporal decay of the PL with a lifetime (τ_PL) of about 0.4 ns (Figure 3b,c and Table 1), compatible with fast modulation of the spontaneous emission (up to GHz rates).

Figure 3. Th-xCNs in PMMA. (a) Absorption (solid line) and PL (dashed line) spectra. (b) Exemplary 2-dimensional PL intensity map showing the spectrally and time-resolved emission of Th-oCN. (c) PL temporal decay for Th-oCN (blue dots), Th-mCN (green dots), and Th-pCN (red dots). The black continuous lines are a fit to the data by a monoexponential curve.

Table 1. Summary of the Photophysical Properties of Th-xCNs in PMMA^a

	λ_max^abs (nm)	λ_max^PL (nm)	Δλ_SS (nm)	Φ_F (%)	τ_PL (ns)	k_r (ns^–1)	k_nr (ns^–1)
Th-oCN	361	457	96	6	0.4	0.15	2.4
Th-mCN	357	460	103	5	0.4	0.13	2.4
Th-pCN	358	440	82	5	0.4	0.13	2.4

^{^a}

λ_max^abs and λ_max^PL: peak wavelength of the absorption and PL spectra, respectively, Δλ_SS: Stokes shift, Φ_F: PL quantum yield, τ_PL: PL lifetime, k_r = Φ_F/τ_PL and k_nr = (1 – Φ_F)/τ_PL: radiative and nonradiative decay rates, respectively.

Photoinduced Birefringence and Optical Switching

The build-up of photoinduced birefringence, Δn, upon light irradiation and its relaxation in dark conditions are shown in Figure 4a–c. For all the Th-xCNs, we find an increase of the photoinduced birefringence over time with the pump laser active, followed by a decrease in absence of pump light, with the first trend being related to the photoalignment of the guest molecules in the PMMA matrix following trans-to-cis photoisomerization, while the latter being related to the thermal relaxation of the metastable cis-isomers back to the trans-ones that are stable at room temperature (Table S1). The photoalignment properties are related to various factors, including the molecular readjustments accompanying the trans–cis–trans isomerization (Figure 1), which are tightly dependent on the polymer host. Here, Th-mCN displays a slower build-up of the anisotropy of the refractive index (Figure 4b), which does not reach saturation in the investigated time interval of 250 s. Instead, Th-pCN (Figure 4c) clearly shows a saturation of the birefringence at Δn = 5.2 × 10^–4 upon optical pumping at I_pump ∼ 113 mW cm^–2. Saturation occurs in about 100 s, almost independently of the used pump (inset of Figure 4c). For the sake of comparison, we recall that this timescale is 2 times faster than that in which Δn saturation is reached in a host/guest system incorporating a thiophene derivative with a nitro group as an electron-acceptor unit [(E)-2-(4-nitrostyryl)-5-phenylthiophene, Th-pNO₂]. (48)

Figure 4. (a–c) Temporal evolution of the photoinduced birefringence, Δn, for the and Th-oCN (a), Th-mCN (b), and Th-pCN (c), respectively, upon switching on and off the pump beam. Pumping intensities: 40 (a), 96 (b), 113 mW cm^–2 (c). The insets show the increase of Δn for various intensities of the pump beam (reported in mW cm^–2). (d) Dependence of Δn on the incident intensity of the pump beam, I_pump (data collected after 250 s with pump on).

Th-oCN exhibits an even more effective kinetics of the refractive index anisotropy build-up (Figure 4a), with Δn ∼5.7 × 10^–4 achieved by lower pumping intensity (40 mW cm^–2). In the framework of third-order NLO phenomena, (43) a linear behavior with slope n₂ is expected for the dependence of the photoinduced birefringence on the pump intensity, Δn = n₂ × I_pump. This is shown in Figure 4d for the three molecules here investigated, showing that Th-oCN allows given Δn values to be obtained by pump beam intensities about 2 and 3 times lower than and Th-mCN and Th-pCN, respectively (see Table S2) and much lower with respect to previously reported Th-pNO₂, for which a Δn ∼ 1.52 × 10^–4 was measured at I_pump = 840 mW cm^–2. (48) This result is highly relevant in view of realizing photoresponsive systems to control with low optical intensity.

Finally, the modulation of the intensity of the probe beam by optical control is evidenced in Figure 5. The temporal stability and repeatability of the intensity modulation of the probe beam are highlighted in the insets of Figure 5a–c and in Figure S8. The decrease of the amplitude of the probe beam modulation follows the decrease of the time interval during which the active molecules are illuminated by the pump laser light, which corresponds to the time interval, in which cyclic conversion between trans and cis conformational states, and the associated increase of optical anisotropy of the refractive index occur. Interestingly, a modulation corresponding to Δn of the order of 10^–6 is still found at about 800 Hz, which is interesting for many applications requiring intensity and/or phase modulation of light beams, such as additive manufacturing, imaging, optical communication, and computation. (49,50) In this respect, it is worth mentioning that the modulation of the probe beam is promoted together with the modulation of the PL intensity, whose lifetime is much shorter than the timescale (∼ms) here used to control the photoinduced birefringence. This would enable concomitant and intrinsically synchronous all-optical switching of light at multiple wavelengths, namely, the wavelengths of the probe beams passing through the Th-xCN samples (638 nm) and of the sample PL (i.e., 440–460 nm).

Figure 5. Amplitude of the modulated birefringence vs the modulation frequency (f_MOD) of the driving, pump beam for Th-oCN (a), Th-mCN (b), and Th-pCN (c), respectively. Insets: exemplary temporal evolution of the optically modulated probe signal, measured at f_MOD = 50 Hz and I_pump = 40 mW cm^–2 for Th-oCN (a), I_pump = 95 mW cm^–2 for Th-mCN (b) and Th-pCN (c), respectively.

Conclusions

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In summary, three light-responsive thiophene compounds based on the stilbene group are introduced, varying the position of their electron-acceptor unit. Quantum chemical calculations allowed the most stable conformers to be identified and their geometrical configuration and properties to be determined. The Th-xCNs show blue PL with a sub-nanosecond (0.4 ns) lifetime. The investigation of the third-order NLO properties evidences effective photoalignment in all the Th-xCN on a timescale of 10² s, with an associated increase of the refractive index anisotropy. Such photoinduced birefringence is exploited for achieving all-optical control on a polarized light beam, and it appears to be more easily induced in Th-oCN which makes it particularly appealing to be used with low driving intensities. The possibility of concomitant all-optical modulation of the light emitted by the photoactive systems and of external light beams makes these compounds highly promising for all those applications where synchronous modulation of multiple light signals is required such as multidimensional analytical and imaging systems and photonic networks.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.jpcc.0c07455.

NMR spectra and data, structures of conformers with higher energies, calculated energy increase of the conformers upon scanning the torsion angles, additional data about all-optical modulation of light intensity, and experimental setup used for characterization of photoinduced anisotropy of the refractive index (PDF)

jp0c07455_si_001.pdf (1.98 MB)

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Author Information

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Corresponding Authors
- Adam Szukalski - NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy; Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland; http://orcid.org/0000-0003-1062-0812; Email: [email protected]
- Abdelkrim El-Ghayoury - MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France; http://orcid.org/0000-0003-2787-3859; Email: [email protected]
- Andrea Camposeo - NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy; http://orcid.org/0000-0002-3533-7389; Email: [email protected]
Authors
- Karolina A. Haupa - Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Daxue Road 1001, 30010 Hsinchu, Taiwan; Institute of Physical Chemistry, Karlsruhe Institute of Technology, Fritz-Haber Weg 2 (Geb. 30.44), D-76131 Karlsruhe, Germany; http://orcid.org/0000-0002-6604-4730
- Alina Adamow - NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy; Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
- Yohan Cheret - MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
- Raphael Hue - MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
- Bouchta Sahraoui - MOLTECH-Anjou, UMR 6200, CNRS, Université Angers, 2 bd Lavoisier, 49045 Angers Cedex, France
- Dario Pisignano - NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S. Silvestro 12, I-56127 Pisa, Italy; Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy; http://orcid.org/0000-0003-3758-5199
- Jaroslaw Mysliwiec - Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
Notes
The authors declare no competing financial interest.

Acknowledgments

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The research leading to these results has received funding from the European Research Council under the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement no. 682157, “xPRINT”), from the Italian Ministry of University and Research PRIN 201795SBA3 project, and from the National Science Center, Poland (2018/31/B/ST8/02832). Calculations have been carried out in Wroclaw Centre for Networking and Supercomputing (http://www.wcss.wroc.pl), grant no. 409. K.A.H. is a recipient of an Alexander von Humboldt fellowship.

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Environmentally responsive photonic polymers
van Heeswijk, Ellen P. A.; Kragt, Augustinus J. J.; Grossiord, Nadia; Schenning, Albertus P. H. J.
Chemical Communications (Cambridge, United Kingdom) (2019), 55 (20), 2880-2891CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
A review. Stimulus-responsive photonic polymer materials that change their reflection color as function of environmental stimuli such as temp., humidity and light, are attractive for various applications (e.g. sensors, smart windows and communication). Polymers provide low d., tunable and patternable materials. This feature article focusses on various autonomously responding photonic polymer materials such as hydrogels, block copolymers and liq. crystals and discusses their potential industrial implementation.
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Isapour, G.; Lattuada, M. Bioinspired Stimuli-Responsive Color-Changing Systems. Adv. Mater. 2018, 30, 1707069, DOI: 10.1002/adma.201707069
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Berkovic, G.; Krongauz, V.; Weiss, V. Spiropyrans and Spirooxazines for Memories and Switches. Chem. Rev. 2000, 100, 1741– 1754, DOI: 10.1021/cr9800715
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Spiropyrans and spirooxazines for memories and switches
Berkovic, Garry; Krongauz, Valeri; Weiss, Victor
Chemical Reviews (Washington, D. C.) (2000), 100 (5), 1741-1753CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review with 94 refs. on applications of spiropyran-merocyanine systems in memories and switches. The formation of organized structures whose optical properties can be affected by an elec. field was discussed along with the nonlinear optical properties of photochromic systems. Employing photochromic spiropyran and spirooxazine systems in real-time holog. is also considered.
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Samai, S.; Qian, Z.; Ling, J.; Guye, K. N.; Ginger, D. S. Optical Properties of Reconfigurable Polymer/Silver Nanoprism Hybrids: Tunable Color and Infrared Scattering Contrast. ACS Appl. Mater. Interfaces 2018, 10, 8976– 8984, DOI: 10.1021/acsami.7b16934
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Optical Properties of Reconfigurable Polymer/Silver Nanoprism Hybrids: Tunable Color and Infrared Scattering Contrast
Samai, Soumyadyuti; Qian, Zhaoxia; Ling, Jian; Guye, Kathryn N.; Ginger, David S.
ACS Applied Materials & Interfaces (2018), 10 (10), 8976-8984CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
We synthesize and characterize stimulus-responsive nanocomposites consisting of poly(N-isopropylacrylamide) (PNIPAM) with controlled loadings of anisotropic plate-like silver nanoprisms. These composites show strong, reversible switching of their optical extinction and scattering properties in response to temp. cycling. We use UV-vis-NIR spectroscopy and dynamic light scattering to characterize the hybrids and show that the loading d. of the silver nanoprisms in the polymer and the size of the nanoprisms are both factors that can be used to tailor the optical response of the composites, extending the range of colors beyond that previously reported with PNIPAM/plasmonic nanoparticle composites. These PNIPAM/silver nanoprism hybrids exhibit thermochromic shifts that are 5-10 times larger than those typically reported for similar structures of PNIPAM composites with silver nanoparticles of a comparable range of loading d. In addn., we show that these composites can exhibit very large ratiometric changes in scattering in the NIR, which could open applications for related materials in thermal management and NIR labeling and taggants.
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Wiersma, D. S.; Cavalieri, S. A temperature-tunable random laser. Nature 2001, 414, 708– 709, DOI: 10.1038/414708a
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Light emission. A temperature-tunable random laser
Wiersma, Diederik S.; Cavalieri, Stefano
Nature (London, United Kingdom) (2001), 414 (6865), 708-709CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
A temp.-tunable random laser was fabricated consisting of sintered glass (SK-11, Schott) infiltrated with a laser dye (DCM, Lambdachrome 6500) which was dissolved in a liq. crystal (4-cyano-4'-n-heptylbiphenyl, 7CB). The light waves are multiply scattered by the sintered glass and 7CB and are amplified by the laser dye which is excited by an external green double-frequency Nd:YAG laser. At low temps., a narrow emission spectrum was obsd., while, at higher temps., the random laser is below the threshold (broad emission spectrum). By varying the temp., the spectral width of the random laser is controlled. At temps. < 42.5°, the onset of laser action was obsd. corresponding with the nematic/isotropic phase transition of 7CB.
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Zhang, W.; Yan, Y.; Gu, J.; Yao, J.; Zhao, Y. S. Low-Threshold Wavelength-Switchable Organic Nanowire Lasers Based on Excited-State Intramolecular Proton Transfer. Angew. Chem., Int. Ed. 2015, 54, 7125, DOI: 10.1002/anie.201502684
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Low-Threshold Wavelength-Switchable Organic Nanowire Lasers Based on Excited-State Intramolecular Proton Transfer
Zhang, Wei; Yan, Yongli; Gu, Jianmin; Yao, Jiannian; Zhao, Yong Sheng
Angewandte Chemie, International Edition (2015), 54 (24), 7125-7129CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
Coherent light signals generated at the nanoscale are crucial to the realization of photonic integrated circuits. Self-assembled nanowires from org. dyes can provide both a gain medium and an effective resonant cavity, which have been utilized for fulfilling miniaturized lasers. Excited-state intramol. proton transfer (ESIPT), a classical mol. photoisomerization process, can be used to build a typical four-level system, which is more favorable for population inversion. Low-power driven lasing in proton-transfer mol. nanowires with an optimized ESIPT energy-level process has been achieved. With high gain and low loss from the ESIPT, the wires can be applied as effective FP-type resonators, which generated single-mode lasing with a very low threshold. The lasing wavelength can be reversibly switched based on a conformation conversion of the excited keto form in the ESIPT process.
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Koos, C.; Vorreau, P.; Vallaitis, T.; Dumon, P.; Bogaerts, W.; Baets, R.; Esembeson, B.; Biaggio, I.; Michinobu, T.; Diederich, F. All-Optical High-Speed Signal Processing with Silicon–Organic Hybrid Slot Waveguides. Nat. Photonics 2009, 3, 216– 219, DOI: 10.1038/nphoton.2009.25
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All-optical high-speed signal processing with silicon-organic hybrid slot waveguides
Koos, C.; Vorreau, P.; Vallaitis, T.; Dumon, P.; Bogaerts, W.; Baets, R.; Esembeson, B.; Biaggio, I.; Michinobu, T.; Diederich, F.; Freude, W.; Leuthold, J.
Nature Photonics (2009), 3 (4), 216-219CODEN: NPAHBY; ISSN:1749-4885. (Nature Publishing Group)
Integrated optical circuits based on Si-on-insulator technol. probably become the mainstay of the photonics industry. Over recent years an impressive range of Si-on-insulator devices was realized, including waveguides, filters and photonic-crystal devices. However, Si-based all-optical switching is still challenging owing to the slow dynamics of 2-photon generated free carriers. Si-org. hybrid integration overcomes such intrinsic limitations by combining the best of 2 worlds, using mature CMOS processing to fabricate the waveguide, and mol. beam deposition to cover it with org. mols. that efficiently mediate all-optical interaction without introducing significant absorption. The authors fabricate a 4-mm-long Si-org. hybrid waveguide with a record nonlinearity coeff. of γ ≈ 1 × 105 W-1 km-1 and perform all-optical demultiplexing of 170.8 Gb s-1 to 42.7 Gb s-1. This is-to the best of knowledge-the fastest Si photonic optical signal processing demonstrated.
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Tao, K.; Wu, Z.; Han, S.; Zhang, J.; Ji, C.; Wang, Y.; Zhang, W.; Luo, J.; Sun, Z. Switchable Behaviors of Quadratic Nonlinear Optical Properties Originating from Bi-Step Phase Transitions in a Molecule-Based Crystal. J. Mater. Chem. C 2018, 6, 4150– 4155, DOI: 10.1039/c8tc00407b
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Switchable behaviors of quadratic nonlinear optical properties originating from bi-step phase transitions in a molecule-based crystal
Tao, Kewen; Wu, Zhenyue; Han, Shiguo; Zhang, Jing; Ji, Chengmin; Wang, Yuyin; Zhang, Weichuan; Luo, Junhua; Sun, Zhihua
Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2018), 6 (15), 4150-4155CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
Solid-state nonlinear optical (NLO) switches are recently emerging as a new class of promising stimuli-responsive materials for photoelec. application. An org. mol. crystal, N-methylcyclohexylamine picrate (1), which exhibits remarkable switching behaviors of quadratic NLO properties with a large contrast of ∼20 between its NLO-on and NLO-off states is reported. This is almost comparable with the conventional photochromic counterparts, and suggests the great potential of 1 as a quadratic NLO-switching candidate. 1 Undergoes bi-step structural phase transitions at T1 = 240 K and T2 = 285 K, which are closely assocd. with its NLO-switching activities. Above T1, disordering of anionic and cationic moieties leads to vanishing of the NLO effect, (i.e. NLO-off state). But below T1, stepwise frozen ordering of the structural moieties generates strong NLO activities, with the NLO response being ∼0.9 times that of KH2PO4. Such an order-disorder transformation accounts for the high-contrast NLO switching of 1. It is believed that this finding affords an effective strategy for designing new stimuli-responsive materials.
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Adamow, A.; Sznitko, L.; Chrzumnicka, E.; Stachera, J.; Szukalski, A.; Martynski, T.; Mysliwiec, J. The Ultra-Photostable and Electrically Modulated Stimulated Emission in Perylene-Based Dye Doped Liquid Crystal. Sci. Rep. 2019, 9, 2143– 2148, DOI: 10.1038/s41598-019-38484-z
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The ultra-photostable and electrically modulated Stimulated Emission in perylene-based dye doped liquid crystal
Adamow A; Sznitko L; Szukalski A; Mysliwiec J; Chrzumnicka E; Stachera J; Martynski T
Scientific reports (2019), 9 (1), 2143 ISSN:.
One of the most important drawback of organic dyes is their low photo-stability which reduces possibility of their commercial utilization. In this article we employ the strategy of dye re-crystallization from oversaturated matrix in order to enhance material's durability. One of the main advantages of perylene derivative is ability to form emissive j-aggregates, good miscibility and incorporation into liquid crystalline matrix. Investigation of perylene-based dye and LC matrix brought as the result very efficient light amplification modulation by applied external electric field. In our article we show that Stimulated Emission (STE) is possible to achieve from perylene-derivative based system, at typical fluence thresholds for laser dyes: 3.9 mJ/cm(2). Moreover, presented system proves ultra-high photostability, showing lack of STE reduction even after 12 000 excitation laser pulses. Furthermore, we proved the possibility of light emission intensity control using external electric field.
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Zhang, X.; Li, Z.; Feng, J.; Yang, F.; Wu, C.; Fan, Q.; Zhou, S.; Yin, Y. Dynamic Tuning of Optical Transmittance of 1D Colloidal Assemblies of Magnetic Nanostructures. Adv. Intell. Syst. 2019, 1, 1900099, DOI: 10.1002/aisy.201900099
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There is no corresponding record for this reference.
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Sagara, Y.; Kato, T. Mechanically Induced Luminescence Changes in Molecular Assemblies. Nat. Chem. 2009, 1, 605– 610, DOI: 10.1038/nchem.411
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Mechanically induced luminescence changes in molecular assemblies
Sagara, Yoshimitsu; Kato, Takashi
Nature Chemistry (2009), 1 (8), 605-610CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
A review; altering the shape and properties of a material through external factors such as heat, light, pressure, pH, elec. or magnetic fields, or the introduction of a guest mol., is an attractive prospect. In this Perspective, piezochromic luminescent materials - which change the color of their luminescence in response to mech. stimuli - are described. Such piezochromism has been obsd. for a few mol. materials that contain luminescent cores in liq.-cryst. and cryst. solid states, as well as for polymeric materials doped with dyes. These changes in photoluminescent color can be activated by various types of mech. pressure such as shearing, grinding or elongation, which can trigger different mechanisms of producing the color. Such stimuli-responsive materials have potential for various applications, including sensors, memory and displays.
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Park, W.; Lee, J.-B. Mechanically Tunable Photonic Crystal Structure. Appl. Phys. Lett. 2004, 85, 4845– 4847, DOI: 10.1063/1.1823019
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Mechanically tunable photonic crystal structure
Park, Wounjhang; Lee, Jeong-Bong
Applied Physics Letters (2004), 85 (21), 4845-4847CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
The authors report a tunable nanophotonic device concept based on flexible photonic crystal, which is comprised of a periodic array of high-index dielec. material and a low-index flexible polymer. Tunability is achieved by applying mech. force with nano-/microelectromech. system actuators. The mech. stress induces changes in the periodicity of the photonic crystal and consequently modifies the photonic band structure. To demonstrate the concept, the authors theor. studied the effect of mech. stress on the anomalous refraction behavior and obsd. a very wide tunability in the beam propagation direction. This concept provides a means to achieve real-time, dynamic control of photonic band structure and will thus expand the utility of photonic crystal structures in advanced nanophotonic systems.
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Ke, Y.; Zhou, C.; Zhou, Y.; Wang, S.; Chan, S. H.; Long, Y. Emerging Thermal-Responsive Materials and Integrated Techniques Targeting the Energy-Efficient Smart Window Application. Adv. Funct. Mater. 2018, 28, 1800113, DOI: 10.1002/adfm.201800113
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There is no corresponding record for this reference.
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Davis, D. A.; Hamilton, A.; Yang, J.; Cremar, L. D.; Van Gough, D.; Potisek, S. L.; Ong, M. T.; Braun, P. V.; Martínez, T. J.; White, S. R. Force-Induced Activation of Covalent Bonds in Mechanoresponsive Polymeric Materials. Nature 2009, 459, 68– 72, DOI: 10.1038/nature07970
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Force-induced activation of covalent bonds in mechanoresponsive polymeric materials
Davis, Douglas A.; Hamilton, Andrew; Yang, Jinglei; Cremar, Lee D.; Van Gough, Dara; Potisek, Stephanie L.; Ong, Mitchell T.; Braun, Paul V.; Martinez, Todd J.; White, Scott R.; Moore, Jeffrey S.; Sottos, Nancy R.
Nature (London, United Kingdom) (2009), 459 (7243), 68-72CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
Mechanochem. transduction enables an extraordinary range of physiol. processes such as the sense of touch, hearing, balance, muscle contraction, and the growth and remodelling of tissue and bone. Although biol. is replete with materials systems that actively and functionally respond to mech. stimuli, the default mechanochem. reaction of bulk polymers to large external stress is the unselective scission of covalent bonds, resulting in damage or failure. An alternative to this degrdn. process is the rational mol. design of synthetic materials such that mech. stress favorably alters material properties. A few mechanosensitive polymers with this property have been developed; but their active response is mediated through non-covalent processes, which may limit the extent to which properties can be modified and the long-term stability in structural materials. Previously, we have shown with dissolved polymer strands incorporating mech. sensitive chem. groups-so-called mechanophores-that the directional nature of mech. forces can selectively break and re-form covalent bonds. We now demonstrate that such force-induced covalent-bond activation can also be realized with mechanophore-linked elastomeric and glassy polymers, by using a mechanophore that changes color as it undergoes a reversible electrocyclic ring-opening reaction under tensile stress and thus allows us to directly and locally visualize the mechanochem. reaction. We find that pronounced changes in color and fluorescence emerge with the accumulation of plastic deformation, indicating that in these polymeric materials the transduction of mech. force into the ring-opening reaction is an activated process. We anticipate that force activation of covalent bonds can serve as a general strategy for the development of new mechanophore building blocks that impart polymeric materials with desirable functionalities ranging from damage sensing to fully regenerative self-healing.
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Yan, X.; Wang, F.; Zheng, B.; Huang, F. Stimuli-Responsive Supramolecular Polymeric Materials. Chem. Soc. Rev. 2012, 41, 6042– 6065, DOI: 10.1039/c2cs35091b
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Stimuli-responsive supramolecular polymeric materials
Yan, Xuzhou; Wang, Feng; Zheng, Bo; Huang, Feihe
Chemical Society Reviews (2012), 41 (18), 6042-6065CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
A review. Supramol. materials, dynamic materials by nature, are defined as materials whose components are bridged via reversible connections and undergo spontaneous and continuous assembly/disassembly processes under specific conditions. In this crit. review, we address recent developments in supramol. polymeric materials, which can respond to appropriate external stimuli at the fundamental level due to the existence of noncovalent interactions of the building blocks.
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Wang, Y.; Tan, X.; Zhang, Y.-M.; Zhu, S.; Zhang, I.; Yu, B.; Wang, K.; Yang, B.; Li, M.; Zou, B. Dynamic Behavior of Molecular Switches in Crystal under Pressure and Its Reflection on Tactile Sensing. J. Am. Chem. Soc. 2015, 137, 931– 939, DOI: 10.1021/ja511499p
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Dynamic Behavior of Molecular Switches in Crystal under Pressure and Its Reflection on Tactile Sensing
Wang, Yi; Tan, Xiao; Zhang, Yu-Mo; Zhu, Shaoyin; Zhang, Ivan; Yu, Binhong; Wang, Kai; Yang, Bing; Li, Minjie; Zou, Bo; Zhang, Sean Xiao-An
Journal of the American Chemical Society (2015), 137 (2), 931-939CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
The pressure-controllable mol. switch of a benzo[1,3]oxazine OX-1 in crystal is demonstrated. Distinct from the light-triggered tautomerization between 2 optical states, applying hydrostatic pressure on the OX-1 crystal results in large-scale and continuous states across the whole visible light range (∼430-∼700 nm), which was not achieved with other stimuli. Based on detailed and systematic control expts. and theor. calcn., the preliminary requirements and mechanism of pressure-dependent tautomerization are fully discussed. The contributions of mol. tautomerization to the large-scale optical modulation are stressed. The importance of studying pressure-responsive materials on understanding tactile sensing is discussed, and a possible mechanotransduction mode is proposed.
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Nie, H.; Self, J. L.; Kuenstler, A. S.; Hayward, R. C.; Read de Alaniz, J. Multiaddressable Photochromic Architectures: from Molecules to Materials. Adv. Opt. Mater. 2019, 7, 1900224, DOI: 10.1002/adom.201900224
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There is no corresponding record for this reference.
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Delaire, J. A.; Nakatani, K. Linear and Nonlinear Optical Properties of Photochromic Molecules and Materials. Chem. Rev. 2000, 100, 1817– 1846, DOI: 10.1021/cr980078m
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Linear and nonlinear optical properties of photochromic molecules and materials
Delaire, Jacques A.; Nakatani, Keitaro
Chemical Reviews (Washington, D. C.) (2000), 100 (5), 1817-1845CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review with 244 refs. about the optical properties and applications of photochromic mols. and materials gained in the last 10-15 yr, excluding the change of their UV-vis absorption spectra. The following photo-induced effects of photochromic materials are described: (i) the excitation of polymers contg. azoaryls or spiropyrans with polarized light leading to transient or permanent dichroism and birefringence, (ii) the excitation of non-centrosym. photochromes with a combination of polarized light and a static elec. field leading to poled materials with 2nd-order, nonlinear optical (NLO) properties, (iii) the irradn. with 2 coherent beams at ω and 2ω leading to all-optical poling, (iv) the irradn. of azo materials with an interference pattern yielding stable-surface relief gratings, and (v) the irradn. of photochromes initially poled in a solid matrix allowing photoswitching of the 2nd- or 3rd-order NLO response and/or annihilation of this response depending on the nature of the matrix. Emphasis was laid on azo polymers and azo-contg. hybrid materials, the photoinduced phenomena of which originated from the cis/trans isomerization reaction proceeding reversibly with high-quantum yields even in solid matrixes.
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Klajn, R. Spiropyran-Based Dynamic Materials. Chem. Soc. Rev. 2014, 43, 148, DOI: 10.1039/c3cs60181a
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Spiropyran-based dynamic materials
Klajn, Rafal
Chemical Society Reviews (2014), 43 (1), 148-184CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
A review. In the past few years, spiropyran has emerged as the mol. of choice for the construction of novel dynamic materials. This unique mol. switch undergoes structural isomerization in response to a variety of orthogonal stimuli, e.g. light, temp., metal ions, redox potential, and mech. stress. Incorporation of this switch onto macromol. supports or inorg. scaffolds allows for the creation of robust dynamic materials. This review discusses the synthesis, switching conditions and use of dynamic materials in which spiropyran has been attached to the surfaces of polymers, biomacromols., inorg. nanoparticles, as well as solid surfaces. The resulting materials show fascinating properties whereby the state of the switch intimately affects a multitude of useful properties of the support. The utility of the spiropyran switch will undoubtedly endow these materials with far-reaching applications in the near future.
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Wang, L.; Li, Q. Photochromism into Nanosystems: Towards Lighting up the Future Nanoworld. Chem. Soc. Rev. 2018, 47, 1044, DOI: 10.1039/c7cs00630f
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Photochromism into nanosystems: towards lighting up the future nanoworld
Wang, Ling; Li, Quan
Chemical Society Reviews (2018), 47 (3), 1044-1097CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
The ability to manipulate the structure and function of promising nanosystems via energy input and external stimuli is emerging as an attractive paradigm for developing reconfigurable and programmable nanomaterials and multifunctional devices. Light stimulus manifestly represents a preferred external phys. and chem. tool for in situ remote command of the functional attributes of nanomaterials and nanosystems due to its unique advantages of high spatial and temporal resoln. and digital controllability. Photochromic moieties are known to undergo reversible photochem. transformations between different states with distinct properties, which have been extensively introduced into various functional nanosystems such as nanomachines, nanoparticles, nanoelectronics, supramol. nanoassemblies, and biol. nanosystems. The integration of photochromism into these nanosystems has endowed the resultant nanostructures or advanced materials with intriguing photoresponsive behaviors and more sophisticated functions. In this Review, we provide an account of the recent advancements in reversible photocontrol of the structures and functions of photochromic nanosystems and their applications. The important design concepts of such truly advanced materials are discussed, their fabrication methods are emphasized, and their applications are highlighted. The Review is concluded by briefly outlining the challenges that need to be addressed and the opportunities that can be tapped into. We hope that the review of the flourishing and vibrant topic with myriad possibilities would shine light on exploring the future nanoworld by encouraging and opening the windows to meaningful multidisciplinary cooperation of engineers from different backgrounds and scientists from the fields such as chem., physics, engineering, biol., nanotechnol. and materials science.
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Zhang, X.; Hou, L.; Samorì, P. Coupling Carbon Nanomaterials with Photochromic Molecules for the Generation of Optically Responsive Materials. Nat. Commun. 2016, 7, 11118, DOI: 10.1038/ncomms11118
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Coupling carbon nanomaterials with photochromic molecules for the generation of optically responsive materials
Zhang, Xiaoyan; Hou, Lili; Samori, Paolo
Nature Communications (2016), 7 (), 11118CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)
The marriage of photochromic mols. with the rapidly expanding portfolio of nanocarbons is providing new multifunctional and responsive nanomaterials. Here, the authors review recent progress in such materials' fabrication and their possible implementations, and suggest future directions of study.
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Kim, D.; Jeong, K.; Kwon, J. E.; Park, H.; Lee, S.; Kim, S.; Park, S. Y. Dual-Color Fluorescent Nanoparticles Showing Perfect Color-Specific Photoswitching for Bioimaging and Super-Resolution Microscopy. Nat. Commun. 2019, 10, 3089, DOI: 10.1038/s41467-019-10986-4
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Dual-color fluorescent nanoparticles showing perfect color-specific photoswitching for bioimaging and super-resolution microscopy
Kim Dojin; Kwon Ji Eon; Park Soo Young; Jeong Keunsoo; Park Hyeonjong; Lee Seokyung; Kim Sehoon; Kim Sehoon
Nature communications (2019), 10 (1), 3089 ISSN:.
Dual-emissive systems showing color-specific photoswitching are promising in bioimaging and super-resolution microscopy. However, their switching efficiency has been limited because a delicate manipulation of all the energy transfer crosstalks in the systems is unfeasible. Here, we report a perfect color-specific photoswitching, which is rationally designed by combining the complete off-to-on fluorescence switching capability of a fluorescent photochromic diarylethene and the frustrated energy transfer to the other fluorescent dye based on the excited-state intramolecular proton transfer (ESIPT) process. Upon alternation of UV and visible light irradiations, the system achieves 100% switching on/off of blue emission from the diarylethene while orange emission from the ESIPT dye is unchanged in the polymer film. By fabricating this system into biocompatible polymer nanoparticles, we demonstrate microscopic imaging of RAW264.7 macrophage cells with reversible blue-color specific fluorescence switching that enables super-resolution imaging with a resolution of 70 nm.
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Wang, H.; Zhang, P.; Krishnan, B. P.; Yu, M.; Liu, J.; Xue, M.; Chen, S.; Zeng, R.; Cui, J.; Chen, J. Switchable Single Fluorescent Polymeric Nanoparticles for Stable White-Light Generation. J. Mater. Chem. C 2018, 6, 9897, DOI: 10.1039/c8tc03757d
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Switchable single fluorescent polymeric nanoparticles for stable white-light generation
Wang, Hong; Zhang, Peisheng; Krishnan, Baiju P.; Yu, Maolin; Liu, Jie; Xue, Mingju; Chen, Shu; Zeng, Rongjin; Cui, Jiaxi; Chen, Jian
Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2018), 6 (37), 9897-9902CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
The development of switchable white-light emitters is extremely challenging but urgently needed for various applications. We describe a class of switchable fluorescent polymeric nanoparticles (SFPNs) that can alternate their emission color among stable white, cyan, or pink. These SFPNs consist of a dye with cyan-light emission and a spiropyran (SP) deriv. with photochromism. When the SP deriv. is transferred to its merocyanine state, fluorescence resonance energy transfer (FRET) occurs from the cyan dye to the merocyanine one. In a rational design of transfer efficiency, a stable white-light emission is achieved. This white-light emission can be switched to the cyan-light one upon photoirradn. or pink-light one by solvent-induced swelling. Such multi-color fluorescent alternation is reversible and therefore allows for data encryption. Because of the facile synthesis, excellent long-term stability, fast photo-responsibility, high-contrast fluorescence, and outstanding switchability of these nanoparticles, we envision that they should have great potential in various applications such as high-resoln. imaging, white luminescence, and data encryption.
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Wang, L.; Liu, Y.; Zhan, X.; Luo, D.; Sun, X. Photochromic Transparent Wood for Photo-Switchable Smart Window Applications. J. Mater. Chem. C 2019, 7, 8649, DOI: 10.1039/c9tc02076d
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Photochromic transparent wood for photo-switchable smart window applications
Wang, Lihong; Liu, Yanjun; Zhan, Xiyun; Luo, Dan; Sun, Xiaowei
Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2019), 7 (28), 8649-8654CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
Transparent wood with high optical transmittance, excellent thermal insulation and high toughness has attracted significant attention as an energy-saving building material. Many research efforts were dedicated to functional transparent wood, from luminescent to electrochromic transparent wood. However, photochromic transparent wood that is highly desirable and crit. for smart window applications has been rarely studied. Herein, we exptl. demonstrate photochromic transparent wood with photo-switching of transmittance in the visible light region and color tuning properties. The photochromic transparent wood was obtained by infiltrating the lignin modified wood template with a mixt. of photochromic material 3',3'-dimethyl-6-nitro-spiro[2H-1-benzopyran-2,2'-indoline]-1'-ethanol (DNSE) and pre-polymd. Me methacrylate (MMA). This photochromic transparent wood exhibits a vibrant purple-to-colorless color change under the illumination of light. In addn., dichroic dye material doped photochromic woods were studied for providing more color change choices. The proposed photochromic transparent wood shows potential applications in mech. robust, energy-efficient, photo-switchable, and colorful smart windows on a large scale.
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Abdollahi, A.; Sahandi-Zangabad, K.; Roghani-Mamaqani, H. Rewritable Anticounterfeiting Polymer Inks Based on Functionalized Stimuli-Responsive Latex Particles Containing Spiropyran Photoswitches: Reversible Photopatterning and Security Marking. ACS Appl. Mater. Interfaces 2018, 10, 39279– 39292, DOI: 10.1021/acsami.8b14865
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Rewritable anticounterfeiting polymer inks based on functionalized stimuli-responsive latex particles containing spiropyran photoswitches: reversible photopatterning and security marking
Abdollahi, Amin; Sahandi-Zangabad, Keyvan; Roghani-Mamaqani, Hossein
ACS Applied Materials & Interfaces (2018), 10 (45), 39279-39292CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
Increase of safety in security documents by using anticounterfeiting inks based on fluorochromic and photochromic compds. has attracted a great deal of attention in the recent years. Herein, we developed novel functionalized stimuli-responsive latex particles contg. spiropyran (1 wt %) by semicontinuous emulsifier-free emulsion polymn., which are usable as anticounterfeiting inks for marking on security documents and also photopatterning on cellulosic papers. The size and morphol. of the latex particles were characterized by SEM and dynamic light scattering and their functionality was characterized by Fourier-transform IR spectroscopy. All the stimuli-responsive latexes are composed of spherical particles with different hydroxyl, epoxy, and carboxylic acid functional groups, and the size of the particles varies in the range of 400-900 nm. Addnl., the latex particles undergo a remarkable light-induced size variation (aggregation-disaggregation) upon UV illumination (365 nm), depending on the functional group type, as a result of π-π stacking interactions and also electrostatic attractions between the different particles. The photochromic behavior, kinetics of the SP .dblharw. MC isomerization, photoswitchability, and photofatigue-resistant characteristics of the prepd. latexes were extensively investigated. The results display that the photochromic behavior and SP .dblharw. MC isomerization can significantly be influenced by the polar interactions between the functional groups and MC mols. As a novel application, the prepd. stimuli-responsive latexes were used as anticounterfeiting inks for writing on cellulosic paper and also security marking on several monies, where the written phrase displayed red fluorescence emission and coloration under and after UV illumination (365 nm), resp. Addnl., the latexes were sprayed on cellulosic papers to prep. stimuli-responsive papers for investigation of their photopatterning ability under UV irradn. and different masking. The presence of functional groups and large particle sizes are the main effective factors for stabilization of the latex particles on cellulosic papers. This is the first report on application of functionalized stimuli-responsive latex particles contg. spiropyran as anticounterfeiting inks for security marking and photopatterning on cellulosic papers, directly and without using further additives.
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Liu, L.; Ren, Y.; Pan, J.; Liu, Z.; Wu, B.; Yan, F. Printable UV-Light Sensor for Human Eye Protection. ACS Appl. Mater. Interfaces 2020, 12, 1495– 1503, DOI: 10.1021/acsami.9b17391
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Printable UV-Light Sensor for Human Eye Protection
Liu, Lili; Ren, Yongyuan; Pan, Ji; Liu, Ziyang; Wu, Bing; Yan, Feng
ACS Applied Materials & Interfaces (2020), 12 (1), 1495-1503CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
Light-emitting diode based electronic screens emit near-UV radiation, which causes harm to the human eye after prolonged exposure. Thus, it is of paramount importance to prep. a sensitive and adjustable visible near-UV sensor for retinal warning. Herein, a series of bipyridine derivs. were synthesized to investigate effects of substituent groups and anions on photochromic properties via both exptl. and theor. studies. The introduction of dual hydrogen bonding urea onto substituted groups significantly accelerated the photochromic rate due to strong intermol. interactions, which reduces mol. spacing and promotes the electron-transfer effect. Moreover, the photochromic rate was tuned by changing the size of the anion. Larger anions widen the mol. spacing and weaken the electron transfer and eventually lead to a decrease in the photochromic rate. Finally, bipyridine derivs. were printed on a polyethylene terephthalate film or paper as a sensitive, adjustable, and visible sensor to monitor near-UV radiation emitted by an light-emitting diode screen.
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Wu, Y.; Guo, Z.; Zhu, W.-H.; Wan, W.; Zhang, J.; Li, W.; Li, X.; Tian, H.; Li, A. D. Q. Photoswitching Between Black and Colourless Spectra Exhibits Resettable Spatiotemporal Logic. Mater. Horiz. 2016, 3, 124, DOI: 10.1039/c5mh00223k
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Photoswitching between black and colourless spectra exhibits resettable spatiotemporal logic
Wu, Yue; Guo, Zhiqian; Zhu, Wei-Hong; Wan, Wei; Zhang, Junji; Li, Wenlong; Li, Xin; Tian, He; Li, Alexander D. Q.
Materials Horizons (2016), 3 (2), 124-129CODEN: MHAOBM; ISSN:2051-6355. (Royal Society of Chemistry)
Logic is the key to computing. Traditionally, logic devices have been fabricated by the top-down approach, whose dimensions are drastically limited. The ultimate goal is to use mol. tailorability to design logics using the "bottom-up" approach. Here we report an unprecedented photochromic mol. that undergoes unimol. logic switching when excited anywhere in the entire UV-visible spectrum, thus a bottom-up, all-photonic, mol. logic gate. Specifically, these mol. photonic logics embedded in the polymer thin films function as the "AND" or "OR" gate at different temporal responses. To achieve high information-processing d., moreover, a ternary flip-flap-flop gate is realized in the mol. logic because the fact that this photochromic mol. can be photoswitched anywhere in its UV-vis spectrum enabled three different lasers (532, 473, and 561 nm) as the inputs to deliver the complex logic optical outputs.
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Li, J.; Bisoyi, H. K.; Tian, J.; Guo, J.; Li, Q. Optically Rewritable Transparent Liquid Crystal Displays Enabled by Light-Driven Chiral Fluorescent Molecular Switches. Adv. Mater. 2019, 31, 1807751, DOI: 10.1002/adma.201807751
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Yerushalmi, R.; Scherz, A.; van der Boom, M. E.; Kraatz, H.-B. Stimuli Responsive Materials: New Avenues Toward Smart Organic Devices. J. Mater. Chem. 2005, 15, 4480– 4487, DOI: 10.1039/b505212b
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Stimuli responsive materials: new avenues toward smart organic devices
Yerushalmi, Roie; Scherz, Avigdor; van der Boom, Milko E.; Kraatz, Heinz-Bernhard
Journal of Materials Chemistry (2005), 15 (42), 4480-4487CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)
A review. "Smart" patternable polymer-based materials that can be designed from various mol. building blocks show great potential, as they may be used in many fields, including nanotechnol., biochem., org. and phys. chem., and materials science. The focus of this highlight will be on the basic design characteristics of practical Stimuli Responsive Materials (SRMs), the wide range of potential applications and the challenges to be accomplished in this rapidly expanding area. In particular, recent developments are described which are related to two of the many fundamental aspects of stimuli triggered responses: those that are photo-triggered and those that are solvent triggered. These selected state-of-the-art examples demonstrate the large scope and diversity in terms of activation mechanism, response time and property control.
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Sobolewska, A.; Bartkiewicz, S.; Miniewicz, A.; Schab-Balcerzak, E. Polarization Dependence of Holographic Grating Recording in Azobenzene-Functionalized Polymers Monitored by Visible and Infrared Light. J. Phys. Chem. B 2010, 114, 9751– 9760, DOI: 10.1021/jp103756h
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Polarization Dependence of Holographic Grating Recording in Azobenzene-Functionalized Polymers Monitored by Visible and Infrared Light
Sobolewska, Anna; Bartkiewicz, Stanislaw; Miniewicz, Andrzej; Schab-Balcerzak, Ewa
Journal of Physical Chemistry B (2010), 114 (30), 9751-9760CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
The holog. grating recording process in thin films of amorphous azobenzene-functionalized polymers has been widely reported in the literature. In spite of the many reports, little is known about the mechanisms responsible for different temporal behaviors of the diffraction efficiency during long recording times. The authors report on exptl. studies of the diffraction efficiency changes during the holog. diffraction grating recording process in photochromic polymer. The gratings were inscribed for four different polarization combinations of the recording beams: s-s, p-p, s-p and right to left circular polarization (RCP-LCP) employing the degenerate two-wave mixing technique. The grating recording process was simultaneously monitored by three different wavelengths: 514.5 nm (writing) and 632.8 and 904 nm (reading). The temporal evolution of the diffraction efficiency (for all polarization configurations and for each wavelengths) was precisely fitted within the model, which assumes simultaneous formation of the absorption grating and three coupling phase gratings shifted by 0 or π with respect to each other. Two of the phase gratings originate from the refractive index grating changes in the bulk (vol.) of a material and the third one from the surface relief modulation. The model enabled the authors to ext. relevant parameters for each grating such as the build-up time const., its final amplitude, and the phase shifts between phase gratings. Performed studies and the discussion of results revealed the main differences in the diffraction grating formation process for s-s, p-p, s-p, and RCP-LCP polarization configurations.
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Miniewicz, A.; Kochalska, A.; Mysliwiec, J.; Samoc, A.; Samoc, M.; Grote, J. G. Deoxyribonucleic Acid-Based Photochromic Material for Fast Dynamic Holography. Appl. Phys. Lett. 2007, 91, 041118, DOI: 10.1063/1.2760169
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Deoxyribonucleic acid-based photochromic material for fast dynamic holography
Miniewicz, Andrzej; Kochalska, Anna; Mysliwiec, Jaroslaw; Samoc, Anna; Samoc, Marek; Grote, James G.
Applied Physics Letters (2007), 91 (4), 041118/1-041118/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
The authors report on a biopolymeric material made of DNA complexed with the cationic surfactant cetyltrimethylammonium chloride (CTMA) and doped with the photochromic Disperse red 1 (DR1) for dynamic holog. recording. The molar ratio of the DNA-CTMA to the dye is about 5:1. They have found that the photochromic properties of DR1 in the DNA-CTMA matrix are favorably modified in speed of response with respect to conventional polymeric matrixes. Dynamic holog. gratings which were inscribed in DR1:DNA-CTMA films are characterized by switching times within a 1-10 ms range. An excellent reversibility of the recording process is reported.
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Dobryakov, A. L.; Quick, M.; Richter, C.; Knie, C.; Ioffe, I. N.; Granovsky, A. A.; Mahrwald, R.; Ernsting, N. P.; Kovalenko, S. A. Photoisomerization pathways and Raman activity of 1,1′-difluorostilbene. J. Chem. Phys. 2017, 146, 044501– 044518, DOI: 10.1063/1.4974357
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Photoisomerization pathways and Raman activity of 1,1'-difluorostilbene
Dobryakov, A. L.; Quick, M.; Richter, C.; Knie, C.; Ioffe, I. N.; Granovsky, A. A.; Mahrwald, R.; Ernsting, N. P.; Kovalenko, S. A.
Journal of Chemical Physics (2017), 146 (4), 044501/1-044501/17CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)
The photoisomerization of 1,1'-difluorostilbene, following S0→S1 optical excitation in soln., was studied with femtosecond broadband transient absorption and stimulated Raman spectroscopy, and by quantum-chem. calcns. In n-hexane, trans-to-cis (t→c) isomerization starts with Franck-Condon relaxation (τ1t = 0.07 ps) followed by nearly barrierless torsion around the ethylenic bond (τ2t ≈ 0.3 ps) to a perpendicular conformation P. About 50% of the excited mols. are trapped in P, while others reach the S1(cis) conformation adiabatically. For the opposite cis-to-trans (c→t) path, the dynamics in n-hexane (τ1c = 0.04 ps, τ2c = 0.7 ps) suggest a 5 kJ/mol barrier between the relaxed S1(cis) and P states. The subsequent P decay with τ3 = 0.4 ps is followed by much slower ground-state recovery (τ4 ≈ 3 ps), indicating an intermediate state X. The t→P and c→P torsion depend on solvent viscosity and polarity, whereas the P→X→S0 relaxation and residual torsion is viscosity-independent but still polarity-dependent. Photoisomerization yields are derived from the transient absorption data and compared to those from actinometric measurements. Low-frequency oscillations in the transient signal are assigned to nuclei motions. Transient and stationary stimulated Raman spectra are compared to calcns. Early Franck-Condon Raman spectra differ from those of the quasistationary trans or cis S1 state. The photoisomerization behavior of stilbene and vinyl-substituted derivs. is compared and the general features are discussed. (c) 2017 American Institute of Physics.
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He, T.; Wang, Y.; Tian, X.; Gao, Y.; Zhao, X.; Grimsdale, A. C.; Lin, X.; Sun, H. An Organic Dye with Very Large Stokes-Shift and Broad Tunability of Fluorescence: Potential Two-Photon Probe for Bioimaging and Ultra-Sensitive Solid-State Gas Sensor. Appl. Phys. Lett. 2016, 108, 011901– 011905, DOI: 10.1063/1.4939232
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An organic dye with very large Stokes-shift and broad tunability of fluorescence: Potential two-photon probe for bioimaging and ultra-sensitive solid-state gas sensor
He, Tingchao; Wang, Yue; Tian, Xiaoqing; Gao, Yang; Zhao, Xin; Grimsdale, Andrew C.; Lin, Xiaodong; Sun, Handong
Applied Physics Letters (2016), 108 (1), 011901/1-011901/5CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
Light-emitting nonlinear optical mols., esp. those with large Stokes shifts and broad tunability of their emission wavelength, have attracted considerable attention for various applications including biomedical imaging and fluorescent sensors. However, most fluorescent chromophores have only limited potential for such applications due to small Stokes shifts, narrow tunability of fluorescence emissions, and small optical nonlinearity in highly polar solvents. In this work, we demonstrate that a two-photon absorbing stilbene chromophore exhibits a large two-photon absorption action cross-section (ηδ = 320 GM) in dimethylsulfoxide (DMSO) and shows broad fluorescence tunability (125 nm) by manipulating the polarity of the surrounding medium. Importantly, a very large Stokes shift of up to 227 nm is achieved in DMSO. Thanks to these features, this chromophore can be utilized as a two-photon probe for bioimaging applications and in an ultrasensitive solid-state gas detector. (c) 2016 American Institute of Physics.
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Szukalski, A.; Haupa, K.; Miniewicz, A.; Mysliwiec, J. Photoinduced Birefringence in PMMA Polymer Doped with Photoisomerizable Pyrazoline Derivative. J. Phys. Chem. C 2015, 119, 10007– 10014, DOI: 10.1021/acs.jpcc.5b01947
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Photoinduced Birefringence in PMMA Polymer Doped with Photoisomerizable Pyrazoline Derivative
Szukalski, Adam; Haupa, Karolina; Miniewicz, Andrzej; Mysliwiec, Jaroslaw
Journal of Physical Chemistry C (2015), 119 (18), 10007-10014CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
Upon S0-S1 excitation, the pyrazoline deriv. mol. (Z)-2-(4-nitrophenyl)-3-(1-phenyl-4,5-dihydro-1H-pyrazol-3-yl)acrylonitrile, abbreviated as PY-oCNNO2, can be transformed from its ground state trans (E) form to bended cis (Z) form. Similar to the case of the well-known family of the photochromic azobenzenes, such a mol. property can be employed to fabrication of photochromic polymers by suitable doping of the chromophores into polymer matrix. In this work, poly(Me methacrylate) thin films doped with PY-oCNNO2 were prepd. and the characteristic for optical switchers dynamic and static photoinduced birefringence (PIB) phenomenon was measured. Possible conformational states of PY-oCNNO2, energy barriers, and assocd. dipole moments were calcd. using TD-DFT quantum chem. methods. The presented expts. show that pyrazoline derivs. constitute a prospective group of materials with a great potential for photonic applications.
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Szukalski, A.; Miniewicz, A.; Haupa, K.; Przybyl, B.; Janczak, J.; Sobolewski, A. L.; Mysliwiec, J. Photo-Physical Transformations in Pyrazoline Derivative Based Systems. J. Phys. Chem. C 2016, 120, 14813– 14819, DOI: 10.1021/acs.jpcc.6b03915
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Photo-Physical Transformations in Pyrazoline Derivative Based Systems
Szukalski, A.; Miniewicz, A.; Haupa, K.; Przybyl, B.; Janczak, J.; Sobolewski, A. L.; Mysliwiec, J.
Journal of Physical Chemistry C (2016), 120 (27), 14813-14819CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
Discovery of E/Z or trans-cis photoisomerization in the azobenzenes and their derivs. had tremendous impact on the whole domain of photochromic materials including photochromic polymers and liq. crystals. Here, a similar configurational photoinduced transformation in a simple deriv. of pyrazoline is shown. The x-ray crystallog. investigations of (E)-3-(4-nitrostyryl)-1-phenyl-4,5-dihydro-1H-pyrazole (abbreviated as PY-pNO2) in grown crystals show two different structures comprising of either cis or trans mols. The performed quantum chem. calcns. confirm the existence of both configurations of PY-pNO2 at the room temp. Photophys. properties of this compd. derived from quantum chem. calcns. predict possibility of trans to cis switching of PY-pNO2 by light. Indeed, mols. of PY-pNO2 embedded in PMMA polymeric matrix when illuminated with 532 nm linearly polarized laser light show the induced optical anisotropy, i.e., birefringence characteristic for photoisomerizable mols. similar to that in the group of the azobenzene derivs.
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Wadsworth, W. S.; Emmons, W. D. The Utility of Phosphonate Carbanions in Olefin Synthesis. J. Am. Chem. Soc. 1961, 83, 1733– 1738, DOI: 10.1021/ja01468a042
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The utility of phosphonate carbanions in olefin synthesis
Wadsworth, William S., Jr.; Emmons, William D.
Journal of the American Chemical Society (1961), 83 (), 1733-8CODEN: JACSAT; ISSN:0002-7863.
The reaction of phosphonate carbanions contg. electron-withdrawing groups with aldehydes or ketones in an aprotic solvent, a useful olefin synthesis, was studied. These reagents were, in general, more reactive than the analogous triarylphosphoranes (Wittig reagents) and had a no. of special features which enhanced their usefulness. (EtO)2P(O)CH2Bz (11.4 g.) added dropwise with stirring to 2.4 g. 50% NaH in 100 cc. dry (MeOCH2)2 at 20°, stirred 1 hr. at room temp., treated below 25° dropwise with 5.3 g. BzH, stirred 1 hr. at room temp., and refluxed 0.5 hr. gave 6.3 g. PhCH:CHBz, m. 52-3°. EtO2CCH2P(O)(OEt)2 (I) added dropwise at 20° to 2.4 g. 50% NaH in 100 cc. dry (MeOCH2)2, stirred 1 hr. at room temp., treated dropwise below 30° with 4.9 g. cyclohexanone, and stirred 15 min. at room temp. yielded 5.8 g. Et cyclohexylideneacetate, b10 88-90°, n25D 1.4704. I (11.2 g.), 2.4 g. 50% NaH in 100 cc. (CH2OMe)2, and 7.2 g. AcCH2CH2CO2Et gave in the usual manner at 50-60° during 1 hr. 7.1 g. EtO2CCH:CMeCH2CH2CO2Et, b0.25 78-80°, n25D 1.4506. PhCH2P(O)(OEt)2 (11.4 g.), 2.4 g. 50% NaH, 5.3 g. BzH, and 100 cc. (MeOCH2)2 refluxed 0.5 hr. gave 5.6 g. trans-stilbene, m. 124.5°. p-[(EtO)2P(O)CH2]2C6H4 (II) (9.45 g.), 1.2 g. 50% NaH, 2.65 g. BzH, and 100 cc. (MeOCH2)2 refluxed 0.5 hr. yielded 4.5 g. (p-PhCH:CH)2C6H4, m. 259-60°. II (9.45 g.), 2.4 g. 50% NaH, 7.6 g. PhCH:CHCHO, and 100 cc. (MeOCH2)2 heated 0.5 hr. at 85° gave 3.0 g. p-(PhCH: CHCH:CH)2C6H4, m. 290-1°. CH2[P(O)(OEt)2]2 (5.3 g.) added dropwise at room temp. to 0.971 g. 50% NaH and 100 cc. (MeOCH2)2, stirred 1 hr., and treated dropwise with stirring with 2.14 g. BzH yielded 2.4 g. PhCH:CHP(O) (OEt)2, b0.35, 116-18°, n25D 1.5208. Di-Et fluorenylphosphonate (III) (7.55 g.), 1.3 g. 50% NaH, 100 cc. dry (MeOCH2)2, and 0.8 g. paraformaldehyde in (MeOCH2)2, processed in the usual manner at 30°, dild. with H2O, and extd. with Et2O gave a soln. of 9-methylenefluorene which with Br-CCl4 gave a cryst. ppt., m. 144°; the bulk of the Et2O soln. evapd. yielded 30.5 g. polymerized product which was insol. in all common solvents. I (86 g.) added dropwise with stirring at room temp. to 18.4 g. 50% NaH in 100 cc. (MeOCH2)2, the mixt. heated 1 hr. at 50° with 52.6 g. BuBr, cooled to 10°, treated with 18.4 g. 50% NaH, stirred 1 hr. at room temp., treated with 12.1 g. paraformaldehyde in 50 cc. (MeOCH2)2 at 20° during 1 hr., and stirred 1 hr. yielded 38.4 g. CH2:CBuCO2Et, b100 68-9°, n25D 1.4254. I (22.4 g.) added dropwise at 20° to 4.8 g. 50% NaH in 100 cc. (MeOCH2)2, stirred 1 hr., treated dropwise below 25° with 16 g. Br, warmed briefly at 40°, cooled to 10°, treated with 4.5 g. 50% NaH and then below 30° with 7.3 g. iso-PrCHO, and worked up gave 14.5 g. Me2CHCH:CBrCO2Et, b10 76-8°, n25D 1.4649. I (11.2 g.) added at 25° dropwise to 2.4 g. 50% NaH in 100 cc. (MeOCH2)2, stirred 1 hr., treated dropwise with 12.7 g. iodine in the min. (MeOCH2)2, stirred 1 hr. at room temp., treated at 10° with 4.8 g. 50% NaH and then at 25° dropwise with 5.3 g. BzH, and heated slowly to 40° gave 5.1 g. PhC≡CCO2Et, b0.1 78-80°, n25D 1.5800. I (11.2 g.), 2.5 g. 50% NaH in 100 cc. (MeOCH2)2, and 7.3 g. EtPhC:C:O gave at 50° 3.5 g. EtPhC:C:CHCO2Et, b0.1 89-90°, n25D 1.5490. (EtO)2P(O)CH2Ph (IV) with BzPh gave similarly 78% Ph2C:CHPh, m. 67°. IV with PhCH:CHCHO yielded 58% (PhCH:CH)2, m. 151°. I with BzH gave 84% PhCH:CHCO2Et, b0.1 70°, n25D 1.5562. I with iso-PrCHO yielded 74% iso-PrCH:CHCO2Et, b15 65°, n25D 1.4284. III with BzH gave 80% 9-benzylidenefluorene, m. 74-5°. (EtO)2P(O)CH2CN and BzH gave 66% PhCH:CHCN, b10 130°, n25D 1.5828. I with CCl3CHO yielded 50% CCl3CH:CHCO2Et, b10 86°, n25D 1.4798. (MeO)2P(O)CH2CO2Et and Me2CO yielded 70% Me2C:CHCO2Et, b760 150°, n25D 1.4331. (EtO)2P(O)CH(CO2Et)CH2CO2Et [prepd. by treating mono-Et maleate with (EtO)3P] with BzH gave 61% PhCH:C(CO2Et)CH2CO2Et, b0.1 119°, n25D 1.5068. I (22.4 g.) added dropwise with stirring at 25° to 5.0 g. 50% NaH in 100 cc. dry (MeOCH2)2, stirred 1 hr., refluxed 4 hrs. with 12.0 g. styrene oxide, cooled to room temp., dild. with H2O, and extd. with Et2O gave 8.0 g. PhCH.CH2.CHCO2Et, b0.5 100-2°, n25D 1.5121. I with EtCH.CH2.O gave similarly 21% EtCH.CH2.CHCO2Et, b15 55°, n25D 1.4215. (EtO)2P(O)CH2CN with styrene oxide yielded 51% PhCH.CH2.CHCN, b0.2 80°, m. 26-7°, n25D 1.5226.
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Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Gaussian 09, Revision A.1; Gaussian, Inc.: Wallingford CT, 2009.
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There is no corresponding record for this reference.
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Boys, S. F.; Bernardi, F. The Calculation of Small Molecular Interactions by the Differences of Separate Total Energies. Some Procedures With Reduced Errors. Mol. Phys. 1970, 19, 553– 566, DOI: 10.1080/00268977000101561
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The calculation of small molecular interactions by the differences of separate total energies. Some procedures with reduced errors
Boys, S. F.; Bernardi, F.
Molecular Physics (1970), 19 (4), 553-566CODEN: MOPHAM; ISSN:0026-8976. (Taylor & Francis Ltd.)
A new direct difference method for the computation of mol. interactions has been based on a bivariational transcorrelated treatment, together with special methods for the balancing of other errors. It appears that these new features can give a strong redn. in the error of the interaction energy, and they seem to be particularly suitable for computations in the important region near the min. energy. It has been generally accepted that this problem is dominated by unresolved difficulties and the relation of the new methods of these apparent difficulties is analyzed here.
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Dunning, T. H. Gaussian basis sets for use in correlated molecular calculations. I. The Atoms Boron through Neon and Hydrogen. J. Chem. Phys. 1989, 90, 1007– 1023, DOI: 10.1063/1.456153
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Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen
Dunning, Thom H., Jr.
Journal of Chemical Physics (1989), 90 (2), 1007-23CODEN: JCPSA6; ISSN:0021-9606.
Guided by the calcns. on oxygen in the literature, basis sets for use in correlated at. and mol. calcns. were developed for all of the first row atoms from boron through neon, and for hydrogen. As in the oxygen atom calcns., the incremental energy lowerings, due to the addn. of correlating functions, fall into distinct groups. This leads to the concept of correlation-consistent basis sets, i.e., sets which include all functions in a given group as well as all functions in any higher groups. Correlation-consistent sets are given for all of the atoms considered. The most accurate sets detd. in this way, [5s4p3d2f1g], consistently yield 99% of the correlation energy obtained with the corresponding at.-natural-orbital sets, even though the latter contains 50% more primitive functions and twice as many primitive polarization functions. It is estd. that this set yields 94-97% of the total (HF + 1 + 2) correlation energy for the atoms neon through boron.
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de Mello, J. C.; Wittmann, H. F.; Friend, R. H. An Improved Experimental Determination of External Photoluminescence Quantum Efficiency. Adv. Mater. 1997, 9, 230, DOI: 10.1002/adma.19970090308
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An improved experimental determination of external photoluminescence quantum efficiency
De Mello, John C.; Wittmann, Felix H.; Friend, Richard H.
Advanced Materials (Weinheim, Germany) (1997), 9 (3), 230-232CODEN: ADVMEW; ISSN:0935-9648. (VCH)
An improved integrating-sphere method is presented that can be used for detg. external photoluminescence quantum yield of thin film semiconductors. The basic exptl. setup is described. Three configurations of the sphere are required for the efficiency measurements: 1st an empty sphere, 2nd with a sample placed in the sphere but the laser beam directed onto the sphere wall, and 3rd the sample placed in the sphere with laser beam directed onto it. The measurement of the luminescence efficiency was carried out on poly-(2-methoxy-5-(2'-ethyl)-hexyloxy-p-phenylenevinylene). A dil. soln. of Rhodamine 6G in ethanol was used as the std. It is shown how the absorption coeff. and the external PL quantum yield can be extd. from the spectra. The external quantum efficiency is η = 9.7 ± 1%, the method of Greenham gives a similar value of η = 10 ± 1.5%. The role of reabsorption and the advantages of the method are addnl. discussed.
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Szukalski, A.; Moffa, M.; Camposeo, A.; Pisignano, D.; Mysliwiec, J. All-Optical Switching in Dye-Doped DNA Nanofibers. J. Mater. Chem. C 2019, 7, 170– 176, DOI: 10.1039/c8tc04677h
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All-optical switching in dye-doped DNA nanofibers
Szukalski, Adam; Moffa, Maria; Camposeo, Andrea; Pisignano, Dario; Mysliwiec, Jaroslaw
Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2019), 7 (1), 170-176CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
All-optical switches are introduced which are based on DNA (DNA) in the form of electrospun fibers, where DNA is semi-intercalated with a push-pull, luminescent nonlinear pyrazoline deriv. Optical birefringence is found in the org. nanofibers, with fully reversible switching controlled through continuous-wave laser irradn. The photoinduced signal is remarkably large, with birefringence highlighted by optically-driven refractive index anisotropy approaching 0.001. Sub-millisecond characteristic switching times are found. Integrating dye-intercalated DNA complex systems in org. nanofibers, as a convenient and efficient approach to template mol. organization and control it by external stimuli, might open new routes for realizing optical logic gates, reconfigurable photonic networks and sensors through phys.-transient biopolymer components.
43
Boyd, R. W. Nonlinear Optics, 3rd ed.; Academic Press: New York, 2008.
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A review. Because of their resolvable crystal structure, org. conjugated small mols. are intrinsically ideal for elucidating the relationship between microstructures and charge transport properties. It has been reported that the charge transport properties depend on mol. structure and mol. packing. In the solid state, π-π stacking of small mols. is significant in the charge transport process. Since π-π stacking of conjugated small mols. is influenced at different degrees by other intra- and intermol. interactions, as a result, π-π stacking and further the charge transport properties can be controlled or tuned by crystal engineering through precise chem. modification. In this perspective, we give some typical examples illustrating the strategy of controlling π-π stacking in single crystals. Furthermore, we attempt to clarify the complex relationship between π-π stacking and other types of mol. interactions, and its influence on charge transport properties.
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Visible-Light-Activated Molecular Switches
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The ability to influence key properties of mol. systems by using light holds much promise for the fields of materials science and life sciences. The cornerstone of such systems is mols. that are able to reversibly photoisomerize between two states, commonly referred to as photoswitches. One serious restriction to the development of functional photodynamic systems is the necessity to trigger switching in at least one direction by UV light, which is often damaging and penetrates only partially through most media. This review provides a summary of the different conceptual strategies for addressing mol. switches in the visible and near-IR regions of the optical spectrum. Such visible-light-activated mol. switches tremendously extend the scope of photoswitchable systems for future applications and technologies.
50
Hoffmann, M.; Papadopoulos, I. N.; Judkewitz, B. Kilohertz Binary Phase Modulator for Pulsed Laser Sources Using a Digital Micromirror Device. Opt. Lett. 2018, 43, 22, DOI: 10.1364/ol.43.000022
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Kilohertz binary phase modulator for pulsed laser sources using a digital micromirror device
Hoffmann Maximilian; Papadopoulos Ioannis N; Judkewitz Benjamin
Optics letters (2018), 43 (1), 22-25 ISSN:.
The controlled modulation of an optical wavefront is required for aberration correction, digital phase conjugation, or patterned photostimulation. For most of these applications, it is desirable to control the wavefront modulation at the highest rates possible. The digital micromirror device (DMD) presents a cost-effective solution to achieve high-speed modulation and often exceeds the speed of the more conventional liquid crystal spatial light modulator but is inherently an amplitude modulator. Furthermore, spatial dispersion caused by DMD diffraction complicates its use with pulsed laser sources, such as those used in nonlinear microscopy. Here we introduce a DMD-based optical design that overcomes these limitations and achieves dispersion-free high-speed binary phase modulation. We show that this phase modulation can be used to switch through binary phase patterns at the rate of 20 kHz in two-photon excitation fluorescence applications.

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Abstract
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Scheme 1
Scheme 1. Scheme of the Synthetic Route of the Th-oCN, Th-mCN, and Th-pCN Derivatives
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Figure 1
Figure 1. Optimized geometries of the most stable conformers of trans- and cis-Th-oCN, Th-mCN, and Th-pCN calculated with the B3LYP/aug-cc-pVDZ method. In-plane view (left) and out-of-plane view (right) are shown for each conformer by considering the plane containing the thiophene group.
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Figure 2
Figure 2. Orientation of dipole moment vectors for the most stable conformers of trans- and cis-Th-oCN, Th-mCN, and Th-pCN. In-plane view (left) and out-of-plane view (right) are shown for each conformer.
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Figure 3
Figure 3. Th-xCNs in PMMA. (a) Absorption (solid line) and PL (dashed line) spectra. (b) Exemplary 2-dimensional PL intensity map showing the spectrally and time-resolved emission of Th-oCN. (c) PL temporal decay for Th-oCN (blue dots), Th-mCN (green dots), and Th-pCN (red dots). The black continuous lines are a fit to the data by a monoexponential curve.
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Figure 4
Figure 4. (a–c) Temporal evolution of the photoinduced birefringence, Δn, for the and Th-oCN (a), Th-mCN (b), and Th-pCN (c), respectively, upon switching on and off the pump beam. Pumping intensities: 40 (a), 96 (b), 113 mW cm^–2 (c). The insets show the increase of Δn for various intensities of the pump beam (reported in mW cm^–2). (d) Dependence of Δn on the incident intensity of the pump beam, I_pump (data collected after 250 s with pump on).
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Figure 5
Figure 5. Amplitude of the modulated birefringence vs the modulation frequency (f_MOD) of the driving, pump beam for Th-oCN (a), Th-mCN (b), and Th-pCN (c), respectively. Insets: exemplary temporal evolution of the optically modulated probe signal, measured at f_MOD = 50 Hz and I_pump = 40 mW cm^–2 for Th-oCN (a), I_pump = 95 mW cm^–2 for Th-mCN (b) and Th-pCN (c), respectively.
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  One of the most important drawback of organic dyes is their low photo-stability which reduces possibility of their commercial utilization. In this article we employ the strategy of dye re-crystallization from oversaturated matrix in order to enhance material's durability. One of the main advantages of perylene derivative is ability to form emissive j-aggregates, good miscibility and incorporation into liquid crystalline matrix. Investigation of perylene-based dye and LC matrix brought as the result very efficient light amplification modulation by applied external electric field. In our article we show that Stimulated Emission (STE) is possible to achieve from perylene-derivative based system, at typical fluence thresholds for laser dyes: 3.9 mJ/cm(2). Moreover, presented system proves ultra-high photostability, showing lack of STE reduction even after 12 000 excitation laser pulses. Furthermore, we proved the possibility of light emission intensity control using external electric field.
11. 11
  Zhang, X.; Li, Z.; Feng, J.; Yang, F.; Wu, C.; Fan, Q.; Zhou, S.; Yin, Y. Dynamic Tuning of Optical Transmittance of 1D Colloidal Assemblies of Magnetic Nanostructures. Adv. Intell. Syst. 2019, 1, 1900099, DOI: 10.1002/aisy.201900099
  There is no corresponding record for this reference.
12. 12
  Sagara, Y.; Kato, T. Mechanically Induced Luminescence Changes in Molecular Assemblies. Nat. Chem. 2009, 1, 605– 610, DOI: 10.1038/nchem.411
  12
  Mechanically induced luminescence changes in molecular assemblies
  Sagara, Yoshimitsu; Kato, Takashi
  Nature Chemistry (2009), 1 (8), 605-610CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
  A review; altering the shape and properties of a material through external factors such as heat, light, pressure, pH, elec. or magnetic fields, or the introduction of a guest mol., is an attractive prospect. In this Perspective, piezochromic luminescent materials - which change the color of their luminescence in response to mech. stimuli - are described. Such piezochromism has been obsd. for a few mol. materials that contain luminescent cores in liq.-cryst. and cryst. solid states, as well as for polymeric materials doped with dyes. These changes in photoluminescent color can be activated by various types of mech. pressure such as shearing, grinding or elongation, which can trigger different mechanisms of producing the color. Such stimuli-responsive materials have potential for various applications, including sensors, memory and displays.
13. 13
  Park, W.; Lee, J.-B. Mechanically Tunable Photonic Crystal Structure. Appl. Phys. Lett. 2004, 85, 4845– 4847, DOI: 10.1063/1.1823019
  13
  Mechanically tunable photonic crystal structure
  Park, Wounjhang; Lee, Jeong-Bong
  Applied Physics Letters (2004), 85 (21), 4845-4847CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
  The authors report a tunable nanophotonic device concept based on flexible photonic crystal, which is comprised of a periodic array of high-index dielec. material and a low-index flexible polymer. Tunability is achieved by applying mech. force with nano-/microelectromech. system actuators. The mech. stress induces changes in the periodicity of the photonic crystal and consequently modifies the photonic band structure. To demonstrate the concept, the authors theor. studied the effect of mech. stress on the anomalous refraction behavior and obsd. a very wide tunability in the beam propagation direction. This concept provides a means to achieve real-time, dynamic control of photonic band structure and will thus expand the utility of photonic crystal structures in advanced nanophotonic systems.
14. 14
  Ke, Y.; Zhou, C.; Zhou, Y.; Wang, S.; Chan, S. H.; Long, Y. Emerging Thermal-Responsive Materials and Integrated Techniques Targeting the Energy-Efficient Smart Window Application. Adv. Funct. Mater. 2018, 28, 1800113, DOI: 10.1002/adfm.201800113
  There is no corresponding record for this reference.
15. 15
  Davis, D. A.; Hamilton, A.; Yang, J.; Cremar, L. D.; Van Gough, D.; Potisek, S. L.; Ong, M. T.; Braun, P. V.; Martínez, T. J.; White, S. R. Force-Induced Activation of Covalent Bonds in Mechanoresponsive Polymeric Materials. Nature 2009, 459, 68– 72, DOI: 10.1038/nature07970
  15
  Force-induced activation of covalent bonds in mechanoresponsive polymeric materials
  Davis, Douglas A.; Hamilton, Andrew; Yang, Jinglei; Cremar, Lee D.; Van Gough, Dara; Potisek, Stephanie L.; Ong, Mitchell T.; Braun, Paul V.; Martinez, Todd J.; White, Scott R.; Moore, Jeffrey S.; Sottos, Nancy R.
  Nature (London, United Kingdom) (2009), 459 (7243), 68-72CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
  Mechanochem. transduction enables an extraordinary range of physiol. processes such as the sense of touch, hearing, balance, muscle contraction, and the growth and remodelling of tissue and bone. Although biol. is replete with materials systems that actively and functionally respond to mech. stimuli, the default mechanochem. reaction of bulk polymers to large external stress is the unselective scission of covalent bonds, resulting in damage or failure. An alternative to this degrdn. process is the rational mol. design of synthetic materials such that mech. stress favorably alters material properties. A few mechanosensitive polymers with this property have been developed; but their active response is mediated through non-covalent processes, which may limit the extent to which properties can be modified and the long-term stability in structural materials. Previously, we have shown with dissolved polymer strands incorporating mech. sensitive chem. groups-so-called mechanophores-that the directional nature of mech. forces can selectively break and re-form covalent bonds. We now demonstrate that such force-induced covalent-bond activation can also be realized with mechanophore-linked elastomeric and glassy polymers, by using a mechanophore that changes color as it undergoes a reversible electrocyclic ring-opening reaction under tensile stress and thus allows us to directly and locally visualize the mechanochem. reaction. We find that pronounced changes in color and fluorescence emerge with the accumulation of plastic deformation, indicating that in these polymeric materials the transduction of mech. force into the ring-opening reaction is an activated process. We anticipate that force activation of covalent bonds can serve as a general strategy for the development of new mechanophore building blocks that impart polymeric materials with desirable functionalities ranging from damage sensing to fully regenerative self-healing.
16. 16
  Yan, X.; Wang, F.; Zheng, B.; Huang, F. Stimuli-Responsive Supramolecular Polymeric Materials. Chem. Soc. Rev. 2012, 41, 6042– 6065, DOI: 10.1039/c2cs35091b
  16
  Stimuli-responsive supramolecular polymeric materials
  Yan, Xuzhou; Wang, Feng; Zheng, Bo; Huang, Feihe
  Chemical Society Reviews (2012), 41 (18), 6042-6065CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  A review. Supramol. materials, dynamic materials by nature, are defined as materials whose components are bridged via reversible connections and undergo spontaneous and continuous assembly/disassembly processes under specific conditions. In this crit. review, we address recent developments in supramol. polymeric materials, which can respond to appropriate external stimuli at the fundamental level due to the existence of noncovalent interactions of the building blocks.
17. 17
  Wang, Y.; Tan, X.; Zhang, Y.-M.; Zhu, S.; Zhang, I.; Yu, B.; Wang, K.; Yang, B.; Li, M.; Zou, B. Dynamic Behavior of Molecular Switches in Crystal under Pressure and Its Reflection on Tactile Sensing. J. Am. Chem. Soc. 2015, 137, 931– 939, DOI: 10.1021/ja511499p
  17
  Dynamic Behavior of Molecular Switches in Crystal under Pressure and Its Reflection on Tactile Sensing
  Wang, Yi; Tan, Xiao; Zhang, Yu-Mo; Zhu, Shaoyin; Zhang, Ivan; Yu, Binhong; Wang, Kai; Yang, Bing; Li, Minjie; Zou, Bo; Zhang, Sean Xiao-An
  Journal of the American Chemical Society (2015), 137 (2), 931-939CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  The pressure-controllable mol. switch of a benzo[1,3]oxazine OX-1 in crystal is demonstrated. Distinct from the light-triggered tautomerization between 2 optical states, applying hydrostatic pressure on the OX-1 crystal results in large-scale and continuous states across the whole visible light range (∼430-∼700 nm), which was not achieved with other stimuli. Based on detailed and systematic control expts. and theor. calcn., the preliminary requirements and mechanism of pressure-dependent tautomerization are fully discussed. The contributions of mol. tautomerization to the large-scale optical modulation are stressed. The importance of studying pressure-responsive materials on understanding tactile sensing is discussed, and a possible mechanotransduction mode is proposed.
18. 18
  Nie, H.; Self, J. L.; Kuenstler, A. S.; Hayward, R. C.; Read de Alaniz, J. Multiaddressable Photochromic Architectures: from Molecules to Materials. Adv. Opt. Mater. 2019, 7, 1900224, DOI: 10.1002/adom.201900224
  There is no corresponding record for this reference.
19. 19
  Delaire, J. A.; Nakatani, K. Linear and Nonlinear Optical Properties of Photochromic Molecules and Materials. Chem. Rev. 2000, 100, 1817– 1846, DOI: 10.1021/cr980078m
  19
  Linear and nonlinear optical properties of photochromic molecules and materials
  Delaire, Jacques A.; Nakatani, Keitaro
  Chemical Reviews (Washington, D. C.) (2000), 100 (5), 1817-1845CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review with 244 refs. about the optical properties and applications of photochromic mols. and materials gained in the last 10-15 yr, excluding the change of their UV-vis absorption spectra. The following photo-induced effects of photochromic materials are described: (i) the excitation of polymers contg. azoaryls or spiropyrans with polarized light leading to transient or permanent dichroism and birefringence, (ii) the excitation of non-centrosym. photochromes with a combination of polarized light and a static elec. field leading to poled materials with 2nd-order, nonlinear optical (NLO) properties, (iii) the irradn. with 2 coherent beams at ω and 2ω leading to all-optical poling, (iv) the irradn. of azo materials with an interference pattern yielding stable-surface relief gratings, and (v) the irradn. of photochromes initially poled in a solid matrix allowing photoswitching of the 2nd- or 3rd-order NLO response and/or annihilation of this response depending on the nature of the matrix. Emphasis was laid on azo polymers and azo-contg. hybrid materials, the photoinduced phenomena of which originated from the cis/trans isomerization reaction proceeding reversibly with high-quantum yields even in solid matrixes.
20. 20
  Klajn, R. Spiropyran-Based Dynamic Materials. Chem. Soc. Rev. 2014, 43, 148, DOI: 10.1039/c3cs60181a
  20
  Spiropyran-based dynamic materials
  Klajn, Rafal
  Chemical Society Reviews (2014), 43 (1), 148-184CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  A review. In the past few years, spiropyran has emerged as the mol. of choice for the construction of novel dynamic materials. This unique mol. switch undergoes structural isomerization in response to a variety of orthogonal stimuli, e.g. light, temp., metal ions, redox potential, and mech. stress. Incorporation of this switch onto macromol. supports or inorg. scaffolds allows for the creation of robust dynamic materials. This review discusses the synthesis, switching conditions and use of dynamic materials in which spiropyran has been attached to the surfaces of polymers, biomacromols., inorg. nanoparticles, as well as solid surfaces. The resulting materials show fascinating properties whereby the state of the switch intimately affects a multitude of useful properties of the support. The utility of the spiropyran switch will undoubtedly endow these materials with far-reaching applications in the near future.
21. 21
  Wang, L.; Li, Q. Photochromism into Nanosystems: Towards Lighting up the Future Nanoworld. Chem. Soc. Rev. 2018, 47, 1044, DOI: 10.1039/c7cs00630f
  21
  Photochromism into nanosystems: towards lighting up the future nanoworld
  Wang, Ling; Li, Quan
  Chemical Society Reviews (2018), 47 (3), 1044-1097CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  The ability to manipulate the structure and function of promising nanosystems via energy input and external stimuli is emerging as an attractive paradigm for developing reconfigurable and programmable nanomaterials and multifunctional devices. Light stimulus manifestly represents a preferred external phys. and chem. tool for in situ remote command of the functional attributes of nanomaterials and nanosystems due to its unique advantages of high spatial and temporal resoln. and digital controllability. Photochromic moieties are known to undergo reversible photochem. transformations between different states with distinct properties, which have been extensively introduced into various functional nanosystems such as nanomachines, nanoparticles, nanoelectronics, supramol. nanoassemblies, and biol. nanosystems. The integration of photochromism into these nanosystems has endowed the resultant nanostructures or advanced materials with intriguing photoresponsive behaviors and more sophisticated functions. In this Review, we provide an account of the recent advancements in reversible photocontrol of the structures and functions of photochromic nanosystems and their applications. The important design concepts of such truly advanced materials are discussed, their fabrication methods are emphasized, and their applications are highlighted. The Review is concluded by briefly outlining the challenges that need to be addressed and the opportunities that can be tapped into. We hope that the review of the flourishing and vibrant topic with myriad possibilities would shine light on exploring the future nanoworld by encouraging and opening the windows to meaningful multidisciplinary cooperation of engineers from different backgrounds and scientists from the fields such as chem., physics, engineering, biol., nanotechnol. and materials science.
22. 22
  Zhang, X.; Hou, L.; Samorì, P. Coupling Carbon Nanomaterials with Photochromic Molecules for the Generation of Optically Responsive Materials. Nat. Commun. 2016, 7, 11118, DOI: 10.1038/ncomms11118
  22
  Coupling carbon nanomaterials with photochromic molecules for the generation of optically responsive materials
  Zhang, Xiaoyan; Hou, Lili; Samori, Paolo
  Nature Communications (2016), 7 (), 11118CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)
  The marriage of photochromic mols. with the rapidly expanding portfolio of nanocarbons is providing new multifunctional and responsive nanomaterials. Here, the authors review recent progress in such materials' fabrication and their possible implementations, and suggest future directions of study.
23. 23
  Kim, D.; Jeong, K.; Kwon, J. E.; Park, H.; Lee, S.; Kim, S.; Park, S. Y. Dual-Color Fluorescent Nanoparticles Showing Perfect Color-Specific Photoswitching for Bioimaging and Super-Resolution Microscopy. Nat. Commun. 2019, 10, 3089, DOI: 10.1038/s41467-019-10986-4
  23
  Dual-color fluorescent nanoparticles showing perfect color-specific photoswitching for bioimaging and super-resolution microscopy
  Kim Dojin; Kwon Ji Eon; Park Soo Young; Jeong Keunsoo; Park Hyeonjong; Lee Seokyung; Kim Sehoon; Kim Sehoon
  Nature communications (2019), 10 (1), 3089 ISSN:.
  Dual-emissive systems showing color-specific photoswitching are promising in bioimaging and super-resolution microscopy. However, their switching efficiency has been limited because a delicate manipulation of all the energy transfer crosstalks in the systems is unfeasible. Here, we report a perfect color-specific photoswitching, which is rationally designed by combining the complete off-to-on fluorescence switching capability of a fluorescent photochromic diarylethene and the frustrated energy transfer to the other fluorescent dye based on the excited-state intramolecular proton transfer (ESIPT) process. Upon alternation of UV and visible light irradiations, the system achieves 100% switching on/off of blue emission from the diarylethene while orange emission from the ESIPT dye is unchanged in the polymer film. By fabricating this system into biocompatible polymer nanoparticles, we demonstrate microscopic imaging of RAW264.7 macrophage cells with reversible blue-color specific fluorescence switching that enables super-resolution imaging with a resolution of 70 nm.
24. 24
  Wang, H.; Zhang, P.; Krishnan, B. P.; Yu, M.; Liu, J.; Xue, M.; Chen, S.; Zeng, R.; Cui, J.; Chen, J. Switchable Single Fluorescent Polymeric Nanoparticles for Stable White-Light Generation. J. Mater. Chem. C 2018, 6, 9897, DOI: 10.1039/c8tc03757d
  24
  Switchable single fluorescent polymeric nanoparticles for stable white-light generation
  Wang, Hong; Zhang, Peisheng; Krishnan, Baiju P.; Yu, Maolin; Liu, Jie; Xue, Mingju; Chen, Shu; Zeng, Rongjin; Cui, Jiaxi; Chen, Jian
  Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2018), 6 (37), 9897-9902CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
  The development of switchable white-light emitters is extremely challenging but urgently needed for various applications. We describe a class of switchable fluorescent polymeric nanoparticles (SFPNs) that can alternate their emission color among stable white, cyan, or pink. These SFPNs consist of a dye with cyan-light emission and a spiropyran (SP) deriv. with photochromism. When the SP deriv. is transferred to its merocyanine state, fluorescence resonance energy transfer (FRET) occurs from the cyan dye to the merocyanine one. In a rational design of transfer efficiency, a stable white-light emission is achieved. This white-light emission can be switched to the cyan-light one upon photoirradn. or pink-light one by solvent-induced swelling. Such multi-color fluorescent alternation is reversible and therefore allows for data encryption. Because of the facile synthesis, excellent long-term stability, fast photo-responsibility, high-contrast fluorescence, and outstanding switchability of these nanoparticles, we envision that they should have great potential in various applications such as high-resoln. imaging, white luminescence, and data encryption.
25. 25
  Wang, L.; Liu, Y.; Zhan, X.; Luo, D.; Sun, X. Photochromic Transparent Wood for Photo-Switchable Smart Window Applications. J. Mater. Chem. C 2019, 7, 8649, DOI: 10.1039/c9tc02076d
  25
  Photochromic transparent wood for photo-switchable smart window applications
  Wang, Lihong; Liu, Yanjun; Zhan, Xiyun; Luo, Dan; Sun, Xiaowei
  Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2019), 7 (28), 8649-8654CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
  Transparent wood with high optical transmittance, excellent thermal insulation and high toughness has attracted significant attention as an energy-saving building material. Many research efforts were dedicated to functional transparent wood, from luminescent to electrochromic transparent wood. However, photochromic transparent wood that is highly desirable and crit. for smart window applications has been rarely studied. Herein, we exptl. demonstrate photochromic transparent wood with photo-switching of transmittance in the visible light region and color tuning properties. The photochromic transparent wood was obtained by infiltrating the lignin modified wood template with a mixt. of photochromic material 3',3'-dimethyl-6-nitro-spiro[2H-1-benzopyran-2,2'-indoline]-1'-ethanol (DNSE) and pre-polymd. Me methacrylate (MMA). This photochromic transparent wood exhibits a vibrant purple-to-colorless color change under the illumination of light. In addn., dichroic dye material doped photochromic woods were studied for providing more color change choices. The proposed photochromic transparent wood shows potential applications in mech. robust, energy-efficient, photo-switchable, and colorful smart windows on a large scale.
26. 26
  Abdollahi, A.; Sahandi-Zangabad, K.; Roghani-Mamaqani, H. Rewritable Anticounterfeiting Polymer Inks Based on Functionalized Stimuli-Responsive Latex Particles Containing Spiropyran Photoswitches: Reversible Photopatterning and Security Marking. ACS Appl. Mater. Interfaces 2018, 10, 39279– 39292, DOI: 10.1021/acsami.8b14865
  26
  Rewritable anticounterfeiting polymer inks based on functionalized stimuli-responsive latex particles containing spiropyran photoswitches: reversible photopatterning and security marking
  Abdollahi, Amin; Sahandi-Zangabad, Keyvan; Roghani-Mamaqani, Hossein
  ACS Applied Materials & Interfaces (2018), 10 (45), 39279-39292CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
  Increase of safety in security documents by using anticounterfeiting inks based on fluorochromic and photochromic compds. has attracted a great deal of attention in the recent years. Herein, we developed novel functionalized stimuli-responsive latex particles contg. spiropyran (1 wt %) by semicontinuous emulsifier-free emulsion polymn., which are usable as anticounterfeiting inks for marking on security documents and also photopatterning on cellulosic papers. The size and morphol. of the latex particles were characterized by SEM and dynamic light scattering and their functionality was characterized by Fourier-transform IR spectroscopy. All the stimuli-responsive latexes are composed of spherical particles with different hydroxyl, epoxy, and carboxylic acid functional groups, and the size of the particles varies in the range of 400-900 nm. Addnl., the latex particles undergo a remarkable light-induced size variation (aggregation-disaggregation) upon UV illumination (365 nm), depending on the functional group type, as a result of π-π stacking interactions and also electrostatic attractions between the different particles. The photochromic behavior, kinetics of the SP .dblharw. MC isomerization, photoswitchability, and photofatigue-resistant characteristics of the prepd. latexes were extensively investigated. The results display that the photochromic behavior and SP .dblharw. MC isomerization can significantly be influenced by the polar interactions between the functional groups and MC mols. As a novel application, the prepd. stimuli-responsive latexes were used as anticounterfeiting inks for writing on cellulosic paper and also security marking on several monies, where the written phrase displayed red fluorescence emission and coloration under and after UV illumination (365 nm), resp. Addnl., the latexes were sprayed on cellulosic papers to prep. stimuli-responsive papers for investigation of their photopatterning ability under UV irradn. and different masking. The presence of functional groups and large particle sizes are the main effective factors for stabilization of the latex particles on cellulosic papers. This is the first report on application of functionalized stimuli-responsive latex particles contg. spiropyran as anticounterfeiting inks for security marking and photopatterning on cellulosic papers, directly and without using further additives.
27. 27
  Liu, L.; Ren, Y.; Pan, J.; Liu, Z.; Wu, B.; Yan, F. Printable UV-Light Sensor for Human Eye Protection. ACS Appl. Mater. Interfaces 2020, 12, 1495– 1503, DOI: 10.1021/acsami.9b17391
  27
  Printable UV-Light Sensor for Human Eye Protection
  Liu, Lili; Ren, Yongyuan; Pan, Ji; Liu, Ziyang; Wu, Bing; Yan, Feng
  ACS Applied Materials & Interfaces (2020), 12 (1), 1495-1503CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)
  Light-emitting diode based electronic screens emit near-UV radiation, which causes harm to the human eye after prolonged exposure. Thus, it is of paramount importance to prep. a sensitive and adjustable visible near-UV sensor for retinal warning. Herein, a series of bipyridine derivs. were synthesized to investigate effects of substituent groups and anions on photochromic properties via both exptl. and theor. studies. The introduction of dual hydrogen bonding urea onto substituted groups significantly accelerated the photochromic rate due to strong intermol. interactions, which reduces mol. spacing and promotes the electron-transfer effect. Moreover, the photochromic rate was tuned by changing the size of the anion. Larger anions widen the mol. spacing and weaken the electron transfer and eventually lead to a decrease in the photochromic rate. Finally, bipyridine derivs. were printed on a polyethylene terephthalate film or paper as a sensitive, adjustable, and visible sensor to monitor near-UV radiation emitted by an light-emitting diode screen.
28. 28
  Wu, Y.; Guo, Z.; Zhu, W.-H.; Wan, W.; Zhang, J.; Li, W.; Li, X.; Tian, H.; Li, A. D. Q. Photoswitching Between Black and Colourless Spectra Exhibits Resettable Spatiotemporal Logic. Mater. Horiz. 2016, 3, 124, DOI: 10.1039/c5mh00223k
  28
  Photoswitching between black and colourless spectra exhibits resettable spatiotemporal logic
  Wu, Yue; Guo, Zhiqian; Zhu, Wei-Hong; Wan, Wei; Zhang, Junji; Li, Wenlong; Li, Xin; Tian, He; Li, Alexander D. Q.
  Materials Horizons (2016), 3 (2), 124-129CODEN: MHAOBM; ISSN:2051-6355. (Royal Society of Chemistry)
  Logic is the key to computing. Traditionally, logic devices have been fabricated by the top-down approach, whose dimensions are drastically limited. The ultimate goal is to use mol. tailorability to design logics using the "bottom-up" approach. Here we report an unprecedented photochromic mol. that undergoes unimol. logic switching when excited anywhere in the entire UV-visible spectrum, thus a bottom-up, all-photonic, mol. logic gate. Specifically, these mol. photonic logics embedded in the polymer thin films function as the "AND" or "OR" gate at different temporal responses. To achieve high information-processing d., moreover, a ternary flip-flap-flop gate is realized in the mol. logic because the fact that this photochromic mol. can be photoswitched anywhere in its UV-vis spectrum enabled three different lasers (532, 473, and 561 nm) as the inputs to deliver the complex logic optical outputs.
29. 29
  Li, J.; Bisoyi, H. K.; Tian, J.; Guo, J.; Li, Q. Optically Rewritable Transparent Liquid Crystal Displays Enabled by Light-Driven Chiral Fluorescent Molecular Switches. Adv. Mater. 2019, 31, 1807751, DOI: 10.1002/adma.201807751
  There is no corresponding record for this reference.
30. 30
  Yerushalmi, R.; Scherz, A.; van der Boom, M. E.; Kraatz, H.-B. Stimuli Responsive Materials: New Avenues Toward Smart Organic Devices. J. Mater. Chem. 2005, 15, 4480– 4487, DOI: 10.1039/b505212b
  30
  Stimuli responsive materials: new avenues toward smart organic devices
  Yerushalmi, Roie; Scherz, Avigdor; van der Boom, Milko E.; Kraatz, Heinz-Bernhard
  Journal of Materials Chemistry (2005), 15 (42), 4480-4487CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)
  A review. "Smart" patternable polymer-based materials that can be designed from various mol. building blocks show great potential, as they may be used in many fields, including nanotechnol., biochem., org. and phys. chem., and materials science. The focus of this highlight will be on the basic design characteristics of practical Stimuli Responsive Materials (SRMs), the wide range of potential applications and the challenges to be accomplished in this rapidly expanding area. In particular, recent developments are described which are related to two of the many fundamental aspects of stimuli triggered responses: those that are photo-triggered and those that are solvent triggered. These selected state-of-the-art examples demonstrate the large scope and diversity in terms of activation mechanism, response time and property control.
31. 31
  Sobolewska, A.; Bartkiewicz, S.; Miniewicz, A.; Schab-Balcerzak, E. Polarization Dependence of Holographic Grating Recording in Azobenzene-Functionalized Polymers Monitored by Visible and Infrared Light. J. Phys. Chem. B 2010, 114, 9751– 9760, DOI: 10.1021/jp103756h
  31
  Polarization Dependence of Holographic Grating Recording in Azobenzene-Functionalized Polymers Monitored by Visible and Infrared Light
  Sobolewska, Anna; Bartkiewicz, Stanislaw; Miniewicz, Andrzej; Schab-Balcerzak, Ewa
  Journal of Physical Chemistry B (2010), 114 (30), 9751-9760CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
  The holog. grating recording process in thin films of amorphous azobenzene-functionalized polymers has been widely reported in the literature. In spite of the many reports, little is known about the mechanisms responsible for different temporal behaviors of the diffraction efficiency during long recording times. The authors report on exptl. studies of the diffraction efficiency changes during the holog. diffraction grating recording process in photochromic polymer. The gratings were inscribed for four different polarization combinations of the recording beams: s-s, p-p, s-p and right to left circular polarization (RCP-LCP) employing the degenerate two-wave mixing technique. The grating recording process was simultaneously monitored by three different wavelengths: 514.5 nm (writing) and 632.8 and 904 nm (reading). The temporal evolution of the diffraction efficiency (for all polarization configurations and for each wavelengths) was precisely fitted within the model, which assumes simultaneous formation of the absorption grating and three coupling phase gratings shifted by 0 or π with respect to each other. Two of the phase gratings originate from the refractive index grating changes in the bulk (vol.) of a material and the third one from the surface relief modulation. The model enabled the authors to ext. relevant parameters for each grating such as the build-up time const., its final amplitude, and the phase shifts between phase gratings. Performed studies and the discussion of results revealed the main differences in the diffraction grating formation process for s-s, p-p, s-p, and RCP-LCP polarization configurations.
32. 32
  Miniewicz, A.; Kochalska, A.; Mysliwiec, J.; Samoc, A.; Samoc, M.; Grote, J. G. Deoxyribonucleic Acid-Based Photochromic Material for Fast Dynamic Holography. Appl. Phys. Lett. 2007, 91, 041118, DOI: 10.1063/1.2760169
  32
  Deoxyribonucleic acid-based photochromic material for fast dynamic holography
  Miniewicz, Andrzej; Kochalska, Anna; Mysliwiec, Jaroslaw; Samoc, Anna; Samoc, Marek; Grote, James G.
  Applied Physics Letters (2007), 91 (4), 041118/1-041118/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
  The authors report on a biopolymeric material made of DNA complexed with the cationic surfactant cetyltrimethylammonium chloride (CTMA) and doped with the photochromic Disperse red 1 (DR1) for dynamic holog. recording. The molar ratio of the DNA-CTMA to the dye is about 5:1. They have found that the photochromic properties of DR1 in the DNA-CTMA matrix are favorably modified in speed of response with respect to conventional polymeric matrixes. Dynamic holog. gratings which were inscribed in DR1:DNA-CTMA films are characterized by switching times within a 1-10 ms range. An excellent reversibility of the recording process is reported.
33. 33
  Dobryakov, A. L.; Quick, M.; Richter, C.; Knie, C.; Ioffe, I. N.; Granovsky, A. A.; Mahrwald, R.; Ernsting, N. P.; Kovalenko, S. A. Photoisomerization pathways and Raman activity of 1,1′-difluorostilbene. J. Chem. Phys. 2017, 146, 044501– 044518, DOI: 10.1063/1.4974357
  33
  Photoisomerization pathways and Raman activity of 1,1'-difluorostilbene
  Dobryakov, A. L.; Quick, M.; Richter, C.; Knie, C.; Ioffe, I. N.; Granovsky, A. A.; Mahrwald, R.; Ernsting, N. P.; Kovalenko, S. A.
  Journal of Chemical Physics (2017), 146 (4), 044501/1-044501/17CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)
  The photoisomerization of 1,1'-difluorostilbene, following S0→S1 optical excitation in soln., was studied with femtosecond broadband transient absorption and stimulated Raman spectroscopy, and by quantum-chem. calcns. In n-hexane, trans-to-cis (t→c) isomerization starts with Franck-Condon relaxation (τ1t = 0.07 ps) followed by nearly barrierless torsion around the ethylenic bond (τ2t ≈ 0.3 ps) to a perpendicular conformation P. About 50% of the excited mols. are trapped in P, while others reach the S1(cis) conformation adiabatically. For the opposite cis-to-trans (c→t) path, the dynamics in n-hexane (τ1c = 0.04 ps, τ2c = 0.7 ps) suggest a 5 kJ/mol barrier between the relaxed S1(cis) and P states. The subsequent P decay with τ3 = 0.4 ps is followed by much slower ground-state recovery (τ4 ≈ 3 ps), indicating an intermediate state X. The t→P and c→P torsion depend on solvent viscosity and polarity, whereas the P→X→S0 relaxation and residual torsion is viscosity-independent but still polarity-dependent. Photoisomerization yields are derived from the transient absorption data and compared to those from actinometric measurements. Low-frequency oscillations in the transient signal are assigned to nuclei motions. Transient and stationary stimulated Raman spectra are compared to calcns. Early Franck-Condon Raman spectra differ from those of the quasistationary trans or cis S1 state. The photoisomerization behavior of stilbene and vinyl-substituted derivs. is compared and the general features are discussed. (c) 2017 American Institute of Physics.
34. 34
  He, T.; Wang, Y.; Tian, X.; Gao, Y.; Zhao, X.; Grimsdale, A. C.; Lin, X.; Sun, H. An Organic Dye with Very Large Stokes-Shift and Broad Tunability of Fluorescence: Potential Two-Photon Probe for Bioimaging and Ultra-Sensitive Solid-State Gas Sensor. Appl. Phys. Lett. 2016, 108, 011901– 011905, DOI: 10.1063/1.4939232
  34
  An organic dye with very large Stokes-shift and broad tunability of fluorescence: Potential two-photon probe for bioimaging and ultra-sensitive solid-state gas sensor
  He, Tingchao; Wang, Yue; Tian, Xiaoqing; Gao, Yang; Zhao, Xin; Grimsdale, Andrew C.; Lin, Xiaodong; Sun, Handong
  Applied Physics Letters (2016), 108 (1), 011901/1-011901/5CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)
  Light-emitting nonlinear optical mols., esp. those with large Stokes shifts and broad tunability of their emission wavelength, have attracted considerable attention for various applications including biomedical imaging and fluorescent sensors. However, most fluorescent chromophores have only limited potential for such applications due to small Stokes shifts, narrow tunability of fluorescence emissions, and small optical nonlinearity in highly polar solvents. In this work, we demonstrate that a two-photon absorbing stilbene chromophore exhibits a large two-photon absorption action cross-section (ηδ = 320 GM) in dimethylsulfoxide (DMSO) and shows broad fluorescence tunability (125 nm) by manipulating the polarity of the surrounding medium. Importantly, a very large Stokes shift of up to 227 nm is achieved in DMSO. Thanks to these features, this chromophore can be utilized as a two-photon probe for bioimaging applications and in an ultrasensitive solid-state gas detector. (c) 2016 American Institute of Physics.
35. 35
  Szukalski, A.; Haupa, K.; Miniewicz, A.; Mysliwiec, J. Photoinduced Birefringence in PMMA Polymer Doped with Photoisomerizable Pyrazoline Derivative. J. Phys. Chem. C 2015, 119, 10007– 10014, DOI: 10.1021/acs.jpcc.5b01947
  35
  Photoinduced Birefringence in PMMA Polymer Doped with Photoisomerizable Pyrazoline Derivative
  Szukalski, Adam; Haupa, Karolina; Miniewicz, Andrzej; Mysliwiec, Jaroslaw
  Journal of Physical Chemistry C (2015), 119 (18), 10007-10014CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
  Upon S0-S1 excitation, the pyrazoline deriv. mol. (Z)-2-(4-nitrophenyl)-3-(1-phenyl-4,5-dihydro-1H-pyrazol-3-yl)acrylonitrile, abbreviated as PY-oCNNO2, can be transformed from its ground state trans (E) form to bended cis (Z) form. Similar to the case of the well-known family of the photochromic azobenzenes, such a mol. property can be employed to fabrication of photochromic polymers by suitable doping of the chromophores into polymer matrix. In this work, poly(Me methacrylate) thin films doped with PY-oCNNO2 were prepd. and the characteristic for optical switchers dynamic and static photoinduced birefringence (PIB) phenomenon was measured. Possible conformational states of PY-oCNNO2, energy barriers, and assocd. dipole moments were calcd. using TD-DFT quantum chem. methods. The presented expts. show that pyrazoline derivs. constitute a prospective group of materials with a great potential for photonic applications.
36. 36
  Szukalski, A.; Miniewicz, A.; Haupa, K.; Przybyl, B.; Janczak, J.; Sobolewski, A. L.; Mysliwiec, J. Photo-Physical Transformations in Pyrazoline Derivative Based Systems. J. Phys. Chem. C 2016, 120, 14813– 14819, DOI: 10.1021/acs.jpcc.6b03915
  36
  Photo-Physical Transformations in Pyrazoline Derivative Based Systems
  Szukalski, A.; Miniewicz, A.; Haupa, K.; Przybyl, B.; Janczak, J.; Sobolewski, A. L.; Mysliwiec, J.
  Journal of Physical Chemistry C (2016), 120 (27), 14813-14819CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
  Discovery of E/Z or trans-cis photoisomerization in the azobenzenes and their derivs. had tremendous impact on the whole domain of photochromic materials including photochromic polymers and liq. crystals. Here, a similar configurational photoinduced transformation in a simple deriv. of pyrazoline is shown. The x-ray crystallog. investigations of (E)-3-(4-nitrostyryl)-1-phenyl-4,5-dihydro-1H-pyrazole (abbreviated as PY-pNO2) in grown crystals show two different structures comprising of either cis or trans mols. The performed quantum chem. calcns. confirm the existence of both configurations of PY-pNO2 at the room temp. Photophys. properties of this compd. derived from quantum chem. calcns. predict possibility of trans to cis switching of PY-pNO2 by light. Indeed, mols. of PY-pNO2 embedded in PMMA polymeric matrix when illuminated with 532 nm linearly polarized laser light show the induced optical anisotropy, i.e., birefringence characteristic for photoisomerizable mols. similar to that in the group of the azobenzene derivs.
37. 37
  Wadsworth, W. S.; Emmons, W. D. The Utility of Phosphonate Carbanions in Olefin Synthesis. J. Am. Chem. Soc. 1961, 83, 1733– 1738, DOI: 10.1021/ja01468a042
  37
  The utility of phosphonate carbanions in olefin synthesis
  Wadsworth, William S., Jr.; Emmons, William D.
  Journal of the American Chemical Society (1961), 83 (), 1733-8CODEN: JACSAT; ISSN:0002-7863.
  The reaction of phosphonate carbanions contg. electron-withdrawing groups with aldehydes or ketones in an aprotic solvent, a useful olefin synthesis, was studied. These reagents were, in general, more reactive than the analogous triarylphosphoranes (Wittig reagents) and had a no. of special features which enhanced their usefulness. (EtO)2P(O)CH2Bz (11.4 g.) added dropwise with stirring to 2.4 g. 50% NaH in 100 cc. dry (MeOCH2)2 at 20°, stirred 1 hr. at room temp., treated below 25° dropwise with 5.3 g. BzH, stirred 1 hr. at room temp., and refluxed 0.5 hr. gave 6.3 g. PhCH:CHBz, m. 52-3°. EtO2CCH2P(O)(OEt)2 (I) added dropwise at 20° to 2.4 g. 50% NaH in 100 cc. dry (MeOCH2)2, stirred 1 hr. at room temp., treated dropwise below 30° with 4.9 g. cyclohexanone, and stirred 15 min. at room temp. yielded 5.8 g. Et cyclohexylideneacetate, b10 88-90°, n25D 1.4704. I (11.2 g.), 2.4 g. 50% NaH in 100 cc. (CH2OMe)2, and 7.2 g. AcCH2CH2CO2Et gave in the usual manner at 50-60° during 1 hr. 7.1 g. EtO2CCH:CMeCH2CH2CO2Et, b0.25 78-80°, n25D 1.4506. PhCH2P(O)(OEt)2 (11.4 g.), 2.4 g. 50% NaH, 5.3 g. BzH, and 100 cc. (MeOCH2)2 refluxed 0.5 hr. gave 5.6 g. trans-stilbene, m. 124.5°. p-[(EtO)2P(O)CH2]2C6H4 (II) (9.45 g.), 1.2 g. 50% NaH, 2.65 g. BzH, and 100 cc. (MeOCH2)2 refluxed 0.5 hr. yielded 4.5 g. (p-PhCH:CH)2C6H4, m. 259-60°. II (9.45 g.), 2.4 g. 50% NaH, 7.6 g. PhCH:CHCHO, and 100 cc. (MeOCH2)2 heated 0.5 hr. at 85° gave 3.0 g. p-(PhCH: CHCH:CH)2C6H4, m. 290-1°. CH2[P(O)(OEt)2]2 (5.3 g.) added dropwise at room temp. to 0.971 g. 50% NaH and 100 cc. (MeOCH2)2, stirred 1 hr., and treated dropwise with stirring with 2.14 g. BzH yielded 2.4 g. PhCH:CHP(O) (OEt)2, b0.35, 116-18°, n25D 1.5208. Di-Et fluorenylphosphonate (III) (7.55 g.), 1.3 g. 50% NaH, 100 cc. dry (MeOCH2)2, and 0.8 g. paraformaldehyde in (MeOCH2)2, processed in the usual manner at 30°, dild. with H2O, and extd. with Et2O gave a soln. of 9-methylenefluorene which with Br-CCl4 gave a cryst. ppt., m. 144°; the bulk of the Et2O soln. evapd. yielded 30.5 g. polymerized product which was insol. in all common solvents. I (86 g.) added dropwise with stirring at room temp. to 18.4 g. 50% NaH in 100 cc. (MeOCH2)2, the mixt. heated 1 hr. at 50° with 52.6 g. BuBr, cooled to 10°, treated with 18.4 g. 50% NaH, stirred 1 hr. at room temp., treated with 12.1 g. paraformaldehyde in 50 cc. (MeOCH2)2 at 20° during 1 hr., and stirred 1 hr. yielded 38.4 g. CH2:CBuCO2Et, b100 68-9°, n25D 1.4254. I (22.4 g.) added dropwise at 20° to 4.8 g. 50% NaH in 100 cc. (MeOCH2)2, stirred 1 hr., treated dropwise below 25° with 16 g. Br, warmed briefly at 40°, cooled to 10°, treated with 4.5 g. 50% NaH and then below 30° with 7.3 g. iso-PrCHO, and worked up gave 14.5 g. Me2CHCH:CBrCO2Et, b10 76-8°, n25D 1.4649. I (11.2 g.) added at 25° dropwise to 2.4 g. 50% NaH in 100 cc. (MeOCH2)2, stirred 1 hr., treated dropwise with 12.7 g. iodine in the min. (MeOCH2)2, stirred 1 hr. at room temp., treated at 10° with 4.8 g. 50% NaH and then at 25° dropwise with 5.3 g. BzH, and heated slowly to 40° gave 5.1 g. PhC≡CCO2Et, b0.1 78-80°, n25D 1.5800. I (11.2 g.), 2.5 g. 50% NaH in 100 cc. (MeOCH2)2, and 7.3 g. EtPhC:C:O gave at 50° 3.5 g. EtPhC:C:CHCO2Et, b0.1 89-90°, n25D 1.5490. (EtO)2P(O)CH2Ph (IV) with BzPh gave similarly 78% Ph2C:CHPh, m. 67°. IV with PhCH:CHCHO yielded 58% (PhCH:CH)2, m. 151°. I with BzH gave 84% PhCH:CHCO2Et, b0.1 70°, n25D 1.5562. I with iso-PrCHO yielded 74% iso-PrCH:CHCO2Et, b15 65°, n25D 1.4284. III with BzH gave 80% 9-benzylidenefluorene, m. 74-5°. (EtO)2P(O)CH2CN and BzH gave 66% PhCH:CHCN, b10 130°, n25D 1.5828. I with CCl3CHO yielded 50% CCl3CH:CHCO2Et, b10 86°, n25D 1.4798. (MeO)2P(O)CH2CO2Et and Me2CO yielded 70% Me2C:CHCO2Et, b760 150°, n25D 1.4331. (EtO)2P(O)CH(CO2Et)CH2CO2Et [prepd. by treating mono-Et maleate with (EtO)3P] with BzH gave 61% PhCH:C(CO2Et)CH2CO2Et, b0.1 119°, n25D 1.5068. I (22.4 g.) added dropwise with stirring at 25° to 5.0 g. 50% NaH in 100 cc. dry (MeOCH2)2, stirred 1 hr., refluxed 4 hrs. with 12.0 g. styrene oxide, cooled to room temp., dild. with H2O, and extd. with Et2O gave 8.0 g. PhCH.CH2.CHCO2Et, b0.5 100-2°, n25D 1.5121. I with EtCH.CH2.O gave similarly 21% EtCH.CH2.CHCO2Et, b15 55°, n25D 1.4215. (EtO)2P(O)CH2CN with styrene oxide yielded 51% PhCH.CH2.CHCN, b0.2 80°, m. 26-7°, n25D 1.5226.
38. 38
  Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Gaussian 09, Revision A.1; Gaussian, Inc.: Wallingford CT, 2009.
  There is no corresponding record for this reference.
39. 39
  Boys, S. F.; Bernardi, F. The Calculation of Small Molecular Interactions by the Differences of Separate Total Energies. Some Procedures With Reduced Errors. Mol. Phys. 1970, 19, 553– 566, DOI: 10.1080/00268977000101561
  39
  The calculation of small molecular interactions by the differences of separate total energies. Some procedures with reduced errors
  Boys, S. F.; Bernardi, F.
  Molecular Physics (1970), 19 (4), 553-566CODEN: MOPHAM; ISSN:0026-8976. (Taylor & Francis Ltd.)
  A new direct difference method for the computation of mol. interactions has been based on a bivariational transcorrelated treatment, together with special methods for the balancing of other errors. It appears that these new features can give a strong redn. in the error of the interaction energy, and they seem to be particularly suitable for computations in the important region near the min. energy. It has been generally accepted that this problem is dominated by unresolved difficulties and the relation of the new methods of these apparent difficulties is analyzed here.
40. 40
  Dunning, T. H. Gaussian basis sets for use in correlated molecular calculations. I. The Atoms Boron through Neon and Hydrogen. J. Chem. Phys. 1989, 90, 1007– 1023, DOI: 10.1063/1.456153
  40
  Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen
  Dunning, Thom H., Jr.
  Journal of Chemical Physics (1989), 90 (2), 1007-23CODEN: JCPSA6; ISSN:0021-9606.
  Guided by the calcns. on oxygen in the literature, basis sets for use in correlated at. and mol. calcns. were developed for all of the first row atoms from boron through neon, and for hydrogen. As in the oxygen atom calcns., the incremental energy lowerings, due to the addn. of correlating functions, fall into distinct groups. This leads to the concept of correlation-consistent basis sets, i.e., sets which include all functions in a given group as well as all functions in any higher groups. Correlation-consistent sets are given for all of the atoms considered. The most accurate sets detd. in this way, [5s4p3d2f1g], consistently yield 99% of the correlation energy obtained with the corresponding at.-natural-orbital sets, even though the latter contains 50% more primitive functions and twice as many primitive polarization functions. It is estd. that this set yields 94-97% of the total (HF + 1 + 2) correlation energy for the atoms neon through boron.
41. 41
  de Mello, J. C.; Wittmann, H. F.; Friend, R. H. An Improved Experimental Determination of External Photoluminescence Quantum Efficiency. Adv. Mater. 1997, 9, 230, DOI: 10.1002/adma.19970090308
  41
  An improved experimental determination of external photoluminescence quantum efficiency
  De Mello, John C.; Wittmann, Felix H.; Friend, Richard H.
  Advanced Materials (Weinheim, Germany) (1997), 9 (3), 230-232CODEN: ADVMEW; ISSN:0935-9648. (VCH)
  An improved integrating-sphere method is presented that can be used for detg. external photoluminescence quantum yield of thin film semiconductors. The basic exptl. setup is described. Three configurations of the sphere are required for the efficiency measurements: 1st an empty sphere, 2nd with a sample placed in the sphere but the laser beam directed onto the sphere wall, and 3rd the sample placed in the sphere with laser beam directed onto it. The measurement of the luminescence efficiency was carried out on poly-(2-methoxy-5-(2'-ethyl)-hexyloxy-p-phenylenevinylene). A dil. soln. of Rhodamine 6G in ethanol was used as the std. It is shown how the absorption coeff. and the external PL quantum yield can be extd. from the spectra. The external quantum efficiency is η = 9.7 ± 1%, the method of Greenham gives a similar value of η = 10 ± 1.5%. The role of reabsorption and the advantages of the method are addnl. discussed.
42. 42
  Szukalski, A.; Moffa, M.; Camposeo, A.; Pisignano, D.; Mysliwiec, J. All-Optical Switching in Dye-Doped DNA Nanofibers. J. Mater. Chem. C 2019, 7, 170– 176, DOI: 10.1039/c8tc04677h
  42
  All-optical switching in dye-doped DNA nanofibers
  Szukalski, Adam; Moffa, Maria; Camposeo, Andrea; Pisignano, Dario; Mysliwiec, Jaroslaw
  Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2019), 7 (1), 170-176CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
  All-optical switches are introduced which are based on DNA (DNA) in the form of electrospun fibers, where DNA is semi-intercalated with a push-pull, luminescent nonlinear pyrazoline deriv. Optical birefringence is found in the org. nanofibers, with fully reversible switching controlled through continuous-wave laser irradn. The photoinduced signal is remarkably large, with birefringence highlighted by optically-driven refractive index anisotropy approaching 0.001. Sub-millisecond characteristic switching times are found. Integrating dye-intercalated DNA complex systems in org. nanofibers, as a convenient and efficient approach to template mol. organization and control it by external stimuli, might open new routes for realizing optical logic gates, reconfigurable photonic networks and sensors through phys.-transient biopolymer components.
43. 43
  Boyd, R. W. Nonlinear Optics, 3rd ed.; Academic Press: New York, 2008.
  There is no corresponding record for this reference.
44. 44
  Miniewicz, A.; Girones, J.; Karpinski, P.; Mossety-Leszczak, B.; Galina, H.; Dutkiewicz, M. Photochromic and Nonlinear Optical Properties of Azo-Functionalized POSS Nanoparticles Dispersed in Nematic Liquid Crystals. J. Mater. Chem. C 2014, 2, 432– 440, DOI: 10.1039/c3tc31791a
  44
  Photochromic and nonlinear optical properties of azo-functionalized POSS nanoparticles dispersed in nematic liquid crystals
  Miniewicz, Andrzej; Girones, Julie; Karpinski, Pawel; Mossety-Leszczak, Beata; Galina, Henryk; Dutkiewicz, Michal
  Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2014), 2 (3), 432-440CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)
  It is well known that addn. of a small amt. of nanoparticles to liq. crystals may enhance their nonlinear optical properties. To date, in most reports, semiconductor- or metallic-core nanoparticles in LCs have been described. Here, we report on the synthesis of two types of novel nanoparticles based on a cubic siloxane cage (RSiO3/2)8, known as polyhedral oligosilsesquioxane (POSS) with the Si-O skeleton surrounded by covalently attached eight groups (R) of azo-benzene mesogens differing in the length of their aliph. chains. These dielec.-core nanoparticles substituted with mesogenic groups are well adapted to the calamitic liq. crystal matrix. Azo-benzene units add an important light-driven functionality to the system via their conformational photoisomerization. We report on the photochromic properties of these new compds. in chloroform. By embedding the nanoparticles in a nematic liq. cryst. matrix, a functional hybrid nanocomposite material has been obtained. Our research was focused on the characterization of the third order nonlinear optical properties in this system linked to photochromism. The exptl. results of all-optical switching in an optical Kerr effect configuration are discussed in the framework of light-induced modification of the aliph. chains contg. azo-benzene photoisomerizing moieties and following local director reorientation in nematic liq. crystals. The described properties are useful in the field of real-time holog.
45. 45
  Poprawa-Smoluch, M.; Baggerman, J.; Zhang, H.; Maas, H. P. A.; De Cola, L.; Brouwer, A. M. Photoisomerization of Disperse Red 1 Studied with Transient Absorption Spectroscopy and Quantum Chemical Calculations. J. Phys. Chem. A 2006, 110, 11926– 11937, DOI: 10.1021/jp054982b
  45
  Photoisomerization of Disperse Red 1 studied with transient absorption spectroscopy and quantum chemical calculations
  Poprawa-Smoluch, Miroslawa; Baggerman, Jacob; Zhang, Hong; Maas, Huub P. A.; De Cola, Luisa; Brouwer, Albert M.
  Journal of Physical Chemistry A (2006), 110 (43), 11926-11937CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
  The photoisomerization of the push-pull substituted azo dye C.I. Disperse Red 1 is studied using femtosecond time-resolved absorption spectroscopy and other spectroscopic and computational techniques. In comparison with azobenzene, the ππ* state is more stabilized by the effects of push-pull substitution than the nπ* state, but the latter is probably still the lowest in energy. This conclusion is based on the photoisomerization kinetics, anisotropy of the excited state absorption spectrum, spectra of the ground states, and quantum chem. calcns. The S1(nπ*) state is formed from the initially excited ππ* state in <0.2 ps, and decays to the ground state with time consts. of 0.9 ps in toluene, 0.5 ps in acetonitrile, and 1.4 ps in ethylene glycol. Thermal isomerization transforms the Z isomer produced to the more stable E isomer with time consts. of 29 s (toluene), 28 ms (acetonitrile), and 2.7 ms (ethylene glycol). The pathway of photoisomerization is likely to be rotation about the N:N bond. Quantum chem. calcns. indicate that along the inversion pathway, ground and excited state energy surfaces remain well sepd., whereas rotation leads to a region in which conical intersections can occur. For the ground-state Z to E isomerization, conclusive evidence is lacking, but inversion is more probably the favored pathway in the push-pull substituted systems than in the parent azobenzene.
46. 46
  Yao, Z.-F.; Wang, J.-Y.; Pei, J. Control of π–π Stacking via Crystal Engineering in Organic Conjugated Small Molecule Crystals. Cryst. Growth Des. 2018, 18, 7– 15, DOI: 10.1021/acs.cgd.7b01385
  46
  Control of π-π Stacking via Crystal Engineering in Organic Conjugated Small Molecule Crystals
  Yao, Ze-Fan; Wang, Jie-Yu; Pei, Jian
  Crystal Growth & Design (2018), 18 (1), 7-15CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)
  A review. Because of their resolvable crystal structure, org. conjugated small mols. are intrinsically ideal for elucidating the relationship between microstructures and charge transport properties. It has been reported that the charge transport properties depend on mol. structure and mol. packing. In the solid state, π-π stacking of small mols. is significant in the charge transport process. Since π-π stacking of conjugated small mols. is influenced at different degrees by other intra- and intermol. interactions, as a result, π-π stacking and further the charge transport properties can be controlled or tuned by crystal engineering through precise chem. modification. In this perspective, we give some typical examples illustrating the strategy of controlling π-π stacking in single crystals. Furthermore, we attempt to clarify the complex relationship between π-π stacking and other types of mol. interactions, and its influence on charge transport properties.
47. 47
  Takacs, C. J.; Sun, Y.; Welch, G. C.; Perez, L. A.; Liu, X.; Wen, W.; Bazan, G. C.; Heeger, A. J. Solar Cell Efficiency, Self-Assembly, and Dipole-Dipole Interactions of Isomorphic Narrow-Band-Gap Molecules. J. Am. Chem. Soc. 2012, 134, 16597– 16606, DOI: 10.1021/ja3050713
  47
  Solar Cell Efficiency, Self-Assembly, and Dipole-Dipole Interactions of Isomorphic Narrow-Band-Gap Molecules
  Takacs, Christopher J.; Sun, Yanming; Welch, Gregory C.; Perez, Louis A.; Liu, Xiaofeng; Wen, Wen; Bazan, Guillermo C.; Heeger, Alan J.
  Journal of the American Chemical Society (2012), 134 (40), 16597-16606CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  The authors examine the correlations of the dipole moment and conformational stability to the self-assembly and solar cell performance within isomorphic, soln.-processable mols. These charge-transfer chromophores are described by a D1-A-D-A-D1 structure comprising electron-rich 2-hexylbithiophene and 3,3'-di-2-ethylhexylsilylene-2,2'-bithiophene moieties as the donor units D1 and D, resp. The building blocks 2,1,3-benzothiadiazole (BT) and [1,2,5]thiadiazolo[3,4-c]pyridine (PT) were used as the electron-deficient acceptor units A. Using a combination of UV-visible spectroscopy, field-effect transistors, solar cell devices, grazing incident wide-angle x-ray scattering, and TEM, 3 PT-contg. compds. (1-3) with varying regiochem. and symmetry, together with the BT-based compd. 5,5'-bis{(4-(7-hexylthiophen-2-yl)thiophen-2-yl)[1,2,5]thiadiazolobenzene}-3,3'-di-2-ethylhexyl-silylene-2,2'-bithiophene (4), are compared and contrasted in soln., in thin films, and as blends with the electron acceptor [6,6]-phenyl-C70-butyric acid Me ester. The mols. with sym. orientations of the PT acceptor, 1 and 2, yield highly ordered blended thin films. The best films, processed with the solvent additive 1,8-diiodooctane, show donor crystallite length scales ∼15-35 nm and photovoltaic power conversion efficiencies (PCEs) of 7.0 and 5.6%, resp. Compd. 3, with an unsym. orientation of PT heterocycles, shows subtle differences in the crystn. behavior and a best PCE of 3.2%. But blends of the BT-contg. donor 4 are highly disordered and give PCEs <0.2%. The authors speculate that the differences in self-assembly arise from the strong influence of the BT acceptor and its orientation on the net dipole moment and geometric description of the chromophore.
48. 48
  Szukalski, A.; Ayadi, A.; Haupa, K.; El-Ghayoury, A.; Sahraoui, B.; Mysliwiec, J. All-Optical Switching and Two-States Light-Controlled Coherent-Incoherent Random Lasing in a Thiophene-Based Donor-Acceptor System. ChemPhysChem 2018, 19, 1605– 1616, DOI: 10.1002/cphc.201800136
  48
  All-Optical Switching and Two-States Light-Controlled Coherent-Incoherent Random Lasing in a Thiophene-Based Donor-Acceptor System
  Szukalski, Adam; Ayadi, Awatef; Haupa, Karolina; El-Ghayoury, Abdelkrim; Sahraoui, Bouchta; Mysliwiec, Jaroslaw
  ChemPhysChem (2018), 19 (13), 1605-1616CODEN: CPCHFT; ISSN:1439-4235. (Wiley-VCH Verlag GmbH & Co. KGaA)
  We describe herein the synthesis and characterization of a thiophene-based donor-acceptor system, namely (E)-2-(4-nitrostyryl)-5-phenylthiophene (Th-pNO2), which was prepd. under Horner-Wadsworth-Emmons conditions. The UV/Vis absorption bands, including the intramol. charge transfer (ICT) band, were fully assigned using DFT and TD-DFT computations. The results of both efficient third-order nonlinear optical properties and light-amplification phenomena are presented. Investigations of photoinduced birefringence (PIB) in optical Kerr effect (OKE) expts. showed a great potential for this particular compd. as an efficient, fully reversible, and fast optical switch. Time consts. for the obsd. trans-cis-trans mol. transitions are in the range of microseconds and give a competitive exptl. result for the well-known and exploited azobenzene derivs. Random lasing (RL) investigations confirmed that this org. system is potentially useful to achieve strong light enhancement, obsd. as a multimode lasing action. Both RL and OKE measurements indicate that this material is a representative of thiophene derivs., which can be utilized to fabricate fast all-optical switches or random lasers (light amplifiers).
49. 49
  Bléger, D.; Hecht, S. Visible-Light-Activated Molecular Switches. Angew. Chem., Int. Ed. 2015, 54, 11338, DOI: 10.1002/anie.201500628
  49
  Visible-Light-Activated Molecular Switches
  Bleger, David; Hecht, Stefan
  Angewandte Chemie, International Edition (2015), 54 (39), 11338-11349CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  The ability to influence key properties of mol. systems by using light holds much promise for the fields of materials science and life sciences. The cornerstone of such systems is mols. that are able to reversibly photoisomerize between two states, commonly referred to as photoswitches. One serious restriction to the development of functional photodynamic systems is the necessity to trigger switching in at least one direction by UV light, which is often damaging and penetrates only partially through most media. This review provides a summary of the different conceptual strategies for addressing mol. switches in the visible and near-IR regions of the optical spectrum. Such visible-light-activated mol. switches tremendously extend the scope of photoswitchable systems for future applications and technologies.
50. 50
  Hoffmann, M.; Papadopoulos, I. N.; Judkewitz, B. Kilohertz Binary Phase Modulator for Pulsed Laser Sources Using a Digital Micromirror Device. Opt. Lett. 2018, 43, 22, DOI: 10.1364/ol.43.000022
  50
  Kilohertz binary phase modulator for pulsed laser sources using a digital micromirror device
  Hoffmann Maximilian; Papadopoulos Ioannis N; Judkewitz Benjamin
  Optics letters (2018), 43 (1), 22-25 ISSN:.
  The controlled modulation of an optical wavefront is required for aberration correction, digital phase conjugation, or patterned photostimulation. For most of these applications, it is desirable to control the wavefront modulation at the highest rates possible. The digital micromirror device (DMD) presents a cost-effective solution to achieve high-speed modulation and often exceeds the speed of the more conventional liquid crystal spatial light modulator but is inherently an amplitude modulator. Furthermore, spatial dispersion caused by DMD diffraction complicates its use with pulsed laser sources, such as those used in nonlinear microscopy. Here we introduce a DMD-based optical design that overcomes these limitations and achieves dispersion-free high-speed binary phase modulation. We show that this phase modulation can be used to switch through binary phase patterns at the rate of 20 kHz in two-photon excitation fluorescence applications.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.jpcc.0c07455.
- NMR spectra and data, structures of conformers with higher energies, calculated energy increase of the conformers upon scanning the torsion angles, additional data about all-optical modulation of light intensity, and experimental setup used for characterization of photoinduced anisotropy of the refractive index (PDF)
- jp0c07455_si_001.pdf (1.98 MB)
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Photoactivated Refractive Index Anisotropy in Fluorescent Thiophene DerivativesClick to copy article linkArticle link copied!

The Journal of Physical Chemistry C

Abstract

Introduction

Experimental Methods

Materials and Characterization Techniques

Scheme 1

Synthesis of Thiophene Derivatives and Film Preparation

Computational Analysis

Absorption and Time-Resolved Fluorescence

Optically Induced Birefringence

Results and Discussion

Quantum Chemical Calculations

Figure 1

Figure 2

Spectroscopy

Figure 3

Photoinduced Birefringence and Optical Switching

Figure 4

Figure 5

Conclusions

Supporting Information

Terms & Conditions

Author Information

Acknowledgments

References

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The Journal of Physical Chemistry C

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Abstract

Scheme 1

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

References

Supporting Information

Supporting Information

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Photoactivated Refractive Index Anisotropy in Fluorescent Thiophene Derivatives
Click to copy article linkArticle link copied!