It is of considerable interest to prepare weakly ligated, labile ligand (WLLL) nanoparticles for applications in areas such as chemical catalysis. WLLL nanoparticles can be defined as nanoparticles with sufficient, albeit minimal, surface ligands of moderate binding strength to meta-stabilize nanoparticles, initial stabilizer ligands that can be readily replaced by other, desired, more strongly coordinating ligands and removed completely when desired. Herein, we describe WLLL nanoparticles prepared from [Ir(1,5-COD)Cl]₂ reduction under H₂, in acetone. The results suggest that H⁺Cl^–-stabilized Ir(0)_n nanoparticles, herein Ir(0)_n·(H⁺Cl^–)_a, serve as a WLLL nanoparticle for the preparation of, as illustrative examples, five specific nanoparticle products: Ir(0)_n·(Cl^–Bu₃NH⁺)_a, Ir(0)_n·(Cl^–Dodec₃NH⁺)_a, Ir(0)_n·(POct₃)_0.2n(Cl^–H⁺)_b, Ir(0)_n·(POct₃)_0.2n, and the γ-Al₂O₃-supported heterogeneous catalyst, Ir(0)_n·(γ-Al₂O₃)_a(Cl^–H⁺)_b. (where a and b vary for the differently ligated nanoparticles; in addition, solvent can be present as a nanoparticle surface ligand). With added POct₃ as a key, prototype example, an important feature is that a minimum, desired, experimentally determinable amount of ligand (e.g., just 0.2 equiv POct₃ per mole of Ir) can be added, which is shown to provide sufficient stabilization that the resultant Ir(0)_n·(POct₃)_0.2n(Cl^–H⁺)_b is isolable. Additionally, the initial labile ligand stabilizer HCl can be removed to yield Ir(0)_n·(POct₃)_0.2n that is >99% free of Cl^– by a AgCl precipitation test. The results provide strong support for the weakly ligated, labile ligand nanoparticle concept and specific support for Ir(0)_n·(H⁺Cl^–)_a as a WLLL nanoparticle.

A hybrid nanofibrous mat consisting of polyurethane, dextran, and 10 wt % of biopigment (i.e., pyocyanin) was facilely fabricated using a direct-conventional electrospinning method. The field emission scanning electron microscopy showed the bead-free fibers with a twisted morphology for the pyocyanin-loaded mat. The addition of pyocyanin enables the unprecedented approach to tailor the hydrophilicity of hybrid mat, as verified from the water contact measurement. Thermomechanical stabilities of electrospun mats were investigated in terms of thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The bacterial inhibition test revealed that the antibacterial activity of electrospun mat containing pyocyanin was 98.54 and 90.2% toward Escherichia coli and Staphylococcus aureus, respectively. By the combined efforts of rapid release of pyocyanin and oxidative stress, the PU–dextran–pyocyanin (PUDP) electrospun mat significantly declined the viable cell number that disrupts the cell morphology. Hence, the proposed PUDP electrospun mat must meet the requirements of efficient antimicrobial material in various applications such as disinfectant wiping, food packaging, and textile industries.

In this paper, we report the growth of a high-quality 100 nm thick InSb layer on a (001) GaAs substrate for InSb-based high-speed electronic device applications. A continuously graded buffer (CGB) technique with In_xAl_1–xSb was used to grow high-quality InSb films on GaAs substrates. The CGB layer was grown by continuously changing the growth temperature and composition of the aluminum and indium during the growth of the buffer layer. Degradation of electrical properties, which normally accompany carrier-defect scattering in a heteroepitaxial layer, was minimized by using the CGB layer. The electrical properties of the InSb films were characterized by Hall measurements, and the electron mobility of the 100 nm-thick InSb film had the largest value, of 39 290 cm²/V·s, among reports of similar thickness. To investigate the relationship between electrical and structural properties, the 100 nm thick InSb film was characterized by energy-dispersive spectroscopy and transmission electron microscopy.

In this work, an in situ SiO₂ passivation technique using atomic layer deposition (ALD) during the growth of gate dielectric TaSiO_x on solid-source molecular beam epitaxy grown (100)In_xGa_1–xAs and (110)In_xGa_1–xAs on InP substrates is reported. X-ray reciprocal space mapping demonstrated quasi-lattice matched In_xGa_1–xAs epitaxy on crystallographically oriented InP substrates. Cross-sectional transmission electron microscopy revealed sharp heterointerfaces between ALD TaSiO_x and (100) and (110)In_xGa_1–xAs epilayers, wherein the presence of a consistent growth of an ∼0.8 nm intentionally formed SiO₂ interfacial passivating layer (IPL) is also observed on each of (100) and (110)In_xGa_1–xAs. X-ray photoelectron spectroscopy (XPS) revealed the incorporation of SiO₂ in the composite TaSiO_x, and valence band offset (ΔE_V) values for TaSiO_x relative to (100) and (110)In_xGa_1–xAs orientations of 2.52 ± 0.05 and 2.65 ± 0.05 eV, respectively, were extracted. The conduction band offset (ΔE_C) was calculated to be 1.3 ± 0.1 eV for (100)In_xGa_1–xAs and 1.43 ± 0.1 eV for (110)In_xGa_1–xAs, using TaSiO_x band gap values of 4.60 and 4.82 eV, respectively, determined from the fitted O 1s XPS loss spectra, and the literature-reported composition-dependent In_xGa_1–xAs band gap. The in situ passivation of In_xGa_1–xAs using SiO₂ IPL during ALD of TaSiO_x and the relatively large ΔE_V and ΔE_C values reported in this work are expected to aid in the future development of thermodynamically stable high-κ gate dielectrics on In_xGa_1–xAs with reduced gate leakage, particularly under low-power device operation.

Efficient access to 8H-isoquinolino[1,2-b]quinazolin-8-ones and phthalazino[2,3-a]cinnoline-8,13-diones through cyclic amide-directed Ru(II)/Ir(III)-catalyzed C–H bond activation, has been developed. Consecutive C–H bond activation, carbene insertion, and condensation annulation processes were realized, affording 8H-isoquinolino[1,2-b]quinazolin-8-one and phthalazino[2,3-a]cinnoline-8,13-dione derivatives in good-to-excellent yields under mild conditions, with H₂O and N₂ being generated as the only byproducts.

A density function approach has been used to screen an appropriate surface modifier for oxidized coal to enhance its hydrophobicity in a flotation process. Two oxidized coal surface models, coal–COOH and coal–COONa, based on the substitution of 10-fused benzene rings with COOH and COONa functional groups, have been constructed to mimic the surface hydrophilic sites at acidic and alkaline pHs, respectively. A nonpolar molecule and five polar candidate molecules with different functional groups have been examined on each oxidized coal model surface. Our present study indicates that octane is ineffective toward increasing the surface hydrophobicity for both coal–COOH and coal–COONa models due to its preferential adsorption on hydrophobic aromatic sheet, although it can spontaneously bind to the coal model surfaces at 298 K. Unlike octane, 4-pentylpyridine will present the preferred hydrophobic conformation on both models. However, its adsorption process is favorable energetically only on the coal–COOH model. The optimized geometries of all four oxygen-containing molecules (1-methoxyheptane, 1-octanol, octanal, and octanoic acid) show that directional hydrogen bonds will be formed between their oxygenated groups and the COOH group of coal–COOH model. This results in the protrusion of the hydrocarbon chain toward the water phase, which is beneficial for increasing coal surface hydrophobicity. However, the calculated Gibbs free energies suggest that octanoic acid is the best candidate. The adsorption of all four oxygen-containing molecules on the coal–COONa model is a spontaneous process. However, only sodium octanoate can be regarded as the effective surface modifier according to its optimized adsorption conformation at alkaline pH.

Vertically formed and well-defined SnO₂ nanosheets are easy to fabricate, involving only a single process that is performed under moderate conditions. In this study, two different sizes of a SnO₂ nanosheet were concurrently formed on a Pt interdigitated electrode chip, with interconnections between the two. As the SnO₂ nanosheets were grown over time, the interconnections became stronger. The ability of the fabricated SnO₂ nanosheets to sense H₂ gas was evaluated in terms of the variation in their resistance. The resistance of a SnO₂ nanosheet decreased with the introduction of H₂ gas and returned to its initial level after the H₂ gas was replaced with air. Also, the response–recovery behaviors were improved as a result of the growth of the SnO₂ nanosheets owing to the presence of many reaction sites and strong interconnections, which may provide multipassages for the electron transfer channel, leading to the acceleration of the reaction between the H₂ gas and SnO₂ nanosheets.

Because of their large surface area and conductivity, some inorganic materials have emerged as good candidates for the trace-level detection of pharmaceutical drugs. In the present work, we demonstrate the detection of an anticancer drug (regorafenib, REG) by using an electrochemical sensor based on a nanocomposite material. We synthesized a zirconia-nanoparticle-decorated reduced graphene oxide composite (ZrO₂/rGO) using a one-pot hydrothermal method. Reduction of the graphene oxide supports of the Zr²⁺ ions with hydrazine hydrate helped in preventing the agglomeration of the zirconia nanoparticles and in obtaining an excellent electrocatalytic response of the nanostructure ZrO₂/rGO-based electrochemical sensor. Structural and morphological characterization of the nanostructure ZrO₂/rGO was performed using various analytical methods. A novel regorafenib (REG) electrochemical sensor was fabricated by immobilizing the as-prepared nanostructure ZrO₂/rGO on to a glassy carbon electrode (GCE). The resulting ZrO₂/rGO/GCE could be used for the rapid and selective determination of REG in the presence of ascorbic acid and uric acid. The ZrO₂/rGO/GCE showed a linear response for the REG analysis in the dynamic range 11–343 nM, with a remarkable lower detection limit and limit of quantifications of 17 and 59 nM, respectively. The newly developed sensor was used for the accurate determination of REG in both serum samples and pharmaceutical formulations, with satisfactory results.

In this study, novel adsorbent ceria nanoparticles (CeNPs) entrapped in tamarind powder (Tm@CeNPs) were efficiently utilized for the simultaneous adsorption of aqueous mercury [Hg(II)] and aqueous lead [Pb(II)]. Surface interactions between the adsorbent and heavy metal ions play an important role in the adsorption process, and the surface morphology can significantly improve the adsorption capacity of the adsorbent. The Langmuir adsorption capacity of Tm@CeNPs for Hg(II) and Pb(II) was found to be 200 and 142.85 mg/g, respectively. The surface area of utilized adsorbent was found to be very high, that is, 412 m²/g. The adsorption kinetics of Tm@CeNPs for both ions follow pseudo-second-order, and the adsorption process is also thermodynamically feasible. Column study favors multilayer adsorption of the heavy metal ion. The spectral analysis of the adsorbent revealed that hydroxyl, carboxylic, and ester groups, as well as CeNPs, are responsible for Hg(II) and Pb(II) adsorption. The cost-benefit analysis confirms the economic viability of the synthesized Tm@CeNPs composite for heavy metal removal. The adsorbent is best suited for Hg(II) adsorption as compared to Pb(II). This is a novel study on the utilization of tamarind leaf powder with CeNPs for heavy metal ion adsorption and its adsorption mechanism, which has not been reported to date.

Presently, tissue engineering approaches have been focused toward finding new potential scaffolds with osteoconductivity on bone-disease-affected cells. This work focused on the cisplatin (CDDP)-loaded graphene oxide (GO)/hydroxyapatite (HAP)/chitosan (CS) composite for enhancing the growth of osteoblast cells and prevent the development of osteosarcoma cells. The prepared composites were characterized for the confirmation of composite formation using Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction techniques. A flowerlike morphology was observed for the GO/HAP/CS-3/CDDP composite. UV–vis spectroscopy was used to observe the controlled release of CDDP from the GO/HAP/CS-3/CDDP composite, and 67.34% of CDDP was released from the composite over a time period of 10 days. The GO/HAP/CS-3/CDDP nanocomposites showed higher viability in comparison with GO/HAP/CS-3 on MG63 osteoblast-like cells and higher cytotoxicity against cancer cells (A549). The synthesized composite was found to show enhanced proliferative, adhesive, and osteoinductive effects on the alkaline phosphatase activity of osteoblast-like cells. Our results suggested that the CDDP-loaded GO/HAP/CS-3 nanocomposite has an immense prospective as a bone tissue replacement in the bone-cancer-affected tissues.

A new synthetic approach is established where both TiO₂ nanoparticles and glucose oxidase (GO_x) are together encapsulated into the cavity of ZIF-8 metal–organic framework (MOF) to fabricate a mediator-free glucose sensor in aqueous media. ZIF-8 possesses high stability both physically and chemically. Moreover, its large surface area and tunable cavity size are supportive to encapsulate both nanoparticles (TiO₂) and enzymes (GO_x). The as-synthesized nanocomposite is methodically characterized by various advanced analytical techniques, which suggests that TiO₂ is uniformly distributed within the cavity of ZIF-8 MOF. High surface area and double-layer capacitance of nanostructured TiO₂ jointly enhance the catalytic biosensor activity. The as-synthesized nanocomposite exhibits commendable stability and is able to detect low-level concentration (80 nM) of glucose in aqueous media by utilizing very low concentration of GO_x (62 μg in 1 mL).

We investigate the band shift and band alignment of two-dimensional (2D) black phosphorus (BP)/MoS₂ van der Waals heterojunction (vdW HJ) via uniaxial strain in terms of first-principles calculations and atomic-bond-relaxation method. We find that the band gap of 2D BP/MoS₂ HJ decreases linearly with applied tensile strain and Mo–S bond breaks down at 10% tensile strain. Meanwhile, the band gap slightly increases and then monotonically decreases under compressive strain and there appears a semiconductor-to-metal transition at −11 and −12% strain in the y and x directions, respectively. Moreover, 2D BP/MoS₂ HJ maintains type-II band alignment for strain applied in the y direction whereas type-II/I band transition appears at −5% strain in the x direction. Moreover, we propose an analytical model to address the strain-modulated band engineering of 2D BP/MoS₂ vdW HJ at the atomic level. Our results suggest a promising way to explain the intrinsic mechanism of strain engineering and manipulate the electronic properties of 2D vdW HJs.

Antimicrobial peptides are promising molecules in uprising consequences of drug-resistant bacteria. The prodomain of furin, a serine protease, expressed in all vertebrates including humans, is known to be important for physiological functions. Here, potent antimicrobial peptides were mapped by extensive analyses of overlapping peptide fragments of the prodomain of human furin. Two peptides, YR26 and YR23, were active against bacterial cells including MRSA-resistant Staphylococcus aureus and Staphylococcus epidermis 51625. Peptides were largely devoid of hemolytic and cytotoxic activity. Bacterial cell killing occurred as a result of the disruption of the permeability barrier of the lipopolysaccharide (LPS)-outer membrane and fragmentation of LPS into small micelles. Furthermore, antibacterial peptides specifically interacted with the negatively charged lipids causing membrane leakage and fusion. The YR26 peptide in sodium dodecyl sulfate micelles demonstrated a long-helix-turn-short-helix structure exhibiting restricted backbone motions. The cell-selective activity of the furin peptides and their unique mode of action on membranes have a significant potential for the development of therapeutics.

Chemical warfare agents such as sarin are highly toxic, and detection of even trace levels is important. Using a hydrogel film containing a built-in two-dimensional chemical potential gradient, we demonstrate the detection of a sarin simulant under conditions potentially as low as a level 1 (6.90 × 10^–9 mg/cm³ for 10 min) Acute Exposure Guideline Level sarin exposure. Specifically, the sarin simulant diisopropyl fluorophosphate (DFP) is aerosol-deposited on a hydrogel film containing a built-in ionic chemical gradient and the enzyme, diisopropyl fluorophosphatase (DFPase). DFPase degrades the DFP, releasing fluoride ions. The fluoride ions are then concentrated by the gradient to a miniature electrochemical sensor embedded in the hydrogel providing a 30-fold amplification of the fluoride ion signal, which is an indication of exposure to DFP, relative to a gradient-free system. This method is general for agents which hydrolyze into chemically detectable ionic species.

An intramolecular aminative Umpolung cyclization strategy has been developed by using α,α-diphenylglycine (2) as the amination and Umpolung reagent. Aldehydes (1) bearing an additional carbonyl group underwent condensation with α,α-diphenylglycine to form an imine, decarboxylation to generate a delocalized 2-azaallylanion, and subsequent intramolecular Umpolung cyclization to produce a variety of exocyclic β-amino alcohols (6) in 60–93% yields with up to >20:1 trans/cis selectivity under mild conditions.

Stainless steel is a ubiquitous structural material and one that finds extensive use in core-internal components in nuclear power plants. Stainless steel features superior corrosion resistance (e.g., as compared to ordinary steel) due to the formation of passivating iron and/or chromium oxides on its surfaces. However, the breakdown of such passivating oxide films, e.g., due to localized deformation and slip line formation following exposure to radiation, or aggressive ions renders stainless steel susceptible to corrosion-related degradation. Herein, the effects of alkali cations (i.e., K⁺, Li⁺) and the interactions between the passivated steel surface and the solution are examined using 304L stainless steel. Scanning electrochemical microscopy and atomic force microscopy are used to examine the inert-to-reactive transition of the steel surface both in the native state and in the presence of applied potentials. Careful analysis of interaction forces, in solution, within ≤10 nm of the steel surface, reveals that the interaction between the hydrated alkali cations and the substrate affects the structure of the electrical double layer (EDL). As a result, a higher surface reactivity is indicated in the presence of Li⁺ relative to K⁺ due to the effects of the former species in disrupting the EDL. These findings provide new insights into the role of the water chemistry not only on affecting metallic corrosion but also in other applications, such as batteries and electrochemical devices.

Choline oxidase catalyzes oxidation of choline into glycine betaine through a two-step reaction pathway employing flavin as the cofactor. On the light of kinetic studies, it is proposed that a hydride ion is transferred from α-carbon of choline/hydrated-betaine aldehyde to the N5 position of flavin in the rate-determining step, which is preceded by deprotonation of hydroxyl group of choline/hydrated-betaine aldehyde to one of the possible basic side chains. Using the crystal structure of glycine betaine–choline oxidase complex, we formulated two computational systems to study the hydride-transfer mechanism including main active-site amino acid side chains, flavin cofactor, and choline as a model system. The first system used pure density functional theory calculations, whereas the second approach used a hybrid ONIOM approach consisting of density functional and molecular mechanics calculations. We were able to formulate in silico model active sites to study the hydride-transfer steps by utilizing noncovalent chemical interactions between choline/betaine aldehyde and active-site amino acid chains using an atomistic approach. We evaluated and compared the geometries and energetics of hydride-transfer process using two different systems. We highlighted chemical interactions and studied the effect of protonation state of an active-site histidine base on the energetics of transfer. Furthermore, we evaluated energetics of the second hydride-transfer process as well as hydration of betaine aldehyde.

Machine learning methods have revolutionized modern science, providing fast and accurate solutions to multiple problems. However, they are commonly treated as “black boxes”. Therefore, in important scientific fields such as medicinal chemistry and drug discovery, machine learning methods are restricted almost exclusively to the task of performing predictions of large and heterogeneous data sets of chemicals. The lack of interpretability prevents the full exploitation of the machine learning models as generators of new chemical knowledge. This work focuses on the development of an ensemble learning model for the prediction and design of potent dual heat shock protein 90 (Hsp90) inhibitors. The model displays accuracy higher than 80% in both training and test sets. To use the ensemble model as a generator of new chemical knowledge, three steps were followed. First, a physicochemical and/or structural interpretation was provided for each molecular descriptor present in the ensemble learning model. Second, the term “pseudolinear equation” was introduced within the context of machine learning to calculate the relative quantitative contributions of different molecular fragments to the inhibitory activity against the two Hsp90 isoforms studied here. Finally, by assembling the fragments with positive contributions, new molecules were designed, being predicted as potent Hsp90 inhibitors. According to Lipinski’s rule of five, the designed molecules were found to exhibit potentially good oral bioavailability, a primordial property that chemicals must have to pass early stages in drug discovery. The present approach based on the combination of ensemble learning and fragment-based topological design holds great promise in drug discovery, and it can be adapted and applied to many different scientific disciplines.

This paper reports the development of robust Pd- and Ru-containing magnetically recoverable catalysts in a one-pot procedure using commercially available, branched polyethyleneimine (PEI) as capping and reducing agent. For both catalytic metals, ∼3 nm nanoparticles (NPs) are stabilized in the PEI shell of magnetite NPs, whose aggregation allows for prompt magnetic separation. The catalyst properties were studied in a model reaction of 4-nitrophenol hydrogenation to 4-aminophenol with NaBH₄. A similar catalytic NP size allowed us to decouple the NP size impact on the catalytic performance from other parameters and to follow the influence of the catalytic metal type and amount as well as the PEI amount on the catalytic activity. The best catalytic performances, the 1.2 min^–1 rate constant and the 433.2 min^–1 turnover frequency, are obtained for the Ru-containing catalyst. This is discussed in terms of stability of Ru hydride facilitating the surface-hydrogen transfer and the presence of Ru⁴⁺ species on the Ru NP surface facilitating the nitro group adsorption, both leading to an increased catalyst efficiency. High catalytic activity as well as the high stability of the catalyst performance in five consecutive catalytic cycles after magnetic separation makes this catalyst promising for nitroarene hydrogenation reactions.

Traditional chemotherapeutics used in cancer therapy do not preferentially accumulate in tumor tissues. The conjugation to delivery vehicles like antibodies or small molecules has been proposed as a strategy to increase the tumor uptake and improve the therapeutic window of these drugs. Here, we report the synthesis and the biological evaluation of a novel small molecule–drug conjugate (SMDC) comprising a high-affinity bidentate acetazolamide derivative, targeting carbonic anhydrase IX (CAIX), and cryptophycin, a potent microtubule destabilizer. The biological activity of the novel SMDC was evaluated in vitro, measuring binding to the CAIX antigen by surface plasmon resonance and cytotoxicity against SKRC-52 cells. In vivo studies showed a delayed growth of tumors in nude mice bearing SKRC-52 renal cell carcinomas.

Among Mononegavirales, the Pneumovirus family stands out by its RNA polymerase processivity that relies on a transcription antiterminator, the M2-1 protein, which also plays a key role in viral particle assembly. Biophysical and structural evidence shows that this RNA-binding tetramer is strongly modulated by a CCCH Zn²⁺ binding motif. We show that while the global dissociation/unfolding free energy is 10 kcal mol^–1, more stable for the respiratory syncytial virus M2-1, the human metapneumovirus (HMPV) counterpart shows a 7 kcal mol^–1 higher intersubunit affinity. Removal of Zn²⁺ from both homologues leads to an apo-monomer of identical secondary structure that further undergoes a slow irreversible oligomerization. Mutation of the histidine residue of the Zn²⁺ motif to cysteine or alanine leads directly to large oligomers, strongly suggesting that metal coordination has an exquisite precision for modulating the quaternary arrangement. Zn²⁺ removal is very slow and requires subdenaturing concentrations of guanidine chloride, suggesting a likely local folding energy barrier. Exploring a broad combination of denaturant and ethylenediaminetetraacetic acid conditions, we showed that the metapneumovirus protein has to overcome a higher energy barrier to trigger Zn²⁺ removal-driven dissociation, in concordance with a slower dissociation kinetics. In silico modeling of open and close conformations for both M2-1 tetramers together with interaction energy calculations reveals that the gradual opening of protomers decreases the number of intersubunit contacts. Half of the interaction energy holding each protomer in the tetramer comes from the CCCH motif, while HMPV-M2-1 harbors additional contacts between the CCCH motif of one subunit and the core domain of a protomer located in trans, allowing the rationalization of the experimental data obtained. Overall, the evidence points at a key role of the CCCH motif in switching between structural and consequently functional alternatives of the M2-1 protein.

T-20 peptide is the first FDA-approved fusion inhibitor against AIDS/HIV-1 gp41 protein. Part of it, the gp41[659–671] peptide, that contains the complete epitope for the neutralizing 2F5 monoclonal antibody, has been found experimentally in a number of divergent structures. Herein, we attempt to reconcile them by using unbiased large-scale all-atom molecular dynamics folding simulations. We show that our approach can successfully capture the peptide’s heterogeneity and reach each and every experimentally determined conformation in sub-angstrom accuracy, whilst preserving the peptide’s disordered nature. Our analysis also unveils that the minor refinements within the AMBER99SB family of force fields can lead to appreciable differences in the predicted conformational stability arising from subtle differences in the helical- and β-region of the Ramachandran plot. Our work underlines the contribution of molecular dynamics simulation in structurally characterizing pharmacologically important peptides of ambiguous structure.

Aggregation-induced emission has provided fluorescence enhancement strategies for metal nanoclusters. However, the morphology of the aggregated nanoclusters tended to be irregular due to the random aggregated route, which would result in the formation of an unstable product. Herein, copper nanoclusters were directly synthesized by using l-cysteine as both the reducing and protection ligand. Initially, the structure of the product was irregular. Furthermore, Ce³⁺ was introduced to re-arrange the aggregates through a crosslinking avenue. It was interesting to find that well-ordered three-dimensional nanomaterials with mesoporous sphere structures were obtained after re-aggregation. On the basis of the stability test at a relatively high temperature and the light-emitting diode fabrication investigation, it revealed that the regulated product demonstrated more promising stability and color purity for practical applications than the random aggregated product with irregular structures.

Redox flow batteries (RFBs) have recently been recognized as a potentially viable technology for scalable energy storage. To take full advantage of RFBs, one possible approach for achieving high energy densities is to maximize a number of redox events by utilizing charge carriers capable of multiple one-electron transfers within the electrochemical window of solvent. However, past efforts to develop more efficient electrolytes for nonaqueous RFBs have mostly been empirical. In this manuscript, we shed light on design principles by theoretically investigating the effects of systematically substituting pyridyl moieties with imine ligands within a series of Fe complexes with some experimental validation. We found that such replacement is an effective strategy for reducing the molecular weight-to-charge ratios of these complexes. Simultaneously, calculations suggest that the reduction potentials and ligand-based redox activity of such substituted N-heterocyclic Fe compounds might be maintained within their +4 → −1 charge states. Additionally, by theoretically examining the role of coordination geometry, vis-à-vis reducing the number of redox noninnocent ligands within the first coordination sphere, we have demonstrated that Fe complexes with one such ligand were also capable of supporting multielectron reduction events and exhibited reduction potentials similar to their parent analogs supported by two or three of the same multidentate ligands. However, some differences in redox nature within the lower (+2 → −1) charge states were also noticed. Specifically, complexes containing two bidentate ligands, or one tridentate ligand, exhibited ligand-based reductions, whereas compounds with one bidentate ligand exhibited metal-centered reductions. The current results pave the way toward the design of the next-generation of Fe complexes with lower molecular weights and greater stored energy for redox flow batteries.

Four compounds, the flavone linarin (1), the triterpene lupenone (2), the tocopherol (vitamin E, 3), and the new natural alkaloid 1,2,3,4-tetrahydro-1,1-dimethyl-6,7-isoquinolindiol (affineine, 4), were the major natural products isolated from Zanthoxylum affine (syn. Zanthoxylum fagara, Rutaceae). Compound 1 is highly abundant in this plant and was isolated as a white precipitate obtained from the acetone and methanol extracts. The structure of these four compounds was established by 1D and 2D NMR spectroscopy including ¹H, ¹³C, DEPT, COSY, HSQC, and HMBC experiments. The hexane, acetone, and methanol extracts, as well as 1, were evaluated for their potential phytotoxic effects in pre- and post-emergent assays, as well as to identify their mechanisms of action. As pre-emergent phytotoxic agents, the hexane, acetone, and methanol extracts inhibited germination and residual growth (root and stem elongation) of Lactuca sativa (lettuce) and Lolium perenne (perennial ryegrass). As post-emergent agents, they inhibited dry biomass. Compound 1 acts as a pre-emergent herbicide, by inhibiting germination, seed respiration, residual seedling growth and, notably, root hair development. Furthermore, 1 inhibited the synthesis of ATP and the electron transport chain of isolated spinach chloroplasts; in this way, it behaves as a Hill reaction inhibitor. The site of inhibition was located at the donor site of PSII from the oxygen evolving complex to Q_A, thus acting as a multisite compound. These results suggest that compound 1 can be used as a lead for a potential green herbicide with different targets.

A promising anticancer therapeutic strategy is the stabilization of telomeric G-quadruplexes using G-quadruplex-binding small molecules. Although many G-quadruplex-specific ligands have been developed, their low potency and selectivity to G-quadruplexes over duplex remains unsolved. Recently, a crystal structure of a telomeric 3′ quadruplex–duplex hybrid was reported and the quadruplex–duplex interface was suggested to a good target to address the issues. However, there are no high-resolution complex structures reported for G-quadruplex ligands except for a docked BSU6037. In this study, molecular dynamic (MD) binding simulations with a free ligand were used to study binding poses and dynamics of four representative ligands: telomestatin, TMPyP4, BSU6037, and BRACO19. The MD data showed that BSU6037 was able to fully intercalate into the interface whereas TMPyP4 and BRACO19 could only maintain partial intercalation into the interface and telomestatin only binds at the quadruplex and duplex ends. Both linear ligands, BSU6037 and BRACO19, were able to interact with the interface, yet they were not selective over duplex DNA. The DNA geometry, binding modes, and binding pathways were systematically characterized, and the binding energy was calculated and compared for each system. The interaction of the ligands to the interface was by the means of an induced-fit binding mechanism rather than a lock–key mechanism, consisting of the DNA unfolding at the interface to allow entrance of the drug and then the refolding and repacking of the DNA and the ligand to further stabilize the G-quadruplex. On the basis of the findings in this study, modifications were suggested to optimize the interface binding for TMPyp4 and telomestatin.

Directed alignment of polymer chains plays an indispensable role in charge transport properties. We focus not only on a specific method to induce the alignment but also on the design of a liquid crystalline (LC) conjugated polymer to take advantage of an intrinsic self-assembly characteristic. We synthesized a lyotropic LC conjugated polymer, CP1-P, having o-nitrobenzyl (ONB) esters as photocleavable side chains and adopted a floating film transfer method to induce the polymer chain alignment through a lyotropic LC phase transition. An optimum amount of a high boiling point solvent (1,2-dichlorobenzene) in chloroform turned out to be an important factor to maximize the polymer chain alignment. The hole transport mobility along the polymer chain alignment direction was 13–14 times higher than that in the direction perpendicular to the alignment. In addition, the removal of side chains resulted in the solvent resistivity while maintaining the alignment feature in organic thin-film transistors.

Dynamic mass redistribution (DMR) and cellular dielectric spectroscopy (CDS) are label-free biosensor technologies that capture real-time integrated cellular responses upon exposure to extra- and intracellular stimuli. They register signaling routes that are accompanied by cell shape changes and/or molecular movement of cells proximal to the biosensor to which they are attached. Here, we report the unexpected observation that robust DMR and CDS signatures are also elicited upon direct stimulation of G protein-activated inwardly rectifying potassium (GIRK) channels, which are involved in the regulation of excitability in the heart and brain. Using ML297, a small-molecule GIRK activator, along with channel blockers and cytoskeletal network inhibitors, we found that GIRK activation exerts its effects on cell shape by a mechanism which depends on actin but not the microtubule network. Because label-free real-time biosensing (i) quantitatively determines concentration dependency of GIRK activators, (ii) accurately assesses the impact of GIRK channel blockers, (iii) is high throughput-compatible, and (iv) visualizes previously unknown cellular consequences downstream of direct GIRK activation, we do not only provide a novel experimental strategy for identification of GIRK ligands but also an entirely new angle to probe GIRK (ligand) biology. We envision that DMR and CDS may add to the repertoire of technologies for systematic exploitation of ion channel function and, in turn, to the identification of novel GIRK ligands in order to treat cardiovascular and neurological disorders.

Lead release in a lead (Pb, anode)–iron oxide (α-Fe₂O₃, cathode) galvanic system was studied under the influence of synthetic extracellular polymeric substances (sEPS). Sodium alginate, bovine serum albumin (BSA), and cytochrome c represented extracellular polysaccharides, proteins, and electrochemically active components, respectively. Microbiologically influenced corrosion was investigated using sEPS and pelleted and resuspended Pseudomonas aeruginosa cells. Relative to the anaerobic inorganic control, Pb release increased by 156, 202, and 198 μg/L when sEPS was present on the cathode side at 200 mg/L (100 mg/L alginate + 100 mg/L BSA), 400 mg/L (200 mg/L alginate + 200 mg/L BSA), and 200 mg/L with 123.84 mg/L cytochrome c, respectively, under anaerobic conditions. When the cathode was aerated, Pb release increased by 75, 260, and −71 μg/L under the aforementioned conditions, all relative to the aerated inorganic control. When sEPS was instead present on the anode side, sEPS caused localized corrosion on Pb and resulted in higher Pb release than predicted by electric current. P. aeruginosa generally enhanced corrosion; when cells were dosed in the anode side, part of the oxidized Pb was immobilized by cells or organic compounds adhered to the electrodes.

Analytical methods based on ultraperformance liquid chromatography/ion-trap mass spectrometry (UPLC/ion-trap MS) were developed for quantification of atractylenolide I, II, and III in the methanol extract of Atractylodes japonica rhizomes with a C₁₈ column in an acidified water/acetonitrile gradient eluent in an LC system, and ion-trap MS coupled with electrospray ionization was employed under positive-ion mode. The three atractylenolides were quantified in all A. japonica samples, and the content of atractylenolide I, II, and III showed a significant correlation to each other. Such high correlation was explained by the mechanistic insights into the biosynthetic pathway of atractylenoide III and I from atractylenoide II by using the biomimetic cytochrome P450 model, [Fe(tmp)](CF₃SO₃) (tmp = meso-tetramesitylporphyrin). Atractylenolides could be transformed by oxidation via the oxidative enzyme in the A. japonica plant. The present study first reports the first oxidative transformation of atractylenolides using the heme iron model complex.

We report herein a synthetic protocol for the preparation of 1,3-dibromo-1,1-difluoro-2-propanone, a new synthon used for the first time in a reaction with aromatic amines and sodium thiocyanate, leading to thiazoles which are useful candidates in drug discovery programs. The new synthon allows to introduce a bromodifluoromethyl group at the C4 of the thiazole, and it is amenable of further transformation such as the Br/F exchange useful in radiopharmaceutics. Application of the strategy to the preparation of a precursor of the biologically relevant DF2755Y is also reported.

The selective interaction of signaling compounds including neurotransmitters and drugs with the dopamine receptors (DARs) is extremely important for the treatment of neurodegenerative diseases. Here, we report a method to probe the selective interactions of signaling compounds with D1 and D2 DARs in living cells using the combined approach of theoretical calculation and surface-enhanced Raman spectroscopy (SERS). When signaling compounds such as DA, amphetamine, methamphetamine, and methylenedioxypyrovalerone interact with D1 dopamine receptors (DRD1), the intracellular cyclic adenosine monophosphate (cAMP) level is increased. However, the intracellular level of cAMP is decreased when D2 dopamine receptors (DRD2) interact with the abovementioned signaling compounds. In our experiments, we have internalized the silica-coated silver nanoparticles (AgNP@SiO₂) in living cells to adsorb biologically generated cAMP which was probed by using SERS. Besides adsorptions of cAMP, AgNP@SiO₂ has a crucial role for the enhancement of Raman cross section of the samples. We observed the characteristic SERS peaks of cAMP when DRD1-overexpressed cells interact with the signaling compounds; these peaks were not observed for other cells including DRD2-overexpressed and DRD1–DRD2-coexpressed cells. Our experimental approach is successful to probe the intracellular cAMP and characterize the selectivity of signaling compounds to different types of DARs. Furthermore, our experimental approach is highly capable for in vivo studies because it can probe intracellular cAMP using a low input power of incident laser without significant cell damage. Our experimental results and density functional theory calculations showed that 780 and 1503 cm^–1 are signature Raman peaks of cAMP. The SERS peak at 780 cm^–1 is associated with C–O, C–C, and C–N stretching and symmetric and asymmetric bending of two O–H bonds of cAMP, whereas the SERS peak at 1503 cm^–1 is contributed by the O₉–H₃ bending mode.

Biodegradation of ferulic acid, by two white-rot fungal strains (Trametes hirsuta MTCC-1171 and Phanerochaete chrysosporium NCIM-1106) was investigated in this study. Both strains could use ferulic acid as a sole carbon source when provided with basal mineral salt medium. T. hirsuta achieved complete degradation of ferulic acid (350 mg L^–1) in 20 h, whereas P. chrysosporium degraded it (250 mg L^–1) in 28 h. The metabolites produced during degradation were distinguished by gas chromatography–mass spectrometry. Bioconversion of ferulic acid to vanillin by P. chrysosporium was also investigated. The optimum experimental conditions for bioconversion to vanillin can be summarized as follows: ferulic acid concentration 250 mg L^–1, temperature 35 °C, initial pH 5.0, mycelial inoculum 0.32 ± 0.01 g L^–1 dry weight, and shaking speed 150 rpm. At optimized conditions, the maximum molar yield obtained was 3.4 ± 0.1%, after 20 h of bioconversion. Considering that the degradation of ferulic acid was determined by laccase and lignin peroxidase to some extent, the possible role of ligninolytic enzymes in overall bioconversion process was also studied. These results illustrate that both strains have the potential of utilizing ferulic acid as a sole carbon source. Moreover, P. chrysosporium can also be explored for its ability to transform ferulic acid into value-added products.

Here, we demonstrate the novel double-component liquid crystalline colloids composed of mesogenic inorganic nanosheets and the rods with dynamically variable length controlled by temperature. As the length-controllable rod, stiff biopolymer microtubule is used, which was successfully polymerized/depolymerized from tubulin proteins through a biochemical process even in the presence of the nanosheets. The mesoscopic structure of the liquid crystal phase was reversibly modifiable as caused by the change of the rod length.

Neutral {CpFe^II(CO)₂[Sn^II(Pc^•3–)]} {Cp is cyclopentadienyl (1, 2) or Cp* is pentamethylcyclopentadienyl (3); Pc: phthalocyanine}, {Cp*Fe^II(CO)₂[Sn^II(Nc^•3–)]} (4, Nc: naphthalocyanine), and {CpFe^II(CO)₂[Sn^II(TPP^•3–)]} (5, TPP: tetraphenylporphyrin) complexes in which CpFe^II(CO)₂ fragments (Cp: Cp or Cp*) are coordinated to Sn^II(macrocycle^•3–) have been obtained. The product complexes were obtained at the reaction of charge transfer from CpFe^I(CO)₂ (Cp: Cp or Cp*) to [Sn^II(macrocycle²⁻)] to form the diamagnetic Fe^II and paramagnetic radical trianionic macrocycles. As a result, these formally neutral complexes contain S = 1/2 spins delocalized over the macrocycles. This provides alternation of the C–N_imine or C–C_meso bonds in the macrocycles, the appearance of new bands in the near-infrared spectra of the complexes, and blue shift of both Soret and Q-bands. The {CpFe^II(CO)₂Sn^II(macrocycle^•3–)} units (Cp: Cp or Cp*, macrocycle: Pc or Nc) form closely packed π-stacking dimers in 1 and 3 or one-dimensional chains in 2 and 4 with effective π–π interaction between the macrocycles. Such packing allows strong antiferromagnetic coupling between S = 1/2 spins. Magnetic interaction can be described well by the Heisenberg model for the isolated dimers in 1 and 3 with exchange interaction J/k_B = −78 and −85 K, respectively. Magnetic behavior of 2 and 4 is described well by the model that includes contributions from an antiferromagnetically coupled S = 1/2 dimer (J_intra) and a Heisenberg S = 1/2 chain with alternating antiferromagnetic spin exchange between the neighbors (J_inter). Compound 2 demonstrates large intradimer interaction of J_intra/k_B = −54 K and essentially weaker interdimer exchange interactions of J_inter/k_B = −6 K, whereas compound 4 shows strong magnetic coupling of spins within the dimers (J_intra/k_B = −170 K) as well as between the dimers (J_inter/k_B = −40 K). Compound {CpFe^II(CO)₂[Sn^II(TPP^•3–)]} (5) shows no π–π interactions between the porphyrin macrocycles, and magnetic coupling is weak in this case (Weiss temperature is −5 K). Preparation of a similar complex with indium(III) chloride phthalocyanine yields {CpFe(CO)₂[In(Pc^2–)]} (6). In this complex, indium(III) atoms are reduced instead of the phthalocyanine macrocycles that explains electron paramagnetic resonance silence of 6 in the 4–295 K range.

Menaquinones (MKs) contain both a redox active quinone moiety and a hydrophobic repeating isoprenyl side chain of varying lengths and degrees of saturation. This characteristic structure allows MKs to play a key role in the respiratory electron transport system of some prokaryotes by shuttling electrons and protons between membrane-bound protein complexes, which act as electron acceptors and donors. Hydrophobic MK molecules with partially and fully saturated isoprenyl side chains are found in a wide range of eubacteria and archaea, and the structural variations of the MK analogues are evolutionarily conserved but poorly understood. For example, Mycobacterium tuberculosis, the causative agent of tuberculosis, uses predominantly MK-9(II-H₂) (saturated at the second isoprene unit) as its electron carrier and depends on the synthesis of MK-9(II-H₂) for survival in host macrophages. Thus, MKs with partially saturated isoprenyl side chains may represent a novel virulence factor. Naturally occurring longer MKs are very hydrophobic, whereas MK analogues that have a truncated (i.e., one to three isoprenes) isoprenyl side chain are less hydrophobic. This improves their solubility in aqueous solutions, allowing rigorous study of their structure and biological activity. We present the synthesis and characterization of two partially saturated MK analogues, MK-2(II-H₂) and MK-3(II-H₂), and two novel fully saturated MK derivatives, MK-2(I,II-H₄) and MK-3(I,II,III-H₆).

A glutathione reductase (GSHR)-like enzyme in Pseudomonas moraviensis stanleyae was previously implicated as underlying the bacterium’s remarkable SeO₃^2– tolerance. Herein, this enzyme is sequenced, recombinantly expressed, and fully characterized. The enzyme is highly adapted for selenodiglutathione substrates (K_m = 336 μM) compared to oxidized glutathione (K_m = 8.22 mM). The recombinant expression of this enzyme in the laboratory strains of Escherichia coli conveys a 10-fold increase in IC₉₀ for SeO₃^2–. Moreover, selenium nanoparticles are observed when the enzyme is overexpressed in the cells exposed to SeO₃^2–, but not in the corresponding no-enzyme controls. The analyses of the structural homology models of the enzyme reveal changes in the parts of the enzyme associated with product release, which may underlie the Se substrate specialization. Combined, the observations of adaptation to Se reduction over oxidized glutathione reduction as well as the portability of this nanoparticle-mediated SeO₃^2– tolerance into other cell lines suggest that the P. moraviensis GSHR may be better described as a GSHR-like metalloid reductase.

The conversion of abundant renewable cellulose into versatile formic acid (FA) is a potential process for efficient energy storage and application. Vanadium(V)-catalyzed oxidation with O₂ in acidic aqueous media now is the most common method to realize the FA production from cellulose with both high yields and high purity. However, vanadium-based catalysts are difficult to synthesize and expensive. Thus, the seeking for cheaper catalysts with the same high efficiency is expected. In this work, after testing a variety of metal salts in acidic aqueous solution for the conversion of cellulose under O₂, iron(III) was found as a cheaper and readily available catalyst for FA formation, with a comparable yield (51.2%, based on carbon) with that of vanadium(V). The effect of reaction parameters was studied. The competition between oxidation and hydrolysis was found and discussed in detail. FeCl₃ and H₂SO₄ can accelerate oxidation and hydrolysis, respectively, whereas suppress the other. The effects can reflect on the product distribution. Intermediates were found and the pathway from cellulose to products was reasonably proposed. The reusability of the catalytic system shows good performance after four runs. The mechanism study suggests a catalytic ability by a mutual transformation between iron(III) and iron(II), where iron(III) oxidizes substrates to iron(II) that is reoxidized by O₂.

2-(4-(9,9-Dimethylacridin-10(9H)-yl)phenyl)-5-phenyl-1,3,4-oxadiazole has an energy difference between the lowest excited singlet and triplet states (ΔE_ST) of ca. 0.24 eV. Introduction of two electronegative fluorine atoms onto the acceptor portion of the molecule to give 2-(4-(9,9-dimethylacridin-10(9H)-yl)-3,5-difluorophenyl)-5-phenyl-1,3,4-oxadiazole lowers the energy of the singlet emission with a negligible effect on the corresponding triplet energy, leading to a donor–acceptor compound with decreased ΔE_ST of ca. 0.13 eV that displays thermally activated delayed fluorescence. Organic light-emitting diodes fabricated using the latter compound display high EQE_max of 21.9% at a luminance of 10 cd/m² and sky-blue emission, however, they suffer from a large efficiency roll-off at increased luminance.

A thick coating of hierarchically porous double-templated TiO₂–ZrO₂–PMMA–PF127 with excellent self-cleaning properties and high transmittance has been developed for the first time on glass substrates using a simple dip-coating technique. Comparative studies of this sample with a thick and transparent coating of single-templated TiO₂–ZrO₂–PMMA have been performed to probe the origin of its exceptional properties. The formation of the composites, successful incorporation of the polymer into the matrix, and the porous nature of the films have been studied. The presence of Ti²⁺ in the double-templated samples has been confirmed, which suggest the chemisorption of water on the surface of the film. The variation in the self-cleaning properties of the samples on UV-illumination has also been studied. The double-templated film is found to possess the capability of good hydrophilic retention even 2 days after UV-irradiation.

A novel “selective surface dissolution” (SSD) method was successfully utilized in previous research to prepare “all-polymer composites” aiming to structural applications. In the current study, this simple, cost-effective, and environmentally friendly method was employed for the first time to synthesize cellulose-derived highly porous three-dimensional (3D) activated carbon materials to assemble superior electrodes for supercapacitors. ZnCl₂ aqueous solution was used to partially dissolve the surface of cellulose fibers. The partially dissolved cellulose I crystalline phase at the fiber surface can be consolidated into fibrillar cellulose polymorphs (e.g., cellulose II) which connects remaining fibers together. By a carefully controlled SSD method, a highly porous 3D cellulosic skeleton with interconnected bridge-like fibrillar linkages and hierarchical pore structures can be created. After carbonization, the 3D fiber construct with interconnected fibrillar linkages and hierarchical pore structures remains and highly porous activated carbons were obtained. The effects of various processing parameters (e.g., solvent concentration, immersion time, etc.) on the morphology of the as-formed activated porous carbons and their electrochemical performance as electrodes in supercapacitors were systematically investigated and discussed. It was concluded that the SSD method is a promising chemical approach to produce large-scale cellulose-derived activated porous carbons in an environmentally friendly manner.

In this article, the polyaniline (PANI)/thermal-exfoliated hexagonal boron nitride (BNO) hierarchical structure (PANI–BNO) was constructed via in situ deposition to improve the dispersion and interfacial adhesion of boron nitride in multi-aromatic polystyrene (PS) and polar thermoplastic polyurethane (TPU). Because of the conjugated structure and polar groups in PANI, the uniform dispersion and strong interfacial adhesion between PANI–BNO and PS and TPU were achieved. Thermogravimetric analysis results showed that the incorporation of PANI–BNO enhanced the thermal stability of PS and TPU, i.e., the temperatures at both 5 and 50 wt % mass loss. In addition, PANI with high charring ability also acted as a critical component to generate a synergistic effect with BNO on reducing the fire hazards of PS and TPU. This well-designed structure led to a remarkable reduction of flammable decomposed products and CO and CO₂ yields. Meanwhile, a dramatic decrease in the real-time smoke density and total smoke production was observed for PS and TPU nanocomposites with 3 wt % PANI–BNO hybrids, respectively. The multiple synergistic effects (synergistic dispersion, char formation, and barrier effect) are believed to be the primary source for these enhanced properties of polymer nanocomposites.

Lanthanide-containing polyoxometalates (POMs) can be used to detect various materials, but their luminescence in water has suffered enormous limitations due to the strong fluorescence quenching. Herein, to resolve this problem, three-dimensional nanoparticles built by mixed Weakley-type europium-containing POMs (Na₉[EuW₁₀O₃₆]·32H₂O, abbreviated to EuW₁₀) and tetra-n-alkyl ammonium (TA) with enhanced fluorescent properties have been designed in aqueous solution using an ionic self-assembly (ISA) technique, which is mainly driven by the electrostatic interaction between EuW₁₀ and TA. The morphology and fluorescent properties of the system as well as some influencing factors (alkyl chain length, amino group, and inorganic salt concentration) were systematically investigated. The results indicated that the fluorescent intensity of EuW₁₀/tetramethylammonium bromide (TMAB) composite increased about 14 times, whereas the extent of increase of fluorescence for EuW₁₀/tetraethylammonium bromide (TEAB) and EuW₁₀/tetrabutylammonium bromide (TMAB) composites gradually decrease due to the bulkier steric hindrance of the longer alkyl chain. Besides, the luminescence of EuW₁₀/TMAB nanoparticles is pH responsive, and the reversibility of their structures and luminescence can be realized upon the addition of NaOH/HCl. Moreover, the EuW₁₀/TMAB system also shows great fluorescence-sensing behavior, which could detect Cu²⁺ with a detection limit of 0.15 μM. Our work provides a facile construction strategy for a functional fluorescent complex via POMs-based supramolecular self-assembly in aqueous solution, which will be further used in biomarkers and sensors.

Magnetic ellipsoidal particles adsorbed at a liquid interface provide exciting opportunities for creating switchable functional materials, where self-assembly can be switched on and off using an external field [Davies et al., Adv. Mater., 2014, 26, 6715]. In order to gain a deeper understanding of this novel system in the presence of an external field, we study the capillary interaction and self-assembly of tilted ellipsoids using analytical theory and finite element simulations. We derive an analytical expression for the dipolar capillary interaction between tilted ellipsoids in elliptical polar coordinates, which exhibits a 1/r² power law dependence in the far field (i.e., large particle separations r) and correctly captures the orientational dependence of the capillary interactions in the near field. Using this dipole potential and finite element simulations, we further analyze the energy landscape of particle clusters consisting of up to eight tilted ellipsoids in contact. For clusters of two particles, we find that the side-to-side configuration is stable, whereas the tip-to-tip configuration is unstable. However, for clusters of more than three particles, we find that circular loops of side-to-side particles become globally stable, whereas linear chains of side-to-side particles become metastable. Furthermore, the energy barrier for the linear-to-loop transition decreases with increasing particle number. Our results explain both thermodynamically and kinetically why tilted ellipsoids assemble side-to-side locally but have a strong tendency to form loops on larger length scales.

The effect of oxygen vacancies (V_O) on α-Fe₂O₃ (110) facet on the performance of photoelectrochemical (PEC) water splitting is researched by both experiments and density functional theory (DFT) calculations. The experimental results manifest that the enhancement in photocurrent density by the presence of V_O is related with increased charge separation and charge-transfer efficiencies. The electrochemical analysis reveals that the sample with V_O demonstrates an enhanced carrier density and reduced charge-transfer resistance. The results of DFT calculation indicate that the better charge separation is also contributed by the decrease of potential on the V_O surface, which improves the hole transport from the bulk to the surface. The reduced charge-transfer resistance is owing to the greatly increased number of active sites. The current study provides important insight into the roles of V_O on α-Fe₂O₃ photoanode, especially on its surface catalysis. The generated lesson is also helpful for the improvement of other PEC photoanode materials.

Au nanoclusters (NCs) with organothiolate protecting ligands are a field of great interest and X-ray absorption spectroscopy is a useful tool for the structure and property studies of these Au NCs. However, the Au NCs normally show broad and low-intensity features in the gold X-ray absorption near-edge structure (XANES) region, lowering the sensitivity of the technique and making it difficult to use for the analysis of Au NCs. In this work we report a sensitive gold L₃-edge XANES study on the bonding properties of the newly discovered Au₃₀(SR)₁₈ NCs utilizing a combined approach of the first derivative XANES spectra and quantum simulations. First derivative XANES spectra are compared with the well-studied Au₂₅(SR)₁₈ with the aim of determining the unique features of Au₃₀(SR)₁₈. It is found that the early XANES region of the Au NCs is significantly influenced by the gold–gold bonding environment in the surface sites, as the varying surface Au–Au bond lengths in Au₂₅(SR)₁₈ and Au₃₀(SR)₁₈ result in pronounced difference in the first derivative XANES. These findings can be consistently explained using site-selective quantum simulations of the XANES spectra based on the Au NC structural models. The XANES method presented in this work offers a useful tool for the sensitive analysis on structure and bonding properties of Au NCs.

Here, we present the low-temperature (∼600 °C) solution combustion method for the fabrication of CoFe₂O₄, NiFe₂O₄, and Co_0.5Ni_0.5Fe₂O₄ nanoparticles (NPs) of 12–64 nm range in pure cubic spinel structure, by adjusting the oxidant (nitrate ions)/reductant (glycine) ratio in the reaction mixture. Although nitrate ions/glycine (N/G) ratios of 3 and 6 were used for the synthesis, phase-pure NPs could be obtained only for the N/G ratio of 6. For the N/G ratio 3, certain amount of Ni²⁺ cations was reduced to metallic nickel. The NH₃ gas generated during the thermal decomposition of the amino acid (glycine, H₂NCH₂COOH) induced the reduction reaction. X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometry, and X-ray photoelectron spectroscopy techniques were utilized to characterize the synthesized materials. XRD analyses of the samples indicate that the Co_0.5Ni_0.5Fe₂O₄ NPs have lattice parameter larger than that of NiFe₂O₄, but smaller than that of CoFe₂O₄ NPs. Although the saturation magnetization (M_s) of Co_0.5Ni_0.5Fe₂O₄ NPs lies in between the saturation magnetization values of CoFe₂O₄ and NiFe₂O₄ NPs, high coercivity (H_c, 875 Oe) of the NPs indicate their hard ferromagnetic behavior. Catalytic behavior of the fabricated spinel NPs revealed that the samples containing metallic Ni are active catalysts for the degradation of 4-nitrophenol in aqueous medium.

One-dimensional MoS₂ nanotubes with the specific surface area of 89.34 m²/g and the average pore size of 2.52 nm were successfully synthesized by the thermolytical approach assisted by halloysite nanotubes. The tribological properties of MoS₂ nanotubes with good dispersion in oil were tested with a four-ball wear tester. The tribological testing results indicated that the average friction coefficient and the average wear scar diameter of the 0.08 wt % MoS₂-based oil at 25 °C decreased about 39.2 and 35.0%, respectively, compared to those of the 150 SN base oil, indicating that the as-prepared MoS₂ nanotubes as a lubricating additive can enhance the tribological performances. Finally, the lubrication mechanism of MoS₂ nanotubes was put forward.

Hydrogen production by water splitting and the removal of aqueous dyes by using a catalyst and solar energy are an ideal future energy source and useful for environmental protection. Graphitic carbon nitride can be used as the photocatalyst with visible light irradiation. However, it typically suffers from the high recombination of carriers and low electrical conductivity. Here, we have developed a facile mix-thermal strategy to prepare carbon black-modified graphitic carbon nitrides, which possess high electrical conductivity, a wide adsorption range of visible light, and a low recombination rate of carriers. With the help of carbon black, highly crystallized graphitic carbon nitrides with built-in triazine and heptazine heterojunctions are obtained. Improved photocatalytic activities have been achieved in carbon black-modified graphitic carbon nitride. The dye removal rate can be three times faster than that of pristine graphitic carbon nitride and the photocatalytic H₂ generation is 234 μmol h^–1 g^–1 under visible light irradiation.

Indoles and benzofurans have been synthesized using a graphene oxide-grafted aminobisphosphine–Pd^II complex (GO@PNP–Pd) under copper-free condition. A range of indole and benzofuran derivatives have been made by the reaction of N-protected 2-iodoanilines and 2-iodophenols with terminal acetylenes in presence of GO@PNP–Pd. The activity of the aminobisphosphine–Pd^II complex remains the same under both homogeneous and heterogeneous conditions. Finally, the recycling ability of the immobilized catalyst (GO@PNP–Pd) has been examined for five consecutive runs with appreciable conversion.

Herein, we disclose the first report on iodo-cycloisomerization of 1-(indol-3-yl)-1-arylbut-3-yn-2-ols to form 3-iodocarbazoles. The synthesis proceeds through a cascade 5-endo-spirocyclization, followed by selective 1,2-alkyl migration. This method governs the green synthesis principles such as open-flask reaction, AcOEt as the solvent, rt reaction with short time, use of iodine, and broad substrate scope with atom and step economy.

A facile and efficient protocol has been developed for mild construction of fused pyrimidines via l-proline-catalyzed reaction of 4-hydroxy coumarins, aldehydes, and 2-aminobenzothiazoles/urea. The reaction has been carried out rapidly and efficiently in water under mild and metal-free conditions. Current etiquette has efficiently synthesized the heterocycles and avoids the use of hazardous solvents over conventional organic solvents. A plausible reaction mechanism has been established in this study. This study represents the first case in which l-proline as a homogeneous catalyst has been explored in the synthesis of fused pyrimidines in water in view of simple procedure and acceptable efficiency. This method gives the target product in excellent yield with ease of workup.

The thermodynamic properties of hydrophobic hydration processes have been analyzed and assessed. The thermodynamic binding functions result to be related to each other by the mathematical relationships of an ergodic algorithmic model (EAM). The active dilution d_A of species A in solution is expressed as d_A = 1/(Φ·x_A) with thermal factor Φ = T^–(C_p,A/R) and (1/x_A) = d_id(A), where d_id(A) = ideal dilution. Entropy function is set as S = f(d_id(A),T). Thermal change of entropy (i.e., entropy intensity change) is represented by the equation (dS)_d = C_p dln T. Configuration change of entropy (i.e., entropy density change) is represented by the equation (dS)_T = (−R dln x_A)_T = (R dln d_id(A))_T. Because every logarithmic function in thermodynamic space corresponds to an exponential function in probability space, the sum functions ΔH_dual = (ΔH_mot + ΔH_th) and ΔS_dual = (ΔS_mot + ΔS_th) of the thermodynamic space give birth, in exponential probability space, to a dual-structure partition function {DS-PF}: exp(−ΔG_dual/RT) = K_dual = (K_mot·ζ_th) = {(exp(−ΔH_mot/RT))(exp(ΔS_mot/R))}·{exp(−ΔH_th/RT) exp(ΔS_th/R)}. Every hydrophobic hydration process can be represented by {DS-PF} = {M-PF}·{T-PF}, indicating biphasic systems. {M-PF} = f(T,d_id(A)), concerning the solute, is monocentric and produces changes of entropy density, contributing to free energy −ΔG_mot, whereas {T-PF} = g(T), concerning the solvent, produces changes of entropy intensity, not contributing to free energy. Entropy density and entropy intensity are equivalent and summed with each other (i.e., they are ergodic). From the dual-structure partition function {DS-PF}, the ergodic algorithmic model (EAM) can be developed. The model EAM consists of a set of mathematical relationships, generating parabolic convoluted binding functions R ln K_dual = −ΔG_dual/T = {f(1/T)*g(T)} and RT ln K_dual = −ΔG_dual = {f(T)*g(ln T)}. The first function in each convoluted couple f(1/T) or f(T) is generated by {M-PF}, whereas the second function, g(T) or g(ln T), respectively, is generated by {T-PF}. The mathematical properties of the thermodynamic functions of hydrophobic hydration processes, experimentally determined, correspond to the geometrical properties of parabolas, with constant curvature amplitude C_ampl = 0.7071/ΔC_p,hydr. The dual structure of the partition function conforms to the biphasic composition of every hydrophobic hydration solution, consisting of a diluted solution, with solvent in excess at constant potential.

Conducting polymers are routinely used in optoelectronic biomaterials, but large polymer polydispersity and poor aqueous compatibility complicate integration with biomolecular templates and development of discrete and defined supramolecular complexes. Herein, we report on a chiro-optical hybrid material generated by the self-assembly of an anionic peptide and a chemically defined cationic pentameric thiophene in aqueous environment. The peptide acts as a stereochemical template for the thiophene and adopts an α-helical conformation upon association, inducing optical activity in the thiophene π–π* transition region. Theoretical calculations confirm the experimentally observed induced structural changes and indicate the importance of electrostatic interactions in the complex. The association process is also probed at the substrate–solvent interface using peptide-functionalized gold nanoparticles, indicating that the peptide can also act as a scaffold when immobilized, resulting in structurally well-defined supramolecular complexes. The hybrid complex could rapidly be assembled, and the kinetics of the formation could be monitored by utilizing the local surface plasmon resonance originating from the gold nanoparticles. We foresee that these findings will aid in designing novel hybrid materials and provide a possible route for the development of functional optoelectronic interfaces for both biomaterials and energy harvesting applications.

Lignin, a major component of lignocellulosic biomass, is a valuable source of phenolic and aromatic compounds. It is, therefore, vital to develop strategies to selectively deconstruct lignin to valuable chemicals. This study focuses on the kinetics of depolymerization of lignin and the production of phenols via a microwave-assisted catalytic process at mild conditions of 80 °C in dimethyl sulfoxide/water medium. Four different catalysts used in this study, viz., Fe₂O₃, LaFeO₃, ZrO₂, and zeolite-Y hydrogen (ZYH), were characterized for structure, specific surface area, and surface morphology. The molecular weight reduction of lignin and the evolution of phenolic monomers and oligomers were monitored using various techniques, and the rate constants of lignin degradation in the presence of different catalysts were determined using a continuous distribution kinetics model, assuming scission of the lignin macromolecule at any random position. The rate constants (min^–1) followed the trend: ZYH (26 × 10^–4) ≈ LaFeO₃ (25 × 10^–4) > ZrO₂ (22 × 10^–4) > Fe₂O₃ ≈ no catalyst (16 × 10^–4). Vanillic acid (15 mg g^–1) and methyl phenol (17 mg g^–1) were the major phenolics obtained with LaFeO₃, whereas coniferaldehyde (13 mg g^–1) was the major phenolic compound with Fe₂O₃. Vanillin was produced at ca. 11 mg g^–1 with both Fe₂O₃ and ZYH. LaFeO₃ is shown to be a promising catalyst for both molecular weight reduction of lignin and the production of monomeric phenols, whereas the use of Fe₂O₃ results in the formation of only phenols, possibly via specific end-chain depolymerization. The selectivities of the monomeric phenols were higher with these two catalysts, whereas with ZYH and ZrO₂, the selectivities of the oligomers were better. The reusability of the catalysts and the effect of catalyst loading on kinetics of lignin depolymerization were also evaluated.

Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011, even the municipal solid waste (MSW) and sewage sludge (SS) in northeastern Japan became contaminated by radioactive nuclides such as ¹³⁷Cs and ¹³⁴Cs. To understand the state of radioactive cesium (r-Cs) in the incineration residues of the municipal wastes, research groups studied the concentration and the chemical form of r-Cs in the residues, as well as its water-leaching behavior. In the present study, we conducted thermodynamic equilibrium calculations to estimate the possible chemical forms of r-Cs in the incineration residues. Thermodynamic data for cesium oxides and aluminosilicates were collected and compiled into a new database to perform equilibrium calculations for systems that include Cs. The calculation results suggested that Cs (radiocesium and stable cesium) in municipal solid waste was transformed into gaseous CsCl or crystalline aluminosilicate at incineration temperatures and, when a molten aluminosilicate phase (i.e., slag phase) was generated, a proportion of the Cs species was dissolved into the slag phase. In the case of sewage sludge, Cs was calculated to be transformed mostly into crystalline aluminosilicate at incineration temperatures, whereas by analogy with the behaviors of Na and K, Ca,Cs-phosphate double salts were also potential incineration products. These results could account for the high leaching rates of r-Cs from the MSW incineration fly ash and the low leaching rates from the MSW incineration bottom ash and SS incineration fly ash reported in earlier studies. In the case of dewatered SS that included a large amount of slaked lime as a flocculant, it was exceptionally difficult for the calculation to represent the fate of Cs, and we needed to include the contribution of silica sand in a fluidized-bed combustor in the equilibrium calculation to represent the low leaching rates of alkali species from the dewatered SS fly ash. From the results of the thermodynamic equilibrium calculations and also from the calculated standard Gibbs energy of cesium aluminosilicate formation/decomposition reactions, the effects of waste composition and incineration temperature on the fate of Cs were examined: High incineration temperature and large amounts of Ca and Cl in the waste composition increased the fraction of gaseous CsCl in the furnace and thus resulted in the high distribution ratios of Cs in the fly ash of MSW and the high leaching rates of Cs from the fly ash.

This work discloses the first ever magnetically retrievable copper isophthalate-based metal-organic framework (MOF) decorated with surface-modified cobalt ferrite (CoFe₂O₄) nanoparticles that have been utilized as catalytic reactors for obtaining a relatively large number of biologically active benzimidazole scaffolds. A facile one-pot solvothermal approach was employed for obtaining spherical and monodisperse CoFe₂O₄ nanoparticles, which were subsequently modified using suitable protecting and functionalizing agents. Finally, these functionalized magnetic nanoparticles were anchored onto the three-dimensional copper isophthalate MOF via a covalent immobilization methodology. The exploitation of advanced microscopic tools such as transmission electron microscopy and scanning electron microscopy provided valuable insights into the morphology of the immobilized MOF. These results indicated that the surface-modified magnetic nanoparticles had grown onto the surface of copper-5-nitroisophthalic acid MOF. A greener C–H functionalization strategy that involves the multicomponent oxidative cross-coupling between two different set of amines (sp²-hybridized nitrogen-containing anilines and sp³-hybridized nitrogen-containing alkyl/aryl amine derivatives) and sodium azide has been incorporated to provide access to a broad spectrum of the value-added target benzimidazole moieties. It is interesting to note that this magnetic MOF-catalyzed protocol not only replaces toxic solvents with water, which is a green solvent, but also enhances the economic competitiveness since the magnetic catalyst can be readily recovered and recycled for eight consecutive runs.

A simple yet effective methodology to obtain high-quality reduced graphene oxide (RGO) using a tetrahydrofuran suspension of GO under hydrogen at moderate pressure has been demonstrated. The extent of reduction as a function of the pressure of hydrogen gas, temperature, and time was studied, where the abstraction of oxygen is achievable with least mutilation of C-sp² bonds, hence upholding the integrity of the graphene sheet. Herein, the formation of a short-lived species is proposed, which is possibly responsible for such reduction. A detailed theoretical calculation along with in situ UV–visible experiments reveals the existence of a transient solvated electron species in the reaction medium. The hydrogen RGO (HRGO) achieved a C/O atomic ratio of 11.3. The conductivity measurements show that HRGO reached as high as 934 S/m, which indicates a high quality of RGO. The process is hassle-free, environmentally benign, and can be scaled up effortlessly without compromising the quality of the material.

The complex structure of activated carbon can be described as a three-dimensional network of graphene layers oriented in random directions. In this work, we propose a new model of the microporous structure, taking into account the degree of activation. We derive a structural relation between porosity, skeletal density, specific surface area, and the number of graphitic blocks per unit volume. In addition, we present a new approach to evaluate the interdependency between porosity and specific surface area by combining high-resolution scanning transmission electron microscopy and subcritical nitrogen adsorption. Finally, we propose a structural metric that predicts the relation between the volumetric storage capacity and the gravimetric storage capacity of supercritical methane at room temperature.

Novel antibiotics are urgently needed. The troponoids [tropones, tropolones, and α-hydroxytropolones (α-HT)] can have anti-bacterial activity. We synthesized or purchased 92 troponoids and evaluated their antibacterial activities against Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa. Preliminary hits were assessed for minimum inhibitory concentrations (MIC₈₀) and cytotoxicity (CC₅₀) against human hepatoma cells. Sixteen troponoids inhibited S. aureus/E. coli/A. baumannii growth by ≥80% growth at <30 μM with CC₅₀ values >50 μM. Two selected tropolones (63 and 285) inhibited 18 methicillin-resistant S. aureus (MRSA) strains with similar MIC₈₀ values as against a reference strain. Two selected thiotropolones (284 and 363) inhibited multidrug-resistant (MDR) E. coli with MIC₈₀ ≤30 μM. One α-HT (261) inhibited MDR-A. baumannii with MIC₈₀ ≤30 μM. This study opens new avenues for development of novel troponoid antibiotics to address the critical need to combat MDR bacterial infections.

Carbon nanofoam (CNF) is a highly porous, amorphous carbon nanomaterial that can be produced through the interaction of a high-fluence laser and a carbon-based target material. The morphology and electrical properties of CNF make it an ideal candidate for supercapacitor applications. In this paper, we prepare and characterize CNF supercapacitor electrodes through two different processes, namely, a direct process and a water-transfer process. We elucidate the influence of the production process on the microstructural properties of the CNF, as well as the final electrochemical performance. We show that a change in morphology due to capillary forces doubles the specific capacitance of the wet-transferred CNF electrodes.

In this study, sodium alginate was employed as a starting material for preparing two kinds of biocompatible adsorbents, including calcium alginate hydrogel beads and magnetic hydrogel beads. Fourier transform infrared spectroscopy, X-ray diffraction pattern, and scanning electron microscopy/energy-dispersive X-ray techniques were used to characterize the prepared adsorbents. The performance of the prepared adsorbents for the removal of methyl violet from aqueous solution was studied in detail. Both kinetics and equilibrium aspects of methyl violet adsorption were investigated, and the obtained equilibrium and kinetics data were described with various adsorption models. The effects of initial dye concentration, adsorbent dosage, and temperature on adsorption performance were investigated. Thermodynamic parameters of adsorption were obtained as well.

Nonelectrolyte solubility in electrolyte solutions follow the Hofmeister series, but the applicability of the series to salt solubility has been less appreciated. This study, using solubility data for thirteen sodium-bearing salts, shows that salts are consistently salted out by electrolytes important to alkaline nuclear waste in the order NaOH > NaCl > NaNO₂ > NaNO₃ at 298.15 K, which is the same order as the Hofmeister series. Graphical presentation allowed for easy separation of the common ion effect (caused by the addition of Na⁺) from the salting-out effect (caused by the presence of anions) because there is a large difference between the solubility of a given salt in different background electrolytes at a common Na⁺ molality. The trend persists even in very high electrolyte concentrations where essentially all of the water molecules must be in the coordination sphere of an ion, which means that the effect of electrolytes on “bulk water” is not the cause of the trend. These specific interactions more likely result from the sharing of water molecules between ions, augmented by differences in ion-pairing of the electrolytes. The Hofmeister series has practical application to the management of alkaline high-level radioactive waste created at nuclear fuel reprocessing facilities, where a predictive understanding of salt solubility is essential for blending wastes of disparate compositions prior to treatment.

In this study, an injectable thermoresponsive hydroxypropyl guar-graft-poly(N-vinylcaprolactam) (HPG-g-PNVCL) copolymer was synthesized by graft polymerization. The reaction parameters such as temperature, time, monomer, and initiator concentrations were varied. In addition, the HPG-g-PNVCL copolymer was modified with nano-hydroxyapatite (n-HA) by in situ covalent cross-linking using divinyl sulfone (DVS) cross-linker to obtain HPG-g-PNVCL/n-HA/DVS composite material. Grafted copolymer and composite materials were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, proton nuclear magnetic resonance spectroscopy (¹H NMR), and differential scanning calorimetry. The morphology of the grafted copolymer (HPG-g-PNVCL) and the composite (HPG-g-PNVCL/n-HA/DVS) was examined using scanning electron microscopy (SEM), which showed interconnected porous honeycomb-like structures. Using Ultraviolet−visible spectroscopy, low critical solution temperature for HPG-g-PNVCL was observed at 34 °C, which is close to the rheology gel point at 33.5 °C. The thermoreversibility of HPG-g-PNVCL was proved by rheological analysis. The HPG-g-PNVCL hydrogel was employed for slow release of the drug molecule. Ciprofloxacin, a commonly known antibiotic, was used for sustainable release from the HPG-g-PNVCL hydrogel as a function of time at 37 °C because of viscous nature and thermogelation of the copolymer. In vitro cytotoxicity study reveals that the HPG-g-PNVCL thermogelling polymer works as a biocompatible scaffold for osteoblastic cell growth. Additionally, in vitro biomineralization study of HPG-g-PNVCL/n-HA/DVS was conducted using a simulated body fluid, and apatite-like structure formation was observed by SEM.

Two novel layer structure compounds, Cs₂HgSb₄S₈ and Cs₂Hg₂Sb₂Se₆, were synthesized in organic solvent under solvothermal conditions. The Cs₂HgSb₄S₈ is formed of [HgSb₄S₈]^2– ribbons and S atoms by corner sharing. The Cs₂Hg₂Sb₂Se₆ is made up of [SbHg₂Se₆]^5– ribbon and disorder trigonal-pyramidal SbSe₃ by sharing μ₃-Se. These compounds are characterized by single-crystal X-ray diffraction, powder X-ray diffraction, solid-state optical absorption spectra, and so on.

Ag10c is a recently reported RNA-cleaving DNAzyme obtained from in vitro selection. Its cleavage activity selectively requires Ag⁺ ions, and thus it has been used as a sensor for Ag⁺ detection. However, the previous selection yielded very limited information regarding its sequence requirement, since only ∼0.1% of the population in the final library were related to Ag10c and most other sequences were inactive. In this work, we performed a reselection by randomizing the 19 important nucleotides in Ag10c in such a way that a purine has an equal chance of being A or G, whereas a pyrimidine has an equal chance of being T or C. The round 3 library of the reselection was carefully analyzed and a statistic understanding of the relative importance of each nucleotide was obtained. At the same time, a more active mutant was identified, containing two mutated nucleotides. Further analysis indicated new base pairs leading to an enzyme with smaller catalytic loops but with ∼200% activity of the original Ag10c, and also excellent selectivity for Ag⁺. Therefore, a more active mutant of Ag10c was obtained and further truncations were successfully performed, which might be better candidates for developing new biosensors for silver. A deeper biochemical understanding was also obtained using this reselection method.

Herein, we report a convenient synthesis of unprecedented aza-diketopiperazines (aza-DKPs). The strategy is based on selective diversification of bicyclic aza-DKP scaffolds by click reaction, N-acylation, and/or N-alkylation. These scaffolds containing either azido or amino groups were obtained by a key Rh(I)-catalyzed hydroformylative cyclohydrocarbonylation reaction of allyl-substituted aza-DKP. The methodology is readily amenable to the parallel synthesis of original aza-DKPs to enlarge the chemical diversity of aza-heterocycles.

Single-chain nanoparticles (SCNPs) are ultrasmall soft nanomaterials constructed via intrachain cross-linking of individual precursor polymer chains, with promising prospects for nanomedicine, catalysis, and sensing, among other different fields. SCNPs are versatile building blocks for the construction of new fluorescent probes with ultrasmall size, higher brightness, and better photostability than previous particle-based systems. Herein, we report on a new, fast, and efficient method to produce SCNPs with intense fluorescence emission in solution which is based on the photoactivation of appropriate aggregation-induced emission (AIE) cross-linking molecules containing azide functional groups. Remarkably, the presence of the azide moiety—that can be transformed to highly reactive nitrene species upon UV irradiation—was found to be essential for the SCNPs to display intense fluorescence emission. We attribute the fluorescence properties of the SCNPs to the immobilization of the initially nonfluorescent AIE molecules via intrachain cross-linking upon photoactivation. Such cross-linking-induced immobilization process activates the AIE mechanism and, hence, leads to fluorescent SCNPs in both solution and solid state.

A molecular anion of tris(8-hydroxyquinolinato)aluminum (Alq₃) was generated by a pulsed discharge to the solid sample under supersonic expansion and its photoelectron spectrum was recorded after mass selection. The vertical detachment energy of Alq₃^– and the adiabatic electron affinity of Alq₃ were determined to be 1.24 ± 0.01 and 0.89 ± 0.04 eV, respectively. By using these energies determined for monomeric Alq₃, the reorganization energy for the intermolecular electron transport in bulk Alq₃ was estimated to be 0.70 ± 0.08 eV.

Biocomposites from bio-based poly(butylene succinate) (BioPBS) and grape pomace (GP) were made by melt extrusion–injection molding. Grape pomace is a low value byproduct from the wine industry that can be utilized as a filler to increase its value and to decrease the amount of polymer required in a composite blend. Experiments were performed with up to 50% grape pomace by weight. Composites were also compatibilized with in situ manufactured maleic anhydride-grafted BioPBS (MA-g-BioPBS). Flexural and impact strength were improved with the addition of GP up to the addition of 50 wt % GP, suggesting that at this loading the formulation reached threshold performance. The blend of (57:40:3) BioPBS/GP/MA-g-BioPBS showed the best overall performance in terms of a balance of both mechanical properties and thermal properties. The increase in impact resistance confirmed that the GP acted as a reinforcing phase. The addition of 3 wt % MA-g-BioPBS in samples containing 40 wt % of grape pomace resulted in improvements of 28.4 and 59% in flexural and impact strengths, respectively, compared to neat BioPBS. Heat distortion temperature increased with the addition of grape pomace by 14.3% in a blend combination of 57% BioPBS, 40% grape pomace, and 3% MA-g-BioPBS compared to neat BioPBS. Scanning electron microscopy results show improved interfacial adhesion with the addition of MA-g-BioPBS and thermogravimetric analysis results prove that the GP is thermally stable under the processing conditions. This study shows that GP can be successfully incorporated into a BioPBS matrix to create biocomposites with improved thermal and mechanical properties.

Palladium nanoparticles (NPs) have been obtained by decomposition of well-defined palladium complexes noncovalently anchored onto the surface of reduced graphene oxide. Morphological analysis by microscopy showed the presence of small palladium NPs homogeneously distributed on the support. Characterization by X-ray photoelectron spectroscopy confirmed that palladium NPs contain Pd(2+) and Pd(0) oxidation states and the presence of N-heterocyclic carbene and bromo ligands. The catalytic properties of the NPs with and without the support have been evaluated in the hydrogenation of alkynes. Supported palladium NPs showed increased activity versus the nonsupported ones and could be recycled up to 10 times without the loss of catalytic activity. The composition of the palladium NPs is different for each catalytic cycle indicating a dynamic process and the formation of different catalytic active species. On the contrary, the unsupported palladium NPs showed limited activity caused by decomposition and could not be recycled. The role of the support has been investigated. The results indicate that the support influences the stability of palladium NPs.

The use of cement raw meals as sorbent precursors for CO₂ capture can reinforce the synergies between the cement production process and calcium looping CO₂ capture technology. In this work, we measure the CO₂-carrying capacity of different calcined samples of a particular marl, which were obtained under very different calcination conditions and setups (a thermogravimetric analyzer, a drop tube furnace, and an industrial calciner). We find that the reactivity toward CO₂ of these calcined materials displays a strong sensitivity to the calcination conditions, in particular to calcination time. A pronounced competition between the belite (Ca₂SiO₄) formation reaction and the formation of free CaO needed for CO₂ capture is detected. As the calcination of the raw meal approaches flash conditions (i.e., >90% calcination conversion in less than 10 s), the belite formation is shown to be minimized, leading to sorbents with CO₂-carrying capacities of approximately 0.4 mol CO₂/mol CaO.

Glycosylation significantly alters the biological and physicochemical properties of small molecules. β-Lactam alcohols comprise eligible substrates for such a transformation based on their distinct relevance in the chemical and medicinal community. In this framework, the unprecedented enzymatic glycosylation of the rigid and highly strained four-membered β-lactam azaheterocycle was studied. For this purpose, cis-3-hydroxy-β-lactams were efficiently prepared in three steps by means of a classical organic synthesis approach, while a biocatalytic step was implemented for the selective formation of the corresponding 3-O-α- and -β-glucosides, hence overcoming the complexities typically encountered in synthetic glycochemistry and contributing to the increasing demand for sustainable processes in the framework of green chemistry. Two carbohydrate-active enzymes were selected based on their broad acceptor specificity and subsequently applied for the α- or β-selective formation of β-lactam-sugar adducts, using sucrose as a glucosyl donor.

In this article, we have performed an all-atom molecular dynamics simulation study to investigate the influence of water on the molecular level arrangement of reline deep eutectic solvent for different hydration levels ranging from 3.4 to 58.1 wt % of water and complemented the observations of recently measured neutron scattering experimental data. This study is particularly important because water is being introduced as a second hydrogen bond donor/acceptor in reline, wherein the structure is primarily governed by hydrogen bonding and electrostatic interactions. We have analyzed the simulated X-ray scattering structure functions, their partial components, and hydrogen bonding interactions to understand the effects of water on various intermolecular interactions in reline–water mixtures. It is observed that at lower hydration level, reline structure is qualitatively retained. At higher hydration level, most water molecules preferentially solvate chloride anions and ammonium group of choline cations mostly impacting choline–choline, choline–chloride, and chloride–chloride interactions. The present study reveals that at and above 41 wt % of water, the molecular arrangement of reline drastically changes and set to transition from reline to an aqueous solution of reline components with further increase in the hydration level. Hydrogen bond analysis reveals the presence of strong chloride–water H-bonding interaction, which gradually replaces choline–chloride and urea–chloride hydrogen bondings as the hydration level in the mixture increases.

In present study, we have synthesized intrinsically conductive poly(1,6-heptadiynes) via cyclopolymerization technique, and further it is composited with the NiFe₂O₄ to fabricate pellet for electrical and electronic applications. The synthesized polymer I–V characteristics were obtained by two-probe measurement technique. The results suggest that the high current density of the synthesized polymer was in the range of 1.2 × 10^–5–3.1 × 10^–5 S/cm, which attributes to the potentially induced hoping charge-carrier mechanism within the conjugated poly(1,6-heptadiynes). NiFe₂O₄ and NiFe₂O₄/poly(1,6-heptadiynes) composite pellets were fabricated by utilizing hydraulic pelletizer. The sample’s electrical measurements were performed via broad-band dielectric impedance spectroscopy, wherein the composite permittivity was about ε = 45 (100 Hz to 10 kHz), which attributes to the NiFe₂O₄ and poly(1,6-heptadiynes) phases; further, this describes the capacitance, which improved from 0.3 to 0.1 pf at 1 kHz. Also, these results suggest the reduced equivalent series resistance (72.1–1 MHz), which attributes to the incorporated intrinsically conducting poly(1,6-heptadiynes). Thus, the reduced dissipation factor (DF = 0.0032) was observed from impedance characteristics of a nanocomposite. Moreover, the improved Q-factor was observed, which was about 8.1–310 at 1 kHz. The resistance and capacitance time constant was also computed to be about 0.29 μs at 1 kHz for NiFe₂O₄/poly(1,6-heptadiynes) nanocomposite. Furthermore, the nanocomposite-enabled capacitor gravimetric energy density and power densities were calculated to be about 0.00575 mJ/g and 9.91 W/g, respectively. Additionally, thermal threatening, that is, heat generated within the capacitor, P_loss is also estimated for the nanocomposite capacitor, which improved from 0.0006 to 8.9 × 10^–6, and these results suggest improved nanocomposite thermal stability. Further, the delineated quantities were compared to the commercially available configurations of tantalum hybrid capacitors and Al and Ta electrolytic capacitors, including carbon electrochemical capacitors, which suggest that the reported nanocomposites could be a suitable candidate for electrical and electronic applications.

Single-chamber microbial fuel cells (MFCs) were constructed using rice bran (carbon source) and pond bottom mud (microbial source). The total electric charge obtained in the MFC combining rice bran with pond bottom mud was four times higher than that in MFC using only rice bran. Phylogenetic analyses revealed dominant growth of fermentative bacteria such as Bacteroides and Clostridium species, and exoelectrogenic Geobacter species in the anode biofilms, suggesting that mutualism of these bacteria is a key factor for effective electricity generation in the MFC. Furthermore, rice bran, consisting of persistent polysaccharide, was pretreated by the hydrodynamic cavitation system to improve the digestibility and enhance the efficiency in MFC, resulting in 26% increase in the total production of electricity.

Adsorption method was first introduced into the propene oxide production via hydrogen peroxide process to remove the microimpurity in the propylene oxide (PO) product solution. It could replace the reactive distillation in separating acetaldehyde with less energy consumption and PO loss. A series of adsorbents (e.g., 3A, 4A, 5A, 10X, and Y) are first used to remove the impurity (i.e., acetaldehyde). It is found that 5A molecular sieves shows the best performance due to uniform porous channels with suitable pore size. Various techniques such as X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared, and N₂ physisorption are employed to investigate the structural properties of the adsorbent. Furthermore, effects of space velocity and temperature are also investigated. Cyclic desorption and adsorption tests indicate the PO yield is 92.2%, and 96.3% of acetaldehyde was removed. The acetaldehyde concentration of PO product was 0.0187%, indicating this method can produce industrial-quality PO that meets the first-level technical requirements.

The reaction of copper(I) iodide (CuI) and N-alkyl pyridinium (RPy⁺, R = H, Me, Et, n-propyl = Pr, n-butyl = Bu, n-pentyl = Pn, and n-hexyl = Hx) or N-butyl-3-substituted pyridinium (N-Bu-3-PyX⁺, X = I, Br, Cl, CN, and OMe) iodide salts yielded pyridinium iodocuprate(I) salts. Crystal structures of iodocuprate ions coupled with RPy⁺ include {Cu₃I₆^3–}_n (R = H), {Cu₂I₃^–}_n (R = Me), {Cu₃I₄^–}_n (R = Et), {Cu₆I₈^2–}_n (R = Pr), and {Cu₅I₇^2–}_n (R = Bu, Pn, Hx). The [N-Bu-3-PyX]⁺ ions were typically paired with the 1-D chain {Cu₅I₇^2–}_n. Diffuse reflectance spectroscopy performed on the [N-Bu-3-PyX]⁺ iodocuprate salts revealed that increasing the electron withdrawing capacity of the [N-Bu-3-PyX]⁺ system reduced the absorption edge of the iodocuprate salt. Variable temperature emission spectra of several [N-Bu-3-PyX]⁺ compounds revealed two emission peaks, one consistent with a cluster-centered halide to metal charge transfer and the other consistent with an intermolecular mixed halide/metal charge transfer to the organic cation. The emission intensity and emission wavelength of the mixed halide/metal to cation charge transfer depends on the organic cation substitution.

The synthesis of hydroxenin monoacetate, a key intermediate in the manufacture of vitamin A, relies on the undesirable use of stoichiometric amounts of organic bases such as pyridine. Although the final product (vitamin A acetate) can be produced from hydroxenin diacetate, using the monoacetylated intermediate improves the overall process yield. Aiming to identify more efficient, environmentally benign alternatives, this work first studies the homogeneous acetylation reaction using pyridine. The addition of the base is found to enhance the rate of hydroxenin monoacetate formation, confirming its catalytic role, but also yields non-negligible amounts of hydroxenin diacetate. On the basis of these insights, Mg- and Al-containing hydrotalcites are explored because of their broad scope as base catalysts and the ability to finely tune their properties. The reaction kinetics are greatly enhanced via controlled thermal activation, forming high surface area mixed metal oxides displaying Lewis basic sites. In contrast, a Brønsted basic material synthesized by the reconstruction of a mixed oxide performs similarly to the as-synthesized hydrotalcite. Variation of the Mg/Al ratio from 1 to 3 has no significant impact, but activity losses are observed at higher values because of a reduced number of basic sites. After optimizing the reaction conditions, hydroxenin monoacetate yields >60% are obtained in five consecutive cycles without the need for any intermediate treatment. The findings confirm the potential of hydrotalcite-derived materials as highly selective catalysts for the production of vitamins with reduced levels of organic waste.

A sequence of oxidative cleavage/double nitroaldol condensation followed by a few simple synthetic transformations can lead to polyhydroxylated di- and triaminocyclohexanes from a readily available bicyclic hydrazine. This new synthetic route provides a simple and general access to densely substituted privileged scaffolds or fragments with a perfect control of their relative configuration.