In this review, the recent studies on 1) the visible-light-induced reduction of CO2 to formic acid catalyzed by formate dehydrogenase (FDH) via the reduction of a 4,4′- or 2,2′-bipyridinium salt (BP2+) by a photosensitizer, 2) the electrochemical properties of BP2+, and 3) the enzymatic kinetic properties of the interaction between the reduced forms of BP2+ and FDH are reviewed. Moreover, visible-light-induced biocatalytic C–C bond formation using CO2 as a feedstock via photoreduction of the phenylviologen derivative is introduced.
The recent studies on the visible-light-induced CO2 reduction to formic acid with formate dehydrogenase (FDH) via the reduction of 4,4′- or 2,2′-bipyridinium salt (BP2+) by photosensitizer, electrochemical properties of BP2+s, and kinetic properties of the interaction between reduced form of BP2+s and FDH by enzymatic analysis are reviewed. Moreover, the visible-light-induced carbon–carbon bond formation from CO2 with biocatalyst via the photoreduction of phenylviologen derivative also is introduced.
The structure–activity relationship of carbon-supported Co catalysts was investigated in solvent-free aerobic oxidation of ethylbenzene under microwave irradiation. A single-site Co species show specifically high catalytic activity under microwave irradiation compared to conventional heating, while the oxidation is not accelerated by microwave when Co nanoparticle catalysts are used.
Hierarchically cellulose monoliths were successfully prepared by non-solvent-induced phase separation (NIPS) without any template. Phase separation was induced by adding ethyl acetate into a cellulose/LiCl-DMAc system. The obtained cellulose monolith with a surface area of 30 m2 g−1 owned both mesoporous and macroporous structures. The pore size of the cellulose monolith could be easily tuned by changing the cellulose concentration. Moreover, the cellulose monoliths showed excellent mechanical properties.
A novel oxynitride, BaYSi2O5N, has been synthesized by a solid-state reaction method. Its crystal structure was determined by single-crystal X-ray analysis. Eu2+- and Ce3+-doped BaYSi2O5N exhibit broad blue emission with peaks around 459 and 412 nm under excitation at 250–450 and 250–370 nm, respectively. This is the first report on the synthesis of oxynitrides in the BaO-Y2O3-SiO2-Si3N4 system.
The use of pentaerythritol in combination with the Na cation in the synthesis of ZSM-5 led to a unique Al distribution in the MFI framework; Al atoms were preferentially located at straight and sinusoidal channels, not the intersection.
Inclusion crystals were effectively formed from a simple naphthalenediimide derivative with toluene, 4-fluorotoluene, and p-xylene by the aid of cooperative intermolecular interactions, such as charge-transfer interactions and inclusion phenomena. The crystals showed intense guest-dependent solid-state emission based on ground state CT complexes between naphthalenediimide and small aromatic guests.
We report the structures and the electronic properties of a novel terphenoquinone derivative having a benzo[1,2-b:4,5-b′]dithiophene (BDT) unit as a central ring. This molecule exhibits the open-shell biradical characters resulting from the thermally accessible open-shell structure. X-ray structure analysis and magnetic measurements clarify that this molecule has a closed-shell ground state, which is lower than the open-shell biradical state by 10.4 kJ mol−1. The electronic absorption and electrochemical measurements reveal the small HOMO–LUMO gap about 1.3 eV of this molecule.
New iridium complexes having functional 8-quinolinolato ligands have been synthesized. By single-crystal X-ray analysis, it was revealed that these new complexes had coordinatively unsaturated structure (five-coordinate trivalent iridium: 16e− complex). Furthermore, one of the new complexes exhibited high catalytic activity for the dehydrogenative oxidation of various aromatic and aliphatic secondary alcohols in aqueous media to give the corresponding ketones in good to excellent yields.
Biologically relevant amines react with acrolein to provide 3-formyl-3,4-dehydropiperidine (FDP) as the oxidative stress product, which has reduction potential via hydrogen transfer. This biogenic process was applied to the domino reduction of electron-deficient nitroarenes in one-pot operation, by simply mixing primary amine, acrolein, nitroarene, and calcium chloride. The reaction can be performed in a gram-scale without the use of hazardous metals.
CuFeO2 is a promising photocathode material for photoelectrochemical water splitting. In this study, a hydrothermal method was used for the first time to directly fabricate CuFeO2 films on an Fe substrate, and the prepared films worked as photocathodes. To enhance the performance of CuFeO2 photocathodes, it is important to optimize their film thickness and surface morphology.
m-Benzene-linked derivatives of partially oxygen-bridged triphenylamine were designed and synthesized as transparent hole-transporting materials, which show absorption bands only in the UV region (–425 nm). Vacuum-deposited films of these compounds retain amorphous states even after heating at 160 °C and exhibit good hole mobility in the same order to the directly connected dimer.
Organoarsenic ligands were synthesized via a safe and easy procedure, superior to the conventional synthetic methodologies. Diiodophenylarsine was prepared in situ, and was readily converted to diarylphenylarsines. Pd-catalyzed Mizoroki–Heck reaction was investigated using the obtained arsenic ligands. It was found that bulky and electron-donating ligands were effective for the reaction, meaning that the success in the screening of arsenic ligand structures was based on the present facile strategy.
Diblock copolymers composed of a water-soluble polyphosphobetaine block with a short chain length and either a cationic or anionic block were prepared. Giant polyion complex vesicles (G-PICsomes), with a size on the order of micrometers, were prepared by dialysis from a mixture of oppositely charged diblock copolymers in a 1.5 M NaCl aqueous solution against pure water. Hydrophilic guest molecules could be encapsulated into the G-PICsomes.
We report that close-packed colloidal crystals with low crack densities could be formed by evaporation method using polymer hydrogels as substrates. Aqueous dispersions of charged polystyrene particles (diameter = 600 nm) were dried on polyacrylamide gels. No distinct crack was observed in the resulting crystals, though many cracks (an area fraction ≈ 8%) were formed when glass substrates were used. This difference appears to be attributable to much longer crystallization time on the gel surface, due to continuous supply of water from inside the gel.
Microcrystals of zinc citrate dihydrate (ZnCit), a nucleating agent of poly(l-lactic acid) (PLLA), were magnetically oriented to obtain a three-dimensional magnetically oriented microcrystal array (3D-MOMA). The structure determined by X-ray analysis of the 3D-MOMA agreed well with that determined using a single crystal. The relationship between the magnetic and crystallographic axes was determined. Since the ZnCit crystal reportedly induces epitaxial growth of PLLAs, their three-dimensional alignment is expected to induce three-dimensional alignment of the PLLA crystals.
The penetration of water into a cellulose acetate (CA) film with m-terphenyl (m-TP) as a waterproofing agent (WPA) was investigated in real time by coherent anti-Stokes Raman scattering (CARS) microspectroscopy. Owing to the WPA, the water penetration was significantly suppressed. It was manifested by a small spectral change in comparison with the CA films without m-TP. Moreover, the amplitude of the Raman band at 1600 cm−1 due to the OH bending mode, which is the marker band of water penetration, was significantly smaller. The present results indicate that m-TP has significant effects as a WPA for CA films on the water penetration process.
Sulfenyl chlorides, i.e., di-coordinated sulfur(II) chlorides are useful precursors for a variety of organic sulfur compounds. Herein, the synthesis, structure, and reactivity of a sulfenyl chloride that bears a bulky tris(dimethylphenylsilyl)methyl group on the sulfur atom are reported. The thermolysis of this sulfenyl chloride resulted in the generation of the corresponding bissilylthioketone via the 1,2-elimination of chlorodimethylphenylsilane.
A new procedure was developed for formylation of arenes to produce aromatic aldehydes using a sodium formate/triphenylphosphine ditriflate system in ethanol at room temperature in good yields. The simplicity of the procedure, short reaction times, and mild reaction conditions are the other advantages of this metal- and carbon monoxide-free protocol.
(R)-(+)-1-Phenylethoxide ligands were introduced into (4-methoxyphenylimido)vanadium(V) or (dimethylhydrazido)vanadium(V) compound to afford the chiral vanadium(V) compounds with the V=N bond, wherein a chiral dimeric structure was formed in a crystalline state through the µ-alkoxido-bridging. Moreover, these chiral imido and hydrazido vanadium(V) compounds were demonstrated to dimerize by self-association at −80 °C even in a solution state.
Hydrazine is widely used in a plenty of fields as a raw material and is closely related to our healthy. A new fluorescent probe of hydrazine was designed and synthesized, choosing imidazo[1,2-a]pyridine as the electron acceptor, based on the intramolecular charge-transfer (ICT) effect. The probe, 2-[4-(imidazo[1,2-a]pyridin-3-ylethynyl)benzylidene]malononitrile (5), responds rapidly to hydrazine and exhibits obvious color changes from yellow to colorless, indicating its use as a color indicator for hydrazine. Sensing mechanism of probe 5 toward hydrazine was deduced through HOMO–LUMO energy levels and the interfacial plots of the molecular orbitals. Its physical and chemical properties were demonstrated by UV, fluorescence, and single-crystal X-ray diffraction via computation and experiment. The calculated data are consistent with experimental results.
Supported Pt catalysts were covered with hydrophilic or hydrophobic silica layers. Both silica-coated Pt catalysts showed high tolerance to high-temperature sintering of Pt metal particles. The coverage with hydrophobic silica enhanced the activity of Pt catalysts for alkene hydrogenation in hydrophilic solvents.
Molecular carbon nanorings, [n]cycloparaphenylenes ([n]CPP), are a unique class of porous molecules with all-benzene surface. Herein, we report the preparation of polymorphs of CPP crystals for the first time, and the discovery of their packing structure-dependent properties. We found that the herringbone-packed structure is thermodynamically more stable than the tubular-packed structure. We revealed that their host–guest interaction depends on the packing structures of CPP: the tubular-packing affords one-dimensional open channels for weak guest sorption, while the herringbone-packing gives closed cavities for strong guest entrapment. This study exemplifies that the solid-state host–guest chemistry of CPP crystals can be directed by controlling their packing structures.
Phthalides have been easily prepared by the treatment of methyl o-iodobenzoates with a silylmethyl Grignard reagent in the presence of ketones. The electron-withdrawing ester moiety of methyl o-iodobenzoates and the low nucleophilicity of the silylmethyl Grignard reagent prompted a smooth iodine–magnesium exchange reaction, at room temperature, without affecting the ester moiety or resulting in an undesired reaction with electrophilic ketones. This simple method, wherein special control of the reaction temperature was unnecessary, has allowed the synthesis of various phthalides, including a phenolphthalein derivative.
The Parallel Cascade Selection Molecular Dynamics (PaCS-MD) is an enhanced conformational sampling to promote structural transitions from a given reactant. We here assessed how a number of initial structures, ninitial, affected the conformational sampling efficiency. We provide clear evidence that a large ninitial accelerated structural transitions. In contrast, a small ninitial showed a high conformational sampling efficiency as an accumulated simulation time over cycles, indicating that both ninitial values are suitable for promoting structural transitions.
The fluorescence blinking phenomenon, which is ubiquitous in single nano-objects, provides kinetic information concerning the underlying photophysics in these objects. However, considerable attention should be paid to the blinking analysis of these objects, especially, when they comprise multiple competitive processes. Here we report on a new protocol for discriminating between the competitive photophysical processes that cause fluorescence blinking. A robust statistical analysis was conducted by progressively changing a range of data to reveal the true blinking statistics caused by the electron-transfer dynamics at dye–TiO2 interfaces.
We present a method for the renaturation of denatured cytochrome c in a phosphonate-type ionic liquid with the addition of a suitable zwitterion and a small amount of water. The polarity of zwitterions was found to be a critical property for the renaturation of cytochrome c. The renatured cytochrome c was reduced by the addition of sodium dithionite, suggesting that the renatured cytochrome c retains its redox ability.
Theoretical schemes to evaluate electronic coupling elements for triplet–triplet annihilation (TTA) processes are proposed using fragment molecular orbital-linear combination of molecular orbital methods. Combining them with the Marcus formula, we estimate rate constants of TTA for 9,10-diphenylanthracene (DPA). We also performed molecular dynamics simulations of diffusion of DPAs in solution to estimate rate constants of molecular encounter in an assumed diffusion-controlled reaction. On the basis of the calculated rate constants, the mechanism of TTA process for DPAs in solution are discussed.
Rattle-type Au@MnO2 hollow nanospheres (R-Au@MnO2) were successfully synthesized through a redox reaction between KMnO4 and Au-cored carbon spheres (ACCSs) which were fabricated by hydrothermal method using aqueous solution of HAuCl4 and glucose. The phase of the MnO2 shell was determined by X-ray diffraction as δ-MnO2. R-Au@MnO2 hollow nanospheres exhibited enhanced catalytic activity that CO could be converted to CO2 by 90% at 103 °C, and also showed good catalytic stability.
In this letter, effective exchange integrals of radical dimers obtained by density functional calculations are decomposed into atomic-pair components. The bond energy density analysis, which was originally proposed to evaluate the energy of a chemical bond, was found to be a useful tool to analyze the magnetic interaction of radical dimers.
Reactions of a stable dialkylphosphinyl radical, 2,2,5,5-tetrakis(trimethylsilyl)-1-phosphacyclopentane-1-yl (1) with BH3-Lewis base (LB) adducts [BH3(LB)] provided hydrophosphine 3, hydrophosphine-borane complex 4, and μ-phosphinodiborane(6) 5 as detectable products via hydrogen abstraction. Theoretical studies revealed that B–H bonds in BH3 become considerably weaker upon coordination of 1, which reflected in facile hydrogen abstraction from phosphinyl radical-BH3 complex.
Fe2O3/SnO2 nanocomposites were successfully synthesized by microwave heating and spray drying process. Spherical secondary particles (less than 5 µm) of the Fe2O3/SnO2 nanocomposites consisted of primary particles (about 5 nm), and the atomic ratio of Sn:Fe was Sn:Fe = 63:37. The Fe2O3/SnO2 nanocomposites preheated at 300 °C worked as a rechargeable electrode material. The initial lithium insertion capacity of 1344 mA h g−1 (cutoff voltage: 10 mV) was achieved, and the rechargeable capacity at the 2nd cycle was 927 mA h g−1.
The stepwise protonation of ethylenediamine-containing peptides at low pH in endosomes is hypothesized to disrupt the endosomal membrane and enhance cytosolic delivery. Incorporation of a novel glutamic acid analog bearing an ethylenediamine moiety into TAT peptides markedly enhanced cytosolic delivery without cytotoxicity.
The electrode–slurry preparation process plays an important role to obtain the maximum performance from lithium-ion batteries. A new electronic conductivity measurement method for the electrode–slurry using alternative current impedance measurement was proposed. Electronic conductivity of the electrode–slurry decreased with increasing the electronic conductive additives. It was found that the proposed method is quite useful to characterize the electrode–slurry.
A simple hydrothermal approach is used to prepare water-soluble carbon quantum dots (W-CQDs) by using glucose as the precursor and PEO106PPO70PEO106 (F127) as the controlling agent. The homogeneous W-CQDs have an average size of 2.6 nm and show well dispersibility. W-CQDs/mesoporous SiO2 composites are synthesized by using mesoporous SiO2 as the carrier. The as-synthesized composites are characterized by SEM, TEM, XRD, and fluorescence spectrometry. The fluorescence intensity and quantum yield of the composite are higher than those of W-CQDs.
Stable benzopyrylium tetrafluoroborates, prepared by palladium-catalyzed annulation of aryl triisopropylsilylethynyl ethers with internal alkynes followed by BF3·OEt2 treatment, exhibited solid-state luminescence upon UV irradiation.