Photoinduced intramolecular electron-transfer reactions in carbazole-fullerene and phenothiazine-fullerene linked compounds in benzene and benzonitrile as studied by fluorescence, transient absorption, time-resolved EPR, and magnetic field effects

Photoinduced intramolecular electron-transfer reactions in carbazole (Cz)-fullerene (C₆₀) (Cz(8)C₆₀) and phenothiazine (Ph)-C₆₀ (Ph(n)C₆₀ (n=8, 10, 12)) linked compounds have been investigated in benzene and benzonitrile by fluorescence, transient absorption, and time-resolved electron paramagnetic resonance measurements, and by magnetic field effects on the decay rate constants of the photogenerated biradicals. In benzonitrile, photoinduced intramolecular electron transfer from Cz to the singlet excited state of C₆₀ (¹C₆₀ ^*) occurred in Cz(8)C₆₀, but not to the triplet excited state (³C₆₀ ^*), while the intramolecular electron-transfer to both¹C₆₀ ^* and³C₆₀ ^* occurred in Ph(n)C₆₀ (n=8, 10, 12). In benzene, on the other hand, no electron transfer to both¹C₆₀ ^* and³C₆₀ ^* took place in all linked compounds. These results were interpreted in terms of the different Gibbs free energy changes in the two solvents.     

Grinding-induced equimolar complex formation between thiourea and ethenzamide

We prepared and characterized a grinding-induced equimolar complex of thiourea with ethenzamide. When thiourea and ethenzamide were co-ground at a molar ratio of 3 : 1, new powder X-ray diffraction (PXRD) peaks were observed in addition to PXRD peaks of thiourea crystals. The optimum stoichiometry of the new structure was confirmed as 1 : 1 mol/mol. Effect of grinding time on the thiourea-ethenzamide equimolar complex formation was investigated by using PXRD, differential scanning calorimetry and Fourier transform infrared spectroscopy. The equimolar crystal structure was confirmed by X-ray diffraction measurements of the single crystal which was recrystallized from ethanol. It was found that the intermolecular hydrogen bond formations between thiourea and ethenzamide molecules contributed to the equimolar complex formation. The complex formation was not observed in the cases where benzamide, salicylamide or 3-ethoxybenzamide was co-ground with thiourea. 2-Alcoxyl benzamide structures should be required for the grinding-induced equimolar complex formation with thiourea.     

Chemical bonding effect in electron scattering by gaseous molecules

The experimental intensity of 30 keV electron small angle scattering by a gaseous molecule is much different from the calculation using usual independent atom model. This is due to the rearrangement of electron distribution in a molecule by the formation of chemical bonds, and is called chemical bonding effect (CBE). The molecules studied are mainly hydrocarbons such as methane, acetylene, ethane, etc. and some non-hydrocarbons. The measurement was carried out on both elastic and total scattering and the effect was found for not only elastic but also inelastic scattering. The effect is relatively large for hydrogen rich molecules as H₂O, NH₃ and hydrocarbons, but is essentially related to the number of atoms contained in molecules. The origin of CBE will attribute mainly to the concentration of inner atomic electrons resulting from chemical bonding.     

Upgrade of the nuclear resonant scattering beamline, BL09XU in SPring-8

An Upgrade of the nuclear resonant scattering beamline, BL09XU in SPring-8 has been conducted. A liquid nitrogen cooled high-heat load monochromator was installed and a 2nd experimental hutch was constructed. The instruments installed in the hutch allow for a variety of sample conditions. Newly developed high-resolution monochromators with better stability including the back scattering geometry monochromator have opened up the easy access to more isotopes and more precise measurements.     

Phase structure of a U(1) lattice gauge theory with dual gauge fields

We introduce a U(1) lattice gauge theory with dual gauge fields and study its phase structure. This system is partly motivated by unconventional superconductors like extended s-wave and d  -wave superconductors in the strongly-correlated electron systems and also studies of the t–J$t\text{–}J$ model in the slave-particle representation. In this theory, the “Cooper-pair” (or RVB spinon-pair) field is put on links of a cubic lattice due to strong on-site repulsion between original electrons in contrast to the ordinary s  -wave pair field on sites. This pair field behaves as a gauge field dual to the U(1) gauge field coupled with the hopping of electrons or quasi-particles of the t–J$t\text{–}J$ model, holons and spinons. By Monte Carlo simulations we study this lattice gauge model and find a first-order phase transition from the normal state to the Higgs (superconducting) phase. Each gauge field works as a Higgs field for the other gauge field. This mechanism requires no scalar fields in contrast to the ordinary Higgs mechanism. An explicit microscopic model is introduced, the low-energy effective theory of which is viewed as a special case of the present model.     

Effects of the Calcination and Reduction Conditions on a Cu/ZnO Methanol Synthesis Catalyst

The CuO crystallite size of the catalysts obtained from aurichalcite greatly depends on the heating rate of calcination for highly active and selective Cu/ZnO catalyst was prepared by reduction with methanol at 443 K for 17 h.     

Molecular states of p-dimethylaminobenzonitrile coground with β-cyclodextrin investigated using solid-state fluorescence spectroscopy

Changes in molecular states of p-dimethylaminobenzonitrile (DMABN) coground with β-cyclodextrin (β-CD) were examined using solid-state fluorescence measurements. Formation of a DMABN/β-CD inclusion complex by coprecipitation was confirmed by powder X-ray diffraction measurement. The powder X-ray diffraction pattern of the ground mixture was a halo pattern and differed from the pattern of the mixture prepared by coprecipitation. Solid-state fluorescence measurements revealed emission by DMABN crystals in a twisted intermolecular charge-transfer state at 473 nm. DMABN in the DMABN/β-CD coprecipitate had a fluorescence emission peak at 393 nm due to its planar structure. In contrast, DMABN in a DMABN/β-CD ground mixture had an emission peak at 473 nm due to its twisted structure. Grinding time-dependent structural changes in DMABN were evaluated using fluorescence lifetime and relative quantum yield measurements. Structural changes in DMABN in the DMABN/β-CD coprecipitate from a planar to a twisted structure were observed with grinding. DMABN, dispersed in microcrystalline cellulose (CC) molecules in a DMABN/CC ground mixture, had a fluorescence emission peak at 473 nm. However, the excitation spectrum of a DMABN/β-CD ground mixture differed from that of DMABN in CC. These results indicated that the molecular state of DMABN accommodated in the β-CD cavity differs between the coprecipitate and the ground mixture.     

Rapid adsorption and entrapment of benzoic acid molecules onto mesoporous silica (FSM-16)

Changes in the molecular state of benzoic acid (BA) in the presence of folded sheet mesoporous material (FSM-16), which has uniformly sized cylindrical mesopores and a large surface area, were assessed with several analyses. When BA was blended with FSM-16 for 5 min (BA content=30%), the X-ray diffraction peaks of BA crystals disappeared, suggesting an amorphous state. Fluorescence analysis of the mixture showed a new fluorescence emission peak for BA at 386 nm after mixing with FSM-16. Fluorescence lifetime analysis of the BA component in the mixture at 386 nm showed a longer lifetime in comparison with that of BA crystals. The solid-state (13)C CP/MAS and PST/MAS NMR spectra of the mixture with FSM-16 showed a significantly different spectral pattern from the mixture with nonporous glass, whose NMR spectra were identical to those of BA crystals. These results indicate that BA molecules disperse quickly into the hexagonal channels of FSM-16 by a simple blending procedure and adsorbed BA molecules had clearly different physicochemical properties to BA crystals.     

Morphology and surface States of colloidal probucol nanoparticles evaluated by atomic force microscopy

Morphology and surface states of colloidal probucol nanoparticles after dispersion of probucol/polyvinylpyrrolidone (PVP)/sodium dodecyl sulphate (SDS) ternary ground mixture into water were investigated by atomic force microscopy (AFM). The observed particles had core-shell structure, i.e. drug nanocrystals were covered with PVP and SDS complex. The AFM phase image and the force curve analyses indicated that probucol nanoparticles with PVP K17 showed layer structure, compared to those with PVPK12. The structural difference was explainable in terms of the molecular states of PVP-SDS complex on the particle surface. These findings support not only the mechanism of drug nanoparticle formation but also the in vivo absorption results with the almost same particle size of ca. 40 nm.