Time-resolved fluorescence studies on the formation and decomposition of the aromatic hydrocarbon-aliphatic amine exciplex in solution

Fluorescence rise and decay processes were measured and rate parameters were determined for the pyrene-tri-n-butylamine and pyrene-N,N-diethylaniline exciplex system in various solvents. An additional activation energy over that for the diffusional motion appears necessary for both exciplex formation and the deactivating quenching processes in the case of the pyrene-tri-n-butylamine system. The rate-determining step for these processes is electron transfer in the encounter collision leading to the nonrelaxed electron transfer state.     

Optical Absorption Spectra for the Solvated Electron Observed in the Pulse Radiolysis of cis- and trans- Isomers of 3- and 4-Methylcyclohexanols

The absorption band maximum of solvated electrons, λ_max(e^?_s), in 3- or 4-methylcyclohexanols is observed at longer wavelengths (818–837 nm), if the OH group is axial, and at shorter wavelengths (721–723 nm), if it is equatorial. It is surmised that the size of cavity for the solvated electron is larger in the former case and smaller in the latter.     

The Wall Effect on Hydrogen Formation in the Vapour-Phase Radiolysis of c-C6D12 and n-C7D16

Vapour-phase radiolysis of c-C₆D₁₂ and n-C₇D₁₆ leads to a relatively large HD yield, up to ～ 20% of the total hydrogen, which cannot be accounted for by incomplete deuteration of c-C₆D₁₂ and n-C₇D₁₆. In order to elucidate the mechanism of the HD formation, we have examined the effect of additives and of physical conditions on the HD yield. By coating the vessel with a layer of Aquadag the HD yield is greatly decreased without appreciable variation of the total hydrogen yield. The HD yield from nontreated vessels also decreases remarkably with increasing total dose; it is increased upon the addition of traces of water; and is less affected by small amounts of c-C₆H₁₂. The addition of SF₆ selectively reduces the HD yield. These experimental results lead us to conclude that inert hydrocarbon ions react by proton transfer with water desorbed from the vessel wall to give hydronium ions which yield HD on subsequent neutralization.     

The structure of a new antibiotic,hygrolidin

The structure of a new antibiotic, hygrolidin has been determined as shown in fig. 3.     

Geometric realization of conformal field theory on Riemann surfaces

Conformal field theory on a family of Riemann surfaces is formulated. We derive equations of motion of vacua which are parametrized by moduli of Riemann surfaces and show that these vacua are characterized uniquely by these equations. Our theory has a deep connection with Sato's theory of KP equations.     

Hadamard graphs. II

The automorphism groups of Hadamard graphs are determined, and some particular properties of the Hadamard graph of size 8 are shown.     

The reaction of diphenyl carbonate with amines and its application to polymer synthesis

Selective formation of biscarbamates from diphenyl carbonate (DPC) and diamines and the preparation of polyurethanes from the carbamates and diols under mild conditions were studied. The reaction of DPC and diamines was significantly affected by catalysts, biscarbamates being exclusively prepared in high yields in the presence of 2-hydroxypyridine. The polycondensation reaction of the biscarbamates with diols was facilitated by catalysts such as metal salts; among the catalysts examined magnesium chloride in pyridine gave the best results. Metal chlorides in pyridine also promoted the reaction of DPC with aromatic amines to give the corresponding ureas, and the direct synthesis of polyureas was achieved by the polycondensation of DPC with diamines in the presence of the chloride.