Jiro Abe

Cross-metathesis of vinyl aromatic heterocycles: comparison of Grubbs catalyst and Schrock catalyst

Abstract Metathesis of 2-vinyl aromatic heterocycles such as furan and thiophene has been investigated in the presence of a ruthenium-based Grubbs catalyst from a synthetic standpoint. The self-metathesis of 2-vinyl aromatic heterocycles was not successful. However, the cross-metathesis of these aromatic heterocycles with 1-octene occurred efficiently, but the selectivity of cross-metathesis product was very low, below 50%. The origin of the low selectivity of heterodimer formation was elucidated through metallacyclobutane intermediate mechanism, observations of carbenes by in situ 1 H NMR, and the reaction products. The effect of oxygen on the reaction behavior was also examined. Furthermore, the data obtained on the Grubbs catalyst were compared with those on a molybdenum-based Schrock catalyst.

Electronic structure of light-induced lophyl radical derived from a novel hexaarylbiimidazole with π-conjugated chromophore

A novel photochromic hexaarylbiimidazole with a bithienyl group as an extended pi-conjugation unit was synthesized and the light-induced lophyl radical was found to be stabilized due to the delocalization of an unpaired electron, and to strongly absorb near-infrared light.

All Optically Induced χ(2)Structures and Their Optical Anisotropy in Betaine Dispersed in Polymer Matrix

This paper is concerned with the noncentrosymmetric alignment of betaine molecules dispersed in a polymeric matrix by an all-optical poling process. Two types of betaine molecules were used: one is betaine-azo with an azobenzene moiety in the molecule and the other is betaine-C8 without an azobenzene moiety in the molecule. The effect of the azobenzene moiety in the molecule on the optical poling efficiency, the formation of χ(2) structure, and its thermal stability was studied. Optical anisotropy of the χ(2) tensor components formed in the matrix in the writing process with linearly polarized beams was evaluated by rotating a sample film or rotating the polarization direction of the fundamental reading beam.

Electrochemical synthesis of a pyridinium-conjugated assembly based on nucleophilic substitution of oligothiophene π-radical cation

A series of pyridinium-conjugated oligothiophenes is synthesized electrochemically by nucleophilic substitution of the oligothiophene π-radical cation. The nucleophilic reaction is designed on the basis of high reactivity of the π-radical cation of oligothiophene with various pyridine derivatives as nucleophiles. While electrochemical oxidation of oligothiophene gave a conducting polythiophene film on an electrode, the addition of pyridine depressed formation of the polythiophene film but the corresponding pyridinium-conjugated oligothiophene was exclusively formed as the product of nucleophilic substitution of the oligothiophene π-radical cation. In prolonged electrolysis at a higher potential, successive (two-step) substitution occurred to yield both mono- and di-(1-pyridinio)oligothiophenes. The nucleophilic substitution reaction was optimized with respect to the electrolytic conditions, and the nucleophilic attack toward the oligothiophene π-radical cation is ndiscussed. The UV-visible absorption spectra and redox activities of the resulting pyridinium-conjugated oligothiophene were measured. Negative solvatochromism due to intramolecular charge transfer (IMCT) and redox behavior resulting from oligothiophene and pyridinium moieties are demonstrated.