Development of High-Performance Photochromic Systems based on 6^|^pi;-Electrocyclization

After a brief introduction of photochromism, the results of the following research subjects elaborating extremely high-performance photochromic systems are described: (1)A photochromic bisthiazolylcoumarin with a phenolic hydroxy group was synthesized and it showed dual-mode luminescence control, i.e. photochromism and pH change, in a methanolic aqueous media; (2)Bisthiazolylindenone ethylene acetal was synthesized and it showed a large cyclization quantum yield caused by fixation of the conformation by intramolecular hydrogen bonds between the hydrogen atom on the acetal and the nitrogen atom of a thiazole as well as the hydrogen atom on the phenyl group of the indene moiety and the nitrogen atom of the other thiazole group; (3)Bisthiazolylindenols were synthesized, in which the hydrogen bond between the hydroxy group and the nitrogen atom of a thiazole played a crucial role in fixing the conformation in favor of photocyclization in a diastereoselective manner; (4)Complete diastereoselectivity of a facially chiral bisthienylethene having intramolecular bridging with a triethyleneglycol tether across the surface of one of the thiophene rings was achieved and, in this compound, the approach of the other thiophene ring was rigorously restricted only from the opposite side of the bridge; (5)Enantioselective photochromic ring closure of a bishydroxymethyl-substituted diarylethene was carried out in the presence of human serum albumin (HSA) in a buffered aqueous solution; and (6)The curious temperature dependence phenomenon for the diastereoselectivity of C2-symmetric bisbenzothienylethene with two chiral substituents was clarified.