Yayoi Yokoyama

Optical resolution of a thermally irreversible photochromic indolylfulgide

The first optical resolution of a photochromic fulgide is performed for a thermally irreversible indolylfulgide to give a pair of enantiomers of helical chirality, and their optical properties and photochemical and thermal enantiotopomerization processes are investigated.

Photochromism of fulgenates possessing crown-ether moiety

Abstract Three indolylfulgenates possessing diesters of 14-crown-4 (2), 17-crown-5 (3), and 20-crown-6 (4) groups were synthesized and their photochromic behaviors in the presence or absence of alkali metal cations (Li+, Na+, K+) were investigated. Notable features are: (1) The association constant of Na+ was the largest for 3, and that for K+ was the largest for 4, (2) The association of E- and Z-forms are stronger than C-form. (3) In the cases of Na+-3 and K+-4, no photocoloration occurred. (4) As for the photochromism of 2, no effects of alkali metal species were observed. These phenomena were elucidated by molecular mechanics calculations.

Novel Thermally Reversible Photochromic Compounds: Dihydrobenzothiophene and Dihydronaphthalene

ABSTRACT Novel thermally reversible photochromic dihydrobenzothiophenes 1 and 2 , and dihydronaphthalenes 3–6 were synthesized. The colored form 1Q returned to the colorless 1R within 150 min, while the decoloration of 2Q was much slower. On the other hand, dihydronaphthalenes returned very quickly. The decoloration rate was controlled by introducing a methoxy group on the phenyl ring.

Photochromism and kinetics of heliochromic benzothienylfulgides

Abstract Four heliochromic benzothienylfulgides were synthesized and their spectral properties, photochromism, and the decoloration kinetics were examined. Photocyclization of E-form occurred on the benzothiophene ring but not on the phenyl ring for 4 and 5. Introduction of an isopropyl group (3) or a phenyl group (4, 5) on the benzothienylmethylidene group retarded the decoloration rate of O-forms. Introduction of a phenyl group (4, 5) also resulted in 40-nm red-shift of absorption and three-fold increase in molar absorption coefficients of O-forms in the visible region.

1,3-Bisarylbutadienes: Novel Thermally Irreversible Photochromic System

ABSTRACT Novel thermally irreversible photochromic compounds 1O , 2O and 3O based on 1,3-bisarylbutadiene system were synthesized. The closed ring-forms 1C and 2C showed absorption maximum at 445 nm, while the closed ring-form 3C , a methyl group of 2C on C-5 of thienyl ring was replaced with a formyl group, showed the absorption maximum at 500 nm.