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    Preparation and photochromic properties of 2,3-bisarylbenz[f]indenones
    (Elsevier Science Sa, 2013) Köse, Mahmut; Orhan, Ersin; Suzuki, Kazushi; Tutar, Ahmet; Ünlü, Cihansel Sancak; Yokoyama, Yasushi
    From 2,3-dibromobenz[f]indenone, four compound: 2,3-bis(5-methyl-2-phenyl-4-thiazolyl)benz [f]indenone 10, 2,3-bis(3,5-dimethyl-4-isoxazolyl)benz[f]indenone 20, 3-(3,5-dimethyl-4-isoxazolyl)-2-(5-methyl-2-phenyl-4-thiazolyl)benz[f]indenone 30 and 2,3-bis(5-methyl-2-phenyl-4-thiazolyl)benz[f]indenol 40 were prepared, and their photochromic properties were investigated. Among them, photochrome 10 (weak photochromic) and its bisthiazolylbenz[f]indenol derivative 40 displayed photochromism. During ring closure photoreaction, photochrome 40 showed high conversion ratio (98.4%) with low diastereomeric excess (38%). (C) 2013 Elsevier B.V. All rights reserved.
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    Synthesis and photochromic properties of 4,5-bisaryl-3(2H)-pyridazinones
    (Elsevier Science Sa, 2016) Orhan, Ersin; Gündoğdu, Leyla; Köse, Mahmut; Yokoyama, Yasushi
    Six novel photochromic bisarylpyridazinones containing 2,5-dimethylthiophene or 5-methy1-2-phenylthiazole unit were synthesized, and their photochromic and fluorescence properties were investigated. The bisarylpyridazinones underwent reversible color change upon irradiation with UV or visible light. The effect of solvents on the absorption spectra of the bisarylpyridazinones was investigated. The closed-ring forms of bisarylpyridazinones displayed negative solvatochromism which was attributed to the high dipolar characters of the molecule. The open-ring forms of bisarylpyridazinones showed fluorescence at 400-480 nm upon excitation at 302 nm, and the intensities of emission bands gradually decreased during the ring-closing photoreactions. Among the synthesized bisarylpyridazinones, 4,5-bis(5-methyl-2-phenylthiazol-4-yl)-2-methyl(or 2-phenyl) pyridazin-3(2H)-ones (50 and 60) displayed rather large absorption and emission spectral change, higher quantum efficiency during the photoreaction compared to others. A high conversion ratio (94%) to the closed form was observed for 50. (C) 2015 Elsevier B.V. All rights reserved.
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    Synthesis, photochromic and fluorescence properties of new bithiazole-containing diarylethenes as cation sensors
    (Elsevier Science Bv, 2018) Gündoğdu, Leyla; Köse, Mahmut; Takeuchi, Sakiko; Yokoyama, Yasushi; Orhan, Ersin
    Two new bithiazole-containing diarylethenes, 1[5-methyl-2-(5-methyl-2-thiazolyl)-4-thiazolyl]-2,5-dimethy1-3-thienyl-3,3,4,4,5,5-hexafluorocyclopentene and 1[5-methyl-2-(5-methyl-2-thiazolyl)-4-thiazolyl]1-2-methyl-3-benzothienyl-3,3,4,4,5,5-hexafluorocyclopentene were synthesized and their photochromic and fluorescent properties have been investigated. They exhibited thermally irreversible photochromism and fluorescent switching in toluene. The effects of complexation of these two compounds with various metal cations such as Na+, Ag+, Hg+, Co2+, Ni2+, Cu2+, Ba2+, Zn2+, Cr3+, Pb2+, Cd2+, Sn2+, Al3+, Fe3+ on photochromic and fluorescent properties were also studied. Metal cations caused small effects on the absorption bands of their ring closed forms. However, fluorescence intensities of both compounds were strongly suppressed by Ni2+, Cu2+ and Fe3+.