Basic study of photochemistry of photochromic molecules

光致变色分子光化学基础研究

• 批准号: 07640680
• 负责人: KASATANI Kazuo
• 金额: $ 1.34万
• 依托单位: Yamaguchi University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640680/
• 关键词: diarylethenes; dithienylethenes; photochromism; photochiromic; molecular orbital calculations; cyanine dyes; photoisomer; counterion effect; ジアリールエテン; ジチエニルエテン; 微粒子; アモルファス; フォトクロミック分子; フォトクロミック反応; 蛍光; ピコ秒; 半経験的分子軌道計算

1. Photochromic reactions of diarylethenesPhotochromic reactions of diarylethenes, cis-1,2-dicyano-1,2-bis (2,4,5-trimethyl-3-thienyl) ethene (Compound 1) and 2,3-bis (2,4,5-trimethyl-3-thienyl) maleic anhydride (Compound 2) were studied. (1) Photochromic reaction with high efficiency was confirmed for compound 1 in mixed LB films of arachidic acid and methyl arachidate on the basis o UV-visible absorption spectra before and after UV irradiation. (2) Conformations of the ground states and excited states of diarylethenes were optimized by a semiempirical molecular orbital method, MOPAC.Barrier heights between conformeres and charge distributions were also calculated. The dependence of photochromic reaction efficiency on polymer (or solvent) polarity was explained in terms of large dipolemoment in the S_1 state. (3) It was found that photochromic reaction efficiency of Compound 2 is high in a polymer matrix with low polarity and low glass-transformation temperature. Photochromic reaction … More efficiency of Compound 1 was not significantly affected by the kind of polymer. (4) Colloidal solutions and amorphous films of diarylethenes were formed and their efficiency of photochromic reactions was studied. Colloidal solution of Compound 1 has an efficiency as high as its hexane solution. However the efficiency was dropped soon after UV irradiation started, because energy transfer from ring-opened form to ring-closed form occurs in solid phase. No photochromic reactions were observed for polycrystal or colloidal solution of Compound 2. On the other hand, a little part of amorphous films of Comopund 2 was colored by UV irradiation.2. Photochromic reactins of cyanine dyesCounterions in a non-polar solvent affect lifetimes of photoisomer of cyanine dyes. The Influence was large for some kinds of dyes. Wavelengths of visible absorption and fluorescence maxima also were affected by counterions. Semiempirical molecular orbital calculations clarified the mechanism of the counterion effects. Less

1.二芳基乙烯的光致变色反应研究了二芳基乙烯、顺-1，2-二氰基-1，2-二(2，4，5-三甲基-3-噻吩基)乙烯(化合物1)和2，3-双(2，4，5-三甲基-3-噻吩基)马来酸酐(化合物2)的光致变色反应。(1)根据紫外光照射前后的紫外-可见吸收光谱，证实了化合物1在花生四酸和花生四酸甲酯混合LB膜中发生了高效的光致变色反应。(2)用半经验分子轨道方法MOPAC优化了二芳基乙烯基态和激发态的构象，并计算了构象间的势垒高度和电荷分布。用S_1态的大偶极矩解释了光致变色反应效率与聚合物(或溶剂)极性的关系。(3)在低极性、低玻璃化温度的聚合物基质中，化合物2的光致变色反应效率较高。光致变色反应…化合物1的更高效率不受聚合物种类的显著影响。(4)形成了二芳基乙烯的胶体溶液和无定形薄膜，并研究了它们的光致变色反应效率。化合物1的胶体溶液具有与其正己烷溶液一样高的效率。然而，紫外光照射后不久，由于能量从开环形式向闭环形式转移，在固相中发生了能量转移，效率下降。化合物2的多晶或胶体溶液没有观察到光致变色反应。另一方面，化合物2的一小部分无定形薄膜在紫外光照射下着色。菁染料的光致变色反应非极性溶剂中的反离子影响菁染料光致异构体的寿命。对部分染料影响较大。反离子对可见吸收波长和荧光最大值也有影响。半经验分子轨道计算阐明了反离子效应的机理。较少