Construction of Redox-type Photochromic Systems Based on Photoinduced Electron Transfer Reactions in Crystalline State

本研究计划旨在利用电子-给体-受体复合物在结晶状态下的光诱导电子转移反应，构建新型的氧化还原型光致变色体系。为了实现这一想法，开发具有双稳态的新型氧化还原分子是必要的。因此，氧化还原对被设计成在电子转移时经历可逆的C-C键形成和裂解。本研究从六苯乙烷衍生物1和双阳离子双（三芳基甲烷）染料2的相互转化开始。发现它们构成动态可逆的氧化还原对，在电子转移时表现出鲜明的颜色变化和剧烈的结构变化。他们肯定是目前最有希望的候选人。然而，不幸的是，试图获得CT晶体的1与各种电子供体一直不成功，阻止我实现我最初的建议。接下来，研究了具有二氰基乙烯基部分的联苯型电子受体。发现2，2 '-二取代衍生物在双电子还原时发生C-C键形成。通过结合还原产物的进一步异构化，后一系统构成具有“写保护”选项的新型电致变色系统的原型。

The research project is intended to construct the novel redox-type photochromic systems based on the photoinduced electron transfer reactions of electron-donor-acceptor complexes in the crystalline state. In order to realize such an idea it is essential to develop a new type of redox molecules exhibiting bistability. Thus, the redox pairs were designed so as to undergo reversible C-C bond formation and cleavage upon electron transfer. The research started from examining the interconversion hexaphenylethane derivatives 1 and dicationic bis (triarylmethane) dyes 2. It has been found that they constitute the dynamic and reversible redox pair showing vivid change in color and drastic structural change upon electron transfer. They surely are the promising candidate for the present purpose. Unfortunately, however, attempts to obtain the CT crystal of 1 with a variety of electron donors have been unsuccessful, preventing me from realizing my initial proposal. Next, the biphenyl-type electron acceptors having dicyanovinyl moieties were investigated. 2,2'-Disubstituted derivative was found to undergo C-C bond formation upon two-electron reduction. By combining the further isomerization of the reduction product, the latter system constitute a prototype of the novel electrochromic system with "write protect" option.