ヘキサフェニルエタン型化合物を基軸とした酸化還元型応答系の構築

抄録

Redox reactions of a series of dicationic dyes (2²⁺, 4²⁺, 6²⁺) having two triarylmethylenium chromophores were studied, which are interconvertible with colorless hexaarylethane derivatives (1, 3) or 9-membered cyclic peroxides (5), respectively, upon two-electron transfer. They constitute a new class of electrochromic systems endowed with high electrochemical bistability since the reversible bond making/breaking causes the drastic changes in the geometrical and electronic structures of the redox pairs. Bond dissociated cation radical 2^+· is the stable intermediate for the interconversion between 1 and 2²⁺, and the unprecedented tricolor chromic systems showing a hysteretic color change were constructed based on 1, 2^+·, and 2²⁺. Drastic change in CD spectrum was observed during the interconversion between chiral helicenes 3 and binaphthylic dications 4²⁺, which is the successful demonstration of electrochiroptical response. Peroxides 5 were readily obtained by two-electron reduction of dications 6²⁺ under air. Since 6²⁺ were regenerated by the “oxidative deoxygenation” reaction of 5, these pairs can serve as a electrochemically controlled oxygen-storage system.