9-Phenylxanthenyl radical can undergo facile C-C bond formation at C9-position when the two units of the radical are connected at C2'-positions to give stable intramolecular dimer (1), which is a clamped hexaphenylethane derivative with an elongated C-C bond. The newly formed bond in 1 can be cleaved easily upon two-electron oxidation to give bis(9-xanthenylium)-type dication (22+), from which the diradical is generated upon two-electron reduction. This review account describes the dynamic redox ("dyrex") pair of colorless 1 and yellow-orange 22+, which provides a versatile scaffold to develop multi-functional electrochromic systems. Both of 1 and 22+ are sterically challenged molecules and thus adopt characteristic skewed geometries. Electrochiroptical response was realized by suppressing the chiral inversion of helicity in 1 and axial chirality in 22+ whereas redox-induced fluorescence switching was attained by attaching the fluorophore whose emission is quenched by xanthenylium in 22+ but not by spiro(xanthene) unit in 1. By the molecular design that allows intramolecular chiral transmission, the spectral changes were also induced by the external stimuli (e.g. heat, pH) other than redox input, which made it possible to construct less well-explored multi-input-multi-output response systems. More advanced functions could be endowed, such as chiral redox memory or reversible O2-storage, by further modification of the prototype.

中文翻译：

---

9,9'-联（x吨）型六苯乙烷衍生物作为高级有机电致变色体系

当自由基的两个单元在C2'-位置连接以产生稳定的分子内二聚体（1 ）时，9-苯基黄嘌呤基团可以在C9-位置容易地形成CC键，这是一种带有细长CC键的被夹紧的六苯基乙烷衍生物。1中新形成的键在两电子氧化时可轻松裂解，得到双（9-黄嘌呤鎓）型金属离子（2 2+ ），在双电子还原时，从中生成双自由基。这篇综述描述了无色1和黄橙色2 2+的动态氧化还原（“ dyrex”）对，它提供了开发多功能电致变色系统的多功能支架。这两个1和2 2+是空间挑战分子，因此采用特征性的偏斜几何形状。通过抑制1的螺旋性和2 2+的轴向手性的手性反转来实现电按摩响应，而氧化还原诱导的荧光转换是通过附着荧光团实现的，该荧光团的发射通过2 2+的x吨鎓而不是螺（iro吨）单元猝灭。在1。通过允许分子内手性传递的分子设计，光谱变化还由氧化还原输入以外的外部刺激（例如，热，pH）引起，这使得构建较少探索的多输入多输出响应系统成为可能。 。通过进一步修改原型，可以赋予更高级的功能，例如手性氧化还原记忆或可逆的O 2储存。