Here, we introduce a C-symmetric molecular design strategy to develop a brand-new visible-light organic photoswitch, named tri-branched multipolar Stenhouse Adduct (TMSA). After doping TMSA into low glass transition polymers ( thermoplastic urethane, TPU) via simple blending and solution casting, the resultant composite films exploit unique geometric and electronic effects of TMSA to afford markedly-improved photoswitching performance compared to those doped with dipolar donor-acceptor Stenhouse Adduct (DASA) counterparts with suppressed solid state photochromism. Importantly, they display good fatigue resistance over 50 photo-discoloration/thermal-recovery cycles with slow degradation, surpassing those literature-reported composites involving various DASAs (<30 cycles). As revealed by combined experiment and computation studies, the multi-dimensional electronic coupling in multipolar TMSA facilitates the thermal cyclization and non-planar branched structures of TMSA afford large free space in polymers for efficient molecular isomerization, while the promoting effect on TMSA isomerization induced by ester-rich polymer micro-environments is more pronounced relative to DASA counterpart.

中文翻译：

---

通过 C3 对称多极设计增强本体聚合物中掺杂的 Stenhouse 加合物的固态光致变色性能

在这里，我们引入了C对称分子设计策略来开发一种全新的可见光有机光开关，称为三分支多极斯滕豪斯加合物（TMSA）。通过简单的共混和溶液浇铸将 TMSA 掺杂到低玻璃化转变聚合物（热塑性聚氨酯，TPU）中后，所得复合薄膜利用 TMSA 独特的几何和电子效应，与掺杂偶极供体-受体 Stenhouse 的薄膜相比，可显着提高光开关性能加合物（DASA）对应物具有抑制固态光致变色的作用。重要的是，它们在 50 个光变色/热恢复循环中表现出良好的抗疲劳性，并且降解缓慢，超过了文献报道的涉及各种 DASA 的复合材料（<30 个循环）。结合实验和计算研究表明，多极性TMSA中的多维电子耦合促进了热环化，TMSA的非平面支化结构为聚合物中提供了大的自由空间，以实现有效的分子异构化，同时对TMSA异构化的促进作用富含酯的聚合物微环境相对于 DASA 对应物更为明显。