Developing photochromic materials and acquiring fundamental knowledge of their underlying photophysics is significant in diverse fields, including optoelectronics, sensing, catalysis, data storage, and more. Herein, we demonstrate how the photochromism of coordination polymers can be realized by creating lanthanide contraction, whose role in directing photophysics has previously remained elusive. Integrating different lanthanide cations and a π-electron conjugated terpyridine-based ligand (tpbz^–) affords nine isomorphous one-dimensional lanthanide coordination polymers of the formula Ln(tpbz)₃ (where the lanthanide [Ln] ranges from europium to lutetium). The decreasing ionic radii of the Ln centers across the 4f block result in increasingly condensed packing of the metal-ligand assembly. This trend affords a spectrally selective photochromic response in the lutetium polymer Lu(tpbz)₃, contrasting sharply with the nonphotochromic earlier analogs. Experimental and theoretical investigations reveal that the chromism can be attributed to the progressively enhanced intermolecular charge transfer of adjacent tpbz^– moieties induced by either Ln contraction or external pressure.

开发光致变色材料并获取其基础光物理学的基础知识在光电、传感、催化、数据存储等多个领域具有重要意义。在这里，我们展示了如何通过产生镧系元素收缩来实现配位聚合物的光致变色，而镧系元素在指导光物理学方面的作用以前一直难以捉摸。整合不同的镧系元素阳离子和 π 电子共轭三联吡啶基配体 (tpbz ^– ) 提供了九种同晶一维镧系元素配位聚合物，其分子式为 Ln(tpbz) ₃（其中镧系元素 [Ln] 的范围从铕到镥）。跨 4f 块的 Ln 中心的离子半径减小导致金属-配体组件的堆积越来越紧密。这种趋势在镥聚合物 Lu(tpbz) ₃中提供了光谱选择性光致变色响应，与早期的非光致变色类似物形成鲜明对比。实验和理论研究表明，色差可归因于相邻 tpbz 分子间电荷转移的逐渐增强——^由Ln 收缩或外部压力引起的部分。