Metal complexes containing organic photoswitches are capable of modulating the steric and electronic environment around the metal center through photoisomerization, enabling their use in photoswitchable catalysis. Herein, we design a new class of photoswitchable tripodal tetradentate ligands L1–L3 that can readily form air-stable Cu(I) complexes (C1-PF₆, C1-BF₄, C2, C3). The design strategy integrates flexible spacers and phenylazopyrazole units in the same ligand framework that ensures efficient photoisomerization and sustained stability of the photoswitched state. The complexes were screened for catalyzing the CuAAC reaction between alkynes and azides and C1-PF₆ was identified as a catalyst capable of exerting temporal control over the reaction through photoisomerization. Based on the optimized conditions and the substrate scope, the ZZZ (photoswitched) form of complex C1-PF₆ exhibits substantially improved catalytic performance compared to its EEE (native) form. In this article, we describe detailed experimental and computational investigations aimed at understanding how photoisomerization regulates the catalytic activity of Cu(I) complexes of arylazopyrazole-based tripodal tetradentate ligands.

中文翻译：

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苯并吡唑配体的空气稳定 Cu(I) 配合物对 CuAAC 反应催化的光控制

含有有机光开关的金属配合物能够通过光异构化调节金属中心周围的空间和电子环境，从而使其能够用于光开关催化。在此，我们设计了一类新型光开关三足四齿配体L1-L3，它可以很容易地形成空气稳定的Cu( I )配合物（C1-PF ₆、C1-BF ₄、C2、C3）。该设计策略将灵活的间隔基和苯基偶氮吡唑单元集成在同一配体框架中，确保有效的光异构化和光开关状态的持续稳定性。筛选了用于催化炔烃和叠氮化物之间的 CuAAC 反应的配合物，并且C1-PF ₆被鉴定为能够通过光异构化对反应进行时间控制的催化剂。基于优化的条件和底物范围，复合物C1-PF ₆的ZZZ（光开关）形式与其EEE（天然）形式相比表现出显着改善的催化性能。在本文中，我们描述了详细的实验和计算研究，旨在了解光异构化如何调节芳基偶氮吡唑基三足四齿配体的Cu( I ) 配合物的催化活性。