Electron-Rich Macrocycle-Based Metal–Organic Frameworks for Efficient Photocatalytic CO<sub>2</sub> Reduction
Zhaohui Zhang, Qiang Xü, Weiran Li, Yunhai Zhu, Jun‐Sheng Qin, Yingkui Yang, Heng Rao, Long Chen
Abstract
Metal–organic frameworks (MOFs) are distinguished by their structural diversity, tunable electronic properties, and exceptional performance in various applications. Notably, the electron-donating ability of ligands significantly enhances the ligand-to-metal charge transfer (LMCT) processes within these frameworks, thereby promoting efficient charge migration. Herein, we developed two electron-rich macrocyclic ligands derived from phenothiazine- and phenoxazine-functionalized calix[3]arenes, alongside their corresponding cobalt-coordinated MOFs. Remarkably, the MOF designated as Co-C[3]PTZ-MOF─constructed using the more electron-donating calix[3]phenothiazine ligand (C[3]PTZ-COOH)─exhibited superior photoresponse and enhanced charge-transport characteristics. This optimized material achieved an exceptional CO 2 photoreduction initial efficiency of 17,800 μmol g –1 h –1 with 81% CO selectivity. The outstanding photocatalytic performance originates from the strong electron-donating nature of the calix[3]arene-based ligands, which facilitated efficient LMCT processes. This study provides valuable insights for designing high-performance photocatalysts through rational engineering of macrocyclic ligands.