Directional Electron Transfer in Porphyrin-Based Heteroleptic Metallacages for Enhanced Visible Light-Driven Photocatalysis

The rational design of supramolecular architectures capable of mediating directional photoinduced electron transfer (PET) remains a central challenge in confined photocatalysis. Herein, we report two porphyrin-based heteroleptic metallacages, constructed via multicomponent coordination-driven self-assembly, for the visible light-driven oxidative coupling of tetraorganoborates. Both metallacages feature well-defined, positively charged cavities that enable selective substrate encapsulation and efficient catalytic turnover. In particular, one metallacage incorporates electron-rich triphenylamine units that engage in directional interligand PET with the porphyrin moieties, as supported by femtosecond transient absorption spectroscopy and density functional theory calculations. This intramolecular PET promotes long-lived charge separation and enhances superoxide anion generation, resulting in markedly improved photocatalytic activity compared to control systems lacking donor–acceptor motifs. This study demonstrates a modular strategy for integrating electron donor and acceptor functionalities within a single supramolecular scaffold and highlights the potential of PET-enhanced cage-based photocatalysis, providing a versatile platform for sustainable light-driven chemical transformations.