3A Cyanide‐Bridged Ru–Fe Supramolecular Photocatalyst for Efficient CO ₂ Reduction

Supramolecular control over electron transfer is a key challenge in artificial photosynthesis. Here, we report a cyano‐bridged Ru–Fe supramolecular photocatalyst that self‐assembles in solution through spontaneous coordination. This preorganized architecture enables ultrafast excited‐state electron transfer from Ru to Fe via a static oxidative quenching pathway, as revealed by pump‐probe transient absorption spectroscopy showing sub‐picosecond formation of the reduced Fe species, in contrast to the reductive quenching mechanisms commonly observed in related systems. Remarkably, reversible coordination of CO ₂ to the supramolecular adduct can be directly monitored by electronic absorption spectroscopy, providing rare experimental access to substrate binding within a molecular photocatalytic system. Under visible‐light irradiation, the system achieves highly efficient CO ₂ ‐to‐CO conversion (AQY 18%), with CO selectivity exceeding 95%, suggesting an intrinsic preference of the supramolecular photocatalyst for CO formation. These findings establish cyano bridging as a powerful design principle for constructing supramolecular photocatalysts, enabling both mechanistic transparency and enhanced performance. More broadly, this strategy defines a modular platform that can be extended to a wide range of catalysts and photocatalytic transformations.