A Crystalline Copper(II) Coordination Polymer for the Efficient Visible‐Light‐Driven Generation of Hydrogen

A crystalline coordination polymer (CP) photocatalyst (Cu‐RSH) which combines redox‐active copper centers with photoactive rhodamine‐derived ligands remains stable in acid and basic solutions from pH 2 to 14, and efficiently catalyzes dihydrogen evolution at a maximum rate of 7.88 mmol g^?1 h^?1 in the absence of a mediator and a co‐catalyst. Cyclic voltammetry, control experiments, and DFT calculations established that copper nodes with open coordination sites and favorable redox potentials, aided by spatially ordered stacking of rhodamine‐based linkers, account for the high catalytic performance of Cu‐RSH. Emission quenching, time‐resolved fluorescence decay, and transient photocurrent experiments disclosed the charge separation and transfer process in the catalytic system. The present study demonstrates the potential of crystalline copper CPs for the practical utilization of light.