Prolonging the Triplet State Lifetimes of Rhenium Complexes with Imidazole‐Pyridine Framework for Efficient CO<sub>2</sub> Photoreduction
Liqi Qiu, Kaihong Chen, Zhi‐Wen Yang, Fang‐Yu Ren, Liang‐Nian He
Abstract
Abstract The photocatalytic reduction of CO 2 into fuels offers the prospect for creating a new CO 2 economy. Harnessing visible light‐driven CO 2 ‐to‐CO reduction mediated by the long‐lived triplet excited state of rhenium(I) tricarbonyl complexes is a challenging approach. We here develop a series of new mononuclear rhenium(I) tricarbonyl complexes ( Re‐1 − Re‐4 ) based on the imidazole‐pyridine skeleton for photo‐driven CO 2 reduction. These catalysts are featured by combining pyridyl‐imidazole with the aromatic ring and different pendant organic groups onto the N1 position of 1,3‐imidazole unit, which display phosphorescence under Ar‐saturated solution even at ambient conditions. By contrast, {Re[9‐(pyren‐1‐yl)‐10‐(pyridin‐2‐yl)‐9H‐pyreno[4,5‐d]imidazole)](CO) 3 Cl} ( Re‐4 ) by introducing pyrene ring at the N1 position of pyrene‐fused imidazole unit exhibits superior catalytic performance with a higher turnover number for CO (TON CO =124) and >99.9 % selectivity, primarily ascribed to the strong visible light‐harvesting ability, long‐lived triplet lifetimes (164.2 μs) and large reductive quenching constant. Moreover, the rhenium(I) tricarbonyl complexes derived from π‐extended pyrene chromophore exhibit a long lifetime corresponding to its ligand‐localized triplet state ( 3 IL) evidenced from spectroscopic investigations and DFT calculations.