Highly efficient CO2 reduction under visible-light on non-covalent Ru⋯Re assembled photocatalyst: Evidence on the electron transfer mechanism

Abstract

Herein, two complexes: Pyrene modified photosensitizer (RuPy) and catalyst (ReCOPy) were synthetized and combined to form a novel bimetallic supramolecular assembly RuPy⋯ReCOPy via a combination of π-π stacking and hydrogen bond interactions. This supramolecular assembly was further characterized by electrochemical and spectroscopic techniques in order to determine its redox and photochemical properties. This novel RuPy⋯ReCOPy supramolecular assembly was demonstrated to display a high level of performance for the photocatalytic conversion of CO2 conversion into CO with turn over frequency and CO quantum yield much higher (TOF: 18 h−1, ΦCO: 0.39) than the value obtained for the benchmark system Ru(bpy)3Cl2 (Ru) with Re(bpy)(CO)3Cl (ReCO) (5.3 h−1, ΦCO: 0.19). Time resolved spectroscopy and Density Functional Theory calculations revealed that an electron transfer mechanism is at the origin of the highly photocatalytic performance of RuPy⋯ReCOPy.