Coordination-driven discrete metallo-supramolecular assembly for rapid and selective photochemical CO2 reduction in aqueous solution

Abstract

A discrete metallo-supramolecular assembly composed of six iron(II) cations and twelve redox-active terpyridine fragments has been developed for the highly efficient visible-light-driven reduction of CO₂ to CO with a TON of 14 956 and 99.6% selectivity in the presence of an organic thermally activated delayed fluorescence (TADF) photosensitizer 4CzIPN in aqueous solution. The photochemical system proceeds rapidly with a turnover frequency (TOF) of 276 min⁻¹. It is demonstrated that the redox-active terpyridine fragments in the assembly are reduced by the photosensitizer which could further act as an electron reservoir for CO₂ reduction, resulting in the highly efficient reduction of CO₂. This work shows that discrete metallo-supramolecular assemblies could be used for robust photochemical CO₂ reduction.