Heavy-Atom-Free Photosensitizers for High-Yield CO_(2)-to-CO Conversion

Heavy-Atom-Free photosensitizers(HAFPs)with abundant resources showgreat potential to construct noble metal-free and high-yield CO_(2)photoreduction systems,but have rarely been achieved due to their poor intersystem crossing(ISC)efficiency.Herein,a library of HAFPs(B-1-B-8)were rationally designed by coupling various anthracene donors and boron dipyrromethene acceptors to break the short-lived excited state limitation of pure organic chromophores.The special orthogonal geometry between electron donor and acceptor contributes totriggering spin-orbit charge transfer-induced ISCs to achieve long-lived triplet and reduced states,which can facilitate consecutive intermolecular electron transfers to further boost CO_(2)reduction.Impressively,the reduced HAFP B-8 can efficiently sensitize iron catalysts to construct noble metal-free photocatalytic systems for highly efficient and selective CO_(2)-to-CO conversion with 1311μmol yield.Experimental and theoretical investigations clearly illustrate the structure-activity relationship,highlighting a new avenue to develop highly efficient organic photosensitizers to boost CO_(2)photoreduction.