Supramolecular assemblies of Cu(II) with a tetraphenylethene-imidazole ligand for tuning photocatalytic CO₂ reduction

Cu(II) supramolecular assemblies [Cu₂(tipe)₂(H₂O)₂](NO₃)₄·2.5H₂O (CuN4) and [Cu₂Cl₄(tipe)(CH₃CN)]·H₂O (CuN2Cl2) (tipe = 1,1,2,2-tetrakis(4-(imidazole-1-yl)phenyl)ethene) were synthesized and utilized for photocatalytic CO₂ reduction. CuN4 exhibits CO production of up to 891 μmol g_cat^-1 with a selectivity of 79.9%, while CuN2Cl2 gives low CO production of 206 μmol g_cat^-1 but with a high selectivity of >99.9% in 5 h. The experimental and DFT calculation results indicate that the coordination environment and non-covalent interactions within the assemblies have a great impact on the photocatalytic CO₂ reduction behavior. This work provides useful insights on Cu(II) assembly catalyzed CO₂ photoreduction.