A three-dimensional (3D) chiral mixed metal-organic framework [Cd4Cl(Ni-L)3(Ni-HL)(H2O)6(DMF)]·4DMF (CMOF 1) based on a new enantiopure dicarboxyl-functionalized Ni(saldpen) metalloligand Ni-H2L and a novel tetranuclear cadmium cluster [Cd4Cl(CO2)7(CO2H)] has been synthesized and characterized by elemental analyses, IR and UV-vis spectra, thermogravimetric analysis, nitrogen and carbon dioxide adsorption, powder and single-crystal X-ray diffractions. Each tetranuclear-cadmium cluster in 1 is linked by eight Ni-L ligands, and each Ni-L ligand is linked by two tetranuclear-cadmium clusters to generate a 3D framework with 1D open channels (∼1.1 × 0.9 nm(2)) along the b-axis. Based on its good stability, permanent porosity, Lewis acid sites and moderate uptake for CO2, 1 can be used as a self-supported heterogeneous catalyst for the synthesis of optically active propylene carbonate by asymmetric cycloaddition of CO2 with racemic propylene oxide under relatively mild conditions.