Post-Cobaltization of Crystalline Trinuclear Copper Cluster-Based Metal–Organic Frameworks for Photocatalytic CO2 Reduction

The emergence of visible-light photocatalytic frameworks provides a sustainable technology for dealing with CO₂ greenhouse gas. Herein, the solvothermal reaction of copper(I) cyclic trinuclear complex (Cu-CTC) with 2,5-dihydroxyterephthalaldehyde (2,5-DHTA) or 3,3’-dihydroxy-^{[1,1’-biphenyl]}-4,4’-dicarbaldehyde (3,3’-DHBDA) led to two crystalline hcb topological copper(I)-organic frameworks USTB-48 and USTB-49, respectively. The post-cobaltization of 2-(benzylideneamino)phenol units in these two frameworks, providing the active catalytic centers in obtained USTB-48(Co) and USTB-49(Co) for photocatalysis of CO₂ reduction. The parent frameworks and post-modificated species have been thoroughly characterized through powder X-ray diffraction analysis and various spectroscopies. The combination of trinuclear copper units and single cobalt centers is able to achieve the CO generation rate up to ca. 8451 μmol⋅g⁻¹⋅h⁻¹ and 96 % selectivity for USTB-48(Co).