Copper-Cluster-Based MOF as a Heterogeneous Catalyst for CO2 Chemical Fixation and Azide–Alkyne Cycloaddition

Developing metal–organic frameworks (MOFs) as heterogeneous catalysts attracts much attention because their high internal surface areas and open metal sites may facilely improve the catalytic activity. In this study, a copper-cluster-based MOF, denoted as {2Cu(L)(A)·3H2O}n (1, L = bis(4-(4H-1,2,4-triazol-4-yl)phenyl)methane, A = deprotonated 1,4-naphthalenedicarboxylic acid), has been constructed. 1 has a (3,10)-connected three-dimensional (3D) porous network structure with a new topology of {48·624·83}{43}2. Structural analysis reveals that copper ions adopt two coordination modes in the secondary building unit, forming polyhedral copper clusters by Cu–O–Cu bridge bonds. Detailed studies show that 1 can be employed as an efficient heterogeneous catalyst for converting CO2 to cyclic carbonates in 81.0–99.0% yield under 1 atm CO2 and solvent-free conditions. Furthermore, 1 retains good catalytic efficiency after 10 cycles (83.0% conversion). Moreover, 1 exhibits good catalytic performance toward azide–alkyne cycloaddition (AAC) reactions in an aqueous solution with the addition of sodium ascorbate, yielding a series of 1,4-disubstituted 1,2,3-triazoles in high yields (over 99.0%) and presenting recyclable ability.