Metal Variance in Multivariate Metal-Organic Frameworks for Boosting Catalytic Conversion of CO₂

Developing efficient, low-cost, MOF catalysts for CO₂ conversion at low CO₂ concentrations under mild conditions is particularly interesting but remains highly challenging. Herein, we prepared an isostructural series of two-dimensional (2D) multivariate metal-organic frameworks (MTV-MOFs) containing copper- and/or silver-based cyclic trinuclear complexes (Cu-CTC and Ag-CTC). These MTV-MOFs can be used as efficient and reusable heterogeneous catalysts for the cyclization of propargylamine with CO₂. The catalytic performance of these MTV-MOFs can be engineered by fine-tuning the Ag/Cu ratio in the framework. Interestingly, the induction of 10% Ag remarkably improved the catalytic efficiency with a turnover frequency (TOF) of 243 h^-1, which is 20-fold higher than that of 100% Cu-based MOF (i.e., TOF = 10.8 h^-1). More impressively, such a bimetallic MOF still exhibited high catalytic activity even for simulated flue gas with 10% CO₂ concentration. Furthermore, the reaction mechanism has been examined through the employment of NMR monitoring experiments and DFT calculations.