Practice of function-oriented synthesis: high-efficiency CO2 conversion and Knoevenagel condensation by two novel In3-based MOFs with high-density active sites under mild conditions

Abstract

Metal–organic frameworks (MOFs) have shown great potential in catalytic fields, and are especially useful for the chemical fixation of hazardous atmospheric gases to produce value-added products. However, the current difficulties in in situ function-oriented synthesis (FOS) of MOFs result in low efficiencies, as well as huge time consumption and energy cost under high temperature and pressure. Here, based on a FOS strategy targeted at high-efficiency CO₂ conversion and Knoevenagel condensation, both of which bear on synergistically catalytic processes, we successfully introduced high densities of multiple active sites, including Lewis acid sites, hydrogen-bonding sites, and Brønsted basic sites, into two novel In₃-cluster-based MOFs, JLU-MOF116 and JLU-MOF117. Both compounds feature hwx topology with rhombic open channels, of which these catalytic sites are well distributed in the inner surfaces. Premised on high CO₂ uptake capacities under mild conditions, both compounds achieved outstanding catalytic performances in CO₂ conversion when compared to a vast majority of MOF materials. Yields, turnover numbers (TONs), and turnover frequencies (TOFs) were high, and even CO₂ conversions under a simulated dry flue gas were unexpectedly efficient, as well as Knoevenagel condensation that was performed with high efficiencies. This work provides insight into the structure–function relationship of MOF materials through FOS, which is beneficial for the catalytic field.