Bimetallic Co-Mg MOF: an efficient heterogeneous catalyst for room-temperature Knoevenagel condensation

Abstract

Developing efficient and environmentally sustainable pathways is a fascinating focus within the field of green chemistry. In this study, a bimetallic Co-Mg metal–organic framework (Co-Mg MOF) was synthesized through solvothermal conditions using Co²⁺ and Mg²⁺ ions along with NH₂BDC (2-amino terephthalic acid) as a rigid ligand. Comprehensive characterization was performed using powder X-ray diffraction (PXRD), nitrogen adsorption–desorption isotherm (BET method), thermogravimetric analysis (TGA), elemental mapping, and inductively coupled plasma (ICP) techniques. The as-synthesized catalyst exhibited great catalytic performance in the Knoevenagel condensation of malononitrile and benzaldehyde, possibly due to its abundance of basic and acidic sites. Besides this, the bimetallic MOF catalyst demonstrated superior catalytic activity compared to its single-metal counterparts (Co-MOF and Mg MOF), this enhanced performance is likely due to the synergic effect of incorporating Mg²⁺ into the Co-MOF framework. With the optimization of reaction conditions, a significant yield of the final products (involving various aldehydes and malononitrile) was achieved at room temperature within a short duration. The as-synthesized catalyst represented good stability and recyclability through the reaction process even after the 4th run. The results showed that the as-synthesized bimetal Co-Mg MOF exhibited superior potential as a catalyst in the Knoevenagel condensation reaction, in the presence of green solvent (ethanol).

Graphical abstract