Metformin modifed UiO-66-NH2 as a super basic nanocatalyst for the four component synthesis of dihydropyridines

This study presents the synthesis of a novel metal-organic framework (UiO-66-NH-nBut-Met) using PSM (post-synthetic modification) of UiO-66-NH₂ with metformin. The formation of UiO-66-NH-nBut-Met nanocatalyst was confirmed using analytical techniques, including BET, TEM, FT-IR, XRD, TGA, SEM, elemental mapping, and CHN analyses. Subsequently, the catalytic performance of the UiO-66-NH-nBut-Met was explored in the four-component synthesis of 1,4-dihydropyridines. The obtained results demonstrated remarkable productivity (excellent yields: 91-97%), within short reaction times (< 7 min) in solvent-free conditions. The enhancement of the catalytic activity of UiO-66-NH-nBut-Met compared to UiO-66-NH₂ can be attributed to metformin (N, N-dimethyl biguanidine) containing polydentate nitrogen donor ligands, as a super-basic agent. Furthermore, the catalyst demonstrated remarkable recyclability, maintaining high catalytic activity even after five consecutive runs.