A mesoporous two-dimensional cobalt-phosphonocarboxylate metal organic framework (Co-MOF) as an efficient and recyclable catalyst for solvent-free multicomponent reactions

A novel two-dimensional cobalt(II)-based metal-organic framework (Co-MOF) was synthesized using combined solvothermal and sonochemical methods. The structure of the compound, [Co(HL)(bipy)(H₂O)]_n (H₃L = m-(phosphonomethyl)benzoic acid), was determined by single-crystal X-ray diffraction and confirmed to form a two-dimensional coordination polymer. The nanostructured form (Co-MOF') was obtained via ultrasonic irradiation and comprehensively characterized by FT-IR, PXRD, SEM, EDX, TGA, and BET techniques. The Co-MOF' exhibited excellent catalytic performance in the one-pot synthesis of 3,4-dihydropyrimidinones (DHPMs) via the Biginelli reaction under green, solvent-free conditions. The catalyst offered high product yields (up to 97%) within short reaction times (30 min), remarkable recyclability over seven cycles without significant loss of activity, and superior performance compared to previously reported MOF-based catalysts. This study highlights the potential of Co-MOF' as an efficient, reusable, and environmentally benign heterogeneous catalyst for multicomponent organic transformations.