Design and catalytic performance of a novel two-dimensional copper metal-organic framework for green synthesis of tetrahydrobenzo[b]pyrans

This study explores development and using a novel two-dimensional metal-organic framework (2D MOF) as a heterogeneous catalyst in organic synthesis. The phosphonocarboxylic acid m-PO₃CH₂C₆H₄CO₂H (MPB) has been employed in synthesizing a metal carboxyarylphosphonate. The 2D MOF [Cu(H₂O)(m-PO₃CH₂C₆H₄CO₂H)]_n was synthesized in both crystal (Cu-MPB) and nanostructure (Cu-MPB') forms, characterized by X-ray single crystallography, SEM, TGA, FT-IR, PXRD, EDX, Mapping, and nitrogen adsorption-desorption, and employed for the efficient green synthesis of tetrahydrobenzo[b]pyrans. The crystal structure features alternating inorganic and organic layers. The organic layers have supramolecular dimers of carboxylic acid groups, two molecules bonded to two inorganic layers. Tetrahydrobenzo[b]pyran yield optimization conditions were determined with water/ethanol as solvents, using a catalyst loading of 0.06 g for 95% yields. The fabricated catalyst exhibited exceptional catalytic performance, wide applicability to different aldehyde substrates, and remarkable reusability, achieving high yields for as many as seven cycles post-reaction. In comparison to earlier catalytic systems, the compound Cu-MPB' showed enhanced efficiency and recyclability. These results underscore the promise of this innovative 2D MOF in promoting sustainable and effective organic synthesis.