Functionalization of magnetic TMU-17-NH2 MOF with organic ligands for stabilization of copper species as an efficient heterogeneous catalyst for the Biginelli reaction and the synthesis of pyran derivatives

A novel magnetic nanocatalyst, Cu@M-TMU-17-NH₂-Gly-Met, was successfully prepared through a multi-step post-synthetic modification strategy. Initially, the TMU-17-NH₂ framework was functionalized with glyoxal, followed by immobilization of metformin to introduce nitrogen-rich coordination sites for copper incorporation. The composition and structural integrity of the resulting nanocomposite were confirmed by FT-IR, TGA, XRD, FE-SEM, EDX, BET, ICP-MS, and VSM analyses. The catalytic performance of the prepared nanocomposite was evaluated in the synthesis of dihydropyrimidinone derivatives via the Biginelli reaction, as well as in the synthesis of 2-amino-4H-pyran derivatives through a multicomponent reaction strategy. The results demonstrated that the catalyst efficiently promoted both reactions under mild conditions, affording high yields (73-92% and 79-98%, respectively) within short reaction times. The catalyst exhibited excellent reusability and stability over several cycles with a gradual and acceptable decrease in yield (from 89% to 74% for the Biginelli reaction, and from 96% to 84% for the pyran synthesis) over seven consecutive cycles for model reaction The combination of high efficiency, ease of separation, and environmental compatibility highlights the potential of this nanocatalyst for practical applications in organic synthesis.