Decorated Cu nanoparticles on ZPD as a novel and highly proficient nanocatalyst for synthesis of chromene and Biginelli reactions

ZPD is a type of metal–organic framework based on zinc ions. Its structure contains 2,5 pyridine dicarboxylic acid as ligand, and it was synthesized by the hydrothermal method. Its metal–organic framework has a high surface area, suitable micropores, and a very regular crystalline structure. In this study, Biginelli reaction and chromene synthesis were realized using Cu@ZPD as a catalyst. The prepared products were obtained with high-to-excellent yield (80–96%). The mentioned catalyst was identified by Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), field emission–scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) mapping, transmission electron microscopy (TEM), and inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses. By using ICP-OES, Cu loading was detected at nearly 3 wt%. The prepared catalyst can be reused 6 times without significantly losing its catalytic activity. Also, ¹HNMR, ¹³CNMR, and FT-IR spectroscopy was used to identify the products.