Zirconium (IV) porphyrin graphene oxide: a new and efficient catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones

A covalently cross-linked graphene oxide (GO) as a catalyst was prepared by a cross-linking process using the nucleophilic reaction of zirconium (IV)-coordinated 5,10,15,20-tetrakis (aminophenyl)porphyrin (ZrPPh) with carboxyl groups of the edges of GO (GO-ZrPPh). The chemical structure of catalyst was characterized by different analyses such as FT-IR, SEM, TEM, EDS, ICP, TGA and UV. All analyses confirm the occurrence of successfully covalent immobilization of ZrPPh on the GO. Also, TEM and SEM images show that ZrPPh has been immobilized in the both of the edges and the basal plane of GO. The activity of the catalyst was studied for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones via Biginelli reaction. The cross-linked catalyst is able to catalyze the reaction in short reaction times and good to excellent yields.