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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.

The synthesis of new derivatives of pyrimido [5,4-e][1,2,4]triazolo[3,4-b][1,3,4]thiadiazine is described. These derivatives have a wide range of medicinal applications. Their inhibitory activity against the enzyme 15-lipoxygenase was also investigated.

In this report, the synthesis of amides from aldoximes (Beckmann rearrangement) has been reported using cobalt(II) porphyrin covalently linked to graphene oxide as a nano heterogeneous catalyst. The prepared catalyst was characterized by applying of FT-IR, TGA, TEM, SEM, EDX, ICP and UV-Vis techniques. All analyses confirm the successful insertion of cobalt into the porphyrin ring and covalently linkage of Co-Porphyrin on the graphene oxide. Moreover, the prepared catalyst was applied in order to investigate its performance in the Beckmann rearrangement. This heterogeneous catalyst exhibited excellent catalytic efficiency with a high yield of products. Also, the suggested catalyst could be recycled for five runs without a dramatic decrease in its catalytic activity or metal leaching. Results and discussion Preparation and characterization of the GO-CoPPhThe catalyst was prepared according to Scheme 1. The porphyrin (PPh) macromolcule was synthesized according to [a] Z.

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