Graphene oxide-supported nickel(ii) complex as a reusable nano catalyst for the synthesis of bis(indolyl)methanes

A novel catalytic system of a nickel(ii) complex of (E)-N '-((2-amino-5-chlorophenyl)(phenyl)methylene)-2-hydroxy-benzohydrazide (APH) supported on graphene oxide (GO) has been prepared. Detailed characterization of the synthesized catalyst has been carried out using NMR, FTIR, HRMS, PXRD, Raman, SEM, TEM, EDX and XPS. Its catalytic efficiency has been explored for the synthesis of various bis(indolyl)methane derivatives. The optimized reaction conditions prove that the catalyst is highly efficient, performs under mild conditions and is required in a very small amount (2 wt%). A diversified library of bis(indolyl)methane derivatives containing various electron donating and withdrawing substituents has been developed in high to excellent yields. The catalyst is equally efficient towards heterocyclic aldehydes. Moreover, owing to the strong covalent interaction between the APH-Ni(ii) complex and GO, the catalyst shows outstanding recyclability for six subsequent cycles without any significant loss in activity.

Automated summary

A novel catalytic system consisting of a nickel(ii) complex of (E)-N'-((2-amino-5-chlorophenyl)(phenyl)methylene)-2-hydroxy-benzohydrazide (APH) supported on graphene oxide (GO) has been synthesized. The synthesized catalyst has been characterized using various techniques, including NMR, FTIR, HRMS, PXRD, Raman, SEM, TEM, EDX, and XPS. The catalytic efficiency of the system has been demonstrated in the synthesis of diverse bis(indolyl)methane derivatives, with high to excellent yields obtained under optimized reaction conditions. The catalyst also exhibits outstanding recyclability for six subsequent cycles without significant loss in activity, thanks to the strong covalent interaction between the APH-Ni(ii) complex and GO.