Fabrication and characterization of a novel easy recoverable and reusable Oligoazomethine-Pd(II) catalyst for Suzuki cross-coupling reactions

Abstract

This study describes (i) the synthesis of a novel highly active, recyclable, easily recoverable and thermally stable oligoazomethine-Pd(II) catalyst (O(PMPA)-Pd) and (ii) its application in the synthesis of various biaryl compounds via Suzuki cross-coupling reactions. Firstly, a novel conjugated oligoazomethine, Oligo(N-(pyridin-2-ylmethylene)pyridin-2-amine) (O(PMPA)), which was used as a support material for the catalyst, was synthesized by oxidative polymerization of N-(pyridin-2-ylmethylene)pyridin-2-amine) (PMPA) using NaOCl oxidant. UV–Vis, FT-IR, 1H NMR, XRD, TG/DTG, and SEM/EDAX analyses were utilized to characterize the synthesized compounds. Then, palladium catalyst (O(PMPA)-Pd) was fabricated and characterized by various techniques. The catalytic efficiency of O(PMPA)-Pd was investigated for the synthesis of various biaryls via Suzuki cross-coupling reactions and structures of the obtained biaryl compounds were illuminated by GC-MS analysis. The catalytic tests were carried out using solventless, rapid, and simple microwave irradiation technique. The tests revealed that O(PMPA)-Pd was successfully utilized in the synthesis of various biaryls with outstanding catalytic effect (99% conversion yield) for 6 min. Higher turnover number (TON) and turnover frequency (TOF) were recorded for Suzuki coupling reactions. Moreover, reproducibility tests indicated that O(PMPA)-Pd catalyst can be reusable for seven consecutive cycles without a significant loss in its catalytic activity (down to 71%) due to its easily recoverability.