Synthesis, Characterization, and Catalytic Activity of a β-Benzimidazole-Bridged Binuclear Oxo-Vanadyl(IV) OctaphenylPorphyrin in Biginelli Reactions.

A binuclear oxo-vanadyl(IV) porphyrin (V2OBP), in which two vanadium(IV) porphyrin macrocycles are connected via benzimidazole groups at the β-position, has been synthesized and characterized using a variety of techniques, including UV-vis spectroscopy, FT-IR, EPR, cyclic voltammetry (CV), density functional theory (DFT) calculations, and mass spectrometry. The catalytic properties of binuclear oxo-vanadyl(IV) porphyrin (V2OBP) were further examined in a one-pot multicomponent Biginelli reaction, resulting in the production of biologically active 3,4-dihydropyrimidin-2-(1H)-one (DHPM) derivatives and their corresponding thiones, all under solvent-free conditions. Its catalytic performance was compared to that of VOP. Various reaction parameters, such as catalyst amount, time, solvent, and temperature, were optimized to maximize the DHPM and thione yields. The β-functionalized V2OBP dimer showed significantly higher conversion rates (86%-97% yield) of DHPMs and thiones under optimized conditions, with high turnover numbers (TON, 7056-8528) and turnover frequencies (TOF, 3024-3411 h- 1), outperforming values reported in the literature. Additionally, the catalyst demonstrated excellent recyclability, remaining effective for up to seven cycles.