Impact of the Catalytic Activity of SiO2 on the Synthesis of Aryl Benzimidazoles and its Mechanism: NMR Studies and Antimicrobial Effect

Abstract

Nano SiO₂ has been effectively utilized as a catalyst in the synthesis of new benzimidazoles. The resulting benzimidazoles have been characterized using ¹H and ¹³C NMR spectroscopy, confirming their structure and purity. This nano catalyst is notable for its ability to produce higher product yields, reduce reaction times, and operate in environmentally friendly reaction media. Additionally, it is versatile in accommodating a wide range of substrates, making it a highly efficient and sustainable option for benzimidazole synthesis. The single crystal X-ray analysis of 2-(naphthalen-1-yl)-1-phenyl-1H-benzo[d]imidazole (1) has been performed and discussed. Compound 1 exhibits substantially planar naphthalene ring system [maximum deviation = 0.0254 (6) A º] and benzimidazole unit [maximum deviation = 0.0258 (6) A º]. A dihedral angle of 61.955 (17) ˚ is made by them. The imidazole ring forms a dihedral angle of 61.73 (4) ˚ with the phenyl ring. The benzimidazoles2-(4-(difluoromethyl)phenyl)-1-phenyl-1H-benzo[d]imidazole (2), 1-(4-chlorobenzyl)-2-(4-chlorophenyl)-1H-benzo[d]imidazole (4) and 1-(4-bromobenzyl)-2-(4-bromophenyl)-1H-benzo[d]imidazole (5) are more active against S.aureus and S.typhi, for antibacterial studies. In comparison to the usual medication, benimidazoles 2 and 4 exhibit greater activity against A. flavus and C. albicans in antifungal tests.