Nickel Oxide Green Synthesized Nanoparticles from Plant Leaves and Its Antimicrobial, Antioxidant Activity and Catalytic Activity in Organic Transformation

Abstract

Benzimidazole derivatives are an important class of compounds known for their wide range of biological and pharmaceutical applications. In the present study, nickel oxide nanoparticles (NiO NPs) were synthesized and employed as an efficient catalyst for the preparation of benzimidazole derivatives. The synthesized NiO NPs were characterized using XRD, FE-SEM, EDX, UV–Vis and FT-IR techniques. The catalyst promoted the reaction of o phenylenediamine with various aromatic aldehydes under controlled conditions, providing the desired benzimidazole derivatives in a convenient manner. The synthesized products were monitored and assessed for purity by thin-layer chromatography (TLC) and melting-point, while the catalyst could be easily recovered for further use. NiO NPs was tested for its antimicrobial activity against S. aureus, B. subtilis, E. coli, K. pneumoniae, and A. niger using the disc diffusion method. No visible zone of inhibition was observed around the NiO NPs discs for any of the tested microorganisms, and the inhibition-zone diameter was recorded as 0 mm in each case. In comparison, the positive controls showed clear zones of inhibition, while DMSO did not show any inhibitory effect. These results indicate that NiO NPs did not exhibit detectable antimicrobial activity against the tested bacterial and fungal strains under the experimental conditions employed.   In addition, the NiO NPs demonstrated notable antioxidant activity (85.07%), approaching that of ascorbic acid. Overall, the findings highlight the potential of NiO NPs as a recyclable catalyst and their biological applications.