Green synthesis of ZnO nanoparticles using Bacillus subtilis and their catalytic performance in the one-pot synthesis of steroidal thiophenes

Abstract

In the present work, we describe a low-cost, unreported and simple procedure for biosynthesis of zinc oxide nanoparticles (ZnO NPs) using Bacillus subtilis as eco-friendly reducing and capping agent. The synthesized ZnO NPs were characterized by UV-Vis spectroscopy, FTIR, XRD, SEM, TEM, PL and TGA techniques. The biosynthesis methods were carried out for its intrinsic advantages, as it is simple, cost-effective, environment-friendly and can be easily scaled up for large scale synthesis. The prepared nano-particles were used as catalyst for the fast and efficient synthesis of steroidal thiophenes. The one pot three-component mixture of steroidal ketones ( 1-3 ), malononitrile/ ethyl cyanoacetate and elemental sulfur were converted into the corresponding steroidal thiophenes ( 4-9 ) in moderate to high yields with excellent selectivity.