Green and ecofriendly synthesis of indole-condensed benzimidazole chalcones in water and their antimicrobial evaluations

An ecofriendly synthesis of novel benzimidazole-substituted indole derivatives catalyzed by ZnO nanoparticles has been developed from simple condensation of acetyl benzimidazole and indole-3-carbaldehyde followed by Michael addition of indoles. This ZnO Nano particles (NP)-catalyzed reaction has been carried out using both step-wise and one-pot methods, and both these methods provide excellent yield of product and less reaction time in water. All the synthesized compounds were characterized by Infrared spectroscopy (IR), Proton Nuclear Magnetic Resonance spectroscopy (Proton NMR), Carbon-13 Proton Nuclear Magnetic Resonance spectroscopy (¹³C-NMR), and mass analysis and screened for their antibacterial activity against clinical strains that include Gram-positive and Gram-negative bacteria.