Enhanced catalytic activity of bio-fabricated ZnO NPs prepared by ultrasound-assisted route for the synthesis of tetraketone and benzylidenemalonitrile in hydrotropic aqueous medium

Mushroom-like mesoporous and hexagonal ZnO nanoparticles were synthesized from plant extract and chemical method respectively, by co-precipitation method in aqueous medium. Different morphological forms of ZnO NPs were characterized by XRD, TGA, FESEM, EDX, FTIR, UV–Vis and BET. Neem (Azadirachta indica) leaf extract and ultrasound irradiation have a crucial role in the formation of different morphologies of ZnO NPs. ZnO NPs synthesized from plant extract and hydrotrope show a synergistic effect that leads to efficient synthesis of benzylidenemalonitrile and tetraketone derivatives at room temperature in water. Simple preparation of the catalyst, excellent yields, reusability of catalyst with consistent activity and ease of product isolation are the most significant advantages of this green protocol. Graphic abstract