Eco-friendly design of TiO2 nanoparticles supported on Fe3O4 coated carbon-based biochar substrate for the synthesis of pyrano-[2, 3-c]-pyrazole derivatives

Abstract

The novel naturally based magnetic biochar/Fe3O4–TiO2 nanocatalyst was developed, characterised, and used to manufacture biologically active dihydropyrano-[2,3-c]-pyrazole [DHPP] derivatives. The one-pot four-component reaction between hydrazine hydrate, malononitrile, ethyl acetoacetate, and various aromatic aldehydes was carried out to synthesize the DHPP. The reaction was carried out in the presence of H2O:EtOH (1:1) as solvent at 60 °C with excellent yield (91–98%). This operationally simple approach has numerous benefits, including a green and clean reaction profile, easy workup and purification methods, a very fast reaction time, high atom efficiency, and low cost as well as magnetically separable nanocatalyst. XRD, FT-IR, TGA, HR-TEM, FE-SEM, EDAX, VSM were used to characterize the nanocatalyst and 13C NMR, 1H NMR, and mass spectrometry were investigate to studies the structure of products. Antimicrobial activity was tested on the resulting products (5a-5l). According to the data, the synthesized compounds were found to have substantial antimicrobial activities against the Gram-positive bacteria S. aureus and S. phyogens, Gram-negative bacteria E. coli and P. aeruginosa, and fungi Candida albicans.