Bio-synthesized Fe(0)/Fe2O3 composite nanoparticles as a catalyst towards the preparation of dihydropyridine derivatives under solvent-free condition at room temperature

Abstract

A sustainable and innovative approach has been developed for synthesizing of Fe(0)/Fe₂O₃ composite nanoparticles (Fe(0)/Fe₂O₃NPs), utilizing the bark extract of the arjun tree (Terminalia arjuna) as a reducing and capping agent. This environmentally friendly Fe(0)/Fe₂O₃NPs was thoroughly characterized using various analytical techniques, including UV–Visible spectroscopy, FT-IR, PXRD, HR-TEM, SEM, and XPS. The nanoparticles were then evaluated as catalysts for facilitating the three-component Hantzsch reaction with acetylacetone, ammonium acetate, and substituted aldehydes, producing bioactive dihydropyridine derivatives. The catalyst exhibited high performance over approximately five cycles, with negligible loss in yield and catalytic efficiency. Additionally, a mechanistic pathway was proposed and elucidated through intermediate mass analysis, supported by Density Functional Theory (DFT) calculations.