Chelation and calcination promoted preparation of perovskite-structured BiFeO₃ nanoparticles: a novel magnetic catalyst for the synthesis of dihydro-2-oxypyrroles

Perovskite-structured Bismuth ferrite (BiFeO₃) nanoparticles as a novel heterogeneous catalyst were designed by an auto combustion route using a different chelating agent and calcination temperature. The effect of different chelating agents like disaccharide (sucrose), α-hydroxy acid (citric acid, tartaric acid), amide (urea) and calcination (150–750 °C) temperature on structure and the catalytic performance of BiFeO₃ have been analyzed. The catalytic performance of BiFeO₃ has been increased by modifying its synthesis with the addition of suitable organic compound and calcination. BiFeO₃ synthesized without the use of chelating agent gave very poor yield, i.e., 36.89%. The augmented effect of the chelating agent on the catalytic performance of BiFeO₃ was obtained in the order of blank < tartaric acid < sucrose < urea < citric acid, whereas the enhancing effect of calcination temperature in the order 150 °C < 450 °C < 550 °C < 650 °C > 750 °C. The calcination temperature results in augmentation in yield of approximately 30% with model reaction on increasing temperature from 150 to 650 °C. Different calcination temperatures (150–750 °C) have been employed to obtain single phase BiFeO₃ nanoparticles. All synthesized BiFeO₃ nanoparticles were fully characterized by FT-IR; XRD; VSM; BET; TGA; XPS and Raman spectroscopy. For the very first time ever we have used them as a recyclable magnetic nanocatalyst in the formation of highly substituted dihydro-2-oxypyrrole by using one-pot, three-component reaction of DMAD, aniline and formaldehyde in methanol at room temperature with 63–88% yield. All the synthesized oxypyrroles have been characterized by various spectroscopic techniques.