Magnesium ferrichromate nanoparticles: an efficient and recyclable catalyst in the synthesis of pyrano[2,3-c]pyrazole derivatives

Magnetically separable magnesium ferrichromate nanoparticles (MgFeCrO4 NPs) were synthesized by aqueous combustion synthesis (ACS) using glycine as the fuel. The as-synthesized powder was characterized using XRD, FTIR, SEM-EDX and SQUID techniques. Rietveld refinement studies inferred the single-phase cubic structure of the nanoferrite. Using Williamson-Hall plot, the lattice strain and the crystallite size were evaluated. Small value of lattice strain is indicative of absence of strain in the crystal lattice. The M-O bonding at the tetrahedral as well as the octahedral position was confirmed by FTIR Spectroscopy. Morphological investigations demonstrated sphere-like nanostructures with 50-100 nm particle size using SEM. Absence of any impurity in the EDX spectrum suggests formation of extremely pure MgFeCrO4 NPs. The room temperature magnetization was studied using vibrating sample magnetometer, and the nanoferrite exhibits superparamagnetic behaviour. The pyrano[2,3-c]pyrazole derivatives were synthesized in water/ethanol solvent system using MgFeCrO4 NPs heterogenous catalyst. A very short reaction time, maximum yield, easy method of separation of product and environmentally safer and milder reaction conditions are some of the advantages of our work along with the retention of catalytic activity up to five cycles.