Preparation of Fe3O4@Carrageenan-Metformin nanoparticles as a new bio-inspired magnetic nanocatalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles

Abstract

k-Carrageenan (Carr) is a significant constituent of red seaweeds with benign nature and easy modification due to available sulfate and hydroxyl functionalities. The current work illustrates the preparation and catalytic application of a magnetic nanocatalyst based on k-carrageenan. The Fe3O4@Carr-Met was prepared by coating magnetic Fe3O4 nanoparticles with Carr and metformin (Met). The successful synthesis of the catalyst was verified by different techniques. These nanoparticles showed excellent activity for the synthesis of dihydropyrano[2, 3-c] pyrazoles. The synergistic effect of sulfonic acid and amino groups may account for the catalytic activity of these nanoparticles. Moreover, Fe3O4 core provides effective magnetic separation. The ease of catalyst preparation, use of a benign solvent system, enhanced activity, and reusability are some of the prominent advantages of the present catalyst. The heterogeneity of Fe3O4@Carr-Met nanoparticles was also supported by a hot filtration test under optimal reaction conditions that confirmed the integrity of these nanoparticles.