Fe3O4@SiO2-Propyl covalented dapsone-copper complex: Synthesis, characterization and application for the synthesis of new derivatives of azo-linked thiazolidinones and their solvatochromism evaluation

Background: Thiazolidinone-4-ones belong to an important heterocyclic compounds because of their broad spectrum of biological activities. Several methods for the synthesis of 4-thiazolidinones were reported in the literature. The main synthetic routes to synthesize 1,3-thiazolidin-4-ones is the three component reaction between amine, a carbonyl compound and a mercapto-acid. Objective: Dapsone-Cu supported on silica coated Fe3O4 (Fe3O4@SiO2-pr@dapsone-Cu) as a new heterogeneous nanoparticle catalyst was synthesized and the structure and morphology of this catalyst were characterized by Fourier transform infrared spectroscopy (FT-IR), Xray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), zeta potential, vibrating sample magnetometry (VSM) and thermal gravimetric analysis (TGA). The new synthesized catalyst was applied as an effective nanocatalyst for the synthesis of new derivatives of azo-linked thiazolidinones through one-pot multi-component reaction of various aromatic aldehydes, thioglycolic acid and 4-aminoazobenzene under solvent-free condition. Methods: A mixture of aldehyde, thioglycolic acid, 4-aminoazobenzene (1 mmol) and 0.05 g Fe3O4@SiO2@dapsone-Cu MNPs were stirred at room temperature under solvent-free condition. Results: We report a facile, green, new and efficient method for the synthesis of thiazolidine-4-ones through three component reaction of various aldehydes, thioglycolic acid and 4-aminoazobenzene in the presence of Fe3O4@SiO2-propyl@dapsone-Cu complex under solvent-free reaction. Conclusion: This new procedure has the notable advantages such as excellent yields, short reaction time, operational simplicity, easy work-up, eco-friendly and using a non-toxic catalyst. Also, the catalyst is easily recoverable in the presence of an enourmous magnet and reused for six consecutive reaction cycles without significant loss of activity.