The surface of the Fe3O4 has been functionalized with 3-chloropropyltrimethoxysilane, which undergoes an SN2 substitution reaction of the chloro group with the nitrogen of ligand (creatinine), offering the Fe3O4@Creatinine. A new recyclable Ag attached Fe3O4 MNPs (Fe3O4 @Creatinine@Ag) has been produced through a post-synthetic method. FT-IR (Fourier Transforms Infrared), TGA (Thermogravimetric Analysis), XRD (X-ray Diffraction), EDS (Energy-Dispersive X-ray Spectroscopy) and VSM (Vibrating Sample Magnetometer) confirm the effectiveness of the performed chemical modification to synthesize the catalyst. This catalyst displays high catalytic performance in the synthesis of 5-substituted 1H-tetrazoles in water and the selective oxidation of sulfides. In the presence of nano- Fe3O4 @Creatinine@Ag as an efficient heterogeneous nano-catalyst, the corresponding 5-substituted 1Htetrazoles and sulfoxide were afforded under the mild condition in good to excellent yields. A wide variety of sulfides furnished the corresponding sulfoxide with classical and ultrasonic methods. The results show that ultrasonic is an appropriate method for the oxidation of sulfides to the related sulfoxide. The catalyst can be separated by simple recovery and reused for several periods without any remarkable decrease in the catalysis activity and selectivity. In the synthesis of this catalyst, the environmentally friendly ligand is used to stabilize the eco-friendly active site on the desired support. What distinguishes this catalyst and this research is its high eco-friendliness in several respects. The structure of this catalyst and also, the reaction are based on green chemistry. At a relatively low temperature compared to the reported work, tetrazole derivatives are prepared in water solvent with good efficiency.
