Fe3O4@TiO2@V2O5 as an efficient magnetic nanoparticle for synthesis of di-indolyl oxindole derivatives

In this work, Fe3O4@TiO2@V2O5 is synthesized via functionalization of Fe3O4 with TiO2 and then modifying with V2O5. The characterization of the synthesized nano-catalyst is performed using several methods including XRD, TEM, SEM, EDS, TGA, and VSM. This nano-catalyst impressively catalyzes the synthesis of 3,3-di-indolyl oxindoles (with an 85-98% yield in 10-80 minutes). Furthermore, the introduced catalyst can be reused in at least five successive reactions with no significant catalytic activity loss. The effects of some influencing parameters on the catalytic efficacy of Fe3O4@TiO2@V2O5 are also assessed. The appropriate product is attained for a wide range of isatins and indoles. Using an inexpensive and reusable catalyst and using the H2O solvent puts this methodology in the green chemistry domain.