Guanidine functionalized core–shell structured magnetic cobalt-ferrite: an efficient nanocatalyst for sonochemical synthesis of spirooxindoles in water

Core/shell nanoparticles have a wide range of applications in the science of chemistry and biomedicine. The core–shell material can be different and modified by changing the ingredients or the ratio of core to the shell. In this research, a CoFe(2)O(4)@SiO(2)-guanidine nanocomposite was prepared and identified as an efficient catalyst for the one-pot synthesis of spirooxindole derivatives in water under ultrasonic irradiation conditions. The advantages of this method are in its simplicity, saving costs and energy, high yields, short reaction times, environmental friendliness, reusability and easy recovery of the catalyst using an external magnet. The catalyst was characterized by XRD, SEM, TEM, EDX, FT-IR, TGA and VSM techniques.