Ag-doped nano magnetic gamma-Fe2O3@DA core-shell hollow spheres: an efficient and recoverable heterogeneous catalyst for A(3) and KA(2) coupling reactions and [3+2] cycloaddition

摘要

An effective protocol for the fabrication of Ag-doped nano magnetic gamma-Fe2O3@DA core-shell hollow spheres (h-Fe2O3@DA/Ag) by a simple hydrothermal method is demonstrated without any templates in the reaction system. The synthesized core-shell structure was successfully characterized in terms of the chemical composition, surface morphology, and magnetic properties using FT-IR, VSM, TGA, TEM, FE-SEM, EDS, and XRD patterns. The possible formation mechanism of this magnetic gamma-Fe2O3@DA/Ag hollow sphere structure is described based on the experimental results. In addition, as a physical property, the apparent shell density was determined using the specific surface area (BET) and shell thickness (BJH). The important, novel and unique catalyst with a hollow structural character and strong magnetic behavior exhibited a high catalytic activity in the A(3) and KA(2) coupling reactions and [3 + 2] cycloaddition for the synthesis of 1H-tetrazoles. Furthermore, the recovered catalyst of the reaction mixture was facilitated by a magnetic field and multiple recycling was carried out without any significant loss in the catalytic activity.