Abstract:Dendrimer chemistry is one of the most fascinating and rapidly expanding areas of modern chemistry. However, solution-phase synthesis of dendrimers is often challenging requiring long reaction time and tedious purification process, which dramatically limits the applications of dendrimers. In this work, polyamidoamine dendrimers were grafted to silica surface through solid phase synthesis methodology, the peripheral amino groups on these dendrimers were modified by 4-hydroxybenzaldehyde, 2,4-dihydroxybenzaldehyde and salicylaldehyde to obtain ligands, and then reacted with SnCl2•2H2O to obtained silica supported dendritic Sn complexes. The ligands and complexes were well characterized by elemental analysis, IR, ICP and XPS. The catalytic performance of the silica supported dendritic Sn complexes was investigated by Baeyer–Villiger oxidation of cyclic and acyclic ketones to their corresponding lactones or esters with 30 % hydrogen peroxide. It was shown that all the complexes exhibit promising catalytic activities for the oxidation. Under the mild condition, all the oxidations give high conversion and selectivity of lactones or esters. The effects of the supporter and ligand on the catalytic activity were also studied, it was discovered that both supporter and the ligand played a vital role in metal loadings and the catalytic activity of the complexes. Moreover, the catalysts could be obtained in a simple and efficient manner and can be recycled and reused.
