Synthesis of structurally enhanced magnetite cored poly(propyleneimine) dendrimer nanohybrid material and evaluation of its functionality in sustainable catalysis of condensation reactions

Abstract

The conventional method of dendrimer synthesis especially poly(propyleneimine) dendrimer (PPI) involves complicated reaction workup and tedious separation strategies. Since it has greater number of nitrogen atom in their structure, its applications are innumerable in different fields. But the PPI dendrimer is used once, it cannot be recycled for subsequent utility. In order to overcome these issues, for the first time divergent synthesis of poly(propyleneimine) dendrimer G3 on silica coated magnetite has been achieved with structurally enhanced PPI dendrimer on core-shell type magnetic silica nanostructure. This nanohybrid material was characterized by using HRTEM, FTIR, XRD, TGA, XPS and VSM studies. Further, nitrogen concentration of PPI dendrimer was quantified by conductometric titration and Prussian blue complex methods. The probing of catalytic efficacy of structurally enhanced magnetite cored poly(propyleneimine) dendrimer G3 as magnetically recyclable heterogeneous organic base catalyst was employed for representative reactions such as Knoevenagel condensation, Knoevenagel-Michael cyclocondensation and Henry reaction at ambient conditions. The catalyst was reused for minimum of eight cycles without significant loss of its catalytic activity.