Synthesis, characterization, crystal structures and biological activities of eight-coordinate zirconium(IV) Schiff base complexes

Abstract

Two eight-coordinate Zr(IV) complexes of tetradentate Schiff base ligands, bis(3-ethoxysalicylidene)-4,5-dimethyl-1,2-phenylenediamine (H2L) and bis(3-ethoxysalicylidene)-2,2-dimethyl-1,3-propanediamine (H2L′), were prepared from Zr(acac)4 in refluxing methanol. The complexes were characterized by physico-chemical and spectroscopic methods. Also, their solid-state structures were determined by single-crystal X-ray diffraction. The crystal structure data showed a tetradentate mode of coordination for both Schiff bases, through N2O2 donor sets. The geometries of the complexes were dodecahedral and square antiprismatic for Zr(L)2 and Zr(L′)2, respectively. The complexes were screened in vitro against various microbes, revealing their antimicrobial activity.