Synthesis, chemical structures elucidation and biological studies on the effect of some vital metal ions on vitamin A: Ca(II), Mg(II), Zn(II), Fe(III) and VO(II) complexes

Complexes of vitamin A as a pharmaceutical ligand with Ca(II), Mg(II), Zn(II), Fe(III) and VO(II), were synthesized and characterized by microanalysis, conductance, infrared and thermogravimetric (TG/DTG and DTA) measurements. The ligand can be coordinated as a monodentate ligand via the oxygen atom of the deprotonated hydroxyl group. Thermal degradation curves revealed that the uncoordinated water molecules are removed in a first stage while the decomposition of ligand besides coordinated water molecules took place in the second and subsequent steps. Vitamin A ligand, as well as its complexes were checked against some kinds of bacteria and fungi and produced a significant effect. The effect of kinetic thermodynamic parameters (E*, Delta H*, Delta S* and Delta G*) of the synthesized complexes upon the TG curves was calculated using Coats-Redfern and Horowitz-Metzger equations.