Complexation Features of Quinoxalyl-Hydrazone Ligand Towards Oxo-Zirconium (IV) and Oxo-Vanadium (IV) Ions for Biological Studies and Catalytic Oxidation of Alcohols

Abstract

Due to the facile design and strong coordinating features of hydrazones, a condensation reaction of 3,4-dihydroquinoxaline-2-carbohydrazide with 2-hydroxybenzaldehyde yielding (HLqh) was implemented aiming to examine its coordination action towards two high valent oxide metals (ZrO²⁺ and VO²⁺ ions) to give two complexes (ZrOLqh·2H₂O and VOLqh, respectively). Their molecular structures were confirmed using appropriate spectroscopic approaches, as well as the elemental composition studies, magnetic characteristics, thermogravimetric investigation, and conductivity behaviors. For the biological approach, HLqh, ZrOLqh·2H₂O, and VOLqh displayed an inhibitive behavior on the proliferated progression of three prevalent fungal and bacterial series and on three considered cancer cell lines, which were studied concerning the influence of O=M^IV ion in ZrOLqh·2H2O and VOLqh in comparison to their unbonded ligand (HLqh) on their inhibitive action. The microbial and cancer examination was elucidated within the inhibiting zone areas in mm and the half-concentration of effectiveness in mM (IC₅₀). Investigating the critical impact of O=M^IV ion in ZrOLqh·2H2O and VOLqh on their interacting binding to ct-DNA, as confirmed by changes in viscosity/spectrophotometric characteristics, was established. The interacting capability of ct-DNA was confirmed by referring to the Gibbs free energy, binding constant, and chromism types. The biological results were supported by docking studies. For the assessment of the catalytic potential, both ZrOLqh·2H2O and VOLqh were addressed (homogeneously) in the redox transformation of BZ (benzyl alcohol) in the presence of an oxidant (hydrogen peroxide) at 358 K. Both catalysts demonstrated performed catalytic redox action towards the formation of benzaldehyde. The yield percentage of benzaldehyde (the selective product, BZO) catalyzed by ZrOLqh·2H2O and VOLqh was 80% after 5 h and 86% after 3 h, respectively. The verified reactivity for each catalyst was attributed to the effect of metal ion nature, which was supported by a proper mechanism.