Chemical speciation of 2,3-dihydroxybenzoic acid complexes with some biologically essential metal ions in 1, 2-propanediol–water mixtures

Abstract

Chemical speciation of Co(II), Ni(II), Cu(II) and Zn(II) complexes of 2,3-dihydroxybenzoic acid in 0.0-60.0% v/v 1, 2-propanediol-water mixtures maintaining an ionic strength of 0.16 mol dm -3 at 303±0.1 K has been studied pH metrically. The predominant complexes formed are ML, ML 2 and ML 2 H 2 for Co(II), Ni(II) and Zn(II) and ML, ML 2 , ML 2 H and ML 2 H 2 for Cu(II). Models containing different numbers of species were refined by using the computer program MINIQUAD75. Selection of the best fit chemical models was based on statistical parameters and residual analysis. The trend in variation of complex stability constants with dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces. Distributions of species, formation equilibria and effect of influential parameters on the stability constants have been presented. The possible structures of the various species are elucidated on the basis of the analysis of the pH-metric data.

On the Role of the Carboxyl Group to the Protective Effect of o-dihydroxybenzoic Acids to Saccharomyces cerevisiae Cells upon Induced Oxidative Stress

“…In the 2,3-diOH-BA the corresponding sites were two, with the negative charge mostly located in the -OOC-C 1 -C 2 −OH part of the molecule (salicyl group), followed by that in the HO-C 2 -C 3 −OH part (catechol group). This is in line with the comments of Hirpaye and Rao [ 34 ] on the complexation sites of the particular compound with various divalent metal cations (Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ ).…”

Electrometric Investigation of the Nature and Stability of Mixed Ligand Complexes of L-Ornithine and 1,10-Phenanthroline With Some Essential Metal Ions in Aqua-TBAB or PEG-400 Surfactant

“…Metal complexes of biogenic ligands have various applications in solution chemistry, and remain to be hot research themes for many researchers [1][2][3][4][5][6][7][8]. Mononuclear binary complexes involving interaction of single metal with one ligand and mixed ligand complexes that contain more than one ligand have been studied for long time [9,10].…”