Complexation of some hydrazones bearing the quinoline ring: potentiometric studies

Abstract

Três hidrazonas (oxímica: MHQ, cetônica: BHQ e fenólica: AHQ) contendo o anel quinolínico foram preparadas e caracterizadas. As suas constantes de dissociação e as constantes de estabilidade dos seus complexos com alguns íons de metais de transição, lantanídeos e actinídeos foram determinadas potenciometricamente em dioxano-água 75% (v/v) a 303K. Adicionalmente, constantes de estabilidade de cobaloximas (complexos Co II -MHQ) foram determinadas a 303K em solvente-água 75% (v/v) (solvente= dioxano, isopropanol, etanol e metanol) e em 75, 70, 65, 60 e 55% (v/v) etanol-água. Uma análise de regressão linear foi usada para a estimativa das constantes de estabilidade em meio aquoso. A ordem de estabilidade de Irving-Williams não é obedecida rigorosamente.Three hydrazones (oximic: MHQ; ketonic: BHQ and phenolic: AHQ) bearing the quinoline moiety were prepared and characterized. Their dissociation constants as well as their stability constants with some transition, lanthanide and actinide metal ions have been investigated potentiometrically in 75% (v/v) dioxane-water at 303K. Also, stability constants of cobaloximes in 75% (v/v) solvent-water (solvent = dioxane, isopropanol, ethanol and methanol) as well as in 75, 70, 65, 60 and 55% (v/v) ethanol-water at 303K were evaluated. A linear regression analysis was used to evaluate the stability constants in the aqueous medium. Irving-Williams order for stability is not strictly obeyed.

pH-metric and theoretical studies of the complexation of 2-[α-(o-hydroxyphenyl) ethylidenehydrazino]-4,6-dimethylquinoline and 2-[α-(o-methoxyphenyl)methylidenehydrazino]-4,6-dimethylquinoline

“…2-Hydrazino-4,6-dimethylquinoline (HQ) is prepared as described in our previous publication [17]. To an ethanolic solution of 2-hydrazino-4,6-dimethylquinoline (HQ) (0.01 mol), o-anizaldehyde or o-hydroxyacetophenone (0.012 mol) was added.…”

“…They have pharmacological activities including antimicrobial, antioxidant, toxicity assessment [12], antiplasmodial, antimalarial [13], antituberculosis [14], anti-inflammatory [15] and anticancer properties [16]. This work is extension of studies on quinolone hydrazones [17][18][19][20][21][22][23][24]. The aim of the pH-metric studies is calculation of the dissociation constants of the ligands and the stability constants of their metal complexes in Egyptian Journal of Chemistry http://ejchem.journals.ekb.eg/…”

Effect of dielectric constant on protonation equilibria of 2, 3-dihydroxybenzoic acid and malonic acid in 1, 2-propanediol-water mixtures

“…Seleem et al (2006) and others (Fazary et al, 2006) reported the effect of the reaction medium on protonation equilibria of different ligands. Different researchers have explained the effect of electrostatic and non electrostatic forces of interaction on different cosolvent-water mixtures that resulted in variation in the values of protonation constants of ligands or change in free energy (Pedada et al, 2009).…”

“…The cation stabilising nature of co-solvent, the composition of the solution, specific solvent-water interactions, solvation power, donor number, acceptor number, charge dispersion and specific interactions of co-solvent with solute account for little deviation from the linear relationship (Seleem et al, 2006).…”

Studies of Uranyl (UO2)+2 and Thorium (Th)4+ Complexes with some Azo-β-diketone in Methanol- water Solvent

“…These compounds can display antitubercular effects, based on their tendency to form metal chelates with transition metal ions. The complexes of 2-substituted phenyl hydrazone ligands with divalent transition and tetravalent lanthanides metal ions in solution and in solid states have been extensively studied in our laboratory (1)(2)(3) as examples, but little are reported with UO 2 (II) and Th (IV) ions (4)(5)(6) .…”