BackgroundThe importance of the isatinic quinolyl hydrazones arises from incorporating the quinoline ring with the indole ring. Quinoline ring has therapeutic and biological activities whereas, the indole ring occurs in Jasmine flowers and Orange blossoms. As a ligand, the isatin moiety is potentially ambidentate and can coordinate the metal ions either through its lactam or lactim forms. In a previous study, the ligational behavior of a phenolic quinolyl hydrazone towards copper(II)- ions has been studied. As continuation of our interest, the present study is planned to check the ligational behavior of an isatinic quinolyl hydrazone.ResultsNew homo- and heteroleptic copper(II)- complexes were obtained from the reaction of an isatinic quinolyl hydrazone (HL) with several copper(II)- salts viz. Clˉ, Brˉ, NO3ˉ, ClO4-, SO42- and AcO-. The obtained complexes have Oh, Td and D4h- symmetry and fulfill the strong coordinating ability of Clˉ, Brˉ, NO3ˉ and SO42- anions. Depending on the type of the anion, the ligand coordinates the copper(II)- ions either through its lactam (NO3ˉ and ClO4-) or lactim (the others) forms.ConclusionThe effect of anion for the same metal ion is obvious from either the geometry of the isolated complexes (Oh, Td and D4h) or the various modes of bonding. Also, the obtained complexes fulfill the strong coordinating ability of Clˉ, Brˉ, NO3ˉ and SO42- anions in consistency with the donor ability of the anions. In case of copper(II)- acetate, a unique homoleptic complex (5) was obtained in which the AcO- anion acts as a base enough to quantitatively deprotonate the hydrazone. The isatinic hydrazone uses its lactim form in most complexes.

BackgroundThe heterocyclic hydrazones constitute an important class of biologically active drug molecules. The hydrazones have also been used as herbicides, insecticides, nematocides, redenticides, and plant growth regulators as well as plasticizers and stabilizers for polymers. The importance of the phenolic quinolyl hydrazones arises from incorporating the quinoline ring with the phenolic compound; 2,4-dihydroxy benzaldehyde. Quinoline ring has therapeutic and biological activities whereas, phenols have antiseptic and disinfectants activities and are used in the preparation of dyes, bakelite and drugs. The present study is planned to check the effect of the counter anions on the type and geometry of the isolated copper(II)- complexes as well as the ligational behavior of the phenolic hydrazone; 4-[(2-(4,8-dimethylquinolin-2-yl)hydrazono)methyl] benzene-1,3-diol; (H2L).ResultsA phenolic quinolyl hydrazone (H2L) was allowed to react with various copper(II)- salts (Cl‾, Br‾, NO3‾, ClO4‾, AcO‾, SO42-). The reactions afforded dimeric complexes (ClO4‾, AcO‾ ), a binuclear complex (NO3‾ ) and mononuclear complexes (the others; Cl‾, Br‾, SO42-). The isolated copper(II)- complexes have octahedral, square pyramid and square planar geometries. Also, they reflect the strong coordinating ability of NO3‾, Cl‾, Br‾, AcO‾ and SO42- anions. Depending on the type of the anion, the ligand showed three different modes of bonding viz. (NN)0 for the mononuclear complexes (3, 4, 6), (NO)- with O- bridging for the dimeric complexes (1, 5) and a mixed mode [(NN)0 + (NO)- with O- bridging] for the binuclear nitrato- complex (2).ConclusionThe ligational behavior of the phenolic hydrazone (H2L) is highly affected by the type of the anion. The isolated copper(II)- complexes reflect the strong coordinating power of the SO42-, AcO‾, Br‾, Cl‾ and NO3‾ anions. Also, they reflect the structural diversity (octahedral, square pyramid and square planar) depending on the type of the counter anion.

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.

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