Thermodynamics of the complexation between salicylaldehyde thiosemicarbazone with Cu2+ ion in methanol +1,4-dioxane binary solutions

Abstract

The complexation reaction between salicylaldehyde thiosemicarbazone, abbreviated as STSC, with Cu(II) ion was studied in binary mixtures of methanol-1,4-dioxane using UV-Vis spectrophotometric and conductometric methods at different temperatures. The formation constants (K f ) for the 1:1 complex, Cu(II)-STSC, were calculated from computer fitting of the absorbance and molar conductance data against various concentrations ratios (c M :c L or c L :c M ) in different binary solvent mixtures. A non-linear correlation was observed for the variation of log K f for the complex against the solvent compositions. Various thermodynamic parameters (ΔH, ΔS and ΔG) for the formation of the Cu(II)-STSC complex were also determined from the temperature dependence of the formation constants (K f ). The results showed that the complexation reaction is affected by the nature and composition of the mixed solvents.

Spectrophotometric and conductometric study of the complexation of N-salicylidene-2-aminophenol with Cu2+ in methanol + 1,4-dioxane binary solutions

“…36 However, a comparison of the stability constants given in Table I and II revealed that Cu 2+ was strongly solvated and hardly complexed by the ligand in solvent mixtures with higher content of MeOH and the stability constants increased with increasing the concentration of DO in binary solvents. 20 This fact is in accordance with the reverse order of their solvating ability as represented by their Gutmann donor numbers. It is known that the solvating ability of a solvent plays an important role in complexation reactions.…”

“…The final K f values and [ML] were then calculated iteratively using the Newton-Raphson method and successive approximation with the aid of a Cprogram. 20…”

“…Hence studies on the thermodynamics of complex formation of Cu 2+ with different Schiff bases in different solvent media are worthy of thorough studies and are demanded. [17][18][19][20] Among the various organic solvents, methanol (MeOH) is one of the simplest amphiphile-like molecules. 21 Alcohols in non-polar solvents associate by means of hydrogen bonds into series of n-mers.…”

Synthesis, antioxidant and antimicrobial activity of carbohydrazones

“…It indicates that steric effect at azomethine carbon substituent cause decrease of their activity. It is interesting that some bis-substituted carbohydrazones (8)(9)(10) showed moderate activity against Gram-positive bacteria, whereas against Gram-negative bacteria exhibited no activity. Obtained activity depends on the studied compound properties (lipophile/hydrophile balance, geometry, proton accepting/donating capabilities, etc.)…”

“…They are usually formed easily from carbonyl compounds and hydrazines in a reversible reaction and can coordinate to metal ions through the azomethine nitrogen. 8,9 They have been reported to exhibit antimicrobial, anticonvulsant, analgesic, anti-inflammatory, antiplatelet, antitubercular and antitumor activities. [10][11][12] It was found that coordination of the Schiff base ligand with transition metals lead to an increase in the antimicrobial 13,14 and antioxidative activities 15,16 in most of cases.…”