A B S T R A C TCyclic Voltammetric studies of calcium acetate salt [Ca(CH3COO)2] in absence or presence of Methylene blue (MB) were performed to predict and analyze the behavior of complexation between the ligand and metal ion in aqueous solution. From these studies, the values of solvation and kinetic parameters [Ep (peak potential), Ip (peak current), ΔEP (peak potential difference), E½ (half wave potential), D (Diffusion coefficient), Ks (electron transfer rate constant), Г (surface coverage) and Qa (quantity of electricity)] were evaluated. In addition, the effect of different concentration and a scan rate of above the calculated quantities were studied. In case of presence MB, the stability constants and Gibbs free energies were performed.

The electrochemical behavior of the complexation between copper chloride salt and succinic hydrazide can be explained using cyclic voltammetric measurements. The complex is formed through the interaction with nitrogen and hydroxyl group or carbonyl group of succinic hydrazides. This interaction can be observed by decreasing in the height peak of current and measuring the (anodic/cathodic) shift of the potentials. All the solvation and thermodynamic parameters for the interaction of copper ions with succinic hydrazide as stability constant, Gibbs free energies, enthalpies and entropies of interaction were calculated. Finally, the activity of the formed complex was compared with the succinic hydrazide by comparing their effects on different types of gram-negative bacteria and fungi indicating high activity of the formed complex and its ability to be used in different medical applications.

ABSTRACT. For lump and nanocobalt sulfate (CoSO4) in pure water, the affiliation and thermodynamic association characteristics were measured at 298.15, 303.15, 308.15, and 313.15 K. Based on the bulk and nano CoSO4 molar conductance, estimates were made for the parameters of the solvation, such as the activity coefficient, free energy of association, enthalpy of association, association constant, and entropy of association. We discussed about each of these solvation parameters. Two stoichiometric complexes were formed by the interaction of bulk and nano CoSO4.7H2O with fuchsin acid: 1:1 and 1:2 In the case of 1:1 (CoSO4.7H2O/fuchsin acid) compared to 1:2 (fuchsin acid in pure water as solvent), the complex Kf and ∆Gf are higher, indicating simpler complex formation. The temperature increase resulted in a drop in the formation constants. The complexation's negative ∆Gf values demonstrate that the process of complex synthesis was spontaneous and that the temperature improved the spontaneity.   KEY WORDS: Molar conductance, Association constants, Fuchsin acid, Nano cobalt sulfate salt, Formation constant   Bull. Chem. Soc. Ethiop. 2023, 37(3), 789-804.                                                           DOI: https://dx.doi.org/10.4314/bcse.v37i3.20

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The complexation reactions between CuCl2 CoCL2 and NiCL2 with 2,3-Pyrazinedicarboxylic acid in methanol (MeOH) at 313.15 K were studied by conductometric methods. The association constants, formation constants and Gibbs free energies were calculated from the conduclometric titration curves. On drawing the relation between molar conductance and the ratio of metal to ligand coflCentrations, different lines were obtained indicating the formation of 1: 1 and 2: 1 (M:L) stoichiometric complexes. The formation constants and Gibbs free energies of different complexes in absolute Methanol at 313.15 Kfollow the order: