A conductometric study on the effect of solvent upon complex formation between kryptofix22dd with Ho3+ metal cation in organic solvents

Abstract

The complexation reaction between Ho³⁺ cation with macrocyclic ligand kryptofix22DD was studied in ethyl acetate (EtOAC), methanol (MeOH), propylene carbonate (PC), tetrahydrofuran (THF) at different temperatures by coductometric method. Kryptofix22DD forms a 1:1 complex with Ho³⁺ cation. The stability of (kryptofix22DD.Ho)³⁺ complex changes with the type of the organic solvents and also with temperature. The stability constant of the complex in the non-aqueous solvents varies in order: EtOAC ≥ THF > PC ≥ MeOH. By plotting the van’t Hoff diagrams, the values of standard thermodynamic parameters such as enthalpy (∆H°_c), entropy (∆S°_c) and Gibbs free energy (ΔG°_C), for formation of (kryptofix22DD.Ho)³⁺ complex were obtained. The results showed that the entropy and enthalpy of complexation reaction between kryptofix22DD with Ho³⁺ metal cation depend on the nature of the solvents.

KEY WORDS: Kryptofix22DD, Ho³⁺ cation, Organic solvents, Complexation, Conductometry

Bull. Chem. Soc. Ethiop. 2019, 33(2), 277-284.

DOI: https://dx.doi.org/10.4314/bcse.v33i2.8