Comparative 4f-4f absorption spectral study for the interactions of Nd(III) with some amino acids: Preliminary thermodynamics and kinetic studies of interaction of Nd(III):glycine with Ca(II).

Spectral analysis of Nd(III) complexes with some amino acids viz.; glycine, l-alanine, l-phenylalanine and l-aspartic acid in the presence and absence of Ca(2+) was carried out in some organic solvents; CH(3)OH, CH(3)CN, DMF and dioxane using comparative absorption spectra of 4f-4f transitions. The study was carried out by evaluating various energy interaction parameters like Slator-Condon (F(k)), Lande factor (ξ(4f)), nephelauxetic ratio (β), bonding parameter (b(1/2)), percent-covalency (δ) by applying partial and multiple regression analysis. The values of oscillator strength (P(obs)) and Judd-Ofelt electric dipole intensity parameter T(λ) (λ=2, 4, 6) for different 4f-4f transitions have been calculated. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength (P(obs)) and T(λ) values, reveal the mode of binding with the different ligands. Kinetic studies for the complexation of Nd(III):glycine:Ca(II) have also been discussed at different temperatures in DMF medium and from it the values of activation energy (E(a)) and thermodynamic parameters like ΔH°, ΔS° and ΔG° for the complexation are evaluated.