Spectroscopic and Thermodynamic Studies for the Complexation of Neodymium(III) with L(-) Asparagine(monohydrate) in Binary and Ternary Organic Solvent Mixtures

Neodymium(III) with L(-) asparagine(monohydrate) complexes in binary and ternary organic solvent mixtures had been spectrophotometrically and thermodynamically investigated. The observed spectra in the visible and near IR-region had been analyzed to calculate interelectronic repulsion parameterSlater-Condon (Fk), Lande spin-orbit coupling constant (ξ4f), covalency parameters (β, b? and δ) and intensity parameters such as oscillator strengths (P) and Judd-Ofelt parameters (T?). The degree of covalency in the complexes increases with increase in oscillator strength values. The hypersensitive band (4I9/2→4G5/2) was correlated with the one of the most intense band of pseudo-hypersensitive i.e., 4I9/2 →4F5/2 transition band to determine the degree of sensitivity of ligand and solvent environment on the complexation. The higher values of covalency parameters and oscillator strength are taken as evidence of participation of f-orbitals in bonding. The positive values of standard enthalpy (?H°) and standard entropy (?S°) confirmed the endothermic nature and the increasing randomness respectively. The negative values of standard free energy (?G°) favours the formation of neodymium (III) with L(-) asparagine(monohydrate) complex in the solution.