Thiyam Samrat Singh and Thiyam David Singh^*,

Department of Chemistry, National Institute of Technology Manipur, Langol, Imphal-795004, India

*Corresponding author: E-mail: davidthiyam@gmail.com

Interaction of N-acetyl-L-cysteine (NAC) with Pr³⁺ (Pr(NO₃)₃·6H₂O) and Nd³⁺ (Nd(NO₃)₃·6H₂O) ions are studied in presence of Ca²⁺ (Ca(NO₃)₃·4H₂O) ion in an aqueous and organic solvent by applying the spectroscopic technique for quantitative probe of 4f-4f transition. The complexation was determined by the variation in the intensities of 4f-4f absorption spectral bands and by applying the change of symmetric properties of electronic-dipole known as Judd-Ofelt parameters T_λ (λ = 2,4,6). On the addition of Ca²⁺ ion in the binary complexation of praseodymium and neodymium with N-acetyl-L-cysteine (NAC) there is an intensification of bands which shows the effect of Ca²⁺ toward the heterobimetallic complex formation. Other parameters like Slater-Condon (F_k), bonding (b^1/2), the Nephelauxetic ratio (β), percentage covalency (δ) are also used to correlate the complexation of metals with N-acetyl-L-cysteine (NAC). With the minor change in coordination around Pr³⁺ and Nd³⁺ ions, the sensitivity of 4f-4f bands is detected and further used to explain the coordination of N-acetyl-L-cysteine (NAC) with Pr³⁺ and Nd³⁺ in presence of Ca²⁺. The variation in oscillator strength (P_obs), energy (E_obs) and dipole intensity parameter help in supporting the heterobimetallic complexation of N-acetyl-L-cysteine. In kinetics investigation, the rate of the complexation of both hypersensitive and pseudo-hypersensitive transition is evaluated at various temperature in DMF solvent. The value of the thermodynamic parameters such as ΔH°, ΔS° and ΔG° and activation energy (E_a) also evaluated.

N-Acetyl-L-cysteine, Nephelauxetic effect, Judd-Offelt, Hypersensitive, Pseudo hypersensitive, Oscillator strength.