Optical Absorption, Kinetics and Thermodynamic Studies of Pr(III) and Nd(III) Ions with N-Acetyl L-Cysteine in Presence of Ca(II) ions

Interaction of N-acetyl-L-cysteine (NAC) with Pr3+ (Pr(NO3)3·6H2O) and Nd3+ (Nd(NO3)3·6H2O) ionsare studied in presence of Ca2+ (Ca(NO3)3·4H2O) ion in an aqueous and organic solvent by applyingthe spectroscopic technique for quantitative probe of 4f-4f transition. The complexation was determinedby the variation in the intensities of 4f-4f absorption spectral bands and by applying the change ofsymmetric properties of electronic-dipole known as Judd-Ofelt parameters Tλ (λ = 2,4,6). On theaddition of Ca2+ ion in the binary complexation of praseodymium and neodymium withN-acetyl-L-cysteine (NAC) there is an intensification of bands which shows the effect of Ca2+ towardthe heterobimetallic complex formation. Other parameters like Slater-Condon (Fk), bonding (b1/2), theNephelauxetic ratio (β), percentage covalency (δ) are also used to correlate the complexation of metalswith 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 ofN-acetyl-L-cysteine (NAC) with Pr3+ and Nd3+ in presence of Ca2+. The variation in oscillator strength(Pobs), energy (Eobs) and dipole intensity parameter help in supporting the heterobimetallic complexationof N-acetyl-L-cysteine. In kinetics investigation, the rate of the complexation of both hypersensitiveand pseudo-hypersensitive transition is evaluated at various temperature in DMF solvent. The value ofthe thermodynamic parameters such as ΔHo, ΔSo and ΔGo and activation energy (Ea) also evaluated.