Department of Chemistry, Manipur University, Canchipur 795 003, Manipur, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Oct;96:370-9. doi: 10.1016/j.saa.2012.05.038. Epub 2012 May 29.
The interaction of gly-gly with Pr(III) and Nd(III) have been studied in different aquated organic solvents like CH(3)OH, CH(3)CN, dioxane and DMF by using 4f-4f transitions spectra. Various energy interaction parameters like Slater Condon (F(k)), Racah (E(k)), Lande (ξ(4f)), nephelauxetic effect (β), bonding (b(1/2)) and percent covalency (δ) parameters have been calculated to explain the nature of complexation. The intensity parameters like oscillator strength (P) and Judd-Ofelt parameters (T(λ), λ=2, 4, 6) also support the mode of binding of gly-gly to metal ions. The results show that Pr(III) and Nd(III) with gly-gly form complexes by ionic linkages with carboxylate anion with weak covalency. The protonation constants and metal-ligand stability constants have also been determined by potentiometric measurements in aqueous medium at different temperatures (290, 300 and 310 K) at constant ionic strength, 0.1 mol dm(-1). The results show the formation of metal-ligand complexes in the stoichiometric ratio 1:1. The stability of complexes is more in Nd(III) complexes as compared to Pr(III) complexes. Thermodynamic parameters (ΔG, ΔH and ΔS) of complexes were also calculated and the negative values of ΔG and ΔH show that the complex reactions are spontaneous and exothermic. The positive values of ΔS indicate high stability of complex reactions which are enthalpy-driven.
甘氨酸与镨(III)和钕(III)在不同水合有机溶剂如甲醇、乙腈、二氧六环和 DMF 中的相互作用已通过 4f-4f 跃迁光谱进行了研究。各种能量相互作用参数，如 Slater Condon（F(k)）、Racah（E(k)）、Lande（ξ(4f)）、负电子亲合能（β）、键合（b(1/2)）和共价度（δ）参数，已被计算出来以解释配合物的性质。强度参数，如振子强度（P）和 Judd-Ofelt 参数（T(λ)，λ=2,4,6）也支持甘氨酸与金属离子结合的方式。结果表明，甘氨酸与镨(III)和钕(III)通过离子键与羧酸盐阴离子形成配合物，具有较弱的共价度。通过在不同温度（290、300 和 310 K）下在恒定离子强度为 0.1 mol dm(-1)的水溶液中进行电位测定，也确定了质子化常数和金属-配体稳定常数。结果表明，在化学计量比为 1:1 的情况下形成了金属-配体配合物。与镨(III)配合物相比，钕(III)配合物的稳定性更高。还计算了配合物的热力学参数（ΔG、ΔH 和 ΔS），ΔG 和 ΔH 的负值表明配合物反应是自发的和放热的。ΔS 的正值表明配合物反应具有较高的稳定性，这是由焓驱动的。
