Photoacoustic spectroscopy study of neodymium complexes with alanine, valine, phenylalanine and tryptophan

摘要

Neodymium. complexes with amino acids: Nd(Ala)(3)Cl-3 . 3H(2)O, Nd(Val)(3)Cl-3 . 3H(2)O, Nd(Phe)Cl-3 . 5H(2)O and Nd(TrP)(3)Cl-3 . 3H(2)O (Ala: L-alanine, Val: L-valine, Phe: L-phenylalanine, Trp: L-tryptophan) are synthesized and their photoacoustic (PA) spectra are reported. The nephelauxetic ratio beta, bonding parameter b(1/2) and Sinha parameter 6 are calculated based on their PA spectra. The variation of these parameters and correlation of them with the nature of metal-ligand bonding are discussed. The PA intensity analysis of the f-f transitions of neodymium ion is carried out by calculating the intensity branching vector. The environmental effect on the f-f transitions of neodymium. ion is also studied. The branching vectors of the f-f transitions of Nd(Ala)(3)Cl-3 . 3H(2)O and Nd(Val)(3)Cl-3 . 3H(2)O are similar, which indicates the perturbation of the two ligand fields is similar. The branching vectors of energy levels (4)G(5/2) + (2)G(7/2) of Nd(Phe)Cl-3 . 5H(2)O and Nd(Trp)(3)Cl-3 . 3H(2)O increase remarkably compared with those of Nd(Ala)(3)Cl-3 . 3H(2)O and Nd(Val)(3)Cl-3 . 3H(2)O. As the degree of covalency increases, the oscillator strength of the hypersensitive transition exhibits a corresponding increase. The relaxation process of Nd(Ala)(3)Cl-3 . 3H(2)O is established through its PA and electron absorption spectroscopy (EAS). A method used to resolve the PA amplitude spectrum is suggested. With the phase spectrum, PA absorption bands of Nd(Trp)(3)Cl-3 . 3H(2)O are resolved well in the region of ligand absorption. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 24]