title: Photoacoustic spectroscopy study of neodymium complexes with alanine, valine, phenylalanine and tryptophan.
abstract: 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 delta 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 4G(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.
authors.affiliation: State Key Laboratory of Modern Acoustics, Institute of Acoustics, Nanjing University, 210093, Nanjing, People's Republic of China. yyang@nju.edu.cn
authors.forename: Yuetao
authors.initials: Y
authors.lastname: Yang
authors.forename: Shuyi
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000042:Absorption; D000162:Acoustics; D000409:Alanine / Q000737:chemistry*; D004583:Electrons; D007477:Ions; D028581:Lanthanoid Series Elements / Q000737:chemistry; D008024:Ligands; D015233:Models, Statistical; D009354:Neodymium / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods*; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D007477:Ions; D028581:Lanthanoid Series Elements; D008024:Ligands; D009354:Neodymium; D010649:Phenylalanine; D014364:Tryptophan; D000409:Alanine