Electronic spectral studies and intra-molecular inter-ligand interaction in mixed ligand complexes of lanthanoids(III) involving histidine and some amino acids

Department of Chemistry, Dr. H. S. Gour University, Sagar-470 003, India E-mail : rashmitiwari @epatra.com Fax: 91-07582-228994 Manuscript received 25 March 2003, revised 18 July 2003, accepted 12 September 2003 The formation constants on binary (log \(K_{ML}^M\)), mixed ligand complexes (log \(K_{MAL}^{MA}\)) and stability quantifying parameters (∆ log K and ∆∆ log K) to examine the extra stabilization due to inter-ligand interaction in PrIII and NdIII complexes involving histidine (hist) as primary ligand and α.alanine (α-ala), tryptophan (trp) or tyrosine (tyr) as secondary ligands, have been evaluated to examine the possible occurrence of intra-molecular inter-ligand interaction and the consequential changes in electronic spectral parameters viz., oscillator strength (P), Judd-Ofelt parameter (\(\tau_\lambda\)), changes in inter-electronic repulsion (Racah) parameter (δEk) and the nephelauxetic ratio (δE3/δE1). The changes in spectral parameters have also been examined in order to observe the changes in these spectral parameters as a result of complexation and also to seek an additional spectral evidence for intra-molecular ligand-ligand interaction