title: Complexation of trivalent americium and lanthanides with terdentate 'N' donor ligands: the role of rigidity in the ligand structure.
abstract: A systematic study on the Ln(3+) complexation behaviour with two terdentate 'N' donor ligands of varying structural rigidity, viz. 5,6-dimethyl-(1,2,4)-triazinylbipyridine (Me2TBipy) and 5,6-dimethyl-(1,2,4)-triazinylphenanthroline (Me2TPhen), is performed in the present work by UV-Vis spectrophotometry, time resolved fluorescence spectroscopy (TRFS) and electrospray ionization mass spectrometric (ESI-MS) studies. These studies indicate the formation of a 1 : 1 complex of La(3+), 1 : 2 complexes of Eu(3+) and Er(3+) with both the ligands. Density functional theoretical (DFT) study is carried out to determine the solution phase structure of the Eu(3+) complex considering the species (from UV-Vis spectrophotometry) and C2v site symmetry around the Eu(3+) ion (from TRFS study). Me2TPhen is found to be a stronger complexing ligand as compared to Me2TBipy irrespective of the Ln(3+) ions. The solid state crystal structure of the La(3+) complex of Me2TPhen is determined using the single crystal X-ray diffraction (SCXRD) technique. The complexation of the trivalent Am(3+) ion is also studied with both these ligands using UV-Vis spectrophotometric titrations which show the formation of 1 : 2 complexes with higher complexation constant values as compared to all the Ln(3+) ions studied, indicating the selectivity of these ligands for the trivalent actinides over the lanthanides.
authors.affiliation: Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India. arunasis12@yahoo.co.in.
authors.forename: Arunasis
authors.initials: A
authors.lastname: Bhattacharyya
authors.forename: Trilochan
authors.initials: T
authors.lastname: Gadly
authors.forename: Priyanath
authors.initials: P
authors.lastname: Pathak
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Ghosh
authors.forename: Manoj
authors.initials: M
authors.lastname: Mohapatra
authors.forename: Tapan K
authors.initials: TK
authors.lastname: Ghanty
authors.forename: Prasanta K
authors.initials: PK
authors.lastname: Mohapatra
mesh_terms: D000576:Americium / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D009584:Nitrogen / Q000737:chemistry; D010618:Phenanthrolines / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D056831:Coordination Complexes; D028581:Lanthanoid Series Elements; D008024:Ligands; D010618:Phenanthrolines; D011725:Pyridines; D009584:Nitrogen; D000576:Americium