Open AccessInfluence of Symmetry on the Luminescence and Radiative Lifetime of Nine-Coordinate Europium Complexes
Author(s) -
Nail M. Shavaleev,
Svetlana V. Eliseeva,
Rosario Scopelliti,
JeanClaude G. Bünzli
Publication year - 2015
Publication title -
inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 233
eISSN - 1520-510X
pISSN - 0020-1669
DOI - 10.1021/acs.inorgchem.5b01580
Subject(s) - chemistry , europium , luminescence , lanthanide , homoleptic , crystallography , coordination sphere , ligand (biochemistry) , phosphorescence , photochemistry , spectroscopy , inorganic chemistry , ion , crystal structure , metal , fluorescence , organic chemistry , biochemistry , physics , receptor , optoelectronics , quantum mechanics
Homoleptic mononuclear nine-coordinate lanthanum(III) and europium(III) tris-complexes [Ln(N(∧)N(∧)O)3]·nH2O with two tridentate N-benzylbenzimidazole pyridine-2-carboxylates exhibit a rare C3-symmetry of the lanthanide coordination polyhedron in the solid state, as confirmed by luminescence spectroscopy and by X-ray crystallography (the three N(∧)N(∧)O ligands are arranged "up-up-up" around the lanthanide ion). The symmetry, however, is changed to the more common C1 upon dissolution of the complexes in dichloromethane, as revealed by luminescence spectroscopy (the three ligands are likely to be arranged "up-up-down"). The new europium complexes emit efficient ligand-sensitized metal-centered luminescence with excited-state lifetimes of 1.56-2.18 ms and quantum yields of 25-41% in the solid and in solution. The change of the symmetry from (a higher) C3 to (a lower) C1 alters the luminescence spectrum, shortens the radiative lifetime, and increases the luminescence efficiency of the europium complexes.