title: Remarkable luminescence properties of lanthanide complexes with asymmetric dodecahedron structures.
abstract: The distorted coordination structures and luminescence properties of novel lanthanide complexes with oxo-linked bidentate phosphane oxide ligands--4,5-bis(diphenylphosphoryl)-9,9-dimethylxanthene (xantpo), 4,5-bis(di-tert-butylphosphoryl)-9,9-dimethylxanthene (tBu-xantpo), and bis[(2-diphenylphosphoryl)phenyl] ether (dpepo)--and low-vibrational frequency hexafluoroacetylacetonato (hfa) ligands are reported. The lanthanide complexes exhibit characteristic square antiprism and trigonal dodecahedron structures with eight-coordinated oxygen atoms. The luminescence properties of these complexes are characterized by their emission quantum yields, emission lifetimes, and their radiative and nonradiative rate constants. Lanthanide complexes with dodecahedron structures offer markedly high emission quantum yields (Eu: 55-72 %, Sm: 2.4-5.0 % in [D(6)]acetone) due to enhancement of the electric dipole transition and suppression of vibrational relaxation. These remarkable luminescence properties are elucidated in terms of their distorted coordination structures.
authors.affiliation: Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University, North-13 West-8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Miyata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Ryuhei
authors.initials: R
authors.lastname: Kawakami
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kita
authors.forename: Katsufumi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Takuya
authors.initials: T
authors.lastname: Nakashima
authors.forename: Takashi
authors.initials: T
authors.lastname: Harada
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kawai
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Hasegawa