title: Enhanced deep-red luminescence of tris(hexafluoroacetylacetonato)samarium(III) complex with phenanthroline in solution by control of ligand coordination.
abstract: The effect of solvent molecule on the emission properties of Sm(hfa)3(phen)2 (hfa = hexafluoroacetylacetonato, phen = phenanthoroline) was investigated using acetone, acetonitrile, and pyridine. 5G(5/2) --> 5H(9/2) transition intensities in pyridine were found to be larger than those in corresponding acetone and acetonitrile. The radiative rate constant in pyridine (4.8 x 10(2) s(-1)) was 2 times larger than those in acetonitrile (2.6 x 10(2) s(-1)) and acetone (2.3 x 10(2) s(-1)), although the nonradiative transition via vibrational relaxation (k(nr) = 1.7 x 10(4) s(-1)) in pyridine was the same as those in acetone and acetonitrile (k(nr) = 1.8 x 10(4) s(-1)), resulting in the enhanced emission quantum yield of Sm(III) complex in pyridine (2.7%). The coordination structures of Sm(hfa)3(phen)2 in acetonitrile, acetone, and pyridine were estimated by X-ray single-crystal analyses. These results indicate that enhancement of the emission properties in pyridine is due to faster radiative rate related to formation of asymmetrical nine-coordinated structure, Sm(hfa)3(phen)(py) (py = pyridine).
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan. hasegawa@ms.naist.jp.
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Tsuruoka
authors.forename: Takahiko
authors.initials: T
authors.lastname: Yoshida
authors.forename: Hideki
authors.initials: H
authors.lastname: Kawai
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kawai