Issue 36, 2009

4,4,5,5,5-Pentafluoro-1-(9H-fluoren-2-yl)-1,3-pentanedione complex of Eu3+ with 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide as a promising light-conversion molecular device

Abstract

A novel β-diketone ligand, 4,4,5,5,5-pentafluoro-1-(9H-fluoren-2-yl)-1,3-pentanedione (Hpffpd), which contains a polyfluorinated alkyl group, as well as a long conjugated fluorene unit, and a chelate phosphine oxide ligand, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide (DDXPO) were synthesized and utilized for the synthesis of two new europium complexes [Eu(pffpd)3(C2H5OH)(H2O)] 1 and [Eu(pffpd)3(DDXPO)] 2. For comparison, the [Eu(pffpd)3(DPEPO)] 3 complex was also synthesized involving a known chelate phosphine oxide, bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO). The synthesized complexes have been characterized by various spectroscopic techniques and their solid-state photophysical properties were investigated. The single-crystal X-ray diffraction analyses of 2 and 3 revealed that these complexes are mononuclear, and that the central Eu3+ ion is surrounded by eight oxygen atoms, six of which are from the three bidentate fluorinated β-diketonates, and the other two oxygen atoms from the chelate phosphine oxide. The coordination polyhedra can be described as distorted square antiprism. Compound 2 has a solid-state photoluminescence quantum yield of 48%, which is about two times higher than that of compound 3 (28%). This may be due to the fact that DDXPO in 1 has the mezzo first triplet excited state energy level (T1) between the first singlet excited energy level (S1) and T1 of Hpffpd, which may support one more additional energy transfer from the T1 energy level of DDXPO to that of Hpffpd, and consequently improves the energy transfer in the Eu3+ complex. Furthermore, DDXPO (average Eu–O = 2.34 Å) in complex 2 coordinates more strongly with the central Eu3+ as compared to DPEPO in complex 3 (average Eu–O = 2.38 Å) which can improve the energy transfer between the ligands and central metal ion, and consequently enhances the photoluminescence efficiency of the corresponding Eu3+ complex.

Graphical abstract: 4,4,5,5,5-Pentafluoro-1-(9H-fluoren-2-yl)-1,3-pentanedione complex of Eu3+ with 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide as a promising light-conversion molecular device

Supplementary files

Article information

Article type
Paper
Submitted
07 Apr 2009
Accepted
17 Jun 2009
First published
23 Jul 2009

Dalton Trans., 2009, 7519-7528

4,4,5,5,5-Pentafluoro-1-(9H-fluoren-2-yl)-1,3-pentanedione complex of Eu3+ with 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene oxide as a promising light-conversion molecular device

D. B. Ambili Raj, S. Biju and M. L. P. Reddy, Dalton Trans., 2009, 7519 DOI: 10.1039/B907031A

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