Excited-state energy dynamics of conjugated polycarbogermane oligomers: Introduction effects of germanium atom into π-conjugated molecular system

Sang Ho Choi, In Wook Hwang, Sung Hee Kim, Young Tae Park, Yong Rok Kim

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Excited-state energy dynamics of the conjugated polycarbogermane oligomers, poly{[1,4-bis(thiophenyl)buta-1,3-diyne]-alt-(dimethylgermane)} (PBTBD-DMG; n = 33), poly{[1,4-bis-(thiophenyl)buta-1,3-diyne]-alt-(diphethylgermane)} (PBTBD-DPG; n = 12), poly{[1,4-bis(phenyl)buta-1,3-diyne]-alt-(dimethylgermane)} (PBPBD-DMG; n = 36), and poly{[1,4-bis(phenyl)buta-1,3-diyne]-alt-(diphenylgermane)} (PBPBD-DPG; n = 2), were investigated by steady-state and picosecond time-resolved fluorescence spectroscopies in liquid solution. The introduction effect of a germanium atom into π-conjugated oligomer backbones and the substitution effect of a methyl or phenyl group on the germanium atom are discussed from solvent polarity-dependent studies. Steady-state and time-resolved fluorescence studies on the thiophene-containing polycarbogermane (PBTBD-DMG and PBTBD-DPG) oligomers revealed considerable solvent polarity-dependent characteristics, whereas those of the phenylene-containing polycarbogermane (PBPBD-DMG and PBPBD-DPG) oligomers do not significantly show such characteristics. As the solvent polarity increased from n-hexane to tetrahydrofuran, the steady-state fluorescence spectra of PBTBD-DMG and PBTBD-DPG oligomers were significantly redshifted, and their fluorescence lifetimes seemed to change from ∼624 to ∼46 ps. These results suggest that the excited-state dynamics of PBTBD-DMG and PBTBD-DPG oligomers are related to an intramolecular charge transfer (ICT) emission process through (d-p) π conjugation between the π-conjugated system and unoccupied 4d orbitals of the germanium atom. These results are supported by quantum chemical (AM1 and CNDO/2) calculations.

Original languageEnglish
Pages (from-to)1298-1306
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number13
Publication statusPublished - 2002 Jul 1


All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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