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Science China Chemistry

, Volume 54, Issue 12, pp 1937–1947 | Cite as

Photophysical properties of heteroaromatic ring-fused (di)benzosiloles

  • Masaki ShimizuEmail author
  • Kenji Mochida
  • Masaki Katoh
  • Tamejiro Hiyama
Articles

Abstract

Benzosiloles fused to heterocycles such as thiophene, benzothiophene, and benzofuran, and indole- and benzosilole-fused dibenzosiloles were prepared by palladium-catalyzed intramolecular coupling of the corresponding 2-(arylsilyl)aryl triflates in good to high yields. Molecular and crystal structures of 5,7-dihydro-5,5,7,7-tetrakis(1-methylethyl)bis[1]benzosilolo-[2,3-b:3′, 2′-d]thiophene, 6-methyl-12,12-diisopropyl-12H-indololo[3,2-b][1]silafluorene, and 5,5,11,11-tetraisopropyl-5,11H-benzosilolo[3,2-c]silafluorene were determined by X-ray diffraction analysis. The UV absorption spectra of the (di)benzosilole derivatives in cyclohexane red-shifted when compared to 1,1-diisopropyldibenzosilole, indicating that replacing a benzene ring of dibenzosilole by the heterocycles as well as fusion of indole and benzosilole moieties onto dibenzosilole narrowed the HOMO-LUMO gaps of the π-conjugation system. The thiophene-fused benzosiloles were faintly fluorescent in solution and in the solid state, whereas the dibenzosiloles exhibited luminescence with moderate and high quantum yields in cyclohexane and in microcrystals, respectively. In other words, aggregation-induced emission was observed for the dibenzosiloles. Notably, 5,5,11,11-tetraisopropyl-5,11H-benzosilolo[3,2-c]silafluorene in microcrystals exhibited violet fluorescence (λ max = 396 nm) with a quantum yield of 0.70. Density functional theory (DFT) calculations of the prepared (di)benzosiloles were also performed.

Keywords

absorption benzosilole fluorescence silicon solid-state emission 

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Copyright information

© Science China Press and Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Masaki Shimizu
    • 1
    Email author
  • Kenji Mochida
    • 1
  • Masaki Katoh
    • 1
  • Tamejiro Hiyama
    • 2
  1. 1.Department of Material Chemistry, Graduate School of EngineeringKyoto University, Kyoto University KatsuraKyotoJapan
  2. 2.Research & Development InitiativeChuo UniversityTokyoJapan

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