title: Synthesis, structure, aggregation-induced emission, self-assembly, and electron mobility of 2,5-bis(triphenylsilylethynyl)-3,4-diphenylsiloles.
abstract: 2,5-Bis(triphenylsilylethynyl)-3,4-diphenylsiloles with different 1,1-substituents [XYSi(CPh)(2) (C-C≡C-SiPh(3))(2)] (Ph=phenyl) were synthesized in high yields by the Sonogashira coupling of 2,5-dibromo-3,4-diphenylsiloles with triphenylsilylacetylene, and two of these were characterized crystallographically. Crystal structures and theoretical calculations showed that the new silole molecules had higher conjugation than 2,5-diarylsiloles. They possessed low HOMO and LUMO energy levels due to the electron-withdrawing effect of the triphenylsilylethynyl groups. Cyclic voltammetry analysis revealed low electron affinities, which were comparable to those of perfluoroarylsiloles. B3LYP/6-31* calculations demonstrated that the new siloles possessed large reorganization energies for electron and hole transfers and high electron mobilities. A mobility of up to 1.2×10(-5) cm(2) V(-1) s(-1) was obtained by the transient electroluminescence method, which was about fivefold higher than that of tris(8-hydroxyquinolinato)aluminum, a widely used electron-transport material, under the same conditions. All of the silole molecules possessed high thermal stability. Although, their solutions were weakly emissive, their nanoparticle suspensions and thin films emitted intense blue-green light upon photoexcitation, demonstrating a novel feature of aggregation-induced emission (AIE). Polarized emissions were observed in the silole crystals. The addition of solvents, which did not dissolve the silole molecules, into silole-containing solutions caused self-assembly of the molecules, which produced macroscopic fibrils with strong light emissions.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
authors.forename: Zujin
authors.initials: Z
authors.lastname: Zhao
authors.forename: Dandan
authors.initials: D
authors.lastname: Liu
authors.forename: Faisal
authors.initials: F
authors.lastname: Mahtab
authors.forename: Linyuan
authors.initials: L
authors.lastname: Xin
authors.forename: Zhongfang
authors.initials: Z
authors.lastname: Shen
authors.forename: Yong
authors.initials: Y
authors.lastname: Yu
authors.forename: Carrie Y K
authors.initials: CY
authors.lastname: Chan
authors.forename: Ping
authors.initials: P
authors.lastname: Lu
authors.forename: Jacky W Y
authors.initials: JW
authors.lastname: Lam
authors.forename: Herman H Y
authors.initials: HH
authors.lastname: Sung
authors.forename: Ian D
authors.initials: ID
authors.lastname: Williams
authors.forename: Bing
authors.initials: B
authors.lastname: Yang
authors.forename: Yuguang
authors.initials: Y
authors.lastname: Ma
authors.forename: Ben Zhong
authors.initials: BZ
authors.lastname: Tang