Shimizu Masaki, Ryuse Daiki, Kinoshita Takumi
Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, 1 Hashikami-cho, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
Chemistry. 2017 Oct 17;23(58):14623-14630. doi: 10.1002/chem.201703235. Epub 2017 Sep 18.
[1]Benzogermolo[3,2-b]indoles, [1]benzogermolo[3,2-b]benzofuran, [1]benzogermolo[3,2-b]benzothiophene, and [1]benzogermolo[3,2-b]benzothiophene-S,S-dioxide were synthesized from the corresponding 3-bromo-2-(2-bromophenyl)benzoheteroles and characterized. A comparison of the absorption spectra of the Ph Ge- and Ph Si-bridged 2-phenylindoles reveals that the Ge bridge has the effect of slightly widening the HOMO-LUMO energy gap of the bridged 2-phenylindole π-system with regard to the Si-bridged system. Replacement of the indole ring by benzofuran or benzothiophene rings induces blueshifts in the absorption spectrum, whereas the absorption spectrum of the benzothiophene-S,S-dioxide derivative was redshifted with respect to the indole derivative. These results are consistent with the changes in the HOMO-LUMO energy gaps calculated by using density functional theory. The Ph Ge-bridged indole, benzofuran, and benzothiophene-S,S-dioxide derivatives exhibit brilliant fluorescence in the violet-to-blue region with good-to-excellent quantum yields in toluene (λ =376-439 nm, Φ=0.62-0.99) and powder form (λ =401-451 nm, Φ=0.64-0.80).
[1]苯并锗茂[3,2 - b]吲哚、[1]苯并锗茂[3,2 - b]苯并呋喃、[1]苯并锗茂[3,2 - b]苯并噻吩和[1]苯并锗茂[3,2 - b]苯并噻吩 - S,S - 二氧化物由相应的3 - 溴 - 2 - (2 - 溴苯基)苯并杂环合成并进行了表征。对苯基锗桥连和苯基硅桥连的2 - 苯基吲哚的吸收光谱进行比较表明，相对于硅桥连体系，锗桥具有略微拓宽桥连2 - 苯基吲哚π - 体系的最高占据分子轨道 - 最低未占据分子轨道（HOMO - LUMO）能隙的作用。用苯并呋喃或苯并噻吩环取代吲哚环会导致吸收光谱发生蓝移，而苯并噻吩 - S,S - 二氧化物衍生物的吸收光谱相对于吲哚衍生物发生了红移。这些结果与使用密度泛函理论计算得到的HOMO - LUMO能隙变化一致。苯基锗桥连的吲哚、苯并呋喃和苯并噻吩 - S,S - 二氧化物衍生物在甲苯（λ = 376 - 439 nm，Φ = 0.62 - 0.99）和粉末形式（λ = 401 - 451 nm，Φ = 0.64 - 0.80）中在紫到蓝区域呈现出明亮的荧光，量子产率良好到优异。
