Effects of substituents on silicon atoms upon absorption and fluorescence properties of 1,3,6,8-tetrakis(silylethynyl)pyrenes

TETRAHEDRON LETTERS

卷:58

Article

Maeda, Hajime¹  Shoji, Tomokazu¹  Segi, Masahito¹ 

[1] Kanazawa Univ, Grad Sch Nat Sci & Technol, Div Mat Chem, Kakuma Machi, Kanazawa, Ishikawa 9201192, Japan

关键词: Tetrakis(silylethynyl)pyrene;    Absorption;    Fluorescence;    Excimer;    Si-29 NMR;   

DOI  :  10.1016/j.tetlet.2017.10.008

来源: Elsevier

【 摘 要 】

Synthesis, UV-vis absorption, and fluorescence spectroscopic properties of 1,3,6,8-tetrakis(silylethynyl) pyrenes 2-10 were studied. Absorption maxima of CH2Cl2 solutions of these compounds appeared at 437-445 nm, and molar absorption coefficients (epsilon) of most of these compounds exceeded 10(5) L mol(-1) cm(-1). Fluorescence emissions measured in dilute CH2Cl2 solutions are observed in visible region, and their intensities remarkably increased compared with that of pyrene. Fluorescence spectra obtained from concentrated CH2Cl2 solutions exhibited broad excimer emissions when steric bulk of substituents on silicon atoms is sufficiently low. Molecular orbital calculations indicated that HOMO-LUMO energy gap decreased with increasing the number of phenyl groups on silicon atoms, and that the silyl groups act as electron-donating groups to tetraethynylpyrene core. Resonances in Si-29 NMR spectra shifts to upfield with increasing the number of phenyl groups on silicon atoms due to the shielding effect of phenyl groups. (C) 2017 Elsevier Ltd. All rights reserved.

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