Effects of substituents in silyl groups on the absorption, fluorescence and structural properties of 1,3,6,8-tetrasilylpyrenes

Abstract

1,3,6,8-Tetrasilylpyrenes and related germyl and stannyl derivatives were synthesized, and their absorption and fluorescence spectroscopic and structural properties were elucidated. The results show that the UV-vis absorption maxima of these substances in CH2Cl2 solutions shift to longer wavelengths as the size of the alkyl groups and numbers of phenyl groups on silicon increase. Fluorescence quantum yields of tetrasilylpyrenes in cyclohexane are larger than that of pyrene, and a pentamethyldisilyl derivative has an emission efficiency of 0.79. Except in the case of the SiMe2H derivative, excimer emission was not observed in concentrated solutions of these substances. The SiMe2H and SiMe3 derivatives were shown to form CT complexes with tetracyanoethylene in CH2Cl2 solutions. The calculated energy barriers for rotation of the silyl groups about the Si-C bond increase as the steric bulk of the silyl group increases. 29Si NMR chemical shifts were found to depend on the sizes of the alkyl groups and numbers of phenyl groups. Data arising from theoretical calculations suggest that the silyl groups act as electron-donating groups, and the donating ability of the groups decreases in the order SiR3 > GeR3 > SnR3.

Cooperation of σ–π and σ*–π* Conjugation in the UV/Vis and Fluorescence Spectra of 9,10-Disilylanthracene

“…Similar results have also been reported by other groups [ 7 , 8 , 9 , 10 ]. After this finding, UV/Vis, fluorescence and other measurements of various silyl-substituted aromatic compounds have been reported, showing electronic effects of silyl groups [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

White Light from Dual Intramolecular Charge-Transfer Emission in a Silylene-Bridged Styrylcarbazole and Pyrene Dyad

“…The components of the chosen dyad (carbazole derivative and pyrene) were selected because they play a pivotal role in many areas of photophysics and optoelectronics. − These popular polycyclic aromatic hydrocarbons and their various derivatives (including silicon-based carbazole ,− and pyrene-containing compounds − ) have found application in optoelectronics, solar cells, TADF and organic light-emitting diode (OLED) materials, or fluorescent probes for elucidation of the geometries of various biomolecules. , There are also interesting studies that report white-light emission from pyrene-based compounds, − and many of them are related to aggregation-induced emission. Furthermore, there are known examples of carbazole–pyrene hybrid compounds for dye-sensitized solar cell applications, OLEDs, − and electroluminescent devices …”

Ab initio study on the excited states of pyrene and its derivatives using multi-reference perturbation theory methods

“…1 These properties can be tailored to meet specic requirements through modications of its chemical structure; [2][3][4][5][6][7][8][9][10][11] therefore, pyrene derivatives are recognized as promising materials for organic light-emitting devices. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] Pyrene is also well known for the formation of an excimer. [26][27][28][29] An aromatic excimer is a dimeric complex of the same aromatic molecules that is formed in the excited state.…”