Synthesis, Structures, and Electronic Properties of Dithienosiloles Bearing Bulky Aryl Groups: Conjugation between a π‐Electron System and “Perpendicular” Aryl Groups

Abstract

AbstractDithienosiloles bearing 2,4,6‐triisopropylphenyl (Tip) and mesityl (Mes) groups at the 2,6‐positions have been synthesized, and their structures and electronic properties have been examined. X‐ray crystallography showed that the bulky aryl groups have a nearly perpendicular orientation to dithienosilole. In the UV/Vis spectra, the lowest energy absorption bands of these dithienosiloles are shifted bathochromically compared to that of the hydrogen‐substituted analog. Theoretical calculations showed that the electronic effect of the bulky aryl groups can be explained by the σ–π and σ*–π* conjugation between the σ and σ* orbitals of the C−C bonds of the perpendicular benzene rings and the π and π* orbitals of the dithienosilole moiety. Furthermore, these dithienosiloles show intense blue fluorescence with high fluorescence quantum yields, as an effect of the perpendicular bulky aryl groups.