Systematic investigation of the effect of trialkylsilyl groups on the crystal structures of perfluorophenyl-substituted thiophene

Abstract

Controlling the crystal packing of perfluorophenyl-substituted aryl molecules (Ar–Ar^F-type molecules) is crucial for their properties. Herein, we investigated the crystal structures of perfluorophenyl-substituted thiophene derivatives bearing three different trialkylsilyl groups: trimethylsilyl, tert-butyldimethylsilyl, and triisopropylsilyl. Single-crystal X-ray diffraction analysis revealed that the compounds exhibited distinct head-to-tail stacking patterns depending on the length and degree of branching of the alkyl chains on the trialkylsilyl groups. Notably, the photophysical properties of the crystals differed, despite being similar in solution. Specifically, the trimethylsilyl and tert-butyldimethylsilyl derivatives exhibited a larger red shift in their excitation and emission wavelengths, as well as higher photoluminescence quantum yields. These results indicate that trialkylsilyl groups can effectively modulate molecular packing to enhance the solid-state properties of these compounds.