Synthesis and Properties of Bis(methylthio)dithienosilole and Its Oxides

A dithienosilole (DTS) possessing methylthio (SMe) groups at the α,α‘-positions of the
thiophene rings was prepared. The electronic states were tunable by oxidation of the sulfur
atoms of DTS(SMe)2 with the corresponding amount of mCPBA, giving DTS(SOMe)2 or DTS(SO2Me)2, and the UV absorption and fluorescence maxima shifted to higher energy regions
by oxidation. DTS(SMe)2 and the oxides were also examined with cyclic voltammetry, which
showed a reversible two-step oxidation for DTS(SMe)2. A polymer having DTS and sulfide
as repeating units was prepared, and its properties were examined. We found that DTS(SMe)2 and poly(DTS sulfide) are potentially useful as hole-transporting materials in
electroluminescence (EL) devices. The structure of DTS(SMe)2 was identified by X-ray
crystallography.