Dithienosiloles

Reaction of 4,4-diphenyl- and 4,4-di(p-tolyl)dithienosilole (DTS) <1998JOM487, 1998CL1233, 1999JOM1453, 2002JOM137> 25a,b with excess tetracyanoethene (TCNE) 168 in DMF afforded coupling products 4,4-diphenyl-and 4,4-di(p-tolyl)-2-(tricyanoethenyl)dithienosilole 169 in 85% and 87% yields, respectively <20020L1891> (Scheme 20). 

Dithienosilole-thiophene copolymers 21 (Fig. 10) can show excellent FET performances.38 With the copolymers as the active layer, remarkably high hole mobility from 0.02 to 0.06 cm2/(V s) can be achieved. Furthermore, the FET devices possess high current on/off ratios of 105—106. The FET devices also display impressive stabilities under repeated on/off cycles up to 2000 in air. 

Dithienosilole-thiophene alternating copolymer 21 is the important example for the electrical conduction of SCPs.42 When the copolymer is doped with iodine, a high electrical conductivity of 400 S cm-1 can be achieved. This value is the highest among SCPs and is also close to that of well-defined poly(3-alkylthiophene). 

Some new silole-based fused ring systems have been reported. Ohshita and coworkers54 and Barton and coworkers51 have reported independently the synthesis of dithienosiloles... 

Dithienosiloles can be prepared by the dilithiation of 3,3/-dibromo-2,2/-bithiophene followed by treatment with dichlorosilanes or equivalents (Scheme 9). Theoretical calculations show that dithienosilole has a lower LUMO level than that of the carbon analog... 

Figure 8 Bibenzothiophene (BBT), dithienosilole (DTS), and BBTS, compounds having a silole ring condensed with benzothiophene.

J. Ohshita, H. Kai, A. Takata, T. Eda, A. Kunai, N. Ohta, K. Komaguchi, M. Shiotani, A. Adachi, K. Sakamaki, K. Okita, Effects of conjugated substituents on the optical, electrochemical and electron-transporting properties of dithienosiloles, Organometallics, 20, 4800-4805 (2001). 

Fig. 17 Important silole-based building blocks are dibenzosilole (BS) and dithienosilole (TS)...

Fig. 43 Dithienosilole- and dibenzosilole-based homopolymers, their mono- and bithiophene...

---