2,5-Di(trimethylsilanyl)dithieno[2,3-b:3′,2′-d]thiophene ((TMS)2-bb-DTT), 2,5- di(trimethylsilanyl)diseleno[2,3-b:3′,2′-d]thiophene ((TMS)2-bb-DST), and 2,5- di(trimethylsilanyl)diseleno[2,3-b:3′,2′-d] selenophene ((TMS)2-bb-DSS) were used as starting materials to synthesize three S-shaped double helicenes (i. e., DH-1, DH-2, and DH-3) through monobromination, formylation, the Wittig reaction, and double oxidative photocyclization. Photocyclization was a highly regioselective process. The molecular structures of DH-1 and DH-2 were confirmed by X-ray single-crystal analysis. Multiple intermolecular interactions, such as C-S, C-Se, S-S, S-Se, and Se-Se, were observed in the crystal packing structures of these compounds. Spectroscopic results and our previous work showed that the combination of molecular structure change and heteroatom replacement from S to Se could precisely modulate molecular energy levels.
Keywords: thiophene; selenophene; double helicene; regioselective synthesis; crystal structure
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Wang, M.; Dang, L.; Xu, W.; Ma, Z.; Shao, L.; Wang, G.; Li, C.; Wang, H. Beilstein Arch. 2022, 202229. doi:10.3762/bxiv.2022.29.v1
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