Syntheses and Crystal Structures of Benzohexathia[7]helicene and Naphthalene Cored Double Helicene

Bis(trimethylsilyl)benzohexathia[7]helicene 1, naphthalene cored double helicene 2 (the fused dimer of 1), and a novel ten-membered cyclic diketone with four moieties of dithieno[2,3-b:3′,2′-d]thiophene (3) were efficiently synthesized. Their crystal structures were determined with single-crystal X-ray analysis. In their crystal packings, they all show mutiple short contacts including intermolecular π···π, π···S, and S···S interactions. UV/vis spectra indicate that significant π-electron delocalization existed in 1, 2, and 3.