2,5-Distyryl-dithieno[2,3-b:2′,3′-d]thiophene (DEP-bt-DTT), an isomer of 2,5-distyryl-dithieno [2,3-b:3′,2′-d]thiophene (DEP-bb-DTT) and 2,5-distyryl-dithieno[3,2-b:2′,3′-d]thiophene (DEP-tt-DTT), was synthesized. Organic field-effect transistors (OFETs) based on these three isomers were fabricated. The structure cell parameters and the formation of intermolecular interactions in their single crystals show regular change when the positions of sulphur atoms vary from top–bottom–top in DEP-tt-DTT to bottom–bottom–top in DEP-bt-DTT, then to bottom–bottom–bottom in DEP-bb-DTT. Combining the results of theoretical calculations and OFET performances, it reveals that: (1) the positions of sulphur atoms determine the contribution extent of sulphur atoms to the molecular conjugation and the formation of intermolecular interactions; (2) the existence of the intermolecular interactions, especially for S–π, benefits for the charge transport; (3) the field-effect mobility (μ) increases with increasing of the sulphur atom contribution to the molecular conjugation.

Based on dithieno[2,3-b:2′,3′-d]thiophene, three novel helicenes including helicene (rac-1), double helicene (rac-2), and benzohexathia[7]helicene (rac-3), and one bull's horn-shaped benzohexathienoacene (4) have been synthesized and reported in this paper. In the helicenes, the sulfur atoms of terminal thiophenes are inside the helical structures. X-ray crystallographic analysis exhibited the helical configuration of rac-1 and the bull's horn-shaped configuration of 4. Multiple types of intermolecular interactions, including S⋯S, C⋯C and π⋯π interactions, were observed between the adjacent molecules in the crystals of rac-1 and 4. In addition, a remarkable bathochromic shift was found in the absorption behaviors for rac-3 and 4 compared to rac-1; the integrated absorbance in rac-2 is approximately twice that of rac-1.

The novel propeller type compound, 2,4,6-tri(anthracen-9-yl)-1,3,5-triazine (TAT) with C₃ symmetry was synthesized by using 9-anthryl lithium with 1,3,5-trichlorotriazine or 2-chloro-4,6-dimethoxy-1,3,5-triazine in the presence of palladium catalyst in 22–48% yield. Another two propeller-like compounds, 2-(anthracen-9-yl)-4,6-dimethoxy-1,3,5-triazine (3) and 2,4-di(anthracen-9-yl)-6-methoxy-1,3,5-triazine (4) were obtained at the same time. The propeller type structures of TAT, 3 and 4 were confirmed by crystal analysis and theoretical calculations. The intramolecular C–C bond rotations between the anthryl groups and the triazine units in molecules TAT, 3 and 4 were regarded as the key factor to understand their spectroscopic behaviors in fluid medium and rigid solution.