Assembly and Fiber Formation of a Gemini-Type Hexathienocoronene Amphiphile for Electrical Conduction

We report the synthesis, characterization, and self-assembly of a new gemini-type amphiphilic hexathienocoronene (HTCGemini), which owes its amphiphilicity to two hydrophobic dodecyl chains on one side of the HTC core and two hydrophilic triethylene glycol (TEG) chains on the other. Bearing a "softer" aromatic HTC core than the conventional hexa-peri-hexabenzocoronenes (HBC), and being more planar than contorted-hexabenzocoronenes (C-HBC), HTCGemini is demonstrated to yield various well-ordered assemblies in solution, at the liquid solid interface, and in solid state by the use of different processing techniques. Regular fibers, helices, and tubes can be formed simply by processing from different solvents. At the liquid solid interface, as visualized by scanning tunneling microscopy (STM), pairs of molecules adsorb very close to each other and arrange in the p2 plane group, driven by packing constraints and weak van der Waals interactions between adjacent molecules. HTCGemini also exhibits phase forming behavior in the bulk upon thermal treatment, resulting in a crystalline, herringbone-like columnar structure. Owning to an electron enriched aromatic core with respect to other reported coronenes, HTCGemini easily forms a stable radical cation, both in solution and in the bulk, upon oxidative doping with nitrosonium tetrafluoroborate (NOBF4). Furthermore, light irradiation of the blend film of HTCGemini and phenyl-C-61-butyric acid methyl ester (PCBM) generates a prominent photocurrent which can be switched repeatedly with a large on/off ratio (6.0 x 10(4)). The self-assembled structures obtained from HTCGemini at different length scales have potential applications in optoelectronic devices, solar cells, and redox sensors.