Substrate-induced self-assembly of donor–acceptor type compounds with terminal thiocarbonyl groups

• Two types of conjugated thiocarbonyl-terminated compounds have been synthesized
• It is proved that thiocarbonyl group is able to be chemisorbed to the gold surface
• Morphology of the films depends on the substrate material used
• Intermolecular interactions largely contribute to formation of the film morphology

Two types of conjugated thiocarbonyl-terminated compounds have been synthesized and their ability to be adsorbed on surfaces of the different nature, namely, glass, polytetrafluoroethylene (PTFE), and gold has been studied. Different morphology of the films prepared by thermal vacuum evaporation and drop-casting from solutions has been observed depending on the surface used. It has been found that gold surface has a unique property to influence self-assembly of both monolayer and larger aggregates or crystals of the compounds, in contrast to glass and PTFE substrates. It was found that thiocarbonyl group is able to be chemisorbed to the gold surface. However, it was concluded that in spite of the fact that the thiocarbonyl groups are important for the chemical interaction with the gold surface, physical adsorption on the substrate surface, compound–compound and compound–solvent (when using solution) interactions are of great significance to drive self-assembly of the final film.