Supramolecular Networks and Wires Dominated by Intermolecular BiEDOT Interactions

The ditopic ligand bpy-PE2P-bpy self-assembles on surfaces and has been investigated by high resolution scanning tunneling microscopy. The molecule shows a cis-to-trans isomerization from its bipyridine terminal units, whereas the biEDOT central bridge is always locked in its trans conformation thanks to the intramolecular sulfur-oxygen interactions. The cis-bpy-PE2P-bpy conformers form linear supramolecular stripe and herringbone structures. Upon protonation, they are transformed to the trans conformers which form both a zigzag structure and different supramolecular wires of variable width. Long single molecular wires can be easily obtained. In the various supramolecular organizations, the intermolecular hydrogen bonds between the bipyridine units vary. On the contrary, the biEDOT moieties are always aligned in a similar way as that observed in crystallized PEDOT nanofibrils and the intermolecular biEDOT interactions remain identical. Our work contributes to the understanding of the impact of EDOT-EDOT interactions on the properties of organic and molecular devices.