Solvent-assisted conformational interconversion of an organic semiconductor with multiple non-covalent interactions

The conformational isomerism originated from the rotation of single bonds significantly affects the properties of conjugated molecules. However, the relatively low energy barrier of the rotation of single bonds often renders a dynamic equilibrium of multiple conformers, raising the challenges of distinguishing the accurate conformation and controlling the conformational interconversion. Here, multiple non-covalent interactions induced by the fluorine atom are introduced into the conjugated molecule to generate two metastable rotamers. The interconversion is readily controlled by solvent, wherein tetrahydrofuran and chloroform show split trends. The isomerically pure powder can be obtained from appropriate solutions. Furthermore, the film-formation process hardly affects the conformation because of the multiple non-covalent interactions. Eventually, this work unravels the effect of rotational isomerisms on optoelectronic properties in thin-film-based devices, paving the way to tune the performance of organic semiconductors by controlling the molecular conformation with multiple non-covalent interactions.