Thionated PDI supramolecular polymers: controlling aggregation mechanisms, morphology and function

Abstract

Controlling the self-assembly of functional organic molecules provides opportunities to optimise the interlinked properties and structures of these materials for specific applications. Perylene diimide (PDI) derivative, PDI1, was used as a model monomer to investigate the effects of heteroatom substitution in supramolecular polymer systems. In addition to the previously reported optoelectronic effects (including shifted absorbance and quenched fluorescence), thionation was found to have a significant impact on the self-assembly behaviour of PDI1. The thionated analogues of this species displayed a diverse range of self-assembled morphologies, rationalised through changes in intermolecular interactions. Furthermore, thionation results in a transition from highly cooperative to isodesmic assembly mechanism. Such mechanistic control should also be applicable to many other supramolecular systems based on either hydrogen-bonding or π-stacking interactions, and presents an important route for the regulation of dynamic polymer properties. Finally, thionation was found to result in a substantial increase in conductivity recorded within analogous supramolecular polymer structures.