Curved Amphipathic Oligothiophenes

Abstract

We have designed and synthesised a new class of molecules which self-assemble based on hydrophobic interactions with an additional driving force for influencing the overall aggregate morphology, namely, molecular curvature. The structure is build from subunits which are substituted with either hydrophilic or hydrophobic substituents. In water, the different substituents on the connected sub-units of the molecule reorient and create a curved structure. This curvature is an additional tool to direct the self-assembly process and it was found that indeed the conventional packing of the molecules can be “disturbed” by the implementation of this curvature. The backbone itself is build from a conjugated oligothiophene structure and therefore it possesses electronic- and photo-physical properties in the form of conductivity, the ability to absorb and emit photonic energy and the ability to have electronic interactions with other electronically active molecular species. These properties have been utilised for the fabrication of self-assembled light harvesting systems in water which not only displayed energy transfer and transport but also charge separation which is a key component in converting solar energy into a useful form of energy. Also the curvature could be utilised as a surface sensor in aqueous systems by changes in the curved molecular structure which could be read in the form of fluorescence output.