Light-controlled formation of vesicles and supramolecular organogels by a cholesterol-bearing amphiphilic molecular switch. 
A new responsive material composed of an amphiphilic light-switchable dithienylethene unit functionalized with a hydrophobic cholesterol unit and a hydrophilic poly(ethylene glycol)-modified pyridinium group has been designed.  This unique single-molecule system shows responsive light-switchable self-assembly in both water and organic solvents.  Light-triggered reversible vesicle formation in aqueous solutions is reported.  The molecule shows a different behavior in apolar aromatic solvents, in which light-controlled formation of organogel fibers is observed.  The light-triggered aggregation behavior of this molecule demonstrates that control of a supramolecular structure with light can be achieved in both aqueous and organic media and that this ability can be present in a single molecule.  This opens the way toward the effective development of new strategies in soft nanotechnology for applications in controlled chemical release systems.