Nanostructures that undergo well-defined shape changes when exposed to light could have applications as actuators or as components of nanoscale machines.  Photochemically reactive molecules can self-assemble into molecular crystals.  By controlling crystallization conditions, the size and shape of these crystals can be controlled.  When these crystals are exposed to light, the oriented molecules undergo photochemical reactions that can drive dynamic shape changes of the crystal.  If the photochemical reaction is reversible, the overall shape changes can also be reversible.  Using a variety of methods, we prepare different classes of single crystal shapes, including nanowires, micro-ribbons, and micro-needles, all composed of photoreactive molecules.  Depending on the nature of the photochemical reaction, the shape of the crystal, and the orientation of the molecules within the shaped crystal, different types of motions can be induced by photoexcitation, including expansion, bending, twisting, and curling.

Photoresponsive self-assembled organic nanostructures

246th National Meeting (2013)

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