Yiqun Zhang Penglei Chen* Lang Jiang Wenping Hu* and Minghua Liu*

Recently nanomaterials with unique morphologies have received great attention owing to their fascinating morphology-dependent properties. Such morphologically dependent properties play an important role in designing nanodevices. Organic nanosystems have peculiar electronic and optical properties and can render considerable variety and flexibility in the molecular design and tunability of physicochemical properties which make them promising candidates for nanodevices. Thus investigation on the morphology-dependent properties of organic nanosystems should be an important topic to be explored intensively.

The researchers of Institute of Chemistry the Chinese Academy of Sciences recently reported a controllable fabrication of supramolecular nanocoils and straight nanoribbons of an anthracene derivative (AN) and their morphologically dependent photoswitching. They found that when the Langmuir film of AN at the air/water interface was compressed nanocoils could be obtain at a lower surface pressure which could be transformed to straight nanoribbons when the surface pressure increased. Interestingly two-end devices based on the two types of nanostructures showed distinct photoswitching properties. While the nanocoils did not show the photocurrent response owning to the less efficient stacking of molecules the nanoribbons exhibited distinguished photocurrent which is switchable during the on/off process owing to the larger overlapping of molecular orbitals of -electrons which led to more efficient charge transport.

This investigation suggests that the interfacial organization of organic building blocks might provide a facile way to control the morphologies as well as the corresponding photoelectric properties of the ultrathin films.

J. Am. Chem. Soc. 2009 131 2756–2757