Reversible cis-trans Isomerization of a Single Azobenzene Molecule

摘要

Since isomers may differ substantially in physical and chemical properties, isomerization offers the possibility of converting less desirable compounds into isomers with desirable properties. The isomerization of dye molecules, such as derivatives of azobenzene (C6H5NNC6H5), has attracted much attention owing to the high potential of these compounds for applications in optoelectronic devices, for example, optical memory, photooptical switches, and displays.[1] Azobenzene has been used as a photoregulator to form or dissociate a duplex that regulates the geometry and function of biomolecules.[2] Azobenzene undergoes a reversible light-induced conformational transition of the NN double bond between an extended (trans) and a compact (cis) conformation in the gas phase and in solution.[1] In nature, specific functions are frequently realized with the aid of such cis-trans isomerization reactions of molecules. Here we describe the cis-trans isomerization of individual molecules of the azobenzene derivative Disperse Orange 3 on Au(111) triggered by tunneling electrons. Inducing chemical reactions of specific single molecules is one intriguing aspect. In a more general context, the understanding and control of molecular functions on a single-molecule level is essential in nanoscale science.[3]