Nanoparticle networks as chemoselective sensing devices.

We theoretically analyzed transport properties of a molecular network constructed of gold nanoparticles linked with oligophenylenevinulene (OPV) molecules. We showed that the conductance of such system was strongly reduced when trinitrotoluene (TNT) became attached to the OPV linkers in the network. The reported results are based on the ab initio electronic structure calculations. These results corroborate and elucidate experiments which revealed significant drops in the conductance the network while the latter was exposed to TNT vapors. The results suggest that the detected sensitivity of transport characteristics of the considered nanoparticle network to TNT may be used to design a sensing nanodevice.

Electrochemically controlled conductance switching in a single molecule: quinone-modified oligo(phenylene vinylene).

Reversible conductance switching in single quinone-oligo(phenylene vinylene) (Q-OPV) molecules was demonstrated using electrochemical STM. The switching was achieved by application of electrochemical potential to the substrate supporting the molecule. The ratio of conductances between the high- and low-conductivity states is over 40. The high-conductivity state is ascribed to strong electron delocalization of the fully conjugated hydroquinone-OPV structure, whereas the low-conductivity state is characterized by disruption of electron delocalization in the quinone-OPV structure.