Figure 4.
Molecular conductance is measured in a STM break junction by monitoring current as the STM probe tip is moved away from the surface (top left). A donor-bridge-acceptor molecular rectifier exhibits an asymmetric I–V curve, also measured with STM (top center). Photodimerization of paired anthracene phenylene ethynylene derivatives isolated in a SAM is visualized with STM (top right). Adapted with permission from ref. 230. An isolated oligo(phenylene ethynylene) molecule inserted in a dodecanethiolate SAM on Au{111} undergoes reversible conductance switching (bottom left). Adapted with permission from ref. 19. Azobenzene inserted in a dodecanethiolate SAM undergoes reversible photoisomerization (bottom middle). Adapted with permission from ref. 15. The ring of a surface-bound rotaxane shuttles between two stations as the electrochemical potential in the cell is cycled from 0.1 V to 0.5 V (bottom right). Adapted with permission from ref. 171.