Highly conductive 40-nm-long molecular wires assembled by stepwise incorporation of metal centres

One of the main goals of molecular electronics is to achieve electronic functions from devices consisting of tailored organic molecules connecting two metal electrodes. The fabrication of nm scale spaced electrodes still results in expensive, and often scarcely reproducible devices1 4. On the other side, the “conductance” of long organic molecules - generally dominated by tunneling mechanism - is very poor5-9. Here, we show that by incorporating of a large number of metal centres (MCs) into rigid molecular backbones, we can obtain very long (up to 40 nm) and highly “conductive” molecular wires (MWs). The MCMWs are assembled “in situ” on metal surfaces via a sequential step wise coordination of metal ions by terpyridine-based ligands10,11. They form highly ordered molecular films of elevated mechanical robustness. The electrical properties, characterized by a junction based on Hg electrodes5,6, indicate that the “conductance” of these MCMWs, i) does not decrease significantly even for very long MWs, and ii) depends on the nature of the incorporated redox centre. The outstanding electrical and mechanical characteristics of these easy-to-assemble molecular systems open the door to a new generation of MWs, able to bridge large gap electrodes, and to form robust films for organic electronics.