Centre for Nanoscale Science and Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
J Am Chem Soc. 2010 Jul 7;132(26):9157-64. doi: 10.1021/ja103327f.
The realization of molecular-scale electronic devices will require the development of novel strategies for controlling electrical properties of metal/molecule/metal junctions, down to the single molecule level. Here, we show that it is possible to exert chemical control over the formation of metal/molecule...molecule/metal junctions in which the molecules interact by pi-stacking. The tip of an STM is used to form one contact, and the substrate the other; the molecules are conjugated oligophenyleneethynylenes (OPEs). Supramolecular pi-pi interactions allow current to flow through the junction, but not if bulky tert-butyl substituents on the phenyl rings prevent such interactions. For the first time, we find evidence that pi-stacked junctions can form even for OPEs with two thiol contacts. Furthermore, we find evidence for metal|molecule|metal junctions involving oligophenyleneethynylene monothiols, in which the second contact must be formed by the interaction of the pi-electrons of the terminal phenyl ring with the metal surface.
实现分子尺度的电子器件需要开发新的策略来控制金属/分子/金属结的电性能，达到单分子水平。在这里，我们展示了可以对π堆叠相互作用的分子之间形成金属/分子/分子/金属结进行化学控制。STM 的尖端形成一个接触点，而衬底则形成另一个接触点；分子是共轭聚对苯乙炔（OPE）。超分子π-π相互作用允许电流通过结，但如果苯环上的大叔丁基取代基阻止了这种相互作用，则不会发生电流。我们首次发现证据表明，即使对于具有两个硫醇接触的 OPE，也可以形成π堆叠结。此外，我们发现证据表明涉及聚对苯乙炔单硫醇的金属|分子|金属结，其中第二个接触点必须通过末端苯基环的π电子与金属表面的相互作用形成。
