Leary E, Höbenreich H, Higgins S J, van Zalinge H, Haiss W, Nichols R J, Finch C M, Grace I, Lambert C J, McGrath R, Smerdon J
Department of Chemistry, Liverpool University, Liverpool, L69 7ZD, United Kingdom.
Phys Rev Lett. 2009 Feb 27;102(8):086801. doi: 10.1103/PhysRevLett.102.086801. Epub 2009 Feb 23.
We present a new route to single-molecule sensing via solvation shells surrounding a current-carrying backbone molecule. As an example, we show that the presence of a water solvation shell "gates" the conductance of a family of oligothiophene-containing molecular wires, and that the longer the oligothiophene, the larger is the effect. For the longest example studied, the molecular conductance is over 2 orders of magnitude larger in the presence of a shell comprising just 10 water molecules. A first principles theoretical investigation of electron transport through the molecules, using the nonequilibrium Green's function method, shows that water molecules interact directly with the thiophene rings, significantly shifting transport resonances and greatly increasing the conductance. This reversible effect is confirmed experimentally through conductance measurements performed in the presence of moist air and dry argon.
我们提出了一种通过围绕载流主链分子的溶剂化壳层进行单分子传感的新途径。例如，我们表明水溶剂化壳层的存在“控制”了一类含寡聚噻吩分子线的电导，并且寡聚噻吩越长，这种效应越大。对于所研究的最长的例子，在仅包含10个水分子的壳层存在下，分子电导增大超过2个数量级。使用非平衡格林函数方法对通过这些分子的电子传输进行的第一性原理理论研究表明，水分子直接与噻吩环相互作用，显著改变传输共振并大大增加电导。通过在潮湿空气和干燥氩气存在下进行的电导测量，实验证实了这种可逆效应。
