National Institute of Advanced Industrial Science and Technology (AIST) , Research Center for Computational Design of Advanced Functional Materials (CD-FMat), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568, Japan.
Center for Bioelectronics and Biosensors, Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States.
J Am Chem Soc. 2017 Mar 1;139(8):2989-2993. doi: 10.1021/jacs.6b10837. Epub 2017 Jan 18.
Using two tetraphenylbenzene isomers differing only by the anchoring points to the gold electrodes, we investigate the influence of quantum interference on the single molecule charge transport. The distinct anchor points are realized by selective halogen-mediated binding to the electrodes by formation of surface-stabilized isomers after iodine cleavage. Both isomers are essentially chemically identical and only weakly perturbed by the electrodes avoiding largely parasitic effects, which allows us to focus solely on the relation between quantum interference and the intrinsic molecular properties. The conductance of the two isomers differs by over 1 order of magnitude and is attributed to constructive and destructive interference. Our ab initio based transport calculations compare very well with the accompanying scanning tunneling microscope break junction measurements of the conductance. The findings are rationalized using a two level model, which shows that the interorbital coupling plays the decisive role for the interference effects.
使用两种仅在锚定点上有所不同的四苯乙烯异构体与金电极相连，我们研究了量子干涉对单分子电荷输运的影响。通过碘裂解后形成的表面稳定异构体，通过选择性卤介导与电极结合，实现了明显不同的锚定点。两种异构体在化学上基本相同，仅受电极的轻微干扰，从而避免了大量寄生效应，这使我们能够专注于量子干涉与内在分子特性之间的关系。两种异构体的电导相差一个数量级以上，这归因于建设性和破坏性干涉。我们基于从头算的输运计算与伴随的扫描隧道显微镜断键测量的电导非常吻合。使用两能级模型对这些发现进行了合理化解释，该模型表明轨道间耦合对于干涉效应起着决定性的作用。
