Probing the Conductance of the σ-System of Bipyridine Using Destructive Interference

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• 作者：Anders Borges ; E-Dean Fung ; Fay Ng ; Latha Venkataraman ; Gemma C. Solomon
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：December 1, 2016
• 年：2016
• 卷：7
• 期：23
• 页码：4825-4829
• 全文大小：335K
• ISSN：1948-7185

文摘

Guidelines to predict trends in the electrical conductance of molecules have been developed for the π-system of conjugated systems. Little is known, however, about the conductance of the underlying σ-systems because the π-system usually dominates the transport. Here we study a family of bipyridine-based molecules using STM-break junction experiments and density functional theory transport calculations. We use different lengths and substitution patterns to probe the role of both the σ-system and the π-system in controlling conductance. By exploiting the destructive interference feature found in the π-system of the meta-coupled six-membered aromatic rings, we show that the conductance of the σ-system of a meta-coupled molecule can be probed directly and can even exceed that of its para-coupled analog. These results add to the understanding of the conductance through the chemically hidden σ-electrons.