Skipper Hannah E, Lawson Brent, Pan Xiaoyun, Degtiareva Vera, Kamenetska Maria
Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States.
Department of Physics, Boston University, Boston, Massachusetts 02215, United States.
ACS Nano. 2023 Aug 22;17(16):16107-16114. doi: 10.1021/acsnano.3c04963. Epub 2023 Aug 4.
Understanding and manipulating quantum interference (QI) effects in single molecule junction conductance can enable the design of molecular-scale devices. Here we demonstrate QI between σ and π molecular orbitals in an ∼4 Å molecule, pyrazine, bridging source and drain electrodes. Using single molecule conductance measurements, first-principles analysis, and electronic transport calculations, we show that this phenomenon leads to distinct patterns of electron transport in nanoscale junctions, such as destructive interference through the para position of a six-membered ring. These QI effects can be tuned to allow conductance switching using environmental pH control. Our work lays out a conceptual framework for engineering QI features in short molecular systems through synthetic and external manipulation that tunes the energies and symmetries of the σ and π channels.
理解并操控单分子结电导中的量子干涉（QI）效应能够实现分子尺度器件的设计。在此，我们展示了在一个约4 Å的分子——吡嗪中，σ和π分子轨道之间的量子干涉，该分子连接着源电极和漏电极。通过单分子电导测量、第一性原理分析以及电子输运计算，我们表明这种现象会导致纳米级结中独特的电子输运模式，比如通过六元环对位的相消干涉。这些量子干涉效应可以通过环境pH值控制进行调节，以实现电导切换。我们的工作通过合成和外部操控来调节σ和π通道的能量与对称性，为在短分子系统中设计量子干涉特性奠定了概念框架。
