Fu Tianren, Smith Shanelle, Camarasa-Gómez María, Yu Xiaofang, Xue Jiayi, Nuckolls Colin, Evers Ferdinand, Venkataraman Latha, Wei Sujun
Department of Chemistry , Columbia University , New York , New York 10027 , USA . Email:
Department of Chemistry , Queensborough Community College of the City University of New York , Bayside , New York 11364 , USA . Email:
Chem Sci. 2019 Sep 16;10(43):9998-10002. doi: 10.1039/c9sc03760h. eCollection 2019 Nov 21.
We demonstrate that imidazole based π-π stacked dimers form strong and efficient conductance pathways in single-molecule junctions using the scanning-tunneling microscope-break junction (STM-BJ) technique and density functional theory-based calculations. We first characterize an imidazole-gold contact by measuring the conductance of imidazolyl-terminated alkanes (, = 3-6). We show that the conductance of these alkanes decays exponentially with increasing length, indicating that the mechanism for electron transport is through tunneling or super-exchange. We also reveal that π-π stacked dimers can be formed between imidazoles and have better coupling than through-bond tunneling. These experimental results are rationalized by calculations of molecular junction transmission using non-equilibrium Green's function formalism. This study verifies the capability of imidazole as a Au-binding ligand to form stable single- and π-stacked molecule junctions at room temperature.
我们利用扫描隧道显微镜-断结（STM-BJ）技术和基于密度泛函理论的计算表明，基于咪唑的π-π堆积二聚体在单分子结中形成了强大而高效的导电通路。我们首先通过测量咪唑基封端的烷烃（， = 3 - 6）的电导来表征咪唑-金接触。我们表明，这些烷烃的电导随长度增加呈指数衰减，这表明电子传输机制是通过隧穿或超交换。我们还揭示了咪唑之间可以形成π-π堆积二聚体，并且比通过键隧穿具有更好的耦合。这些实验结果通过使用非平衡格林函数形式的分子结传输计算得到了合理的解释。这项研究验证了咪唑作为金结合配体在室温下形成稳定的单分子和π堆积分子结的能力。
