Enhanced coupling through π-stacking in imidazole-based molecular junctions
Enhanced coupling through π-stacking in imidazole-based molecular junctions
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DOI：
10.1039/c9sc03760h
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发表时间：
2019-11-21
期刊：
影响因子：
8.4
通讯作者：
Wei, Sujun
中科院分区：
文献类型：
--
作者：
Fu, Tianren;Smith, Shanelle;Wei, Sujun
我们利用扫描隧道显微镜-断裂结(STM-BJ)技术和基于密度泛函理论的计算，证明了咪唑基的pi-pi堆积二聚体在单分子结中形成了强大而有效的电导通道。我们首先通过测量咪唑基末端烷烃(im-N-im，N=3-6)的电导来表征咪唑-金接触。结果表明，这些烷烃的电导随长度的增加呈指数衰减，表明电子输运机制是通过隧穿或超交换。我们还揭示了pi-pi堆积二聚体可以在咪唑之间形成，并且比通键隧穿具有更好的耦合能力。用非平衡态格林函数理论对分子结传输进行了计算，验证了实验结果的合理性。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层和pi堆积分子结的能力。
We demonstrate that imidazole based pi-pi 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 (im-N-im, N = 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 pi-pi 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 pi-stacked molecule junctions at room temperature.