Huang Miao-Ling, Zhang Fan, Wang Chen, Zheng Ju-Fang, Mao Hui-Ling, Xie Hu-Jun, Shao Yong, Zhou Xiao-Shun, Liu Jin-Xuan, Zhuang Jin-Liang
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China.
Key Lab for Functional Materials Chemistry of Guizhou Province, School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001, China.
Micromachines (Basel). 2018 May 13;9(5):234. doi: 10.3390/mi9050234.
In this article, we have investigated the influence of the nitro side-group on the single molecular conductance of pyridine-based molecules by scanning tunneling microscopy break junction. Single molecular conductance of 4,4'-bipyridine (BPY), 3-nitro-4-(pyridin-4-yl)pyridine (BPY-N), and 3-nitro-4-(3-nitropyridin-4-yl)pyridine (BPY-2N) were measured by contact with Au electrodes. For the BPY molecular junction, two sets of conductance were found with values around 10 G₀ (high G) and 10 G₀ (low G). The addition of nitro side-group(s) onto the pyridine ring resulted in lower conductance of 10 G₀ for BPY-N and 10 G₀ for BPY-2N, respectively, which can be attributed to the twist angle of two pyridine rings. Moreover, the steric hindrance of nitro group(s) also affects the contacting configuration of electrode-molecule-electrode. As a consequence, only one set of conductance value was observed for BPY-N and BPY-2N. Our work clearly shows the important role of side-groups on the electron transport of single-molecule junctions.
在本文中，我们通过扫描隧道显微镜断结法研究了硝基侧基对吡啶基分子单分子电导的影响。通过与金电极接触测量了4,4'-联吡啶（BPY）、3-硝基-4-(吡啶-4-基)吡啶（BPY-N）和3-硝基-4-(3-硝基吡啶-4-基)吡啶（BPY-2N）的单分子电导。对于BPY分子结，发现了两组电导值，分别约为10G₀（高G）和10G₀（低G）。在吡啶环上添加硝基侧基分别导致BPY-N和BPY-2N的电导降低至10G₀和10G₀，这可归因于两个吡啶环的扭转角。此外，硝基的空间位阻也影响电极-分子-电极的接触构型。因此，对于BPY-N和BPY-2N仅观察到一组电导值。我们的工作清楚地表明了侧基在单分子结电子传输中的重要作用。
