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Gold-Carbon Contacts from Oxidative Addition of Aryl Iodides
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-03-26 , DOI: 10.1021/jacs.0c01466
Rachel L. Starr , Tianren Fu , Evan A. Doud , Ilana Stone , Xavier Roy , Latha Venkataraman

Aryl halide are ubiquitous functional groups in organic chemistry, yet despite their obvious appeal as surface-binding linkers and as precursors for controlled graphene nanoribbon synthesis, they have seldom been used as such in molecular electronics. The confusion regarding the bonding of aryl iodides to Au electrodes is a case in point, with ambiguous reports of both dative Au-I and covalent Au-C contacts. Here we form single-molecule junctions with a series of oligophenylene molecular wires terminated asymmetrically with iodine and thiomethyl to show that the dative Au-I contact has a lower conductance than the covalent Au-C interaction, which we propose occurs via an in situ oxidative addition reaction at the Au surface. Furthermore, we confirm the formation of the Au-C bond by measuring an analogous series of molecules prepared ex situ with the complex AuI(PPh3) in place of the iodide. Density functional theory-based transport calculations support our experimental observations that Au-C linkages have higher conductance than Au-I linkages. Finally, we demonstrate selective promotion of the Au-C bond formation by controlling the bias applied across the junction. In addition to establishing the different binding modes of aryl iodides, our results chart a path to actively controlling oxidative addition on an Au surface using an applied bias.

中文翻译:

芳基碘氧化加成的金-碳接触

芳基卤是有机化学中无处不在的官能团,尽管它们作为表面结合连接剂和受控石墨烯纳米带合成的前体具有明显的吸引力,但它们很少被用于分子电子学。关于芳基碘化物与 Au 电极键合的混淆就是一个很好的例子,关于配价 Au-I 和共价 Au-C 接触的报道含糊不清。在这里,我们使用一系列以碘和硫甲基不对称终止的低聚亚苯基分子线形成单分子连接,以表明与共价 Au-C 相互作用相比,配价 Au-I 接触具有更低的电导,我们建议通过原位氧化反应发生。 Au表面的加成反应。此外,我们通过测量用复合物 AuI(PPh3) 代替碘化物制备的一系列类似分子来确认 Au-C 键的形成。基于密度泛函理论的输运计算支持我们的实验观察结果,即 Au-C 连接比 Au-I 连接具有更高的电导率。最后,我们证明了通过控制施加在结上的偏压来选择性促进 Au-C 键的形成。除了建立芳基碘化物的不同结合模式外,我们的结果还绘制了一条使用偏置主动控制 Au 表面氧化加成的途径。我们通过控制施加在结上的偏压来证明选择性促进 Au-C 键的形成。除了建立芳基碘化物的不同结合模式外,我们的结果还绘制了一条使用偏置主动控制 Au 表面氧化加成的途径。我们通过控制施加在结上的偏压来证明选择性促进 Au-C 键的形成。除了建立芳基碘化物的不同结合模式外,我们的结果还绘制了一条使用偏置主动控制 Au 表面氧化加成的途径。
更新日期:2020-03-26
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