Observation of Electrochemically Controlled Quantum Interference in a Single Anthraquinone-Based Norbornylogous Bridge Molecule
Observation of Electrochemically Controlled Quantum Interference in a Single Anthraquinone-Based Norbornylogous Bridge Molecule
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DOI：
10.1002/anie.201107765
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发表时间：
2012-01-01
影响因子：
16.6
通讯作者：
Paddon-Row, Michael N.
中科院分区：
文献类型：
--
作者：
Darwish, Nadim;Diez-Perez, Ismael;Paddon-Row, Michael N.
人们对从基本角度和单分子技术中的潜在应用来了解单分子的电学特性有着相当大的兴趣。[1-4]分子电子学的一个重要目标是能够通过电化学门控来切换单个分子的电导，在这种情况下，蒽醌/氢蒽醌、AQ/H2AQ、氧化还原电对已被提议作为合适的研究候选者。[5]事实上，计算 [6] 预测基于 AQ 的分子开关中电导的电化学门控应该很强，电导开 (H2AQ)/关 (AQ) 比率达到几个数量级。这种切换机制是由于交叉共轭 AQ 中各个电导通道之间存在破坏性量子干涉 (QI)，而线性共轭 H2AQ 中不存在这种情况，从而导致 AQ 的电导率低于 H2AQ。最近，Fracasso 等人[7]已经通过实验证实了 QI 在芳基乙炔基硫醇盐（芳基=蒽，AQ，9, 10-二氢蒽）的自组装单层（SAM）的整体电导研究中的运行。[7]我们现在报告了电化学控制 QI 在新型基于 AQ 的降冰片桥四硫醇 5AQ5（方案 1）中运行的第一个实验证据，来自使用扫描隧道显微镜 (STM) 断裂连接技术进行单分子电导测量。[8]我们证明 5AQ5 中的 AQ 部分可以在
There is considerable ongoing interest in understanding the electrical properties of single molecules both from a fundamental point of view and for potential applications in singlemolecule technologies.[1–4] An important goal in molecular electronics is the ability to switch, by means of electrochemical gating, the conductance through a single molecule and, in this context, the anthraquinone/hydroanthraquinone, AQ/H2AQ, redox couple has been proposed as a suitable candidate for study.[5] Indeed, calculations [6] predict that electrochemical gating of conductance in AQ-based molecular switches should be strong, with conductance on (H2AQ)/off (AQ) ratios of several orders of magnitude. The switching mechanism is due to the presence of destructive quantum interference (QI) between various conductance channels in the cross-conjugated AQ, which is absent in the linearconjugated H2AQ, thereby resulting in lower conductance in AQ, compared to H2AQ. Recently, Fracasso etal.[7] have experimentally confirmed the operation of QI in bulk conductance studies of self-assembled monolayers (SAMs) of arylethynylene thiolates (aryl= anthracene, AQ, 9, 10-dihydroanthracene).[7]We now report the first experimental evidence for the operation of electrochemically controlled QI in a novel AQ-based norbornylogous bridge tetrathiol, 5AQ5 (Scheme 1), from single-molecule conductance measurements using the scanning tunneling microscopy (STM) break junction technique.[8] We show that the AQ moiety in 5AQ5 can be electrochemically and reversibly switched in situ between the