Department of Chemistry and ‡Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.
Nano Lett. 2014 May 14;14(5):2941-5. doi: 10.1021/nl5010702. Epub 2014 Apr 22.
We have designed and synthesized five azulene derivatives containing gold-binding groups at different points of connectivity within the azulene core to probe the effects of quantum interference through single-molecule conductance measurements. We compare conducting paths through the 5-membered ring, 7-membered ring, and across the long axis of azulene. We find that changing the points of connectivity in the azulene impacts the optical properties (as determined from UV-vis absorption spectra) and the conductivity. Importantly, we show here that simple models cannot be used to predict quantum interference characteristics of nonalternant hydrocarbons. As an exemplary case, we show that azulene derivatives that are predicted to exhibit destructive interference based on widely accepted atom-counting models show a significant conductance at low biases. Although simple models to predict the low-bias conductance do not hold with all azulene derivatives, we demonstrate that the measured conductance trend for all molecules studied actually agrees with predictions based on the more complete GW calculations for model systems.
我们设计并合成了五个含金结合基团的薁衍生物，这些基团在薁核的不同连接点上，以通过单分子电导测量来探测量子干涉的影响。我们比较了通过五元环、七元环和薁长轴的传导路径。我们发现改变薁中的连接点会影响光学性质（由紫外-可见吸收光谱确定）和电导率。重要的是，我们在这里表明，简单的模型不能用于预测非交替烃的量子干涉特性。作为一个典型的例子，我们表明，根据广泛接受的原子计数模型预测会表现出相消干涉的薁衍生物在低偏压下显示出显著的电导。尽管简单的模型无法预测所有薁衍生物的低偏压电导，但我们证明，所有研究分子的测量电导趋势实际上与基于模型系统的更完整 GW 计算的预测一致。
