当前位置：
X-MOL 学术
›
J. Phys. Chem. C
›
论文详情
Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Enantioselective Effects in the Electrical Excitation of Amine Single-Molecule Rotors
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-02-05 , DOI: 10.1021/acs.jpcc.0c10767 Tedros A. Balema 1 , Yilang Liu 2 , Natalie A. Wasio 1 , Amanda M. Larson 1 , Dipna A. Patel 1 , Prashant Deshlahra 2 , E. Charles H. Sykes 1
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-02-05 , DOI: 10.1021/acs.jpcc.0c10767 Tedros A. Balema 1 , Yilang Liu 2 , Natalie A. Wasio 1 , Amanda M. Larson 1 , Dipna A. Patel 1 , Prashant Deshlahra 2 , E. Charles H. Sykes 1
Affiliation
|
This paper describes a single-molecule study of N-methylbutylamine molecular rotors supported on a Cu(111) surface. It is first demonstrated that the chirality of the individual rotating molecules can be directly determined by scanning tunneling microscopy (STM) imaging and understood with density functional theory (DFT) simulations. Tunneling electrons from the STM tip are then utilized to excite vibrational modes of the molecule that drives the rotational motion. Experimental action spectra were used to demonstrate that the electrically induced rotational motion of N-methylbutylamine occurs above 360 meV, which coincides with C–H stretching vibrational modes. The measurements also reveal that, above this 360 meV threshold, the excitation occurs via a one-electron process. DFT calculations indicated that the rotation barrier is over an order of magnitude smaller, meaning that the rotor is excited via high-energy vibrational modes that then couple to the low energy rotational mode. Furthermore, by adjusting the electron flux, individual rotational motions between the six different stable orientations of the molecule on the Cu(111) surface were monitored in real time. It was found that, for most STM tips used to electrically excite the rotors, the rotation of one enantiomer is faster than the other. This confirms an earlier report that STM tips can themselves be chiral and illustrates the fact that diastereomerism arising from a chiral STM tip interacting with a chiral molecule can lead to significant physical differences in the rotation rates of R versus S molecular rotors. This result has ramifications for interpreting the data from experiments where nanoscale electrical contacts to chiral molecules are made in devices like break junctions and scanning probe experiments.
中文翻译：
胺单分子转子电激发中的对映选择性作用
本文介绍了支持在Cu（111）表面上的N-甲基丁胺分子转子的单分子研究。首先证明了单个旋转分子的手性可以通过扫描隧道显微镜（STM）成像直接确定，并可以通过密度泛函理论（DFT）模拟来理解。然后，利用来自STM尖端的隧穿电子来激发驱动旋转运动的分子的振动模式。实验作用谱用于证明N-甲基丁胺的电感应旋转运动发生在360 meV以上，这与C–H拉伸振动模式一致。测量结果还表明，在此360 meV阈值以上，通过单电子过程。DFT计算表明，旋转势垒小了一个数量级，这意味着转子通过高能振动模式被激励，然后耦合到低能旋转模式。此外，通过调节电子通量，可以实时监视Cu（111）表面上分子的六个不同稳定取向之间的单个旋转运动。已发现，对于大多数用于电激励转子的STM尖端，一种对映体的旋转要快于另一种。这证实了较早的报道，即STM尖端本身可以是手性的，并说明了一个事实，即由手性STM尖端与手性分子相互作用而产生的非对映异构现象可能导致其旋转速率出现明显的物理差异。R与S分子转子。该结果对解释实验中的数据有影响，其中在断开连接和扫描探针实验等设备中与手性分子进行了纳米级电接触。
更新日期：2021-02-18
中文翻译：
胺单分子转子电激发中的对映选择性作用
本文介绍了支持在Cu（111）表面上的N-甲基丁胺分子转子的单分子研究。首先证明了单个旋转分子的手性可以通过扫描隧道显微镜（STM）成像直接确定，并可以通过密度泛函理论（DFT）模拟来理解。然后，利用来自STM尖端的隧穿电子来激发驱动旋转运动的分子的振动模式。实验作用谱用于证明N-甲基丁胺的电感应旋转运动发生在360 meV以上，这与C–H拉伸振动模式一致。测量结果还表明，在此360 meV阈值以上，通过单电子过程。DFT计算表明，旋转势垒小了一个数量级，这意味着转子通过高能振动模式被激励，然后耦合到低能旋转模式。此外，通过调节电子通量，可以实时监视Cu（111）表面上分子的六个不同稳定取向之间的单个旋转运动。已发现，对于大多数用于电激励转子的STM尖端，一种对映体的旋转要快于另一种。这证实了较早的报道，即STM尖端本身可以是手性的，并说明了一个事实，即由手性STM尖端与手性分子相互作用而产生的非对映异构现象可能导致其旋转速率出现明显的物理差异。R与S分子转子。该结果对解释实验中的数据有影响，其中在断开连接和扫描探针实验等设备中与手性分子进行了纳米级电接触。
京公网安备 11010802027423号