Controlling Molecular Switching via Chemical Functionality: Ethyl vs Methoxy Rotors
Controlling Molecular Switching via Chemical Functionality: Ethyl vs Methoxy Rotors
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通过化学官能团控制分子开关：乙基与甲氧基转子
DOI：
10.1021/acs.jpcc.9b06664
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Groden, Kyle
中科院分区：
文献类型：
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作者：
Balema, Tedros A.;Ulumuddin, Nisa;Murphy, Colin J.;Slough, Diana P.;Smith, Zachary C.;Hannagan, Ryan T.;Wasio, Natalie A.;Larson, Amanda M.;Patel, Dipna A.;Groden, Kyle
表面束缚分子旋转体为在单分子水平上研究分子运动的结构和动力学提供了一种有用的方法。然而，当大多数分子吸附在金属表面时，它们与金属的相互作用会极大地改变它们的性质，使得先验设计变得不可能。我们报道了一种情况，当一类分子转子附着在表面上时，对其稳定取向的气相预测是成立的。这种可转移性是通过将分子转子部分安装在作为表面催化的1-溴-4-乙苯和1-溴-4-甲氧基苯的Ullmann偶联反应中间体的金属-有机络合物上实现的。气相计算表明，当乙基分子转子垂直于苯环取向时最稳定，而甲氧基转子的稳定取向与苯环平行。我们的STM成像结果证实了这一行为，甲氧基转子表现出与表面在平面内的切换，而乙基转子则相对于表面切换到平面外。此外，这两个转子表现出不同的旋转激励特性。作用谱测量表明，虽然乙基转子的旋转过程的直接激励阈值电压与旋转势垒相同(45 MeV)，但甲氧基转子所需的外加电压(300 MV)明显大于气相中甲氧基苯的128 meV扭转势垒。密度泛函理论(DFT)对甲氧基苯分子在铜(111)面上的计算表明，虽然与铜(111)面的相互作用没有改变甲氧基转子的择优取向，但转动势垒提高到246 meV，与实验观察到的结果更接近。这项研究基于分子转子的化学性质及其与表面的相互作用，深入了解了决定分子转子动力学的因素。
Surface-bound molecular rotors provide a useful way to study the structure and dynamics of molecular motion at the single-molecule level. However, when most molecules adsorb on a metal surface, their interaction with the metal changes their properties dramatically, making a priori design impossible. We report a case in which gas-phase predictions of the stable orientations of a class of molecular rotors hold true when they are attached to a surface. This transferability is achieved by mounting the molecular rotor moiety on a metal–organic complex formed as an intermediate in the surface-catalyzed Ullmann coupling reaction of 1-bromo-4-ethylbenzene versus 1-bromo-4-methoxybenzene. Gas-phase calculations predict that, while the ethyl molecular rotor is most stable when oriented perpendicular to the phenyl ring, the methoxy rotor’s stable orientation is in plane with the phenyl ring. Our STM imaging results confirm this behavior, with the methoxy rotor exhibiting switching in plane with the surface versus the ethyl rotor, which switches out of plane with respect to the surface. Furthermore, the two rotors exhibit different rotational excitation characteristics. Action spectra measurements reveal that, while the threshold voltage for direct excitation of the rotational process of the ethyl rotor is identical to the rotational barrier (45 meV), the methoxy rotors require a significantly larger applied voltage (300 mV) than the 128 meV torsional barrier calculated for methoxybenzene in the gas phase. Density functional theory (DFT) calculations of a methoxybenzene molecule on Cu(111) reveal that, while interaction with the Cu(111) surface does not change the preferred orientations of the methoxy rotor, the barrier for rotation is raised to 246 meV, which is much closer to that observed experimentally. This study offers insight into the factors determining the dynamics of molecular rotors based on both the chemical nature of the rotor and its interaction with the surface.
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DOI：
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发表时间：
1968
期刊：
影响因子：
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作者：
I. Degen
通讯作者：
I. Degen
吸附到 Ag(111) 表面的苯衍生物：结合位点和电子结构。
DOI：
10.1063/1.4908267
发表时间：
2015
期刊：
The Journal of chemical physics
影响因子：
--
作者：
Daniel P. Miller;S. Simpson;Nina Tymińska;E. Zurek
通讯作者：
E. Zurek
Cu(111) 上卤代苯和苯基的 NEXAFS 研究
影响因子：
1.9
作者：
Michael X. Yang;M. Xi;Haojie Yuan;B. Bent;P. Stevens;J. White
通讯作者：
J. White
影响因子：
4.4
作者：
Carrasco, Javier;Liu, Wei;Tkatchenko, Alexandre
通讯作者：
Tkatchenko, Alexandre
运动中的化学——单向旋转分子马达。
影响因子：
--
作者：
Christian P. Mandl;B. König
通讯作者：
B. König