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从实验验验证的分子动力学模拟中,在Au (111) 表面上自组装的双稳定[2]rotaxanes单层的结构和特性
Seung Soon Jang1, Yun Hee Jang, Yong-Hoon Kim
1Materials and Process Simulation Center (139-74), California Institute of Technology, Pasadena, CA 91125, USA.
Journal of the American Chemical Society
|February 3, 2005
概括
黄金表面上的双面性 [2] 罗塔克桑具有可控制的切换特性. 分子动力学模拟显示了最佳的包装和稳定性,实验验证证证了表面行为和水接触角度.
科学领域:
- 超分子化学 超分子化学
- 材料科学 材料科学 材料科学
- 表面科学是一门学科.
背景情况:
- 可靠的 [2] 罗塔克桑具有可控制的切换特性,由机械穿运动驱动.
- 这些分子机器可以存在于两个不同的协同形态状态:基态 (GSCC) 和元稳态 (MSCC).
- 了解它们在表面上的行为对于设备应用至关重要.
研究的目的:
- 在Au (111) 表面上研究可可视化[2]rotaxanes的自我组装单层 (SAM) 的结构和特性.
- 为了确定这些SAM的最佳表面覆盖面和包装密度.
- 分析不同协同形态状态下的罗塔SAM的稳定性,方向和表面张力.
主要方法:
- 原子分子动力学 (MD) 模拟利用从DFT计算中优化的一种力场.
- 分析每个罗塔的总能量和平行表面应力,以确定最佳包装.
- 使用Langmuir-Blodgett单层等技术进行实验验证,以验证预测的表面特性.
主要成果:
- 对于GSCC和MSCC,最佳的包装密度为115 Å2/分子,GSCC更稳定14 kcal/mol.
- SAMs保持六角包装在最佳密度;偏差发生在更高的密度.
- 计算的表面张力差异预测了不同的水接触角度,经过实验证实了这一点.
结论:
- 这项研究阐明了AU (111) 上双稳定 [2] 氧 SAMs 的结构和能量格局.
- 对于稳定状态和超稳定状态,确定了最佳的表面覆盖和分子方向.
- 这些发现为设计具有可调节性质的表面绑定分子开关提供了基础.
相关概念视频
02:18Conformations of Ethane and Propane
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Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered ethane, the...
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered ethane, the...
02:29Conformations of Cycloalkanes
Adolf von Baeyer attempted to explain the instabilities of small and large cycloalkane rings using the concept of angle strain — the strain caused by the deviation of bond angles from the ideal 109.5° tetrahedral value for sp3 hybridized carbons. However, while cyclopropane and cyclobutane are strained, as expected from their highly compressed bond angles, cyclopentane is more strained than predicted, and cyclohexane is virtually strain-free. Hence, Baeyer’s theory that was based on the...
02:11Conformations of Cyclohexane
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The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
02:02Chair Conformation of Cyclohexane
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This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
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