物理化学学报 >> 2013, Vol. 29 >> Issue (08): 1609-1617.doi: 10.3866/PKU.WHXB201306032

热力学，动力学和结构化学 上一篇    下一篇

p-π共轭分子的氨基面外弯曲振动模的拉曼光谱

陶莎, 于利娟, 吴德印, 田中群   

  1. 厦门大学化学化工学院化学系, 固体表面物理化学国家重点实验室, 福建 厦门 361005
  • 收稿日期:2013-04-16 修回日期:2013-05-31 发布日期:2013-07-09
  • 通讯作者: 吴德印 E-mail:dywu@xmu.edu.cn
  • 基金资助:

    国家自然科学基金(91027009, 21021002, 20973143), 国家重点基础研究发展规划项目(973) (2009CB930703)和厦门大学(2010121020)资助

Raman Spectra of Amino Wagging Vibrational Modes in p-π-Conjugated Molecules

TAO Sha, YU Li-Juan, WU De-Yin, TIAN Zhong-Qun   

  1. State Key Laboratory for Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, P. R. China
  • Received:2013-04-16 Revised:2013-05-31 Published:2013-07-09
  • Contact: WU De-Yin E-mail:dywu@xmu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (91027009, 21021002, 20973143), National Key Basic Research Program of China (973) (2009CB930703), and Xiamen University, China (2010121020).

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摘要：

拉曼光谱是一种用途广泛的无损分子检测技术, 其能够提供化学物质的分子结构指纹信息. 一种面外弯曲振动模被称作wagging 振动, 它的信号尤为特殊, 其频率和强度都非常依赖于检测环境. 以乙烯胺和苯胺为例, 采用密度泛函理论计算研究了p-π共轭分子分别与水簇和银簇作用的平衡结构、成键作用和拉曼光谱.结果表明, 弱相互作用, 如分子与金属表面的弱吸附作用以及分子与水之间的氢键作用, 均使氨基面外弯曲振动模(ωNH2)的拉曼信号发生显著的变化. 考虑溶剂化效应后, 氢键作用减弱, 计算拉曼光谱趋于一致. 通过进一步对电子结构的分析, 解释了面外弯曲振动信号显著增强的原因, 揭示了面外弯曲振动模与分子p-π共轭作用之间的关系.

关键词: 面外弯曲振动模, 分子间弱相互作用, 氢键, 乙烯胺, 苯胺, 拉曼光谱, 密度泛函理论

Abstract:

Raman spectroscopy has been widely used as a non-destructive testing and molecular recognition technology, providing fingerprint information for chemical and biological molecular structures. One type of out-of-plane bending vibration observed in Raman spectroscopy is named the‘wagging vibration’. The Raman signal of the wagging mode is very sensitive; not only the vibrational frequency but also the Raman intensity depends strongly on environment factors. In this report, density functional theory (DFT) calculations are used to study the equilibrium structures, binding interactions, and Raman spectra of vinylamine and aniline as well as their complexes with silver clusters and water clusters. Vinylamine-silver and aniline-silver clusters were used to simulate the interactions of the molecules adsorbed on silver surfaces, while vinylamine-water and aniline-water clusters were used to investigate the hydrogen bonding interactions of vinylamine and aniline with water clusters. Our calculated results show that the Raman signal of the amino wagging mode strongly depends on the hydrogen bonding interaction of the nitrogen lone pair in the amino group with the O―H bond of water. Increasing the size of the water clusters causes a large blue shift and considerable enhancement in the intensity of the wagging vibration. When the polarized continuum model was used to consider the solvation effect, the electrostatic interaction contributing to the hydrogen bond was weakened. In this case, the simulated Raman spectra were similar to each other. For vinylamine and aniline interacting with silver clusters, the Raman signals of the amino wagging vibration were changed by the weak binding interaction, revealing the relationship between the abnormal signal of wagging vibrations and the weak interaction in p-π-conjugated systems.

Key words: Wagging vibration mode, Weak intermolecular interaction, Hydrogen bond, Vinylamine, Aniline, Raman spectroscopy, Density functional theory