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化学学报
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化学学报 ›› 2009, Vol. 67 ›› Issue (16): 1851-1858. 上一篇    下一篇

研究论文

半胱氨酸阴离子与咪唑阳离子间相互作用的理论研究

吴 阳* 张甜甜 李静蕊

  

  1. (辽宁大学化学院 沈阳 110036)

  • 投稿日期:2008-12-12 修回日期:2009-03-09 发布日期:2009-08-28
  • 通讯作者: 吴阳

A Theoretical Investigation of Interaction between 1-Ethyl-3-methyl- imidazolium Cation and Cysteine Anion

Wu, Yang* Zhang, Tiantian Li, Jingrui   

  1. (College of Chemistry, Liaoning University, Shenyang 110036)
  • Received:2008-12-12 Revised:2009-03-09 Published:2009-08-28
  • Contact: Wu, Yang

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1291

被引次数

29

采用密度泛函理论在B3LYP/6-311＋G(d,p)水平上对1-乙基-3-甲基咪唑阳离子和半胱氨酸阴离子形成的气态阴阳离子对([Emim][Cys])进行理论研究. 通过几何结构优化以及频率分析得到势能面上7个稳定的离子对构型. 计算结果表明[Emim]＋和[Cys]－之间存在较强的氢键相互作用, 其稳定化能主要来源于[Cys]－中羰基O的孤对电子lp(O) 和[Emim]＋中C—H反键轨道 s*(C—H) 之间的相互作用, lp(O)®s*(C—H). [Emim][Cys]_S1是最稳定的离子对构型, 考虑BSSE的相互作用能为－387.66 kJ/mol. 从NPA和NBO分析以及AIM (Atoms in Molecules)计算等方面阐述了半胱氨酸阴离子与咪唑阳离子之间氢键相互作用的本质, 并初步探讨了阴阳离子对相互作用对氨基酸离子液体性质的影响.

关键词: 氨基酸离子液体, 1-乙基-3-甲基咪唑半胱氨酸离子液体, 氢键, 自然布居分析(NPA), 自然键轨道分析(NBO), 分子中的原子理论(AIM), 红外光谱

The interaction mechanisms between the cation and anion in 1-ethyl-3-methyl-imidazolium cysteine ionic liquids [Emim][Cys] were investigated at the B3LYP/6-311＋G(d,p) level. Seven isomers of [Emim][Cys] were optimized, and their vibrational frequencies were calculated to verify the stationary structures. The optimized structures, energies and natural population analysis (NPA) were presented and analyzed in terms of their possible correlation with the interaction energies and the H-bond separations. Theoretical results indicate that the [Emim]＋ and [Cys]－ can form considerably strong H-bond interactions, which is mainly attributed to the interaction between the lone pairs of carbonyl O atom in [Cys]－ and the antibonding orbital of C—H in [Emim]＋, lp(O)®s*(C—H). For the most stable isomer [Emim][Cys]_S1, the carbonyl O atoms of [Cys]－ would prefer to interact with the C(2)—H of the imidazolium ring and the C—H of the methyl group of [Emim]＋, and interaction energy is －387.66 kJ/mol with BSSE correction. The H-bond chemical nature of [Emim][Cys] was investigated by atoms in molecules (AIM) and natural bond orbital (NBO) analyses.

Key words: amino acid ionic liquid, [Emim][Cys], H-bond, natural population analysis (NPA), natural bond orbital (NBO), atoms in molecules (AIM), IR spectra