摘要
离子液以其独特的性质广受关注,被誉为"绿色设计者溶剂",人们对其潜在的利用价值做了大量的研究。本文采用半经验PM3法和密度泛函(DFT)方法相结合,计算研究1-乙基-3-甲基咪唑四氟硼酸盐([EMIM][BF_4])离子液的分子结构及其氢键作用。经PM3法预优化和在B3LYP/6-31G(d)水平上再优化得到离子对的最稳定结构,通过自然键轨道(NBO)分析阴阳离子间的电荷分布,经振动频率和强度分析得理论红外谱图。结果发现:[EMIM][BF_4]离子液阴阳离子间有电荷转移,咪唑环上靠近阴离子的C-H键伸缩振动频率发生红移,且振动强度加强,阴阳离子间存在着弱氢键的作用。
Ionic Liquids （ILs）, due to their unique properties and solvent capabilities have been motivating an extraordinary growth on experimental and theoretical investigations. Many ILs have been developed to fulfill specific applications and therefore this class of com- pounds has been termed as “ Green designer solvents”. In this artide, the molecular structure and hydrogen bonds have been calculated by semiempifieal PM3 method and density functional theory （DFT） for the ionic liquid 1- ethyl -3-methylimidazolium tetrafluoroborate （ [ EMIM] [ BF4 ] ）. It has been optimized by PM3 method and DFT of quantum chemistry at BLYP/6-31 G（d） level. The theoretical IR spectra of [ EMIM ] [ BF4]were obtained from the calculated vibrational frequencies and intensities. The changes of atomic charge assignments have been investigated by Natural Bond Orbital （NBO） analysis. The computational results show that some charges have transferred between the anion and the cation. The C-H bond, near the anion most, has red shift efect comparing to the monomer, there do exist weak hydrogen bonds between the cations and the anions of the ILs[ EMIM] [ BF4 ].
出处
《计算机与应用化学》
CAS
CSCD
北大核心
2010年第5期699-702,共4页
Computers and Applied Chemistry
基金
广西教育厅立项项目(200808LX357)
关键词
离子液体
1-乙基-3-甲基咪唑四氟硼酸盐
量子化学
密度泛函
Ionic Liquids, 1- ethyl -3-methylimidazolium tetrafluoroborate, quantum chemistry, density functional theory
