物理化学学报 >> 2013, Vol. 29 >> Issue (08): 1618-1622.doi: 10.3866/PKU.WHXB201305272

热力学,动力学和结构化学 上一篇    下一篇

离子液体[BMIM]Br与[BMIM][BF4]配比浓度对Br-离子电荷转移的调节

马静远, 邹杨, 姜政, 黄宇营   

  1. 中国科学院上海应用物理研究所, 上海 201204
  • 收稿日期:2013-03-25 修回日期:2013-05-24 发布日期:2013-07-09
  • 通讯作者: 黄宇营 E-mail:huangyuying@sinap.ac.cn
  • 基金资助:

    国家自然科学基金(11079007, 11005148, 10705046)及中国科学院知识创新工程重大交叉项目(KJCX2-YW-N43)资助

Effect of the Ratio between Ionic Liquids [BMIM]Br and [BMIM][BF4] on the Charge Transfer of Br-

MA Jing-Yuan, ZOU Yang, JIANG Zheng, HUANG Yu-Ying   

  1. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, P. R. China
  • Received:2013-03-25 Revised:2013-05-24 Published:2013-07-09
  • Contact: HUANG Yu-Ying E-mail:huangyuying@sinap.ac.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (11079007, 11005148, 10705046) and Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (KJCX2-YW-N43).

摘要:

利用X射线吸收精细结构光谱(XAFS)及紫外吸收光谱两种方法, 分析了离子液体1-丁基-3-甲基咪唑溴盐([BMIM]Br)中逐渐掺入1-丁基-3-甲基咪唑四氟硼酸盐([BMIM][BF4])时, Br-阴离子与咪唑阳离子之间氢键作用及电荷偏移量的改变. 随着[BMIM][BF4]加入量增多, Br 元素XAFS近边(XANES)显示吸收峰降低, 吸收边位置向低能端位移0.9 eV; 扩展边(EXAFS)算出径向结构显示Br 与近邻原子间平均配位数降低、平均键长增长; 紫外光谱也有明显蓝移减色效应. 这些结果都表明Br4-的掺入改变了Br-与阳离子间的电荷偏移量, 负电荷更多地转移到Br-上, 量化计算的数据同样支持该结论.

关键词: 离子液体, 电荷转移, X射线吸收精细结构光谱, 吸收边, 紫外光谱

Abstract:

We analyzed the change of hydrogen bonding between Br- and imidazolium cations when the ionic liquid 1-butyl-3-methylimidazolium bromide ([BMIM]Br) was gradually mixed with 1-butyl-3- methylimidazolium tetrafluoroborate ([BMIM] [BF4]) using X-ray absorption fine structure (XAFS) and ultraviolet absorption spectroscopies. As the content of [BMIM][BF4] increased, the intensity of the K-edge main peak of Br reduced in X-ray absorption near edge structure (XANES) spectra, and the absorption edge moved 0.9 eV to lower energy. Meanwhile, the radial structure given by extended X-ray absorption fine structure (EXAFS) indicated that the distribution number reduced and average hydrogen bond length increased. UV spectra showed a clear blue shift and peaks decreased in intensity as the content of [BMIM][BF4] increased. All of these results indicate that more negative charge was transferred to Br- as the content of [BMIM][BF4] increased. The data obtained from quantum chemical calculations also support this conclusion.

Key words: Ionic liquid, Charge transfer, X-ray absorption fine structure spectroscopy, Absorption edge, UV spectroscopy

MSC2000: 

  • O641