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

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0．9eV；扩展边（EXAFS）算出径向结构显示Br与近邻原子问平均配位数降低、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BF2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...

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Bibliographic Details
Published in物理化学学报 Vol. 29; no. 8; pp. 1618 - 1622
Main Author 马静远 邹杨 姜政 黄宇营
Format Journal Article
LanguageChinese
Published 中国科学院上海应用物理研究所,上海,201204 2013
Subjects
X射线吸收精细结构光谱
吸收边
电荷转移
离子液体
紫外光谱
吸收边
UV spectroscopy
电荷转移
X射线吸收精细结构光谱
离子液体
Charge transfer
紫外光谱
ray absorption fine structure spectroscopy
Ionic liquid
Absorption edge
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ISSN1000-6818
DOI10.3866/PKU.WHXB201305272

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Summary: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0．9eV；扩展边（EXAFS）算出径向结构显示Br与近邻原子问平均配位数降低、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BF2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．
Bibliography:11-1892/06
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] [BF,]） using X-ray absorption fine structure （XAFS） and ultraviolet absorption spectroscopies. As the content of [BMIM][BF,] 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][BF,] increased. All of these results indicate that more negative charge was transferred to Br- as the content of [BMIM][BF,] increased. The data obtained from quantum chemical calculations also support this conc
ISSN:1000-6818
DOI:10.3866/PKU.WHXB201305272