Structural Analysis of [ChCl]m[ZnCl2]n Ionic Liquid by X-ray Absorption Fine Structure Spectroscopy

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• 作者：Yang Zou ; Hongjie Xu* ; Guozhong Wu* ; Zheng Jiang ; Shimou Chen ; Yuying Huang ; Wei Huang ; Xiangjun Wei
• 刊名：Journal of Physical Chemistry B
• 出版年：2009
• 出版时间：February 19, 2009
• 年：2009
• 卷：113
• 期：7
• 页码：2066-2070
• 全文大小：142K
• 年卷期：v.113,no.7(February 19, 2009)
• ISSN：1520-5207

文摘

The components and structures of ionic liquid ChCl−ZnCl₂ in different ChCl:ZnCl₂ ratios were investigated using XAFS (X-ray absorption fine structure) technique. The average coordination number and distance of Zn species at different x(ZnCl₂) (mole fraction of ZnCl₂ when synthesizing) were calculated. It is shown that x(ZnCl₂) has a regular influence on the coordination number of Zn species, due to the change of anion forms and structures in the ChCl−ZnCl₂ ionic liquid. The possible forms and structures of Zn species in the ionic liquids were analyzed according to the coordination number. XAFS and DSC (differential scanning calorimetry) analysis imply that besides ZnCl₃⁻ and Zn₂Cl₅⁻ anions, the Cl−Zn−Cl ion pair is a main species in the ionic liquid at higher x(ZnCl₂). This newly discovered Zn species has substantial influence on the properties of the ionic liquid. From the analysis of the coordination numbers and coordination distance, a new mechanism of interactions between Ch⁺ cation and Cl−Zn−Cl ion pairs or Cl⁻ is proposed.