title: Structural analysis of [ChCl](m)[ZnCl(2)](n) ionic liquid by X-ray absorption fine structure spectroscopy.
abstract: The components and structures of ionic liquid ChCl-ZnCl(2) in different ChCl:ZnCl(2) ratios were investigated using XAFS (X-ray absorption fine structure) technique. The average coordination number and distance of Zn species at different x(ZnCl(2)) (mole fraction of ZnCl(2) when synthesizing) were calculated. It is shown that x(ZnCl(2)) has a regular influence on the coordination number of Zn species, due to the change of anion forms and structures in the ChCl-ZnCl(2) 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 ZnCl(3)(-) and Zn(2)Cl(5)(-) anions, the Cl-Zn-Cl ion pair is a main species in the ionic liquid at higher x(ZnCl(2)). 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.
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zou
authors.forename: Hongjie
authors.initials: H
authors.lastname: Xu
authors.forename: Guozhong
authors.initials: G
authors.lastname: Wu
authors.forename: Zheng
authors.initials: Z
authors.lastname: Jiang
authors.forename: Shimou
authors.initials: S
authors.lastname: Chen
authors.forename: Yuying
authors.initials: Y
authors.lastname: Huang
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Wei
mesh_terms: D002152:Calorimetry, Differential Scanning; D002712:Chlorides / Q000737:chemistry*; D004983:Ethanolamines / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D015394:Molecular Structure; D013057:Spectrum Analysis / Q000379:methods; D013696:Temperature; D014965:X-Rays; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D002712:Chlorides; D004983:Ethanolamines; D052578:Ionic Liquids; D017967:Zinc Compounds; C016837:zinc chloride