通过X射线吸收精细结构光谱对[氯化胆碱](m)[氯化锌](n)离子液体进行结构分析。

Structural analysis of [ChCl](m)[ZnCl(2)](n) ionic liquid by X-ray absorption fine structure spectroscopy.

作者信息

Zou Yang, Xu Hongjie, Wu Guozhong, Jiang Zheng, Chen Shimou, Huang Yuying, Huang Wei, Wei Xiangjun

机构信息

Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China.

出版信息

J Phys Chem B. 2009 Feb 19;113(7):2066-70. doi: 10.1021/jp809788u.

DOI:10.1021/jp809788u

PMID:19173638

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.

摘要

采用X射线吸收精细结构（XAFS）技术研究了不同氯化胆碱（ChCl）与氯化锌（ZnCl₂）比例下离子液体ChCl-ZnCl₂的组成和结构。计算了不同x(ZnCl₂)（合成时ZnCl₂的摩尔分数）下锌物种的平均配位数和距离。结果表明，由于ChCl-ZnCl₂离子液体中阴离子形式和结构的变化，x(ZnCl₂)对锌物种的配位数有规律的影响。根据配位数分析了离子液体中锌物种的可能形式和结构。XAFS和差示扫描量热法（DSC）分析表明，除了ZnCl₃⁻和Zn₂Cl₅⁻阴离子外，在较高x(ZnCl₂)时，Cl-Zn-Cl离子对是离子液体中的主要物种。这种新发现的锌物种对离子液体的性质有重大影响。通过对配位数和配位距离的分析，提出了Ch⁺阳离子与Cl-Zn-Cl离子对或Cl⁻之间相互作用的新机制。