Ionic Structures of Nanobased FeCl3/[C4mim]Cl Ionic Liquids

• Published in: The journal of physical chemistry. B Vol. 116; no. 22; pp. 6461 - 6464
• Main Authors: Li, Ji-Guang, Hu, Yu-Feng, Sun, Shu-Feng, Ling, Shan, Zhang, Jin-Zhu
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07.06.2012
• Subjects: Chlorides - chemistry; Ferric Compounds - chemistry; Imidazoles - chemistry; Ionic Liquids - chemistry; Ions - chemistry; Molecular Structure; Nanostructures - chemistry; Particle Size; Surface Properties; Thermodynamics
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp206819h

We synthesized a series of FeCl3/[C4mim]Cl (iron(III) chloride with 1-butyl-3-methylimidazolium chloride) ionic liquids. The temperature dependence of the Raman spectra of the FeCl3/[C4mim]Cl ionic liquids was measured for the first time to analyze their ionic species. In addition, the infrared spectra, thermodynamic properties, and freeze-fracture transmission electron microscopy were combined together with the Raman spectra to reveal the microscopic information of the FeCl3/[C4mim]Cl ionic liquids. When the mole ratio of FeCl3/[C4mim]Cl is less than 1, the Raman scattering identifies the presence of [FeCl4]− in the ionic liquid. When FeCl3 is in excess, [Fe2Cl7]− begins to appear. Besides, we found that the relative intensity of the two symmetry vibrations of [Fe2Cl7]− is changing as the temperature is varied. The strength of the interionic interactions in FeCl3/[C4mim]Cl ionic liquids follows the order 1/1.5 > 1.5/1 > 1/1 due to the formation of [FeCl4]− and [Fe2Cl7]−. The nanostructures in FeCl3/[C4mim]Cl ionic liquids were observed for the first time by using biological imaging. The sizes of the local domains are found to be tens of nanometers.