Related Experiment Video
Updated: Mar 18, 2026
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Raman Spectroscopic Study on Alkyl Chain Conformation in 1-Butyl-3-methylimidazolium Ionic Liquids and their Aqueous
Dheeraj K Singh1, Seoncheol Cha1, Dahyun Nam1
1Department of Physics, Sogang University, Seoul, 121-742, Korea.
Abstract:
Ionic liquids of 1-butyl-3-methylimidazolium ([BMIM]) cation with different anions (Cl- , Br- , I- , and BF4- ), and their aqueous mixtures were investigated by using Raman spectroscopy and dispersion-included density functional theory (DFT). The characteristic Raman bands at 600 and 624 cm-1 for two isomers of the butyl chain in the imidazolium cation showed significant changes in intensity for different anions as well as in aqueous solutions. The area ratio of these two bands followed the order I- >Br- >Cl- >BF4- (in terms of the anion X in [BMIM]X), indicating that the butyl chain of [BMIM]I tends to adopt the trans conformation. The butyl chain was found to adopt the gauche conformation upon dilution, irrespective of the anion type. The Raman bands in the butyl C-H stretch region for [BMIM]X (X=Cl- , Br- , and I- ) blueshifted significantly with the increase in the water concentration, whereas that for [BMIM]BF4 changed very little upon dilution. The blueshift in the C-H stretch region upon dilution also followed the order: [BMIM]I>[BMIM]Br>[BMIM]Cl>[BMIM]BF4 , the same order as the above trans conformation preference of the butyl chain in pure imidazolium ionic liquids, which suggested that the cation-anion interaction plays a role in determining the conformation of the chain.
More Related Videos
06:31Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators
Published on: November 27, 2015
11:04Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature
Published on: December 20, 2016
Related Concept Videos
02:20Conformations of Butane
01:22Mass Spectrometry: Alkyl Halide Fragmentation
02:45Alkyl Halides
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
02:30Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
02:01Isomerism in Alkenes
An isomer is called cis-2-butene when the methyl groups are on the same side of the double bond, and the other stereoisomer, in which methyl groups are on the opposite side of the double bond, is called trans-2-butene. The cis and trans stereoisomers are not...