title: Effect of side-chain length on structural and dynamic properties of ionic liquids with hydroxyl cationic tails.
abstract: The recent study has revealed that ionic liquids (ILs) with hydroxyl cationic tails are polar liquids without tightly aggregated nonpolar tail domains. Nevertheless, the influence of varying side-chain length on their microscopic structure and dynamics is still unclear. By performing all-atom molecular dynamics simulations for 1-(n-hydroxyalkyl)-3-methylimidazolium nitrate, where n varies from 2 to 12, we found that, with increasing side-chain length, both the nonpolar region and the flexibility of cationic tails increase. The larger nonpolar region pushes both the charged groups (heads and anions) and nonpolar groups (methylene groups on the side chains) to become more organized, while the increasing tail flexibility allows the hydroxyl terminals to retain a relatively uniform distribution. The increase of side-chain length does not apparently alter the polar nature of the ILs with hydroxyl tails, and has little effect on the total number of formed hydrogen bonds, but slows down the dynamics of ILs.
authors.affiliation: State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences , 55 East Zhongguancun Road, P.O. Box 2735, Beijing, 100190 China.
authors.forename: Kuo
authors.initials: K
authors.lastname: Wei
authors.forename: Li
authors.initials: L
authors.lastname: Deng
authors.forename: Yanting
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhong-Can
authors.initials: ZC
authors.lastname: Ou-Yang
authors.forename: Guodong
authors.initials: G
authors.lastname: Wang
mesh_terms: D002412:Cations / Q000737:chemistry; D004058:Diffusion; D006860:Hydrogen Bonding; D006878:Hydroxides / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D056004:Molecular Dynamics Simulation
chemical_list: D002412:Cations; D006878:Hydroxides; D052578:Ionic Liquids; C031356:hydroxide ion