Ionic liquids structure and dynamics

Atomistic Simulations of Neat Ionic Liquids - Structure and Dynamics... 

Russina, O., Triolo, A., Gontrani, L., Caminiti, R., Xiao, D., Hines Jr., L., Bartsch, R.A., Quitevis, E., Plechkova, N. and Seddon, K., Morphology and intermolecular dynamics of 1-aHqrl-3-methylimidazolium bis (trifluoromethane)sulfonyl amide ionic liquids structural and dynamic evidence of nanoscale segregation, J. Phys. Condens. Matter 21, 424121 (2009). 

H. Weingartner, NMR Studies of Ionic Liquids Structure and Dynamics, Curr. Opin. Colloid Interface ScL, 2013, 18, 183. 

Weingartner H (2013) NMR studies of ionic liquids structure and dynamics. Cutr Opin CoUoid Interface Sd 18(3) 183-189. doi 10.1016/j.cods.2013.04.001... 

The balance of this Introduction will be committed to an overview of the chemical structures and macroscopic properties of ionic liquid systems. Section II provides a brief overview of the properties of high temperature molten salts, to provide a reference against which room temperature species may be compared. Section III considers the liquid structure and dynamics of neat ILs, and Sections IV and V discuss their operation as solvents at the microscopic level. 

Youngs, T.G.A., and Hardacre, C., Application of static charge transfer within an ionic liquid forcefield and its effect on structure and dynamics, submitted to Chem. Phys. Chem., in press. 

Bhargava, B.L., and Balasubramanian, S., Intermolecular structure and dynamics in an ionic liquid A Car-Parrinello molecular dynamics simulation study of 1,3-dimethylimidazolium chloride, Chem. Phys. Lett., 417, 486-491, 2006. 

Triolo, A., Mandanici, A., Russina, O., Rodriguez-Mora, V., Cutroni, M., Hardacre, C., Nieuwenhuyzen, M., Bleif, H.-J., Keller, L., and Ramos, M. A., Thermodynamics, structure, and dynamics in room temperature ionic liquids The case of l-butyl-3-methyl Imidazolium hexafluorophosphate ([bmim][PFJ),7. Phys. Chem. B, 110,21357-21364, 2006. 

To this end, we review the physics of high temperature fused salts and draw on observations made in these systems to understand the microscopic structure of ionic liquids. We also review some physics of glass-forming liquids, focusing on concepts necessary to understand structural and dynamic inhomogeneity in ILs. We provide a broad review of attempts to characterize ILs empirically, and discuss those results with reference to simulation and theoretical studies. The overall objective of this study is to develop a conceptual toolbox that can be used to interpret experimental results in ILs and help identify useful new questions for the field. To this end, we present a series of principles describing the nature of solvation in ionic liquids at the conclusion of this chapter. 

This discussion of the structure and dynamics of fused salts provides only the briefest overview of their properties. However, even this minimal background will prove a useful reference point as we turn our attention to room temperature ionic liquids. 

As discussed below, ionic liquids often behave comparably to conventional polar organic solvents [6, 8, 10]. But the physics underlying solvation are entirely different. As noted above, ILs are characterized by considerable structural and dynamic inhomogeneity, and even simple concepts, such as the dipole moment, cannot be productively applied. We are therefore in the unusual position of needing to explain how an exotic microscopic environment produces conventional macroscopic behavior. To this end, we will review empirical characterizations of the ionic liquid environment, and then turn our attention to the underlying physics of solute-solvent interactions. 

Pinilla et al. studied the structure and dynamics of [MMIM]Q confined between two parallel solid walls [146], this was the first simulation of an ionic-hquid/solid interface. Simulations were performed at various interwall distances. Mass and charge density along the confinement axis revealed a structure of foyers parallel to the walls and a corresponding oscillatory profile of electrostatic potential. In particular, the potential drop between a point inside the sohd wall and the center of the liquid slab was —0.5 V. Orientational correlation functions indicated that, at the interface, cations orient tilted with respect to the surface but that such orientational order is lost thereafter. A rather singular result vras that the ionic diffusion under confinement was faster than in the bulk, at least for the non[Pg.239]

Rajput, N. N., J. Monk, R. Singh, and F. R. Hnng. 2012. On the infinence of pore size and pore loading on structural and dynamical heterogeneities of an ionic liquid confined in a slit nanopore. Journal of Physical Chemistry C 116 5169-5181. 

H. V. Spohr, G. N. Patey, Structural and dynamical properties of ionic liquids The influence of charge location, J. Chem. Phys., 130, 1-11 (2009). 

Niu SA, Cao Z, Li S, Yan TY (2010) Structure and transport properties of the LiPF6 doped 1-ethyl-2,3-dimethyl-imidazolium hexaftuorophosphate ionic liquids a molecular dynamics study. J Phys Chem B 114 877... 

The last section was devoted to a range of real-world applications treated with ab initio molecular dynamics simulations. Results of gas to liquid phase transition simulations, structural and dynamical properties of liquids such as common solvents as well as the emerging neoteric media of ionic liquids were presented. After a short discussion of chemical reactions concerning homogeneous catalysis, we presented an overview of electrochemical reactions and related processes. 

This review presents recent developments in the application of nuclear magnetic resonance (NMR) spectroscopy to study ionic liquids. In addition to routine structural characterization of synthesized ionic liquids, availability of multitude of advanced NMR techniques enables researchers to probe the structure and dynamics of these materials. Also most of the ionic liquids contain a host of NMR-active nuclei that are perfectly suitable for multinuclear NMR experiments. This review focuses on the application of NMR techniques, such as pulsed field gradient, relaxometry, nuclear Overhauser effect, electrophoretic NMR, and other novel experiments designed to investigate pure ionic liquids and the interaction of ionic liquids with various salts and solutes. 

T. Umecky, K. Suga, E. Masaki, T. Takamuku, T. Makino, M. Kanakubo, Solvation structure and dynamics of Li in Lewis-basic ionic liquid of l-octyl-4-aza-l-azoniabicyclo[2.2.2]octane bis(trifluoromethanesulfonyl)amide, J. Mol. Liq. 209 (2015) 557-562. 

T. Endo, M. Imanari, Y. Hidaka, H. Seki, K. Nishikawa, S. Sen, Structure and dynamics of room temperature ionic liquids with bromide anion results from Br NMR spectroscopy, Magn. Reson. Chem. 53 (5) (2015) 369-378. 

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