@article {503, title = {Molecular Dynamics Simulation of the Energetic Room Temperature Ionic Liquid 1-Hydroxyethyl-4Amino-1, 2, 4-Triazolium Nitrate (HEATN)}, journal = {J. Phys. Chem. B}, volume = {112}, year = {2008}, pages = {3121-3131}, doi = {10.1021/jp710653g}, author = {Jiang, W. and T. Yan and Wang, Y. and G. A. Voth} } @article {502, title = {A Multiscale Coarse-Graining Study of Liquid/Vacuum Interface of Room-Temperature Ionic Liquids with Alkyl Substituents of Different Lengths}, journal = {J. Phys. Chem. C}, volume = {112}, year = {2008}, pages = {1132-1139}, doi = {10.1021/jp077643m}, author = {Jiang, W. and Wang, Y. and T. Yan and G. A. Voth} } @article {501, title = {Molecular Dynamics Simulation of Nanostructural Organization in Ionic Liquid/Water Mixtures}, journal = {J Phys Chem B}, volume = {111}, number = {18}, year = {2007}, note = {Jiang, Wei Wang, Yanting Voth, Gregory A Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S. United States The journal of physical chemistry. B J Phys Chem B. 2007 May 10;111(18):4812-8. Epub 2007 Feb 27.}, pages = {4812-8}, abstract = {

Molecular dynamics simulations have been carried out to investigate nanostructural organization in mixtures of 1-octyl-3-methylimidazolium nitrate ionic liquid and water at multiple water concentrations. Evolution of the polar network, water network, and micelle structures is visualized and analyzed via partial radial distribution functions. The calculated static partial structure factors show that within the range of water contents examined, polar networks, water networks, and micelles possess an approximately invariant characteristic length at around 20 A. Furthermore, the above calculations point out that, as the amount of water increases, the polar network is continuously broken up (screened) by the intruding water, while the structural organization of the water network and the micelle exhibits a turnover. At the turnover point, the most ordered micelle (cation-cation) structure and water (water-anion-water) network are formed. Thereafter, the structural organization abates drastically, and only loose micelle structure exists due to the dominant water-water interactions. The simulated turnover of structural organization agrees with the sharpest peak in the experimentally obtained structure factor in aqueous solutions of similar ionic liquids; the simulated water structure reveals that water can form liquidlike associated aggregates due to the planar symmetry and strong basicity of NO(3)-, in agreement with experiment. The turnover of structural organization of micelles results from the persistent competition between the hydrophobic interactions of the nonpolar groups and the breakup of the charged polar network with increasing water content, whereas the turnover of the water network results from the competition between the water-water and water-anion interactions.

}, keywords = {*Computer Simulation Imidazoles/*chemistry Ionic Liquids/*chemistry Micelles *Models, Chemical Models, Molecular Molecular Structure Nanostructures/*chemistry Water/chemistry}, doi = {10.1021/jp067142l}, author = {Jiang, W. and Wang, Y. and G. A. Voth} } @inbook {743, title = {Spatial Heterogeneity in Ionic Liquids}, booktitle = {Ionic Liquids IV. Not Just Solvents Anymore}, year = {2007}, pages = {272-307}, publisher = {American Chemical Society}, organization = {American Chemical Society}, address = {Washington DC}, doi = {10.1021/bk-2007-0975.ch020}, author = {Wang, Y. and Jiang, W. and G. A. Voth}, editor = {Brennecke, J. F. and Rogers, R. D. and Seddon, K. R.} } @article {698, title = {Understanding ionic liquids through atomistic and coarse-grained molecular dynamics simulations}, journal = {Acc Chem Res}, volume = {40}, number = {11}, year = {2007}, note = {Wang, Yanting Jiang, Wei Yan, Tianying Voth, Gregory A Research Support, Non-U.S. Gov{\textquoteright}t Research Support, U.S. Gov{\textquoteright}t, Non-P.H.S. Review United States Accounts of chemical research Acc Chem Res. 2007 Nov;40(11):1193-9. Epub 2007 Oct 13.}, pages = {1193-9}, abstract = {

Understanding the physical properties of ionic liquids (ILs) via computer simulation is important for their potential technological applications. The goal of our IL research is to obtain a unified understanding of the properties of ILs with respect to their underlying molecular structure. From atomistic molecular dynamics simulations, the many-body electronic polarization effect was found to be important for modeling ILs, especially their dynamics. The multiscale coarse-graining methodology has also been employed to increase the simulation speed by a factor of 100 or more, thereby making it possible to study the mesoscopic behavior of ILs by computer simulations. With these simulation techniques, ILs with an amphiphilic cation were found to exhibit a spatial heterogeneity due to the aggregation of their nonpolar alkyl tails. This spatial heterogeneity is a key feature in interpreting many physical phenomena of ILs, such as their heterogeneous self-diffusion and surface layering, as well as their surfactant-like micelles formed in IL/water mixtures.

}, keywords = {Chemical Models, Chemistry, Molecular Physicochemical Phenomena Surface Properties, Physical *Computer Simulation Ionic Liquids/*chemistry *Models}, doi = {10.1021/ar700160p}, author = {Wang, Y. and Jiang, W. and T. Yan and G. A. Voth} } @article {720, title = {Structure of the Liquid-Vacuum Interface of Room-Temperature Ionic Liquids: A Molecular Dynamics Study}, journal = {J Phys Chem B}, volume = {110}, number = {4}, year = {2006}, note = {Yan, Tianying Li, Shu Jiang, Wei Gao, Xueping Xiang, Bing Voth, Gregory A United States The journal of physical chemistry. B J Phys Chem B. 2006 Feb 2;110(4):1800-6.}, pages = {1800-6}, abstract = {

Molecular dynamics simulations for the liquid-vacuum interface of the ionic liquid 1-ethyl-3-methylimidazolium nitrate (EMIM+/NO3-) were performed for both electronically polarizable and nonpolarizable potential energy surfaces. The interfacial structural properties, such as the oscillation in the number density profile, the orientational ordering, and the local clustering in the interfacial region, were calculated. The simulations with both the polarizable and nonpolarizable model demonstrate the existence of an inhomogeneous interfacial structure normal to the surface layer. It was found for both models that the ethyl tail group on EMIM+ is likely to protrude outward from the surface. In the outmost surface layer, the cation is likely to lie on the surface with the imidazolium ring parallel to the interface, while there is a second region with enhanced density from that in the bulk where the cation preferably slants with the imidazolium ring tending to be perpendicular to the surface. The results also reveal that the electronic polarization effect is important for the ionic liquid interface. It is found that the cation is likely to be segregated at the ionic liquid surface for the polarizable model, while for the nonpolarizable model, the anion is found to be more likely to exhibit such behavior. The surface tension of the polarizable model (58.5 +/- 0.5 mN/m) is much smaller than that of the nonpolarizable model (82.7 +/- 0.6 mN/m), in better agreement with extrapolated experimental measurements on similar ionic liquid systems.

}, doi = {10.1021/jp055890p}, author = {T. Yan and Li, S. and Jiang, W. and Gao, X. and Xiang, B. and G. A. Voth} }