Liquid structure and the ion-ion interactions of ethylammonium nitrate ionic liquid studied by large angle X-ray scattering and molecular dynamics simulations (特集計算化学アプリケーションによる生命・物質科学の探求)

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Room temperature ionic liquids (RTILs) are useful as new solvents or materials owing to their favorable properties such as negligible vapor pressure, non-flammability, and wide electrochemical window. For further development of new RTILs, it is indispensable to understand macroscopic properties as solvent and/or liquids of RTILs at a molecular or atomistic level. Here, liquid structure and the ion-ion interactions of room temperature ionic liquid ethylammonium nitrate (EAN) were studied by means of large angle X-ray scattering (LAXS) experiment and molecular dynamics simulations. X-ray interference function for EAN shows a small peak of 0.62 Å–1 indicating nano-scale segregation in the ionic liquid. X-ray radial distribution function as the form of D(r) – 4πr2ρ0 evidently shows a peak of 3.4 and broad ones of 4.7, 8 and 12 Å, suggesting that EAN has long range ordering in the liquid state. The intra-molecular X-ray interference function was estimated on the basis of molecular geometries found in crystals to yield the inter-molecular X-ray pair correlation functionG_mathrm{inter}mathrm{LAXS}(r). In G_mathrm{inter}mathrm{LAXS}(r), peaks of 3.0, 3.4, and 4.7 Å were found as the atom-atom correlation. The peak of 3.0 Å can be assigned to the atom-atom correlation of N (C2H5NH3+)O (NO3–) in the NHO hydrogen bonding. In addition, the peak of 3.4 Å is also ascribable to C (C2H5NH3+)O (NO3–) correlations in the CHO interactions. Molecular dynamics simulations based on newly developed force fields to describe a series of primary ammonium cation were performed to ascribe the peaks found in G_mathrm{inter}mathrm{LAXS}(r). The X-ray interference function imathrm{MD}(s) and the pair correlation function Gmathrm{MD}(r) derived from simulations were reasonably in agreement with the experimental ones. According to the partial atom-atom correlation functions derived from the simulations, the experimentally observed peaks of 3.0 and 3.4 Å can be ascribable to the NHO and the CHO correlations in the closest ethylammonium and nitrate interaction, respectively. The CHO interactions may play an important role in macroscopic properties of this kind of ionic liquids.
日本コンピュータ化学会の論文
2008-12-15

Liquid structure and the ion-ion interactions of ethylammonium nitrate ionic liquid studied by large angle X-ray scattering and molecular dynamics simulations (特集計算化学アプリケーションによる生命・物質科学の探求)

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関連論文

スポンサーリンク

Liquid structure and the ion-ion interactions of ethylammonium nitrate ionic liquid studied by large angle X-ray scattering and molecular dynamics simulations (特集 計算化学アプリケーションによる生命・物質科学の探求)

スポンサーリンク

概要

著者

関連論文

スポンサーリンク

Liquid structure and the ion-ion interactions of ethylammonium nitrate ionic liquid studied by large angle X-ray scattering and molecular dynamics simulations (特集計算化学アプリケーションによる生命・物質科学の探求)