STRUCTURE AND INTERACTION BETWEEN THE [BMIM][Ala] ALANINE ANION AND THE 1-BUTYL-3-METHYLIMIDAZOLIUM CATION IN ION PAIRS

amino acid ionic liquids (AAILs) density functional theory (DFT) natural bond orbital (NBO) second order interaction energy

CRYSTAL STRUCTURES OF TWO 4-PHENYLBENZOPHENONES, Структурный анализ сульфокатионообменника в форме глицина, ...

2013. 54, 4 UDC 541.6:548.737 STRUCTURE AND INTERACTION BETWEEN THE [BMIM][Ala] ALANINE ANION AND THE 1-BUTYL-3-METHYLIMIDAZOLIUM CATION IN ION PAIRS Z.W. Li1, W.S. Wu1, Z.Y. Du2, X.Y. Hao1 1College of Chemistry and Chemical Engineering, Zhaoqing University, Zhaoqing 526061, China 2 E-mail:lzwgzzd@163.com School of Light Industry and Chemical Engineering, Technical University of Guangdong, Guangzhou 510006, P. R. China Received March, 12, 2012 The equilibrium geometries and vibrational frequencies of the ionic liquid 1-butyl-3-methylimidazolium cation and the alanine anion [BMIM][Ala] are studied using density functional theory (DFT) at the B3PW91/6-311+G(d,p) leve1. <...> The most stable structures of the anion, the cation, and the ion pairs are obtained and characterized, and the geometry parameters of the ion pairs confirm the presence of a hydrogen bonding interaction between the anion and the cation. <...> Natural bond orbital (NBO) analysis is also performed to analyze the atomic charge distribution and charge transfer in the [BMIM]+ cation and [BMIM][Ala] ionic liquids. <...> The results show that there are the electrostatic interaction and multiple hydrogen bond interactions between the cation and the anion of the ionic liquids, and the stability of the ground state of the ion pairs mostly results from the hydrogen bonding between the lone pairs of O atoms in the anion and H in the imidazole cycle of the cation. <...> There are some changes in microstructures and the charge distribution during the formation of the ion pairs. <...> Keywords: amino acid ionic liquids (AAILs), density functional theory (DFT), natural bond orbital (NBO), second order interaction energy. <...> The coupling of the imidazolium cation with natural amino acids or the coupling of the amino acid cation with other anions can develop a novel concept of amino acid ionic liquids (AAILs) composed of natural amino acid ions. <...> These AAILs not only possess the particular physical and chemical properties mentioned above, but also possess some great merits, such as low costs, are biodegradable and biocompatible, containing multi-functional groups, a strong hydrogen bonding ability and abundant source [ 8, 9 ], as revealed by the works of the groups of Ohno [ 9, 10 ] and Kou [ 11, 12 ]. <...> In addition, the physicochemical properties of AAILs can easily be adjusted by modifying their <...>

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