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Improving the Alkaline Stability of Imidazolium Cations by Substitution
Author(s) -
Dong Huilong,
Gu Fenglou,
Li Min,
Lin Bencai,
Si Zhihong,
Hou Tingjun,
Yan Feng,
Lee ShuitTong,
Li Youyong
Publication year - 2014
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201402262
Subject(s) - homo/lumo , chemistry , hyperconjugation , alkyl , density functional theory , computational chemistry , medicinal chemistry , organic chemistry , molecule
Imidazolium cations are promising candidates for preparing anion‐exchange membranes because of their good alkaline stability. Substitution of imidazolium cations is an efficient way to improve their alkaline stability. By combining density functional theory calculations with experimental results, it is found that the LUMO energy correlates with the alkaline stability of imidazolium cations. The results indicate that alkyl groups are the most suitable substituents for the N3 position of imidazolium cations, and the LUMO energies of alkyl‐substituted imidazolium cations depend on the electron‐donating effect and the hyperconjugation effect. Comparing 1,2‐dimethylimidazolium cations (1,2‐DMIm + ) and 1,3‐dimethylimidazolium cations (1,3‐DMIm + ) with the same substituents reveals that the hyperconjugation effect is more significant in influencing the LUMO energy of 1,3‐DMIms. This investigation reveals that LUMO energy is a helpful aid in predicting the alkaline stability of imidazolium cations.