Men Shuang, Jin Yujuan, Licence Peter
School of Material Science and Engineering, Shenyang Ligong University, Shenyang, 110159, P. R. China.
Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics, Beijing Technology and Business University, Beijing, 100048, P. R. China.
Phys Chem Chem Phys. 2020 Aug 5;22(30):17394-17400. doi: 10.1039/d0cp02325f.
In this study, X-ray photoelectron spectroscopy is used to probe the impact of the N3-substituted alkyl group on the electronic environment of the cation and the anion by comparing two types of imidazolium cations, 1-alkyl-3-butylimidazolium and 1-alkyl-3-methylimidazolium. Due to the more intense inductive effect changing from methyl to butyl, the electronic environment of the cationic nitrogen can be significantly affected, which is reflected in a shift of N 1s binding energy. The magnitude of the binding energy shift is found to be more pronounced in the case of the less basic anion and inversely proportional to the basicity of the anion. The increase of the N3-substituted alkyl chain length can also influence the charge-transfer effect from the anion to the cation. This gives rise to a change in the electronic environment of the anion. Such an impact is found to be concentrated on the anion-based component bearing more negative point charges.
在本研究中，通过比较两种咪唑鎓阳离子，即1-烷基-3-丁基咪唑鎓和1-烷基-3-甲基咪唑鎓，利用X射线光电子能谱来探究N3-取代烷基对阳离子和阴离子电子环境的影响。由于从甲基到丁基的诱导效应更强，阳离子氮的电子环境会受到显著影响，这体现在N 1s结合能的位移上。发现结合能位移的幅度在碱性较弱的阴离子情况下更为明显，且与阴离子的碱性成反比。N3-取代烷基链长度的增加也会影响从阴离子到阳离子的电荷转移效应。这导致阴离子的电子环境发生变化。发现这种影响集中在带有更多负电荷点的基于阴离子的组分上。
