Gao Yan'an, Zhao Xueyan, Dong Bin, Zheng Liqiang, Li Na, Zhang Shaohua
Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, China.
J Phys Chem B. 2006 May 4;110(17):8576-81. doi: 10.1021/jp057478f.
The three kinds of ionic liquid (IL) surfactants, 1-dodecyl-3-methylimidazolium hexafluorophosphate (C(12)mimPF(6)), 1-tetradecyl-3-methylimidazolium hexafluorophosphate (C(14)mimPF(6)), and 1-hexadecyl-3-methylimidazolium hexafluorophosphate (C(16)mimPF(6)), were used to form the inclusion complexes (ICs) with beta-cyclodextrin (beta-CD). The surface tension measurements revealed that there were two kinds of inclusion formations, 1:1 and 1:2 (beta-CD/IL) stoichiometry for beta-CD-C(12)mimPF(6) and beta-CD-C(14)mimPF(6) ICs, and only 1:1 stoichiometry for beta-CD-C(16)mimPF(6) ICs. These inclusion compounds were further characterized by XRD, (13)C CP/MAS NMR, (1)H NMR, rotating frame nuclear Overhauser effect spectroscopy (ROESY), and thermogravimetry (TGA). The results showed that these ICs were fine crystalline powder. The host-guest system presented a channel-type structure, and each glucose unit of beta-CD was in a similar environment. It was suggested that hydrophobicity played a crucial role in supporting the formation of ICs. The decomposition temperature of these ICs was lower than those of their precursors. Furthermore, the possible inclusion structures were also speculated. These inclusion behaviors are likely to be used to recover ILs in the process of their preparation.
三种离子液体（IL）表面活性剂，1-十二烷基-3-甲基咪唑六氟磷酸盐（C(12)mimPF(6)）、1-十四烷基-3-甲基咪唑六氟磷酸盐（C(14)mimPF(6)）和1-十六烷基-3-甲基咪唑六氟磷酸盐（C(16)mimPF(6)），用于与β-环糊精（β-CD）形成包合物（ICs）。表面张力测量结果表明，存在两种包合形式，β-CD-C(12)mimPF(6)和β-CD-C(14)mimPF(6)包合物的化学计量比为1:1和1:2（β-CD/IL），而β-CD-C(16)mimPF(6)包合物只有1:1的化学计量比。这些包合物通过X射线衍射（XRD）、(13)C交叉极化/魔角旋转核磁共振（(13)C CP/MAS NMR）、(1)H核磁共振（(1)H NMR）、旋转框架核Overhauser效应光谱（ROESY）和热重分析（TGA）进一步表征。结果表明，这些包合物为细晶粉末。主客体体系呈现出通道型结构，β-CD的每个葡萄糖单元处于相似的环境中。研究表明，疏水性在支持包合物的形成中起关键作用。这些包合物的分解温度低于其前体。此外，还推测了可能的包合结构。这些包合行为可能用于在离子液体的制备过程中回收离子液体。
