Complex formation of ionic liquid surfactant and -cyclodextrin离子液+环糊精.pdf

Aw s w s i c s i ? K 1 e  c ( ( a f f c o t a c F a i 0 dColloids and Surfaces A: Physicochem. Eng. Aspects 292 (2007) 196–201 Complex formation of ionic liquid surfactant and -cyclodextrin Na Li a, Jie Liu b, Xueyan Zhao a, Yan’an Gao a, Liqiang Zheng a,?, Jin Zhang a, Li Yu a a Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, China b Department of Chemistry, Liaocheng University, Liaocheng, China Received 25 February 2006; received in revised form 23 June 2006; accepted 23 June 2006 Available online 30 June 2006 bstract An ionic liquid (IL) surfactant, 1-dodecyl-3-methylimidazolium hexafluorophosphate (C12mimPF6) can form the inclusion complexes (ICs) ith -cyclodextrin (-CD). The surface tension measurements revealed that there were two kinds of inclusion formations, 1:1 and 1:2 (-CD/IL) toichiometry for -CD-C12mimPF6 ICs. The inclusion complexation interaction was further confirmed by FT-IR spectra. The inclusion compound as also characterized by Powder X-ray diffraction (XRD), 13C CP/MAS NMR, 2D 1H-1H COSY and TGA. The results showed that the host–guest ystem presented a channel type structure and each glucose unit of -CD was in a similar environment. Only the tails of C12mimPF6 were included nto the cavity of -CD. The formation mechanism of the -CD-C mimPF was also discussed. It was suggested that hydrophobicity played a12 6 rucial role in supporting the formation of -CD-C12mimPF6 ICs and hydrogen bonding was dispensable to maintain the channel type crystal tructure. The weak hydrophobic driven force made the -CD-C12mimPF6 unstable, which was reflected by TGA curves. In addition, possible nclusion structures of -CD-C12mimPF6 were speculated. 2006 Elsevier B.V. All rights reserved. h s m i T o m t b g t t p i feywords: -Cyclodextrin; Ionic liquid; Inclusion complexes; Surfactant . Introduction Cyclodextrins (CDs) are cyclic oligosaccharides of six to ight glucose units linked -1,4-linkag