Unique nuclear magnetic resonance behaviour of γ-cyclodextrin in organic solvents
- 59 Downloads
The nuclear magnetic resonance (NMR) behaviour of dry α-, β-, and γ-cyclodextrin (CyD) in non-aqueous solutions with the solvents pyridine-d5, N,N-dimethyl formamide-d7 (DMF-d7), and dimethyl sulfoxide-d6 (DMSO-d6) were examined in order to study the interactions among hydroxyl groups on the rims of CyD. All signals were assigned using H-H correlation spectroscopy (COSY) and 1H-detected multiple quantum coherence spectroscopy (HMQC) spectra. In pyridine-d5, the hydroxyl groups of γ-CyD and water were observed as appreciably broad signals. Over 95 °C, a white precipitate appeared immediately, and after 4 days, it disappeared completely. All signals of α- and β-CyDs were sharp and exhibited a high field shift as the temperature increased. These spectral changes were reversible, but in the case of γ-CyD in dry pyridine-d5, the time temperature-fall for reaching the equilibrium state took longer than that of temperature rise. The dependency of NMR spectroscopy of γ-CyD on the solvent, the concentration of water, and temperature suggested that hydroxyl groups on γ-CyD are sufficiently flexible to interact via intermolecular hydrogen bond formation and to form insoluble aggregates.
KeywordsNMR γ-Cyclodextrin Pyridine Hydrogen bonding Non-aqueous solvent
We are grateful to Dr. Toshiaki Narusawa for his calculation and useful comments regarding drawing molecular structures with MOPAC.
- 1.Szejtli, J.: Comprehensive Supramolecular Chemistry, vol. 3. Oxford, Pergamon (1996)Google Scholar
- 4.Yasumoto, A., Gotoh, H., Imran, A.B., Hara, M., Seki, T., Sakai, Y., Ito, K., Takeoka, Y.: Highly responsive hydrogel prepared using poly(N-isopropylacrylamide)-grafted polyrotaxane as a building block designed by reversible deactivation radical polymerization and click chemistry. Macromolecules 50(1), 364–374 (2017)CrossRefGoogle Scholar
- 6.Davidson, C.D., Fishman, Y.I., Puskás, I., Szemán, J., Sohajda, T., McCauliff, L.A., Sikora, J., Storch, J., Vanier, M.T., Szente, L., Walkley, S.U., Dobrenis, K.: Efficacy and ototoxicity of different cyclodextrins in Niemann-Pick C disease. Ann. Clin. Transl. Neurol. 3(5), 366–380 (2016)CrossRefGoogle Scholar
- 7.Ory, D.S., Ottinger, E.A., Farhat, N., King, N.Y., Jiang, K.A., Weissfeld, X., Berry-Kravis, L., Davidson, E., Bianconi, C.D., Keener, S., Rao, L.A., Soldatos, R., Sidhu, A., Walters, R., Xu, K.A., Thurm, X., Solomon, A., Pavan, B., Machielse, W.J., Kao, B.N., Silber, M., McKew, S.A., Brewer, J.C., Vite, C.C., Walkley, C.H., Austin, S.U., Porter, C.P.: F. D.: Intrathecal 2-hydroxypropyl-β-cyclodextrin decreases neurological disease progression in Niemann-Pick disease, type C1: a non-randomised, open-label, phase 1–2 trial. Lancet 390(10104), 1758–1768 (2017)CrossRefGoogle Scholar
- 14.WinMOPAC v3.9, Fujitsu Ltd, Tokyo, Japan, (2004)Google Scholar
- 15.Stewart, J.J.P.: MOPAC2002 v1.5. Fujitsu Ltd, Tokyo (2003)Google Scholar
- 21.Ryzhakov, A., D-Thi, T., Stappaerts, J., Bertoletti, L., Kimpe, K., Couto, A.R.S., Saokham, P., Mooter, G.V., Augustijns, P., Somsen, G.W., Kurkov, S., Inghelbrecht, S., Arien, A., Jimidar, M.I., Schrijnemakers, K., Loftsson, T.: Self-assembly of cyclodextrins and their complexes in aqueous solutions. J. Pharm. Sci. 105, 2556–2569 (2016)CrossRefGoogle Scholar