Slow Intermolecular Complexation–Decomplexation Exchanges of Cyclodextrins in Fullerene and Its Derivative Complexes. Issue 34 (7th December 2017)

• Record Type: Journal Article
• Authors: Ikeda, Atsushi; Mae, Tomoya; Sugikawa, Kouta; Komaguchi, Kenji; Konishi, Toshifumi; Hirao, Takehiro; Haino, Takeharu
• Is Part Of: ChemistrySelect. Volume 2:Issue 34(2017)
• Page Start: 11322
• Page End: 11327
• Publication Date: 2017-12-07
• Subjects: cyclodextrins -- fullerenes -- host-guest systems -- pseudorotaxanes -- NMR spectroscopy; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201702319
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: Fullerenes (C60 and C70 ) and several functionalized C60 derivatives can be encapsulated in two γ‐cyclodextrins (γ‐CDxs). Although intermolecular complexation–decomplexation exchange of γ‐CDx is known to be very slow, the exchange rates have yet to be quantitatively measured. Herein, we determined that the pseudo‐first‐order association and dissociation rate constants for the γ‐CDx2 C70 complex were 4.3 and 0.6 s −1 at 23 °C, respectively. In contrast, the intermolecular exchange rates for the γ‐CDx2 C60 and C60 derivative complexes were slower than the time scale of exchange spectroscopy NMR experiments and the exchange rate constants were in the order of 10 −4 s −1 . Furthermore, a γ‐CDx2 C60 derivative complex was shown to have different intermolecular exchange rates for the two γ‐CDxs depending on steric hindrance from the substituent on the C60 derivative. Abstract : Intermolecular exchange rates of the intermolecular exchange rates for γ‐cyclodextrin2 C60 and C60 derivative complexes were slower than the time scale of exchange spectroscopy NMR experiments and the exchange rate constants were in the order of 10 −4 s −1 . Furthermore, the γ‐cyclodextrin2 C60 derivative has different intermolecular exchange rates via two pathways because of steric hindrance by a substituent on the C60 derivative.