36707-88-7Relevant articles and documents
Orientational isomers of α-cyclodextrin [2]semi-rotaxanes with asymmetric dicationic threads
Baer, Andrew J.,Macartney, Donal H.
, p. 1448 - 1453 (2007/10/03)
Two series of novel dicationic threading molecules [Quin(CH 2)10R]2+ and [3,5-Lut(CH2) 10R]2+, where Quin- = quinuclidinium. 3,5-Lut+ = 3,5-lutidinium, and R+ = N(CH3) 3+ and N(CH3)2CH2CH 3+, form [2]semi-rotaxanes with α-cyclodextrin (α-CD) in aqueous solution. The quinuclidinium and 3.5-lutidinium arc sufficiently bulky to prevent threading while the R+ groups allow for slow threading by α-CD at 25°C. The resulting [2]semi-rotaxanes exist in two orientational isomers owing to the asymmetry of both the α-CD cavity and the threading molecules. Two-dimensional 1H NMR spectroscopy and kinetics experiments reveal that the isomer in which the narrower rim (primary OHs) is positioned near the R+ group is the kinetically preferred isomer, while the other isomer is the thermodynamically preferred product. The kinetics and mechanism of the formation, dissociation, and interconversion of the two isomers have been determined at 25°C. The Royal Society of Chemistry 2005.
