Is [N+-H⋯O] hydrogen bonding the most important noncovalent interaction in macrocycle-dibenzylammonium ion complexes?
Journal
Journal of Organic Chemistry
Journal Volume
71
Journal Issue
6
Pages
2373-2383
Date Issued
2006
Author(s)
Cheng, P.-N.
Huang, P.-Y.
Li, W.-S.
Ueng, S.-H.
Hung, W.-C.
Liu, Y.-H.
Lai, C.-C.
Wang, Y.
Chao, I.
Abstract
We report a new host molecule in which one diethylene glycol chain (i.e., a loop possessing only three oxygen atoms) incorporated along with two phenolic aromatic rings is linked by a xylene spacer into a macroring. The design of the molecular structure of this macrocycle "amplifies" any potential [cation...pi], [N+-H...pi], and [N+C-H...pi] interactions between the dibenzylammonium (DBA+) ion and the phenolic rings of the macrocycle; as such, these species display a very strong binding affinity in CD3NO2 (Ka = 15,000 M(-1)). The macroring also coordinates to bipyridinium ions in a [2]pseudorotaxane fashion, which makes it the smallest macrocycle (i.e., a 25-membered ring) known to complex both DBA+ and bipyridinium ions in solution. To confirm unambiguously that these pseudorotaxanes exist in solution, we synthesized their corresponding interlocked molecules, namely rotaxanes and catenanes.
Type
journal article