Ring size affects the kinetic and thermodynamic formation of [2]rotaxanes featuring an unsymmetric bis-crown ether component†
Abstract
Bridging of a [2]pseudorotaxane formed from an unsymmetric mono-crown ether and an ammonium salt has provided two types of [2]rotaxanes, with the axle component positioned within a large (4L) and small (4S) ring, respectively. 1H NMR spectroscopy has revealed that 4L is the kinetically favored [2]rotaxane, whereas 4S is thermodynamically favored at low temperature.
- This article is part of the themed collection: Mechanical Bond and Dynamic Covalent Bond