CH···O Hydrogen Bonds in “Clicked” Diketopiperazine-Based Amide Rotaxanes

Two amide [2]rotaxanes were synthesized in high yields using a novel N,N′-dipropargyl diketopiperazine axle centerpiece as the template to which the stoppers are attached through “click chemistry”. 1H and 2D NMR spectra provide evidence for two different H-bonding motifs, in one of which the triazole CH groups form C–H···OC bonds with the wheel carbonyl O atoms. This motif can be controlled and switched reversibly by competitive anion binding.