CH···O Hydrogen Bonds in Clicked Diketopiperazine-Based Amide Rotaxanes
E.V. Dzyuba, L. Kaufmann, N.L. Löw, A.K. Meyer, H.D.F. Winkler, K. Rissanen, C.A. Schalley – 2011
Two amide 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.