Conformational Control of [2]Rotaxane by Hydrogen Bond

Abstract

A series of [2]rotaxanes with various functional groups in the axle component was synthesized by the oxidative dimerization of alkynes, which is mediated by a macrocyclic phenanthroline–Cu complex. The rotaxanes were fully characterized by spectroscopic methods, and the structure of a rotaxane was determined by X-ray crystallographic analysis. The interaction between the ring component and the axle component was studied in detail to understand the conformation of the rotaxanes. The presence of the hydrogen bond between the phenanthroline moiety in the macrocyclic component and the acidic proton in the axle component influenced the conformation of rotaxane.

Fluorinated [2]rotaxanes with spirofluorene motifs: a non-symmetric distribution of the ring component along the axle component

“…This type of interaction has been reported in the solid state by several groups including ours. 22 The bulkiness of the alkylene chain compared to the diyne structure could also be a driving force for the localization of the ring component in the proximity of the diyne moiety.…”

POSSaxanes: active-template synthesis of organic–inorganic rotaxanes incorporating cubic silsesquioxane stoppers

“…The characteristic triazole CH singlet of the 10b thread underwent a downfield shift from 7.55 ppm to 8.30 ppm in 10b-A, resulting from the CHÁ Á ÁN hydrogen bonding between the triazole linker of the axle and bipyridine of the macrocycle. 24 The incorporation of the POSS stopper was also evident from the presence of the characteristic set of resonances corresponding to the protons of iso-butyl groups at the POSS vertices in the 1 H NMR spectrum of 10b-A (Fig. S31, ESI †).…”