Novel pseudorotaxanes based on fluorine-containing cyclophanes and phenyl ether derivatives

Abstract

Self-assembly of π-electron-deficient cyclophanes, in particular π-electron-deficient fluorine-containing bipyridine cyclophanes, is still the important branch of supramolecular chemistry today. Two kinds of novel pseudorotaxanes were constructed by the self-assembly of fluorine-containing cyclophanes with phenyl ether derivatives. Interactions between two fluorine-containing cyclophanes 2 and 3 with phenyl ether BHEEB (1,4-Bis[2-(2-hydroxyethoxy)ethoxy]benzene) 1 were well investigated by variable-temperature nuclear magnetic resonance (VT NMR), 1H NMR titrations, solid-state findings (single-crystal X-ray diffraction) and a theoretical study. The introduction of the fluorine atom to the host cyclobis (paraquat-p-phenylene) (CBPQT) decreased π–π stacking interactions between CBPQT and BHEEB. The average binding energies of 5FCBPQT–BHEEB 1·3 were lower than the average binding energies of 1FCBPQT–BHEEB 1·2 since 5FCBPQT 3 was introduced having more electron-withdrawing fluorine atoms to CBPQT which is not good for the π–π stacking interaction.