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

Self-assembly of pi-electron-deficient cyclophanes, in particular pi-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), H-1 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 pi-pi 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 pi-pi stacking interaction.