Fig. 4: X-ray single crystal structure of G4@4b ∙ H⁺.

a The over view of G4@4b ∙ H⁺ is presented as a stick model, showing four hydrogen bonds between guest and host. b Host and guest are shown with stick model and space-filling model in the side view of G4@4b ∙ H⁺, respectively. G4 is fully encapsulated in the cavity of 4b•H⁺. Most of hydrogen atoms and PF₆⁻ counter ions are omitted for viewing clarity. Color codes: carbon, gray or orange; oxygen, red; nitrogen, blue.