Interaction and Supramocular Self-Assembly of Cucurbit[7]uril with 2,2'-(Heptane-1,7-diyl) Dibenzimidazolium Chloride

The interaction and supramolecular self-assembly of cucurbit[7]uril (Q[7]) with 2,2'-(heptane-1,7-diyl) dibenzimidazolium chloride (SBHt) in aqueous solution were investigated by H NMR spectroscopy, fluorescence spectroscopy in details. The pKa shift of guest in the presence of Q[7] was first investigated in order to decide the pH of medium condition for investigation of host-guest interaction and supramolecular self-assembly. H NMR spectroscopy analysis revealed that Q[7] included the alkylene chain of guest and formed a simple 1∶1 host-guest binding model complex at a low rate of NQ[7]/NSBHt, while at higher ratios of Q[7] to guest, two host Q[7] prefer to include the benzimidazolyl moieties of guest and formed a dumbbell shape inclusion complex. The typical reversible interaction modes were controlled by concentration of the ratio of host and guest, and the process was further conformed by fluorescence spectroscopy technology. The single X-ray crystal structure analysis showed a 1∶1 host-guest inclusion complex in which the alkyl chain of SBHt was folded in order to effectively interact with Q[7] through ion-dipole interactions and hydrogen bonding.