Synthesis of a novel water-soluble cylindrical macrotricyclic host and its complexation with N-methylquinolinium and N-methylisoquinolinium salts: formation of 1 : 2 complexes in water.

A novel water-soluble cylindrical macrotricyclic host containing one central cavity and two dibenzo-24-crown-8 lateral cavities was synthesized. It could form 1 : 2 complexes with N-methylquinolinium salts or N-methylisoquinolinium salts in water solution and in the solid state, in which multiple hydrogen-bonding and π-π stacking interactions between the host and the guests played an important role. Moreover, the complexation and decomplexation of the complexes between the host and the guests could be achieved by changing the pH of the solution, and the process could also be observed by the naked eye.