A stimuli-responsive supramolecular assembly between inverted cucurbit[7]uril and hemicyanine dye

The effect of inverted curcurbit[7]uril (iQ[7]) on the binding mode of 2-(4-(dimethylamino)styryl)-1-methylpyridinium (DASPMI) was determined in this study. A large fluorescence enhancement of DASPMI was realized by the formation of an inclusion complex with iQ[7]. A 1:1 inclusion complex was determined through UV absorption and fluorescence spectroscopies, H-1 nuclear magnetic resonance (NMR) spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and isothermal titration calorimetry (ITC) at different pH values. In addition, we also devised a method for the controlled release of DASPMI from the iQ[7] macrocycle by adding ,-diamino-p-xylene.