Supramolecular Complexation between Porphyrin‐Viologen Dyad and Cucurbit[7]uril

Abstract

AbstractWe here report the synthesis of a porphyrin‐viologen dyad, and its supramolecular complexation with cucurbit[7]uril (CB[7]). The synthesized dyad was characterized by 1H NMR spectroscopy and ESI mass spectrometry. The dyad readily forms a stable 1:1 supramolecular complex with CB[7], as evidenced by 1H NMR, ESI mass spectrometry, and isothermal titration calorimetry. The formation constant for the 1:1 complex determined by the photometric titration is (5.5 ± 0.2) × 104 M−1 at 25 °C in DMSO, which is nearly consistent with that obtained by titration calorimetry. We also uncovered the shuttling motion of the CB[7] ring in the supramolecular complex by variable temperature experiments in 1H NMR spectroscopy. Influences on the fluorescence of dyad by the supramolecular complexation with CB[7] was investigated in DMSO. When CB[7] was added to a solution of the dyad, the fluorescence intensities of dyad remarkably diminish accompanying with shifts to shorter wavelengths. While the electrochemical behavior of dyad in DMSO exhibits six redox waves, the redox waves exhibit irreversible behaviors in the presence of CB[7].