Supramolecular Assembly of 2,7‐Dimethyldiazapyrenium and Cucurbit[8]uril: A New Fluorescent Host for Detection of Catechol and Dopamine

Abstract

The formation of a highly stable inclusion complex between 2,7-dimethyldiazapyrenium (Me₂DAP²⁺) and the cucurbit[8]uril host (CB8) was demonstrated by X-ray crystallography; MALDI-TOF mass spectrometry; and ¹H NMR, electronic absorption, and emission spectroscopy. The equilibrium association constant was determined to be 8.9(±0.2)×10⁵ L mol⁻¹ from UV-visible data and 8.4(±1.5)×10⁵ L mol⁻¹ from fluorescence data. The Me₂DAP²⁺⋅CB8 inclusion complex acted as a host to bind compounds containing aromatic π-donor moieties (D), such as catechol and dopamine. This point was demonstrated by ¹H NMR spectroscopy, and electrochemical and emission measurements. Fluorescence detection of the Me₂DAP²⁺⋅D⋅CB8 ternary complexes was evident in aqueous solution and on the surface of silica particles, to which fluorescent diazapyrenium units had been covalently immobilized.