Photoinduced Radical Luminescence of Diazapyrene Derivatives upon Complexation with Cucurbit[n]uril Hosts

Molecular design with an electron donor‐acceptor (D‐A) structure and host‐guest complexation are effective strategies for stabilizing radicals. Herein, we report the design and synthesis of cationic diazapyrene derivatives featuring a D‐A structure, as well as the influence of host‐guest complexation on their photoinduced organic radical photophysical properties. Compared to the methylated diazapyrene 1, the other three derivatives 2‐4, containing triphenylamine, coumarin, and naphthalene units as D groups, respectively, are more favorable for the generation of radicals. Binding studies reveal that cucurbit[8]uril (CB[8]) forms 1:1 inclusion complexes with derivatives 2‐4, while CB[10] forms a 2:2 inclusion complex with 2 and supramolecular polymers with 3 and 4. The radical luminescence of derivatives 1‐4 in aqueous solution is significantly promoted upon complexation with CB[8] or CB[10]. Additionally, the emission color of 3 shifts from cyan to yellow‐green upon light irradiation in the presence of CB[8].