Aggregation-Induced emissive molecule with large stokes shift based on naphthalimide and triphenylamine

Aggregation-induced emission (AIE) phenomenon is one of the research highlights in the field of optoelectric materials. However, the most advanced AIE materials emit the short wavelength fluorescence in blue to green region. The efficient energy transfer process was achieved via overlay the spectra of chromophores, which can construct the AIE-active molecule (NIPTPACN) with large Stokes shift. The 4-phenylnaphthalimide (NIP) with blue AIE fluorescence developed in our lab was selected as the energy donor and the β-cyanoethenyltriphenylamine (TPACN) with red fluorescence was selected as the acceptor. The obtained NIPTPACN can output the strong red fluorescence centered at 608 nm in aqueous solution (aggregated state) under excitation at 365 nm. The Stokes shift of NIPTPACN reaches 248 nm and the fluorescent intensity of NIPTPACN at 608 nm is 82.6-fold than the one of the solo TPACN fluorophore. This work successfully constructs an AIE-active molecule with long emission wavelength and large Stokes shift, which can provide the new strategy based on the fluorescence resonance energy transfer (FRET) mechanism.