Synthesis And Performance Study Of 3,4-disubstituted 1,8-naphthalimide Fluorescent Molecular Probes

In this paper, 3,4-disubstituted-1,8-naphthalimide fluorescent molecular probes (H1-H9) were designed and synthesized using the raw material 3-nitro-4-bromo-N-[2-(2′-hydroxy ethoxy)ethyl]-1,8-naphthalimides through reaction with amines and then reduction. The structures of all compounds were identified by IR, ¹H-NMR and ¹³C-NMR.After the preliminary selection, the recognition of four water-solvable probes which were 3-amido-4-butyl-N-[2-(2′-hydroxyethoxy)ethyl]-1,8-naphthalimide (H1), 3-amido-4-[2-(N′,N′- dimethylamino)ethylamino]-N-[2-(2′-hydroxyethoxy)ethyl]-1,8-naphthalimide (H2), 3-amido- 4-hydroxyethylethylamino-N-[2-(2′-hydroxyethoxy)ethyl]-1,8-naphthalimide (H8), 3-amido-4 -[8′-(amino)quinolyl]-N-[2-(2′-hydroxyethoxy)ethyl]-1,8-naphthalimide (H9) were studied.The results show that H1 exhibits a high selectivity towards Cu²⁺ with 7 folds fluorescence enhancement and a 100 nm red-shift in emission in HEPES-NaOH buffer aqueous solution. H2 displays selectivity and sensitivity for Hg²⁺ with 3.6 folds fluorescence enhancement and a 30 nm red-shift in absorption in HEPES- NaOH buffer aqueous solution. H8 exhibits selectivity towards Cd²⁺, Hg²⁺, Pb²⁺ with fluorescence enhancement in HEPES-NaOH buffer aqueous solution. H9 displays high selectivity and sensitivity for Cu²⁺ with fluorescence enhancement, a large 100 nm red shift in absorption and a color change from yellow to red in HEPES-NaOH buffer aqueous solution, which made H9 serve as a dual-channel responsive probe for Cu²⁺.