A Novel Turn-On the Fluorescence Sensor for H2S and its Applications in Bioimaging

A fluorescent probe II, 6-azido-2-(2-hydroxyethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione with specific identification environment H2S, was designed and synthesized based on 4-bromine-1,8-naphthalimide and ethanamine. We used 4-bromine-1,8-naphthimide as raw materials to synthesize a new type of reactive fluorescent probe based on the mechanism of intramolecular charge transfer. These two materials are easily obtainable, low in cost, and can be synthesized through a simple two-step reaction. 1,8-Naphthalene anhydride has a moderate fluorescent ability as it introduces an electron-donating group at position 4. A change to its conjugate system can cause a push-pull electronic effect in the molecule and result in a very strong luminous effect. The structure of probe II was characterized by IR, ESI, and NMR. The preliminary screening was under the UV lamp. We found that probe II had a certain specific recognition effect on H2S in the DMSO solvent. After the solvent screening, DMSO was selected as a solvent to identify H2S specifically for the probe. The fluorescence spectroscopy illustrated that probe II showed green fluorescence in the DMSO solution. With the continuous addition of H2S, probe II showed red fluorescence at 510 nm, which produced a strong fluorescence emission peak that stood out from the rest of the spectrum. The experimental results showed that the probe had a very good sensitivity at detecting H2S (with a minimum concentration of 1 × 10–7 mol/L). Meanwhile, dozens of cations and anions do not interfere with the recognition of H2S by the probe molecule in the DMSO system. At the same time, we found that probe II could also recognize H2S by cell imaging technology.