Design, Synthesis And Application Of Fluorescence Probes For Small Gas Molecules

Some environmental pollution of small gas molecules and biological gas signal molecules such as SO2, NO2, H2S, NO and CO are closely related human life and health.Therefore, detection of these small gas molecules has vital significance. Herein three types of fluorescent probes for the detection of HSO3-and HS- derived respectively from SO2 and H2S were designed and synthesized because these small gas molecues is difficult to capture and detect quantitatively as well as small gas molecules were detected mainly in the form of their derivatives which are reported. The main contents are as following:(1) Synthesis and properties of fluorescent probes based on benzothiazole for HSO3-. In this part,we employed the 2-(2'-hydroxyphenyl) -benzothiazole (HBT) fluorophore as the signal reporter and nitroolefin as the responding site to synthesis two fluorescent HSO3-probes (HBT-N1 and HBT-N2). The two probes have low fluorescence because the nitroolefin group produces a PET effect on the fluorophore. Conjugate addition reaction between HSO3- and nitroolefin group can destroy the double bond of nitroolefin moiety,which blocking the PET effect and resulting in fluorescence recovery. The detection limits of HBT-N1 and HBT-N2 for HSO3- were respectively determined as 89 nM and 13 nM,showing that the two probes have a good selectivity and sensitivity. The two probes were successfully used to image HSO3- ions in living cells.(2) Synthesis and properties of chromenylium-based fluorescent probes for HSO3-. A novel ratiometric fluorescence probe QPCT based on chromenylium derivative was developed. QPCT can react with HSO3- via conjugation addition reaction and then destroy the ?-? conjugation. Upon addition with HSO3-, the UV-vis absorption of the probe blue-shift from pink to yellow, and the color of the probe turned from orange to green under 365 nm UV lamp. The results of spectral analysis showed that the probe QPCT had good selectivity and sensitivity, the response time was 450 s, and the detection limit was 4.4 × 10-7 M. In addition, the probe QPCT has been successfully applied to the determination of HSO3- in food samples.(3) Synthesis and properties of fluorescent probe based benzothiazole for H2S. In this part, we employed the 2-(2'-hydroxyphenyl)-benzothiazole (HBT) fluorophore as the signal reporter and Schiff base as the recognition group to construct a fluorescent H2S probe (HBT-C) based on the paramagnetism of Cu2+ and ESIPT process. Upon treatment with Cu2+, the probe is low fluorescence because of the paramagnetism of Cu2+ and blocking the ESIPT process. After the addition of S2-, its flurescence intensity was recovered because of forming CuS. The HBT-C-Cu2+ complex can not only excludes the interference of other thiol molecules in the body, but also has high sensitivity. The detection limit was as low as 8 nM.