Synthesis And Properties Of Near Infrared Fluorescent Probes For Detecting O₂^·-,HNO,H₂S And PhSH

Fluorescent probes have become an important tool for detecting small molecules in living cells due to their advantages such as high sensitivity,strong specificity,and high spatiotemporal resolution.Traditional fluorescent probes have visible region emission wavelengths,which are greatly interfered by the spontaneous fluorescence of organisms.Near-infrared（NIR）fluorescent probes with emission wavelengths ranging from 650 nm to 900 nm can effectively avoid interference from spontaneous fluorescence of biomolecules.Simultaneously,the NIR fluorescence probes can image deeper tissues and cause less damaging to biological samples.Therefore,it is of great significance to design near-infrared fluorescence probes to study small molecules in organisms.In this paper,four NIR probes(NB-O₂^·-,PITC-HNO,DCM-H₂S and DC-Ph SH)were synthesized based on nile blue,xanthene,benzopyran nitrile and isophorone fluorophores,which were used to detect O₂^·-,HNO,H₂S and Ph SH.The structures of the four target compounds were confirmed by ¹H NMR,¹³C NMR and HRMS.1.The probe NB-O₂^·-can specifically recognize O₂^·-in methanol-PBS buffer system,with high sensitivity,rapid response（T<10 s）and low detection limit（4.5n M）,The color of solution changes from blue to blue purple.2.The probe PITC-HNO can specifically recognize HNO in DMF-PBS buffer system with significantly obvious color change,reaching the maximum response platform within 8 minutes and has strong anti-interference ability.3.The probe DCM-H₂S can recognize H₂S in the CH₃OH-PBS buffer system,with good specificity,high sensitivity,and detection limit as low as 0.35μM.The color of solution changes from yellow to red,which can be recognized by the naked eye.4.The probe DC-Ph SH can specifically recognize Ph SH in DMF-PBS buffer system,and does not respond to other active sulfur,and can realize naked eye recognition of Ph SH through the color change of the solution system.