Design,Synthesis And Properties Of Fluorescent Probes For Hydrogen Sulfide Based On Quinoline-Vinyl-Phenol Conjugation

Hydrogen sulfide（H₂S）plays a crucial role in maintaining physiological processes such as vasodilation,insulin release,and regulation of inflammation as well as neuronal excitability.Excess H₂S can lead to several diseases such as Parkinson’s disease,Down syndrome,Alzheimer’s disease,and liver cirrhosis.Moreover,H₂S is widespread present in organosulfur rich foods and as a food spoilage marker due to releasing rotten egg odor.Therefore,the development of novel fluorescent molecular probes of H₂S for food safety and physiological environments is considered of great interest in the field of chemistry and sensing.In this thesis,the conjugate skeleton of quinoline-vinyl-phenol was used as fluorophores,and 2,4-dinitrophenyl ether was used as H₂S recognition site to investigate the salinization by quinoline quaternary ammonium and the strategy of o-aldehyde assisted thiolysis of dinitrophenyl ether.Two kinds of hydrogen sulfide fluorescent probes 4NS and 4ANS were designed and synthesized,and its structures were confirmed by standard structural spectral analysis.The optical properties and application of the probes 4NS and 4ANS were also investigated,and the details are as follows:In Chapter 2,a novel probe 4NS was synthesized from the starting conjugated quinoline-vinyl-phenol skeleton（3a）by etherification and salinization reactions.In CH₃CN/PBS（9:1,p H=7.4,v/v）,the fluorescence probe 4NS has high selectivity for H₂S(UV red-shift 170nm,fluorescence quenching atλ_em=490 nm),fast response time（15 min）and low detection limit（54 n M）.The sensing mechanism was confirmed by spectral and LC-MS analysis,which showed H₂S-triggered intermolecular thiolysis of dinitrophenyl ether to form labile zwitterionic[4NS-O^-],followed by intramolecular rearrangement and ultimately lead to a neutral quinoline-alkenone conjugate（QLT）.In addition,the 4NS-loaded test strips was successfully applied to detect H₂S in practical food spoilage.In Chapter 3,in order to enhance the sensitivity of probe 4NS,the target probe 4ANS was designed to accelerate the intramolecular thiolysis of dinitrophenyl ether using the fast nucleophilic addition of H₂S to the aldehyde group.The probe 4ANS was synthesized from the starting conjugate quinoline-vinyl-phenol skeleton（3b）by etherification and salinization.In DMSO/PBS（1:1,p H=7.4,v/v）solvent,the fluorescence probe 4ANS has high selectivity(UV red-shift 117 nm,fluorescence light-up atλ_em=544 nm),fast response time（3 min）and low detection limit（15 n M）for H₂S.The sensing mechanism was confirmed by HRMS analysis,which showed the fast nucleophilic addition of H₂S to an aldehyde group followed by the intramolecular fast thiolysis of dinitrophenyl ether take place,further release PG to product fluorophore 4ANS-PG.In addition,the 4ANS-loaded test strips was successfully applied to detect H₂S produced by food spoilage,the biocompatibility and imaging ability of4ANS for H₂S in living cells were also evaluated.