Design,Synthesis And Application Of Fluorescence Probe For The Detection Of Thiophenol

BackgroundThiophenol is an important organic synthetic additive and has been widely used in the synthesis of pesticides,medicines and functional polymers.On account of their highly toxic nature,direct exposure of organisms to thiophenols could result in serious health problem that was widely concerned.Due to its characteristics of high sensitivity,low detection limit,low toxicity and real-time visualized intelligent analysis,fluorescence detection method is widely used in the detection of ions,molecules and even biomolecules in life science,forensic medicine,environmental science and other multi-disciplinary fields.Therefore,the design and synthesis of novel thiophenol fluorescent probes are of great significance in environmental detection and forensic identification.ObjectivesFluorescent probes for the detection of thiophenol with high selectivity,low detection limit,high specificity and visualization were designed and synthesized.They are applied in water sample testing and cell fluorescence imaging experiment to further study the practical value of the probe.Methods1 Design and synthesis of fluorescent probes L1,L2,L3 for the detection of thiophenol.The structures of these probes were characterized by mass spectrometry and NMR spectra.2 UV-vis spectroscopy and fluorescence spectroscopy were performed to measure the response of the probes to various metal ions,sulfur anions,amino acids and thiophenols.3 The mechanism of fluorescent probes L1,L2 and L3 response to thiophenol was analyzed.4 The cancer cells were cultured,and the cytotoxicity of probes was detected by MTT assay.5 Fluorescent imaging experiments in vivo and environmental water samples were performed to study the application of probes in biology and environment.Results1 A novel fluorescent probe L1 based on julolidine was synthesized for the detection of thiophenol on the basis of a unique thiophenol-mediated substitution-cyclization reaction.The probe 1 displayed 420-fold fluorescence intensity enhancement and highly selective and sensitive response for thiophenol over other competing sulfur species.This probe showed an excellent linear relationship in 10-140 mM and the low detection limit of29 nM.The recognition mechanism of probe L1 toward thiophenol was supported by the NMR spectrum and ESI-MS.Furthermore,the probe L1 was successfully applied for detection of thiophenol in living HepG2 cells.2 A novel Ru-based phosphorescent probe L2 was designed for the detection of thiophenol using 2,4-dinitrobenzenesulfonate as a sensing unit.The probe exhibited a remarkable off–on type of phosphorescent response towards thiophenol over other commonly encountered metal ions,anions,and aliphatic thiols.The probe was able to work in pure water medium.This probe displayed a large Stokes shift(216 nm)and long luminescence lifetime,and the detection limit reached as low as 30 nM.Moreover,detection of thiophenol is based on the thiol-induced cleavage of a sulfonamide linkage to generate a strongly phosphorescent species,which showed obvious Aggregation-Induced Emission Enhancement(AIEE)activity.Furthermore,the potential for practical applications of this probe has been successfully demonstrated in monitoring thiophenol in real water samples and on test paper.3 A novel spiropyran-based colorimetric fluorescent probe L3 was successfully synthesized.The probe uses 2,4-dinitrophenyl as the thiophenol response site and was detected by ring-opening/ring-closing isomerization Thiophenol.After the addition of thiophenol,the UV-visible spectrum of probe L3 showed a significant change,which had a good linear relationship with the concentration of thiophenol,and caused the obvious color to change from purple to colorless.In the presence of other interfering ions,naked eye observation is possible.Probe L3 showed fast colorimetric reaction(30 seconds)and high sensitivity(detection limit 0.55?M)for thiophenol.The fluorescence response of this probe also shows good selectivity and sensitivity to thiophenol.The detection mechanism of the nucleophilic substitution-cyclization reaction was determined by ~1HNMR and MS analysis.In addition,L3 probe can detect the content of thiophenol in real water samples.Conclusions1 The fluorescent probes L1 for the detection of thiophenol was successfully designed,synthesized and applied to cell fluorescence imaging experiments;2 The fluorescent probe L2 for the detection of thiophenol was successfully designed and synthesized,which can detect thiophenol in water samples and test papers;3 The fluorescent probe L3 for the detection of thiophenol was designed and synthesized to accurately quantify phenol in water samples.