Synthesis And Application Of Pyridine-based Fluorescent Probe For Sensing Of PH And HSO₃^-

Chapter 1:The composition,category,recognition mechanism,various skeleton structure of the fluorescence probe are introduced.In addition,we present their research progress in detail.Based on the summary of previous work,we present our research in this thesis.Chapter 2:A new pH fluorescent probe 3-?N-butylcarbazol-3-dicyanovinyl?-pyridine?Probe 1?is synthesized for extremely acidic conditions.Probe 1 displays excellent pH-dependent performance with a pK_a of 2.93 and responds linearly to minor pH changes in the range of 2.60-3.30.It has good selectivity,large Stokes shift?122 nm?,sensitivity and short response time.More importantly,it has been applied successfully to imaging extreme acidity in E.coli cells,indicating that the probe can afford practical application in biological systems.Chapter 3:A aggregation induced emissions active fluorescence probe1-?pyrene-1-yl?-3-?pyridine-4-yl?-acrylketone?Probe 2?is designed and synthesized.The fluorescence probe for sensing pH and HSO₃^-can be distinguished by the spectral properties in different media.The pH titrations indicate that the fluorescence intensity of probe at 460 nm was reduced and a new emission band at 414 nm concomitantly emerge with pH range from7.10 to 1.36 in CH₃CN/H₂O?1/3,V/V?.A sigmoidal plot of pH vs.the I_{460 nm}/I_{414 nm} emission ratios predictes an apparent pK_a of of 4.26 and respond linearly to minor pH fluctuations within the acidic range of 3.00-5.50.And the emission at 455 nm exhibits a remarkable emission enhancement with pK_a 10.91 and linear response to extreme-alkalinity range of 9.75-11.35 in CH₃CN/H₂O?1/19,V/V?.Interestingly,the probe also responds to HSO₃^-with an obvious turn off fluorescence signal in in PBS buffer?pH=5.00,1.5%DMSO?.And the detection limits?LOD?of the probe for HSO₃^-was 1.9 nM.The mechanism is investigated by ¹HNMR and HRMS.Furthermore,the probe has been applied successfully to pH and HSO₃^-imaging in live cells.Chapter 4:We report a novel fluorescent probe?1-?pyrene-1-yl?-3-?6-methoxypyridine-3-yl?-acrylketone,Probe 3?for detection pH and HSO₃^-with D-?-A by connecting pyrene as an electron donor?D?and6-methoxypyridine-3-formaldehyde as an electron acceptor?A?.With the pH decreases from 7.30 to 1.10,a significant increase in monomer emission at417 nm along with a concomitant decrease in excimer emission at 527 nm is observed.A sigmoidal plot of pH vs.the I_{417 nm}/I_{527 nm} emission ratios predicted an apparent pKa of 2.70 and a good linearity in the range of1.26-3.97.When the pH increases from 7.30 to 13.41,the fluorescence intensity of the excimer emission of receptor probe remarkably decreases while the monomer emission intensity significantly increased.A pKa value of9.32 was obtained using the plot of the emission ratios I_{527 nm}/I_{460 nm} and a good linearity in the range of 8.54-10.36.In addition,the probe also responded to HSO₃^-with an obvious turn off fluorescence signal,and the detection limits?LOD?of for HSO₃^-was 0.32?M.Furthermore,this probe is successfully applied to imaging pH and HSO₃^-in live cells.It is expected that probe would be effective tools for studying significant biological processes at the issue and organism levels.