Design,Synthesis And Performance Research Of Several New Type Fluorescent Probes

Fluorescence imaging has become a powerful tool in medical diagnosis and biological analysis.A large number of fluorescent probes for detecting metal ions,active sulfur,and p H have been developed.However,due to their problems such as short absorption and emission wavelengths,aggregation-caused quenching（ACQ）effect,poor selectivity,etc.,they are difficult to use for vivo imaging.Therefore,it is still of great significance to develop various types of fluorescent probes that are simple,selective,and sensitive.In this paper,cyanines,rhodamine-like skeletons and other kinds of fluorescence skeletons were used to design and synthesize 9 fluorescent probes with specific recognition for Cu²⁺,Fe³⁺,Na₂S,p H and biological thiols.The details are as follows:1.The near-infrared fluorescent probe TM1 was synthesized with cyanine as the skeleton,which has both the fluorescence resonance energy transfer effect（FRET）and the aggregation induced emission effect（AIE）to specifically recognize the divalent copper ion.Through the spectrum testing,it is found that the probe TM1 in the THF/H₂O（6:4,v/v）solution can specifically recognize Cu²⁺and has good anti-interference performance.TM1 has dual-channel fluorescence recognition for Cu²⁺too.It has the characteristics of a chemical ratiometer when excited at 750 nm,and the detection limit is 1.4×10^-6mol/L.It also has wide linear detection range（0-0.1 m M）.It is 1:1 coordination reaction with Cu²⁺.We use nuclear magnetic titration to explore the response mechanism.It has the ability to detect Cu²⁺qualitatively that can be distinguished by the naked eye.Stokes shift reaches 370 nm,and the p H in the range of 5-9 has little effect on the spectrum.In summary,it has the potential to be applied to biological imaging.2.The near-infrared fluorescent probe TM2 was synthesized with rhodamine-like skeleton.The recognition group quinoline-like and the electron-rich group dimethylaminophenyl were synthesized by condensation reaction to synthesize another novel Cu²⁺probe TM4.Through the spectrum test,it is found that the probe TM2 in ethanol/H₂O（5:5,v/v）solution has good selectivity and anti-interference ability for Cu²⁺recognition,and the detection limit is 2.3×10^-6mol/L.The linear detection range is wide（0-0.2 m M）,and the probe is complexed with Cu²⁺in a ratio of 1:1.It has the ability to detect Cu²⁺qualitatively that can be distinguished by the naked eye.Secondly,we use the addition of p H and Cu²⁺as the chemical input,the fluorescence intensity as the output,and the probe molecule is designed to be used as an"And gate"logic gate.The probe TM4 has good selectivity for Cu²⁺except Hg²⁺in ethanol/H₂O（5:5,v/v）solution,with a detection limit of 5.8×10^-7mol/L.It is suitable for the detection of very small amounts of Cu²⁺in cells,and other properties need to be further explored.3.A new type of Na₂S near-infrared probe TM3 was synthesized using cyanine as a skeleton.Through the spectrum test,it is found that the probe TM3 in ethanol/H₂O（5:5,v/v）solution has good selectivity and anti-interference ability for the recognition of Na₂S,and the detection limit is 2.0×10^-7mol/L.The probe is complexed with Na₂S at a ratio of 1:1,and the probe also has the ability to detect Na₂S qualitatively that can be distinguished by the naked eye.4.Two novel rhodamine-like p H probes TM5 and TM7 were synthesized through structural modification of rhodamine.The Fe³⁺probe TM6 was synthesized by introducing the thiosemicarbazide recognition group on the basis of probe TM5.Through the spectrum test,common metal ions have no interference to the probe TM5,and can accurately detect the p H change in the range of p H 2.5-3.5.The p H of the probe TM5 is reversible,and under natural light,it can distinguish four kinds of acid-base conditions:strong acid,weak acid,weak base,and strong base by changing the color of the solution.The p H recognition of the probe TM7 is only interfered by Hg²⁺.TM7 is suitable for accurately detecting p H changes in the range of p H 4.0-6.5,and the probe has good reversibility.Probe TM6 has an"off-on"effect on Fe³⁺recognition.The detection limit of Fe³⁺is 7.2×10^-6mol/L,and it has the ability to distinguish the presence of Fe³⁺in the solution under visible light.5.By introducing the recognition sulfhydryl group 2,4-dinitrobenzenesulfonyl,the biothiol probes TM8 and TM9 were successfully synthesized.Through the spectrum test,it is found that the probe TM8 in DMSO/H₂O（5:5,v/v）solution has good selectivity ability to recognition of sulfhydryl compounds such as cysteine,homocysteine and 2-aminothiophenol.2-Aminothiophenol has the characteristics of a stoichiometric meter,with a detection limit of4.2×10^-7mol/L.The concentration of homocysteine has a linear relationship with the fluorescence intensity in the range of 0-100μM,and the detection limit is 3.56×10^-5mol/L.Probe TM8 also showed a chemical ratio fluorescence response to cysteine,with a detection limit of 1.67×10^-5mol·L^-1.In the meantime,the color change of the probe TM8 under visible light can identify the presence of homocysteine with the naked eye.The probe TM9 can specifically detect the concentration of cysteine without being interfered by other common amino acids.The detection limit of cysteine is 4.4×10^-5mol/L.