Construction And Application Of Fluorescent Probes Based On Pyrene And Carbazole

Fluorescent probes have attracted the attention of researchers due to the advantages of unique sensitivity,excellent selectivity,commercial availability,easy operation and real-time imaging in vitro and in vivo.In recent years,fluorescent probes for detecting various anions,cations,p H,thiols,active oxides and even proteins have been widely designed and applied in the fields of chemistry,environmental science and biomedicine.The pyrene and carbazole fluorophores possess high fluorescence quantum yields,large conjugated systems and excellent optical properties have been chosen for designing various fluorescent probes.In this paper,four fluorescent probes were synthesized using pyrene or carbazole as fluorophore,and they were used to specifically recognize CN^-,ClO^-and H₂S.This paper mainly includes the following six chapters:Chapter 1: A brief overview of the concept of molecular recognition and fluorescent probe,as well as the composition and common recognition mechanisms of fluorescent probes.The research progress of fluorescent probes with pyrene and carbazole as fluorophore is also introduced.Chapter 2: The fluorescent probe 1-?pyren-1-yl?-3-?2,6-dichlorophenyl?-acrylketone?Probe 1?was synthesized for the detection of cyanide?CN^-?.The fluorescence intensity of Probe 1 at 464 nm was significantly increased when CN^-was added.The fluorescence intensity showed a good linear relationship with the concentration of CN^-in the range of 2.5-12.5 ?M,and the detection limit was 37 n M.Probe 1 exhibited outstanding selectivity toward CN^-.The reaction mechanism between Probe 1 and CN^-was supported by DFT and TD-DFT calculations.In addition,Probe 1 had been successfully employed for the imaging of CN^-in cells,C.elegans and zebrafishes.Besides,the probe was also successfully applied to detect the concentration of CN^-in spiked tap water samples.Chapter 3: A "turn-on" fluorescent probe?Probe 2?for selectively recognizing ClO^-had been reported.In ethanol/PBS?1/1,v/v,p H 7.4?solution,the introdection of ClO^-gradually decreased the absorbance of Probe 2 at 477 nm,and the fluorescence intensity at 490 nm gradually increased.The concentration of ClO^-exhibited a good linear relationship between the absorbance and fluorescence intensity.The strong oxidation of ClO^-caused the C=C bond to be cleaved,and the molecular structure of the probe changes to cause changes in the absorption spectra and the emission spectra.The probe showed high sensitivity for the detedction of ClO^-with a detection limit of 0.19 ?M.Moreover,Probe 2 was successfully applied in Hep G2 cell imaging.Chapter 4: A chalcone derivative?Probe 3?was designed based on the carbazole fluorophore for sensitive and rapid detection of ClO^-.Among many analytes,the probe exhibited unique selectivity and anti-interference ability to ClO^-.The p-methoxyphenol group in Probe 3 was oxidized to phenylhydrazine by ClO^-,thereby emitted strong fluorescence at 525 nm.The fluorescence intensity showed a linear relationship with the Cl Oconcentration in the range of 53.6-107.2 ?M with a detection limit of 0.30 ?M.Fluorescence imaging results indicated that Probe 3 can be used to visually detect ClO^-in Hep G2 cells.Chapter 5: The new carbazole-based fluorescent probe Probe 4 was designed and synthesized for the high selective detection of H₂S based on HS-facilitated sulfur pyran resulting in UV-vis and fluorescent spectra changes.At the same time,the probe showed good sensitivity for detecting H₂S with a low detection limit of 0.16 ?M.The detection process could be monitored by naked eyes: with the addition of H₂S,the probe system changed from yellow to pink.Importantly,the probe could be applied in monitoring H₂S in Hep G2 cells and Chlorella.Chapter 6: This part summarizes the studies involved in this paper and prospects the future direction and goals.