Synthesis And Photophysical Properties Of Benzothiophene-fused BODIPY And BOPHY

Near-infrared（NIR,650-1100 nm）fluorescent dyes have the characteristics of low phototoxicity,strong photothermal properties,little interference and toxicity to biological tissues,and strong cell penetration.Therefore,it is widely used in the fields of cell analysis and detection,clinical diagnosis and biomolecular labeling.It closely links various fields of study,including chemistry,materials science and biomedicine.In recent years,more and more near-infrared fluorescent dyes have been widely used in photodynamic therapy（PDT）,photothermal ablation therapy（PTT）,biofluorescence imaging and other fields.Among them,fluoroboron dipyrrole（BODIPY）fluorescent dyes,as a newly developed near-infrared organic fluorescent dye molecule,have received extensive attention from scientists in related fields such as chemistry,biomedicine,environmental science and life science.This paper mainly studies the monofluoroboron complex fluorescent dye BODIPY and the double fluoroboron complex fluorescent dye BOPHY.We expanded the molecular delocalization pathway,enhanced the rigidity of molecular structure and conjugated system through modification strategies such as aromatic ring fusion,aromatic ring substitution,and introduction of push-pull electron groups,resulting in a series of thiophene[3,2-g]indole and The benzothiophenes of thiophene[3,2-e]indole were fused with BODIPY and BOPHY,and their photophysical properties were investigated.The first chapter of this paper introduces the research progress of BODIPY and BOPHY fluorescent dyes.In the second chapter,a series of thiophene[3,2-g]indole and thiophene[3,2-e] indole derivative precursor.This route has the characteristics of cheap raw materials,simple route and diversified final products,and the introduction of methyl groups into the thiophene ring makes the precursor more electron-rich.Based on this,the subsequent synthesis of benzothiophene-fused BODIPY and BOPHY was carried out.The third chapter of this paper is based on the thiophene[3,2-g]indole and thiophene[3,2-e]indole precursors synthesized in the second chapter,through the classical BODIPY synthesis method（condensation,oxidation and fluoroboron complex A series of asymmetric benzothiophene fused BODIPY with different substituents were successfully obtained through Knoevanegal condensation reactions,and their photophysical properties were systematically studied.The results show that their maximum absorption wavelengths are located at 550-692 nm,their maximum emission wavelengths are located at 583-765 nm,their Stokes shifts are located at 12-121 nm,their fluorescence quantum yields are located at 0.0002-0.46,and their fluorescence lifetimes are located at 0.05-3.56 ns.Among them,BODIPY 3-13 has the best optical properties in toluene solvent,such as more significant absorption wavelength（695 nm）and emission wavelength（749 nm）,high fluorescence quantum yield（0.46）,longer fluorescence lifetime（2.95 ns）,high molar extinction coefficient（lgε=5.08）and large Stokes shift（54 nm）.Based on their optical properties,it can be seen that the electron-withdrawing ester group has an adverse effect on the absorption and emission wavelengths,the electron-donating group is conducive to the red shift of the absorption and emission wavelengths,and the introduction of aryl substituents can effectively extend the BODIPY parent π-conjugated system.,effectively enhance its optical properties,and the thiophene[3,2-e]indole condensed mode is more conducive to the redshift of BODIPY absorption and emission wavelengths.In chapter 4,a series of thiophene[3,2-g]indole and thiophene[3,2-e]indole precursors synthesized in chapter 2 were successfully synthesized through condensation,fluoroboron complexation and other reactions.Benzothiophene fused with BOPHY,and its optical properties were studied.The results show that their maximum absorption wavelength is located at 569-589 nm,their maximum emission wavelength is located at 595-623 nm,and the Stokes shift is located at 26-37 nm,among which BOPHY 4-10 has the maximum absorption wavelength（588.6 nm）and emission wavelength（622.8 nm）nm）,BOPHY 4-9had the largest Stokes shift（37 nm）.Based on their optical properties,it can be seen that the electron-withdrawing ester group has an adverse effect on the absorption and emission wavelengths of BOPHY,the electron-donating group is conducive to the red-shift of the absorption and emission wavelengths,and the thiophene[3,2-e]indole condensed mode It is more conducive to the red shift of BOPHY absorption and emission wavelengths.