Construction And Application Of Novel AIE Molecules And Coumarin-based Near-infrared Fluorescent Molecules

Due to the high solid-state luminous efficiency and large Stokes shift,AggregationInduced Emission luminogens(AIEgens)with Excited-State Intramolecular Proton Transfer(ESIPT)process have received wide attention in the field of bioimaging.In the first part of this thesis,a series of AIE molecules(TS,TS-OMe,TS-NMe2)were synthesized by introducing N,N-diphenylamino structure into the salicylaldehyde structure.Because of the AIE effect and the ESIPT process,TS derivatives exhibit strong fluorescence emission and large Stokes shift(>140 nm)in the aggregation state.In the aggregation state of the molecule,the movement of the benzene rings in the triphenylamine structure is restricted,and its relatively twisted structure avoids the possibility of ?-? stacking between the molecules,which leads to aggregation induced luminescence.By changing substituents in the triphenylamine unit,the solid-state emission of compound can be changed from 490 nm to 570 nm.Since TS derivatives have good biocompatibility and lipophilicity,they can specifically and quickly(<5 min)label lipid droplets in cells without washing.Meanwhile,TS derivatives can successfully image the lipid-rich tissue in vivo.In addition,TS and TS-OMe have good hydrophilicity and selective imaging ability for Gram-positive bacteria.Fluorescent materials with advanced functionalities provide powerful tools to visualize subcellular microstructures,which significantly boost our understanding of complex biological behaviors.Coumarin is widely used as a fluorescent molecule with large Stokes shift,high fluorescence quantum yield.Hence,a series of fluorescent molecules NIRn(n=1?4)with near-infrared emission(>650 nm)were synthesized.The fluorescence spectrum shows that the emission wavelength of NIR3 and NIR4 has a significant red shift compared with that of NIR-3C by enhancing the push-pull electron effect.Compared with NIR2,the emission wavelength of NIR1-3C is red shifted(>30 nm)by changing the electron withdrawing group.The preliminary cell imaging of NIR11C,NIR1-3C,NIR2 and NIR3 showed that all of the above molecules could stain HeLa cells.And the preliminary co-dyeing experiment of NIR1-3C and commercial membrane dye DiO showed that NIR1-3C could realize the specific imaging of cell membrane.