Tetraphenylethene Derivatives: Design,Synthesis And Fluorescent Properties

With the rapid development of visual imaging technology,organic fluorescent dyes have been widely used in fluorescent probes,chemical sensors,biological imaging,disease diagnosis and treatment,organic photoelectric materials,stimulus response materials,etc.,attracting more and more attention in the field of biomedical and material chemistry.Among them,organic fluorescent molecules with aggregation-induced emission(AIE)properties have attracted extensive attention due to their unique fluorescence phenomenon.In recent years,AIE molecules with different functions have been designed,synthesized and applied in fluorescence related fields.Tetraphenylethene(TPE),as a typical AIE molecule,is simple to synthesize,easy to modify and functionalize its structure,and has excellent fluorescence properties.It has been developed in biological imaging,chemical detection,photoelectric materials and stimuli-responsive materials.In this work,a series of TPE-based fluorophores were constructed by modifying the structure of tetraphenylethene,the structure and optical properties of these new fluorescent dyes were investigated in detail.The following results were obtained:Four tetraphenylene-chalcones hybrid derivatives have been designed and synthesized.Their structures were characterized by NMR and HRMS,and their optical properties have also been investigated.These new organic fluorophores exhibited relatively large Stokes shifts(>85 nm)and absorption extinction coefficients(more than 10⁴ M^-1 cm^-1),solvation effects,and some of them also showed moderate AIE effects and solid fluorescence.More significantly,TPE-N shows good fluorescence emission(solution,solid and aggregation states).Single-crystal analysis indicates that molecular stacking patterns are the critical reason affecting the optical properties in solid state.Theoretical calculations explain the fluorescence behaviors of fluorescent dyes well.Cell experiments demonstrated that four fluorophores can be employed for imaging in living cells.Five tetraphenylene-imidazole derivatives have been designed and synthesized.Their structures were characterized by NMR and HRMS,and their optical properties have also been investigated.The results of fluorescence spectra illustrated that the five derivatives exhibited obvious AIE characteristics.Meanwhile,TM-2,TM-3 and TM-5 show excellent solid emission fluorescence properties(?_TM-3=36.21%)and reversible mechanochromic behavior.Cell experiments demonstrated that tetrastyrene-imidazole derivatives can be employed for imaging in living cells.A synthetic methodology for the synthesis of 4,5-dicyano-1H-imidazoles as fluorescent dye framework was designed.Using the copper modified manganese oxide-based octahedralmolecular sieves(CuO_x/OMS-2)as catalyst and DMA as solvent,4,5-dicyano-1H-imidazoles derivatives were synthesized by intramolecur cyclization of butenedionitrile derivatives containing imine structure at 120?.This synthetic methodology has high yield for aryl compounds containing electron-donating groups.