The Synthesis And Properties Of New Boron-azadipyrromethene NIR Dyes

BF₂-chelated azadipyrromethenes?aza-BODIPY?are a category of near-infrared?NIR?fluorescent dyes which have been attracting considerable interests in recent years,since their significant photochemical properties and facilely molecular modification endow them potential applications in various techniques and research fields i.e.biological imaging,molecular probes,fluorescent sensors,solar cells,photodynamic therapy etc.In this thesis,four aza-BODIPY dyes?5a-d?with fluorenyl and tetraphenylethylene substituents modifying on 1,7-or 3,5-positions were synthesized starting from aryl formaldehyde and aryl methyl ketone with yields of60%-75%.All the new compounds were characterized by ¹H-NMR,¹³C-NMR and high resolution mass spectrometry?HRMS?.Furthermore,the single crystal of aza-BODIPY 5a was obtained and its detailed crystal structure was analyzed by single crystal X-ray diffraction.The photophysical properties of aza-BODIPY dyes were measured by UV-vis absorption and fluorescence spectroscopy and the results indicated that the maximum absorbance and fluorescence wavelength of these dyes were in NIR region(?_abs=677-708 nm,?_em=713-754 nm)with high molar absorption coefficients and fluorescence quantum yields.Then the fluorescence quantum yield of these dyes is up to 0.45 in toluene.It can be deduced that the extension of?-conjugation system by introducing fluorenyl and tetraphenylethylene groups on 1,7-or 3,5-positions bathochromically shifted the absorbance and fluorescence maxima significantly while the substitution on 3,5-positions has larger impact.The cell imaging experiments were operated based on the photophysical performances of the aza-BODIPY dyes,and it turned out that aza-BODIPY 5d could penetrate through cytomembrane and exhibit intense intracellular luminescence,which implied that this NIR fluorescent dye can be promising candidate for fluorescent probe of specific living cell imaging.We subsequently made a preliminary exploration of tetraphenylethylene substituted aza-BODIPY dyes about the aggregation induced emission?AIE?phenomenon.