Synthesis And Properties Study Of β BODIPY Deriveds Fluorescent Dyes

At present,fluorescent compounds with various functions play an increasingly important role in chemical,biological and environmental sciences.Designing and synthesizing functional fluorescent dyes that can be used in different fields is of great importantance.Boron fluoride complex dipyrromethene(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene,BODIPY)have received considerable attention recently because they possess many distinctive and desirable properties.There are many advantages over some common fluorescent dyes: higher molar extinction coefficient,higher fluorescence quantum yield,narrower UV absorption,and fluorescence emission peak which endow it with a higher sensitivity when used as fluorescent labels.In addition,due to its small molecular mass,higher photophysical and photochemical stability and its property that it is not easily affected by the pH value and the polarity of the solvent,its application field is getting broader and broader.In recent years,people’s interest in BODIPY fluorescent dyes has increased year by year.In addition to the properties mentioned above,its parent structure can also be derivatized,substituted,or functionalized in a direct manner to produce new spectral properties.In the past few decades,many functionalized BODIPYs have been synthesized and reported.At present,highly diversified BODIPY derivatives have been widely used in many fields.However,the fluorescence emission wavelength of BODIPY is around 500 nm,which greatly limits the application of this type of compound in the red to near–infrared region.The functional modification of BODIPY cores and the extension of their emission wavelengths to the near–infrared region has become an important subject.There are mainly two methods to increase the BODIPY emission wavelength.On the one hand,the conjugate system of the BODIPY mother nucleus is increased and the π–electron delocalization area is increased on the other hand.Both of these methods can effectively move the wavelength of BODIPY toward long wavelengths.The Knoevenagel condensation with aromatic aldehydes is an important method to produce BODIPY derivatives with long wavelength BODIPY derivatives.At present,there are many near–infrared BODIPY dyes prepared with this method.In addition,increasing the β–area of BODIPY backbone is verified experimentally to be an effective way to increase the molecular conjugation surface and the molecular wavelength.In this paper,one/two reactive aldehyde groups are introduced to the 2,6–position of the BODIPY backbone via the Vilsmerier–Haack reaction centered on the BODIPY core,and then a series of different functionalized small molecules are reacted with them.The conjugation system increased or the area of the pyrrole ring is increased,which causes a wavelength red–shift.A series of spectral properties are measured to verify the conjecture.Because the 3,5–methyl groups on the BODIPY backbone have some acidity,they can be condensed with active aromatic aldehydes by the Knoevenagel reaction under the action of the catalyst.A new fluorescent compound with long wavelength was synthesized.The structure of the compound was identified and its photophysical and photochemical properties were determined.Compared with BODIPY core,its wavelength got a remarkable red shift,larger Stocks displacement and stable spectral properties.