Study On The Synthesis And Photophysical Properties Of ?-Cycloaromatized BODIPYs

Boron Dipyrromethene?BODIPY?is a kind of fluorescent compounds that have been widely studied in recent decades.It has excellent photophysical properties,such as high stability,high fluorescence quantum yield and large molar extinction coefficient.However,the absorption and emission wavelength of the classical BODIPY is relatively short,generally limited to 470-530 nm,which greatly limits its application in biological,chemical and material fields.Therefore,it is of great significance to design and synthesize BODIPY whose absorption and emission spectra reach the near-infrared region.For this purpose,we have designed and synthesized a series of?-position aromatic ring fused BODIPY dyes with rigid structure through post-modification of BODIPY core,and investigated their photophysical properties and structure-activity relationships in detail.The main research contents are as follows:?1?Through Suzuki coupling reaction between o-alkynyl phenylborate containing methoxy substituent and halogen substituted BODIPY,followed by the intramolecular ring fusion reaction catalyzed by transition metals,the aromatic ring-fused BODIPYs were constructed.The optimized reaction conditions?catalyst,temperature,reaction time,etc.?were found after detailed investigation.Using Pt Cl₂ as catalyst,two kinds of isomers with completely different spectral properties were obtained,and their structures and properties were characterized and examined.The maximum absorption and emission wavelength of the 6-member aromatic ring fused product located at 591 nm and 621 nm respectively,and that of the 5-member aromatic ring fused product was571 nm and 600 nm respectively.The structure property relationship is studied by theoretical calculation.?2?On the basis of the above reactions,the effects of different substituents?hydrogen and trifluoromethyl?with different electron effect on the reactivity and the structures of final ring-fused products were studied.The maximum absorption and emission wavelength of the 6-member aromatic ring fused product with the substituent group of hydrogen atom located at 570 nm and 593 nm respectively,and the maximum absorption and emission wavelength of the 6-member aromatic ring fused product with the substituent group of trifluoromethyl located at 567 nm and 597 nm respectively.The results show that the electron-withdrawing substituent and neutral substituent favored in the formation of six-membered aromatic ring fused products,while strong electron-donating substituent facilitated the formation of both five-membered and six-membered aromatic ring fused products in one pot reaction.?3?In order to further extend the absorption and emission of BODIPYs to the near infrared region,we tried to synthetic bis-aromatic ring?-fused BODIPYs.We tried the same reaction conditions with the synthesis of the mono-aromatic ring fused?-fused BODIPYs,some unfused products were obtained,and their structures and properties were characterized and studied.