Design And Synthesis Of Heterocyclic-Ring-Fused BODIPY Oligomeric Near-Infrared Dyes

As an important fluorophore,BODIPY has found wide applications in bioimaging,photothermal therapy and organic optoelectronic materials in recent years due to its excellent spectral properties,easy accessibility and facile modifications/derivatizations.Currently,their further applicapability has been hampered by their relatively short absorption and emission wavelengths.Therefore,it requires the development of novel BODIPYs with near-infrared absorption/emission properties.Besides the structural modification of BODIPY core to expand itsπ-conjugation to construct near-infrared BODIPY dyes,the development of conjugated BODIPY oligomers has attracted wide research interests lately due to their ability to effective expanding theπ-conjugation of BODIPY and bring the desired red-shift of the spectrum.However,the construction of BODIPY oligomers is still in the initial stage,and the number of conjugated BODIPY oligomers is still very limited.Currently the reported conjugated BODIPY oligomers are mainly those conjugated linearly linked BODIPY dimers and trimers,and there is a lack of effective strategies for the efficient construction of higher linearly conjugated BODIPY oligomers.Meanwhile,the construction of（hetero）aromatic-ring-annulated BODIPY oligomers are still very few.In comparison with those conjugated linearly BODIPY dimers,aromatic-ring-fused BODIPY dimers can achieve the red-shift of the absorption while maintaining the good rigid structure of the dye,and expanding its light absorption cross-section.To solve these above issues,in this thesis we have performed a systematical investigations of the construction of heteroaromatic-ring-fused BODIPY oligomers.We have investigated the construction of pyrrole-ring-fused BODIPY dimers and their corresponding analogs（diazo-phosphorus heterocyclic-ring-fused BODIPY dimers）.We also have also investigated the optical properties of these dyes.These researches are detailed in the following:In Charpter 1,we have developed a new synthetic method to accessα-N-bridged BODIPY dimers,trimers and hexamers based on a simple nucleophilic substitution of?-chloro BODIPY with?-ammino BODIPY.Although the further oxidation to get the corresponding pyrrole-fused BODIPY oligomers failed.Still,the resultant key precursor,α-N-bridged BODIPY oligomers are good NIR dyes and show excellent electronic and optical properties,the absorption wavelength ofα-N-bridged BODIPY Dimer reaches 716nm.Among those,α-N-bridged BODIPY dimers can be converted to the corresponding amino-radicals.α-N-bridged BODIPY trimers are NIR fluorescent dyes,with absorption maximum at 748 nm,large Stockes-shift,and excellent AIE properties.α-N-bridged BODIPY hexamers has absorption covered in the entire visible to NIR range（400-1100nm）with the emission wavelength reaches the NIR-II region（978 nm）.It has potential applicapability as NIR light-absorbing materials and the dyes for photothermal therapy and imaging.In Charpter 2,we have developed a highly efficient synthetic strategy to access seriesα-amino-substitutedβ,β-BODIPY dimmers based on a one-step oxidation ofα-amino-substituted BODIPY with m-CPBA（m-chloroperoxybenzoic acid）.These resultant BODIPY dimers have large Stokes-shifts,and their maximum emission wavelengths reach 657 nm,733 nm and 716 nm,respectively.The complexation of these dimers with dichlorophenylphosphine generates novel N,P-containing seven-member-ring fused BODIPY dimer,which shows a maximum absorption at 747 nm with a large molar extinction coefficient(155400 M^-1cm^-1).These related research results are helpful for the future research in the construction and deverivation of novel NIR BODIPY dyes,and novel BODIPY oligomers.