Study On Synthesis And Spectral Properties Of Seven-membered Fluoroboron Fluorescent Dyes

Due to the characteristics with excellent photophysical and photochemical properties,organic difluoroboron(BF₂)complexes are widely used in numerous applications.From the difference of organic ligands,there are mainly three kinds of these organic BF₂complexes,categorized into N,N-bidentate,O,O-bidentate as well as N,O-bidentate compounds.Among them,the N,N-bidentate and O,O-bidentate organic BF₂complexes have been well developed and thoroughly studied,BODIPY and 1,3-dioxa-2-borine are regarded as their typical representatives.In sharp contrast,the development of N,O-bidentate organic BF₂complexes is still in its infancy,so it is highly desirable to develop novel N,O-bidentate organic BF₂complexes.In addition,the central structure of organic BF₂complexes is mostly six-membered rings,so the research of seven-membered BF₂complexes with a greater degree of conjugation in theory is also very promising.Therefore,a series of seven-membered N,O fluoroboron fluorescent dyes(BOPYIN)were designed and synthesized in this paper,and by modifying the structure,the spectrum and structural properties were studied to obtain the following result:A series of seven-element N,O fluoroboron fluorescent dyes with novel structures have been designed and synthesized,with a yield of 40%-60%.As a kind of seven-membered N,O fluoroboron fluorescent dye,the intermediate is synthesized in one step through a simple method.In order to increase the conjugation of molecules,the intermediates are reacted with aromatic aldehydes to obtain a series of conjugated seven-membered N,O fluoroboron dyes.Their absorption and emission spectra show a large red shift relative to the intermediates,and the Stokes shift increases.Among them,the dimethylamino substitution is the most significant(the largest displacement in DMSO,219 nm),and the fluorescence quantum yield is 20%.In addition,during the synthesis process,it was discovered that the fluorine-boron bond of this series of fluorine-boron compounds was broken in alcohol or water,and the spectral properties of the defluorinated boron compounds were also studied.A series of new seven-membered N,N fluoroboron compounds were designed and synthesized.The main purpose is to explore the influence of the types and positions of substituents on the pyrrole on the spectral properties of the compound.The substituents are ester groups and phenyl groups,and the positions of substitution are 3-position and 4-position.There is no obvious difference in the spectral performance of the ester group at different substitution positions,but when the substituent is phenyl,the fluorescence quantum yield of4-position substitution is significantly higher than that of 3-position substitution,and the maximum fluorescence quantum yield is 97%.A"switching"water-soluble hemicyanine dye(MC)was designed and synthesized.Its stable state is ring-opening.When MC reacts with organic/inorganic bases in a solvent,it will undergo spirocyclization to obtain a closed-ring SP product.The color of the solution has also changed from yellow to colorless,which can be used in the field of sensing.