Theoretical Studies On The Structures And Optical Properties Of 1,8-naphthyridine Fluoroboron Fluorescent Compounds

Fluorescent compounds of boron-dipyrromethene?4,4-difluoro-4-bora-3a,4a-diaza-s-indacene,BODIPY?have attracted attention due to their unique optical properties.However,it has disadvantages of flueorescence quenching when in solid state and shorter wavelength,which limits its application.Therefore,it is crucial to design and develop such novel fluorescent material with excellent spectral properties.In this thesis,the density functional theory was used to study and analyze the electronic structure and fluorescence properties of 1,8-naphthyridine boron difluoride?BF₂?monomer/dimer fluorescent molecules.Quantum chemistry calculations indicated that when the conjugated degree of the 1,8-naphthyridine-BF₂fluorescent molecules skeleton structure was gradually increased,the absorption/emission wavelength of the fluorescent molecules would constantly undergo red shifts.The ionization potential of the molecules would continuously decrease and its electron affinity would increase,which would increase the ability of the electron emission and hole injection.The theoretical studies also revealed the influence of the electron-withdrawing/push-pull electron group on the electronic characteristics and fluorescence properties of 1,8-naphthyridine boron difluoride.When the electron-donating group?methyl?in the moleculars structure were replaced by electron-withdrawing group?chlorine atom?,the electron affinity and the electrons injection the fluorescent molecules would increase/facilitate,but its effect on the spectral properties was not significant.In addition,the polarizable continuum model method was used to simulate the influence of the polarity of the external solution on the fluorescence properties of 1,8-naphthyridine-BF₂ fluorescent molecules.The theoretical simulation results predicted that the absorption/emission wavelengths of the novel 1,8-naphthyridine-BF₂ molecules both exhibited a weak blue shift with increasing polarity of the solution,indicating its optical properties stability.Take the fluorescence molecule 4 as an example:478.07 nm?Toluene?>473.83 nm?CH₂Cl₂?>473.55 nm?THF?>471.51 nm?Acetone?>470.90 nm?CH₃CN?>470.49 nm?CH₃OH?.In this thesis,theoretical studies on the structure and optical properties of the novel fluorescent molecules with the combination of BODIPY and 1,8-naphthyridine laid a theoretical foundation for understanding the structure-activity relationship of fluorescent materials.And it provided a theoretical basis for the laboratory to further develop and design efficient and stable organic luminescent materials.