Synthesis And Research Of Boron-dipyrromethene Fluorescent Dichroic Liquid Crystal Dyes

The guest-host LCD display mode is still the mainstream display mode in today's society.Through the research on the guest-host LCD in recent years,it can be found that selecting a guest with excellent performance can easily and efficiently improve the performance of the guest-host LCD.As a guest component,there are a wide variety of dichroic dyes.At present,the main researches are azo,anthraquinone,naphthalimide,etc.,but due to their respective structural defects,it is difficult to modify and change,which limits the display to a certain extent Development,for example,poor light stability of azo,poor solubility of anthraquinones in liquid crystals,etc.Therefore,the design and development of guest dye molecules with excellent performance has great practical value.Boron-dipyrromethene has excellent photophysical and photochemical properties,mainly manifested in the advantages of high fluorescence quantum yield,multiple modification sites,good light stability,and not easy to be affected by PH and environment.Boron-dipyrromethene have received extensive attention in the field of organic functional materials.In this thesis,Boron-dipyrromethene is used as the matrix to modify the active sites at positions 8 and 2 of the matrix,and a functional group is introduced to design and prepare two series of fluorescent dichroic liquid crystal dyes.All dyes are characterized by ^1HNMR,^13CNMR and HRMS.At the same time,it is subjected to ultraviolet fluorescence spectrum test,polarized ultraviolet fluorescence spectrum test,photoelectric characteristic test and liquid crystal behavior test,etc.to study its characteristics and analyze and discuss the data.Dye B based on 2-position modified bicyclohexyl structurethe,showing red Fluorescence.Maximum absorption wavelength in methylene chloride is concentrated around 526nm,and the maximum emission wavelength is concentrated around 565nm,This series of dyes also have strong absorption,and the molar extinction coefficient still reaches 10⁵.And dye B in E7 shows a high dichroic ratio and order parameters.The S_F of the three compounds in this series are above 0.6,specially,B3 reaches 0.72;Dye B has been verified by DSC and POM test.Dye B based on 2-position modified bicyclohexyl structurethe,which not only improves the linear conjugation degree of the molecule,but also has excellent bidirectional performance and the wavelength shift of the prepared new molecule increases.Dye B can increase the selectivity of liquid crystal display materials.