Synthesis And Study Of Naphthalene Anhydride Derivatives Fluorescent Dichroic Liquid Crystal Materials

Guest-host liquid crystal displays（GH-LCDs）hasn’t been widely applied because of the lack of high performance dichroic dyes.Three series of fluorescent dichroic dyes have been designed and synthesized using 4-bromo-1,8-naphthalene anhydride as the starting material.All dyes are characterized by ¹H NMR,¹³C NMR and HRMS.Spectral properties including UV,fluorescence,and polarization spectra and the liquid crystal phase of all compounds have been tested.Birefringence,threshold voltage and response time of some compounds have been tested.All the test data are summarized and explained.The maximum absorption wavelength of the 4-biphenylacetylene-1,8-naphthalimide（A）are 393 nm,and the maximum fluorescence emission wavelength are close to 500 nm.The Stokes shift of A1 and A2 are 107 nm.The fluorescence quantum yield of A3 in ethyl acetate solvent is 0.84,and the Stokes shift of A3 in dimethyl sulfoxide solvent is 141 nm.The absorption order parameter of A5 is 0.75,and the fluorescence order parameter of compound A6 is 0.71.The absorption order parameter of A2-A6 are more than 0.65,and they all meet the requirements of absorption dichroic dye.All compounds show liquid crystal texture and compounds A1,A2,and A4 exhibit nematic and smectic liquid crystal textures,which are also verified by DSC.The liquid crystal phase of A2 is as wide as 123.8℃,and A6 begin to apper liquid crystal phase at 55.63℃.The birefringence of compound A1 is 0.596.Some compounds have met the requirements for dichroic dyes in the guest-host liquid crystal display mode.Both A4 and A5 doping reduces the response time of the liquid crystal E7.After A4 and A5dissolved in liquid crystal E7,the response time of E7 is reduced by 23%and 19%.The maximum absorption wavelength of the 4-amyl bicyclohexyl-1,8-naphthalimide（B）are around 400 nm,and the maximum fluorescence emission wavelength are close to 500 nm.The Stokes shift of the compound B1 is 110 nm.The fluorescence quantum yield of B6 in the ethyl acetate solvent is 0.84.The absorption order parameter of B5 is 0.71.The fluorescence order parameter of B4 is 0.68.The six compounds all show liquid crystal texture.Compounds B2,B4,and B6 exhibit nematic and smectic liquid crystal textures and the liquid crystal phase width of them exceeds 130℃.After B3 dissolved in liquid crystal E7,the response time of E7is reduced by 41%.After B6 dissolved in liquid crystal E7,the threshold voltage of E7 is reduced by 9%.The maximum absorption wavelength of the 4-phenylacetylene-1,8-naphthalimide（C）are close to 380 nm,Bright blue-fluorescence was observed when C are under the irradiation of uv light.The highest fluorescence quantum yield of C3 in dichloromethane solvent is 0.75.The absorption order parameter of C3 is 0.65.The fluorescence order parameter of C1 is 0.5.The three compounds all show liquid crystal texture.Compounds C1 exhibit nematic and smectic liquid crystal textures and the liquid crystal phase is as wide as 112.5℃,which are also verified by DSC.The birefringence of C3 is 0.3575.C2 doping reduces the response time of the liquid crystal E7 by 5.48ms.After C3 dissolved in liquid crystal E7,the response time of E7 is reduced by 18%.