Synthesis And Properties Of Bent-core Liquid Crystal Compounds With Azo Groups

The bend-core liquid crystal molecules is a new type of liquid crystal material discovered in recent years.It has abundant liquid crystal phase and has special physical properties such as(inverse)ferroelectricity,spontaneous polarization and chiral supramolecular structure.The azobenzene compound has a broad application prospect in the field of optical information storage,Light quantum information transformation,molecular manipulator and nonlinear optical materials due to the fact that the azo bond can undergo photogenerated,cis-trans isomerization under the irradiation of ultraviolet light,In this paper,the azo bond is introduced into the nucleus of the curved center.From the point of view of the molecular structure design,a new type of photo-sensitive bent liquid crystal compounds is designed and synthesized in order to obtain the new material with azo groups.In paper,The four kinds of azo-containing curved liquid crystal molecules were synthesized.The bridged linkage of compounds such as series?,? and ? are contained two azo bonds,and the core of series ? contained single azo bond.From athe molecular structure design,these four series of bent molecules are 1,3-benzene as the center of cured,benzene ring between the azo bond and ester bond as a berdged linkage,the molecular end of alkyl chain.These molecules structures were characterized by Infrared absorption spectrum(IR),nuclear magnetic resonance(NMR)and Mass Spectrometry(MS)to confirm.Then their thermodynamics behaviors and liquid crystalline properties were detented by differential scanning calorimeter(DSC)and polarizing optical microscope(POM)analysis.The series I and II have a smectic phase,and the series III and IV have a nematic phase.Moreover the photosensitivity under UV-Vis was studied,and the four series had similar UV-Vis absorption spectra.With the increase of ultraviolet light irradiation time,the absorption peak intensity at 365 nm And the absorption peak intensity at 450 nm gradually increased,and the photo-isomerization was balanced after about 5 min of ultraviolet light.All the liquid crystal compounds had good photosensitivity;The target compound was doped into the nematic phase liquid crystal,after 365 nm UV light irradiation,also observed when the liquid crystal phase changes,to achieve the photo-control liquid crystal phase changes,will be very likely to be applied to the field of light control.