Synthesis And Liquid Crystallinity Of Benzimidazole Heterocyclic Azobenzene Derivatives

As one of the traditional photochromic entities,azobenzene can undergo a reversible photoisomerization effect under ultraviolet or visible light irradiation.Therefore,azobenzene-based liquid crystal materials have been used in dynamic holography,dynamic holography,Optoelectronic fields such as optical storage devices,optical switches and display technology.Due to the existence of N atoms in liquid crystal compounds containing imidazole heterocycles,the polarity,dielectric constant and geometric configuration of the molecules are affected,so that the phase transition temperature and liquid crystal phase type of liquid crystal compounds are changed.Therefore,imidazole heterocycles are designed and synthesized in It plays an important role in new liquid crystal materials.In this paper,a benzimidazole heterocycle was introduced into the azobenzene-based liquid crystal molecules with excellent optical properties,aiming to obtain azobenzene-based organic liquid crystal compounds with novel structures and better properties.Using benzaldehyde derivatives and o-phenylenediamine derivatives as raw materials,through cyclization oxidation,methylation,diazotization,acylation,etc.,three series of benzimidazoles with alkoxy chains of different lengths were synthesized.nitrogen compounds.The molecular structure is regulated by changing the end groups and increasing the rigid structure of the central core.The three series of compounds all exhibit bivariable liquid crystal behavior.The MZCn series and BMZCn series are smectic liquid crystals.With the increase of the carbon chain,the liquid crystal range of the MZCn series gradually increases,increasing by 114.4 °C.The structure is strengthened and the carbon chain length is increased,the molecular aspect ratio does not change much,and the liquid crystal interval slowly increases by24.6 °C.The introduction of thiophene groups in the SFMZCn series changed the polarity and configuration of the molecules,which not only increased the melting point of the crystals,but also changed the SFMZCn series from smectic to nematic liquid crystals.With the increase of carbon chains,the liquid crystal range decreased by 24.3 °C.Benzimidazole azo compounds have a wide liquid crystal interval,good stability and excellent optical properties,which play a positive role in the research of heterocyclic liquid crystal materials.