Synthesis And Properties Of Azo-compounds Based On Schiff-base Group

In recent years,organic photochromic materials have played an important role in many high-tech fields,such as optical information storage,nonlinear optical materials and military camouflage and so on,due to their high discoloration efficiency,fast response bright color and other characteristics.The azo-compounds with schiff-base group are excellent photochromic materials.Under the light-induced,the azobenzene structure not only could occur cis-trans isomerization,but also the Schiff-base group could change structure and it also has the thermochromic performence.As we all know,azobenzene photochromic compounds have the disadvantages of shorter wavelength absorption,and the Schiff-base also has poor thermal stability and low temperature of color changing and so on.This research will try to make the new azo-compound with the Schiff-base group compounds with longer wavelength absorption,thermal stability,and good stability with metal compounds polymer.Molecular Structures have an effect on the performance of photochromic and thermochromic compounds.The substituents on the benzene ring of azobenzene structure will have a certain influence on the absorption peak position.Whether electron withdrawing group or electron-donating group when it is connected conjugated system,it could led to large ? bond electron mobility increases,and the ??? transition in the molecules of the energy gap would decrease.The electron is boiled out by light,and the absorption wavelength moves to the long-wavelength direction.Under the light or heating,the o-hydroxy-schiff base group could change its enol to the ketone structure,which makes the compound's original non-planarity change to the plane.Also the electron withdrawing group or electron-donating group would affect the structure change,and the reversible thermochromic property of schiff-base will be different.This paper synthesized a series of azo-compound with Schiff-base group,which based on the reaction with different substituented aniline and salicylaldehyde,and then reacting with different amine compounds to.The schiff-base group forms conjugated system with azobenzene,so the absorption wavelength shifted to longer wavelengths in photochromic side,meanwhile the Schiff base structure with the adjacent hydroxyl group in the compound has the thermochromic properties,and the introduction of the zincion in molecular structure to form complex has improved thermochromic temperature and stability.In the experiment,we use FTIR to characterize the structure changes of the azo-compound with Schiff base before and after complexing the metal ion,and use the UV spectrum to show the changes of maximum absorption wavelength,molar extinction coefficient and the optical response properties before and after complexing the metal ion,and use the POM to characterize the change of melting point and metachromatism before and after complexing the metal ion,and use Fluorescence photometry instrument to characterize the change of fluorescence intensity before and after complexing the metal ion.From the experiment we can know that the azo dyes with schiff-base group have photochromic and thermochromism performance before and after complexing with metallic compound,and comparing to complexing without metal ion,the compounds with metal ion's maximum absorption wavelengh move to the direction of longer wavelengh,and the thermal stability,melting point,temperature of color changing and fluorescence intensity all have a improvement.The changes tell us that the introduction of the metal ion in azo-compound with schiff-base group has great influence on the photochromism and thermochromism.