Design,Synthesis And Characterization Of Tetraarylimidazole Luminescent Small Molecules And Tetraarylimidazole-containing Polyamide

In recent years,as a new type of luminescent materials,organic solid fluorescent materials have received great attention from researchers.Designing and synthesizing luminescent molecules with excellent luminous performance,stable intensity,adjustable wavelength,and easy fabrication of devices will promote the development of luminescent materials and provide the possibility for their potential practical applications.Aramid is a special organic polymer material with high temperature resistance,radiation resistance,chemical corrosion resistance,high temperature insulation and other properties,widely used in national defense,electrical appliances and industrial fields.In order to meet the needs of high-performance polymer materials in the development of optoelectronic devices,it is a meaningful research work to develop functional polyaramids with excellent comprehensive performanceIn this paper,based on the comprehensive literature and the preliminary research of the research group,several new luminescent molecules with tetraarylimidazole as the parent structure are designed and prepared.At the same time,the synthesis and properties of polyarylamide containing tetraaryl imidazole structure based on three-component polymerization reaction were carried out.The main work of the thesis includes the following three parts:(1)Starting from benzyl,a series of tetraarylimidazole derivatives were prepared by Debus-Radziszewski imidazole synthesis method,and their structures were analyzed.The ultraviolet absorption intensity,fluorescence emission wavelength,quantum yield and fluorescence intensity of the luminescent molecule with the parent structure of tetraarylimidazole as the parent structure were studied using ultraviolet-visible absorption spectrum,solid state fluorescence spectrum,and fluorescence spectrum under different solvents.The impact of the AIE effect.The study found that structural modification at the 2nd position of the imidazole ring can significantly change the ultraviolet absorbance of the molecule.Among them,the introduction of an amino group at this position can enhance the absorbance and emit abright blue fluorescence;when introducing a cyano or ethynyl group Make it emit blue light and its fluorescence intensity will be increased,while its emission wavelength has a significant red-shift phenomenon.The fluorescence intensity was detected by the water content test,and it was found that the prepared compounds 3-7showed the strongest fluorescence intensity when the water content was 20%.(2)Based on the above research,three new luminescent small molecules containing phenylethynyl substituted tetraarylimidazole structure were designed and synthesized.According to the ultraviolet-visible absorption spectrum,compound 4-2and compound 4-3 have intramolecular charge transfer phenomena,showing the typical ultraviolet spectrum performance of D-?-A type luminescent molecules.The solid fluorescence of compound 4-3 is relatively weakest.In terms of the influence of substituents,the change of the solid-state fluorescence emission wavelength of the three compounds is affected by the electron donating ability of the groups to which they are attached.If a carbazole group with stronger electron donating ability is introduced,it will redshift.From the fluorescence quantum yield of the compound,it can be seen that compound 4-2 exhibits the largest fluorescence quantum yield because of its large conjugation with the biimidazole ring structure.All three compounds show a certain degree of AIE effect,which may be related to the distortion of their intramolecular space,which leads to the formation of aggregates and the precipitation of solvents when the water content is large.(3)Small organic molecules containing tetraarylimidazole structure not only have good fluorescence properties,but also have potential practical applications in terms of thermal properties.Because the presence of polyphenyl in the structure can improve its thermal stability,and the presence of heterocyclic ring is of great benefit to its solubility,we designed and synthesized five kinds of polyaryl amides with tetraaryl imidazole as the main structural unit..Starting from benzyl,by Debus-Radziszewski imidazole synthesis method1,2-bis(4-nitrobenzene)-4,5-diphenyl-1H-imidazole,catalytic reduction by palladium/carbon-hydrazine hydrate gives 1,2-bis(4-aminobenzene)-4,5-diphenyl-1H-imidazole,and then through diazotization and iodine "one-pot method" to obtain monomer ?1,2-bis(4-iod Phenyl)-4,5-diphenyl-1H-imidazole.On the basis of constructing the model reaction,under the catalysis of bistriphenylphosphine palladium dichloride and cuprous iodide,it undergoes a three-component "one-pot" polymerization reaction with aromatic diamine and carbon monoxide to prepare A series of novel polyaramids containing tetraarylimidazole structure in the main chain were obtained,and their structures and properties were characterized.Preliminary research shows that this series of polymers is amorphous structure and exhibits excellent thermal stability.The decomposition temperature of 10% thermal weight loss can reach up to 454?.It can be dissolved in DMF,DMAc,NMP and other solvents at room temperature.Dichloromethane,chloroform and other low-polar solvents can also be dissolved by heating.