Design And Synthesis Of New Cyclic Phosphazene Based Blue Light-emitting Dendrimers

Due to the characteristic low driving voltage, high brightness, full-colour emission,rapid response and self-emitting properties of organic light-emitting diodes, organiclight-emitting diodes have attracted the attention of the researchers. Organic light-emittingdiodes are considered as the next generation of liquid crystal display in the display area.Organic light-emitting materials play a key role in the sandwich structure of organiclight-emitting diodes. As the need of full-color display, the light-emitting materials’development in red, green and blue should be kept pace. However the reseach of bluelight-emitting materials has the shortage in lifetime, color purity and efficiency referring tothe development of red and green light-emitting materials.In order to obtain new emitting materials with an improved thermal stability, deep blueand the luminescence efficiency, we designed a new type of cyclic phosphazene based bluelight-emitting dendrimers, in which the rigid spherical cyclic phosphazene core ischemically bonded with the anthracene branches.Based on the unique structure of the designed light-emitting materials, three synthesisroutes have been studied for the preparation of the target molecule. And the experimentresults showed that the self-designed router is better referring to yield and feasibility.Beyond that, we also studied the synthesis of anthracenebornic from the ratio of rawmaterial and the post-processing. Acoording to the experiments results, the optimal ratio ofn-BuLi:9-bromoanthracene: triisopropyl borate is1.2:1:1.5(mol). The post-processingemploys the technology of recrystallization, and the reagent used in the recrystallization istetrachloromethane, which is better than n-hexane. The yield is78%.The last synthetic step of the target product is Suzuki reaction. We failed to get thetarget product when using the familiar catalyst: palladium acetate and triphenyl phosphine,so we changed to (beta-4)-platinum and got the target product. Meanwhile we alsoimproved the operation processing of oxygen free, and got a better result. On account of theunique structure of target product, we found a new post-processing way: recrystallizationfrom chloroformic solution by pouring it into the methanol. The yield is52%, which ismuch higher than extraction separation.In the end, we test the performance of the new designed blue light-emitting materialspreliminary by using the ultraviolet absorption spectrum and fluorescence emission spectrum.