Synthesis And Characteristics Of Nitrogen-containing Triphenylene-Based Discotic Liquid Crystals As Optoelectronic Materials

This thesis mainly designed and synthesized a variety of novel nitrogen-containing triphenylene-based discotic molecules,which were easy to form columnar structures and had potential properties of one-dimensional charge and energy migration.Besides,their phase transitions,properties of liquid crystal and photophysical had been investigated.The main contents are as follows:Firstly,this thesis discovered a new mothod for one-step synthesis of mono-hydroxy-triphenylene(MHT,an important intermediate for synthesis of triphenylene-based discotic molecules).This new method used only dialkoxy-benzene(DAB)and excess FeCl3 as starting material,and the highest yield of MHT could reach 65%,much higher than the reported highest yield of 25%in the literatures by one-step approaches.The process and mechanism of the one-step reaction,and the applicability of this new method was further studied.Secondly,starting from the mono-hydroxy-triphenylene(MHT),the mono-amino-triphenylene(MAT)was further synthesized.Then,under the contions of dichloro-dicyano-benzoquinone(DDQ)and trifluoroacetic acid(TFA,0.5%),the oxidative coupling of two molecules of MATs could directly produce the corresponding D-A-D ?-conjugated triphenylene dimers 109(a:R=C6H13,b:R=C10H21),linked via a prazine bridge.This synthetic method was much simpler and easier than the traditional one,which used o-dione and o-diamine as precursors.Both of 109a and b were discotic liquid crystals,and had a wide range for spectral absorption and light-emitting properties.Besides,molecular modeling studies indicated that such material probably had a certain property of charge migration.Then,on the basis of MAT,the amide-group-containing triphenylene derivatives 122-125(a:R=C6H13,b:R=C10H21)were further designed and synthesized,including the triphenylene monomers(122),the para-position dimers(123),the meta-position dimers(124)and the trimers(125).Between these molecules,hydrogen bonds could be formed.All these compounds,except 125a,were discotic liquid crystals,and part of them could form columnar phases and face-on alignment or the discotic nematic phase.Their photophysical properties were also studied.Finally,on the basis of MAT,the D-A triphenylene-perylene dimer(133)and D-A-D triphenylene-perylene-triphenylene trimers(134)had been designed and tried to be synthesized.