Synthesis And Properties Of Triphenylene-Based Fused Ring Organic Compounds

Polycyclic aromatic hydrocarbons have the characteristics of high electron mobility,large current switching ratio,and good solubility.In recent years,lots of polycyclic aromatic hydrocarbons such as triphenylene,coronene,etc.have been widely used in organic semiconductor devices.In this way,the synthesis and application of polycyclic aromatic hydrocarbon compounds have received increasing attention.In view of the good photoelectric properties of polycyclic aromatic hydrocarbons,a series of polycyclic aromatic hydrocarbon compounds have been desigened and completed,synthesized and characterized in this paper.These compounds are based on a simple polycyclic aromatic hydrocarbon triphenylene as the core,through a ?-conjugated system of triphenylene.They are obtained by extending and introducing different substituents.In addition,in studying the performance of these target compounds with macrocyclic conjugated structures,we were surprised to find that such compounds can exhibit good fluorescence properties.The first part of this article deals with the synthesis and properties of 2,x-dibromo-5,6,11,12,17,18-hexamethoxytribenzo [a,g,m] coronene and its' derivatives.In the experiment,phthalate was used as the raw material.Ferric chloride and concentrated sulfuric acid catalyzed trimerization to generate 2,3,6,7,10,11-hexamethoxybenzophenanthrene,and then bromine was added,finally compound 1,2,7,8,13,14-hexamethoxy-tribenzo[a,g,m]coronene was obtained by Suzuki cross-coupling with phenylboronic acid,oxidation and ring closure by ferric chloride in nitromethane solution.And then the key intermediate 2,x-dibromo-5,6,11,12,17,18-hexamethoxytribenzo[a,g,m]coronene was obtained by bromine under mild conditions,finally a series of different boric acids underwent Suzuki cross-coupling to obtain the desired target compounds.At the same time,the newly synthesized 2,x-dibromo-5,6,11,12,17,18-hexamethoxytribenzo [a,g,m]coronene and its' aromatic substitutes were subjected to ultravioletvisible and fluorescence spectra,and it was found that the introduction of aromatic groups can increase the fluorescence intensity of the compound in the same solvent and at the same concentration,and target molecules with different aryl substitutions also exhibit a certain difference in fluorescence intensity.Density functional theory(DFT)calculations also point out that by introducing new aromatic groups,certain conjugation can occur with the tribenzo[a,g,m]coronene core,thereby reducing the difference between the LUMO and HOMO orbital energy levels of the molecule.The second part of the paper is the synthesis and properties of 14,16-dihydrobenzo [2,3-c] thienophthalene.We used o-xylene as the raw material to conduct the experimental route of two different synthesis strategies.An experimental method with high synthesis yield is presented.The specific experimental procedure is to use o-xylene as the raw material,first react with liquid bromine to obtain 4,5-dibromo-o-xylene,and then Suzuki coupling with 1-naphthaleneboronic acid;oxidation ring closure by ferric chloride in nitromethane solution to obtain 14,15-dimethylbenzo[s]phthalocyanine,and finally bromines on the methyl group with NBS,and intramolecular ring closure takes place with sodium sulfide to construct a dihydrothiophene ring to get the target compound.Finally,in the UV-Vis spectroscopy and fluorescence emission spectroscopy of the target compound,we found that the maximum absorption wavelength of 14,16-dihydrobenzo[2,3-c]thienophthalene is 306 nm and the maximum emission at 467 nm,density functional theory(DFT)calculations can prove that by introducing a new aromatic ring at the 13 th and 14 th positions of chrysanthemum,its conjugate structure can be effectively expanded.Therefore,we believe that these compounds can be used as a new type of organic blue lightemitting materials.