Study On Synthetic Methods Of Multinuclear C-HBC Derivatives

In recent years,various organic optoelectronic materials with excellent properties have been developed through bottom-up organic synthesis methods,and the exploration of the relationship between molecular structure and material properties has made great progress.Nevertheless,it is still challenging to explore further extended structures and application diversity.Polycyclic aromatic hydrocarbons（PAHs）,as a typical class of organic optoelectronic materials,exhibit many unique optoelectronic properties due to their extended conjugation and diverse structures,making them gradually lead the development of organic optoelectronic materials,while hexabenzocoronene（HBC）derivatives are the star molecules of them.This thesis mainly focuses on the problem ofπ-extended conjugate structures and application diversity are difficult to meet the needs of reality in the field of organic optoelectronic materials,with the idea of extending conjugation and introducing heteroatoms to reduce the band gap,in order to explore and develop HBC-based organic optoelectronic materials through organic synthesis.We adopt a de novo synthesis strategy to focus on the controllable synthesis of extended conjugation and molecular doping.Based on the research of contorted hexabenzocoronene（c-HBC）,three bicore c-HBC derivatives were designed with c-HBC as the core:carbon,thia and aza heteronuclear molecules.After verifying the feasibility of the synthesis route,we found that the ring closure was carried out in the form of helicene rather than linear ribbons.We have completed the synthesis in 16 steps,characterization and partial photoelectric performance testing of the helical thia-bicore c-HBC molecule with long side chains.In order to improve the synthetic route,we have tried strategies such as selective functionalization of pentacenequinone,stepwise aldol condensation,and selective oxidation of alkenes.Among them,the selective oxidation strategy is relatively convenient to obtain target product while the yield needs to be further improved.In this study,we found that these-OC₁₂H₂₅ substituent can increase the solubility of the molecule.But they also make it’s difficult to cultivate single crystal because long-side chains lead the molecule more flexible.In order to cultivate single crystal,we successively replaced the long side chain substituents of carbon or thia bicore c-HBC molecules with short chain-OC₄H₉,heavy atom-Br and-^tBu functional groups to increase intermolecular interactions,but no single crystal has been obtained yet.The synthesis of aza linear molecules and the preparation of linear molecules by the strategy of Suzuki coupling needs further exploration.In addition,we found that the precursor of octabenzocircumbiphenyl（OBCB）can be obtained in one step when the intermediate 6-（diphenylmethylene）-6,13-dihydropentacene was exposed to strong basicity and anthraquinone in the study of biscore c-HBC derivatives.We speculate that this reaction proceeds via radical mechanism.Compared with the Barton-Kellogg coupling strategy reported by Colin Nuckolls’group in 2013,which needs 6 steps in order to prepare the precursor of OBCB,our method can greatly shorten the synthesis steps.So that this method is of great significance for the synthesis of symmetricalπ-extended PAHs.Finally,in order to understand the structure-property relationships of c-HBC compounds in system,we also designed the tricore c-HBC derivatives with Suzuki coupling strategy,based on previous studies of bicore c-HBC derivatives,and the synthesis is nearly completed.Compared with the previous method for synthesizing bicore c-HBC derivatives,this synthetic route has the advantages of easy amplification,no unstable intermediates,good reaction reproducibility and easy post-modification.