Design,Synthesis And Physical Property Of Graphene-like Arenes Containing Helicene Unit

Polycyclic aromatic hydrocarbons?PAHs?are?-conjugated systems,possessing good charge transfer characteristics and controllable photophysical properties.They can be widely used as active layers in organic electronic devices.At present,these devices mainly include organic photovoltaics?OPVs?,organic light emitting diodes?OLEDs?,organic field effect transistors?OFETs?,and organic memories?OMDs?.Therefore,constructing novel organic semiconductors is not only a big challenge for synthetic researches,but also provide key materials for organic devices.In this thesis,we designed and synthesized three types of?-conjugated systems:twistacene,substituted hexabenzoovalenes and functionalized heleicene derivatives.Twistacene referring to the end-capping acenes with pyrene unit shows fascinating twisted configuration,which can suppress the?-stacking to a certain extent.The configuration is benifical for enhance the solubility in common organic solvents without sacrificing the optoelctronic properties.After oxcidation via Scholl reaction,the as-formed substituted ovalene derivatives exhibit excellent absorbance and broad absorption profile.Helicene derivatives with unique structures might be used in asymmetric catalysis,nonlinear optics and supramolecular chemistry.This thesis is mainly divided into the following sections:?1?A series of symmetrical twistarenes 3a-3n containing different functional groups such as halogen atoms,4-diphenylaminophenyl,alkynyl,nitro,nonylthio,methoxyl groups have been synthesized via classical Diels-Alder cycloaddition coupling process.The absolute configuration of one of the twistarenes with nitro groups was determined through single crystal X-ray diffraction analysis.The effect of the substutents on their optoelectronic properties were investigated in a comparative manner.The resulting twistarenes 3 could be oxidaized via anhydrous iron chloride to produce substituted hexabenzoovalenes.Compared with molecules 3,the ovalene derivatives present obvious absorption and emission spectra.The results suggest that this work can enrich the synthetic assets and further functionalization is on the way.?2?Two novel helicene derivatives 6 and 9 have been prepared and characterized with the assistance of Pd catalyst.The X-ray diffraction analysis suggests that molecule 6including[5]helicene presents two enantiomers?P,P?and?M,M?and there exists strong?-stacking interaction among molecules,which might be beneficial to exciton and carrier transfer.The racemic energy barriers of 6 and 9 were calculated to be 11.09 kcal/mol and13.36 kcal/mol respectively,basedon DFT calculation.Because of their low values,both of them can racemize at room temperature and are not be separated by HPLC.Under the oxidation of nitrosonium hexafluoroantimonate?NOSbF₆?,the former forms a dication,while the latter forms radical cation,and then a dication.This work provides more room for the construction of new helicene derivatives.?3?In the part,three novel helicene derivatives containing[4]helicene and[5]helicene units have been synthesized?12?16a?16b?.The bromine-modified twistacenes were transferred to the cyclized compounds with cyclopenta units,which were oxidized via TfOH and DDQ to afford target compounds.Molucules 16a and 16b possess mismatched structures and we only obtain 16a until now.The photoelectric properties of these molecules are being tested.