Novel Boron,nitrogen-embedded Fused Aromatics And Their Derivatives: Molecular Design,synthesis And Properties

Fuesd aromatics and their derivatives have been widely studied for the applications in organic electronic materials.Through the introduction of different heteroatoms or functional groups,the properties of fuesd aromatics could be effectively tuned.In this dissertation,several new types of rigid conjugated skeleton with multiple functionalized sites were obtained by introducing boron and nitrogen heteroatoms into the outer edge structures of fuesd aromatics,generating a series of novel boron,nitrogenembedded fuesd aromatics and their derivatives.The solid structures,photophysical properties and electrochemical behaviors of these molecules were systematically studied,and the applications of using BN-embedded fuesd aromatics as active materials in the fabrication of optoelectronic devices were explored.Chapter ?: Graphene and other two-dimensional(2D)nanomaterials and their development in organic electronic applications are introduced.The importance of tuning the electronic structure of graphene by doping non-carbon atoms(such as boron,nitrogen,etc.)is highlighted.Besides,the necessity of developing boron,nitrogen containing small molecules for the bottom-up approaches for the preparation of 2D nanomaterials,as well as BN-embedded fuesd aromatics acting as model compounds for the understanding of the properties of relevant 2D nanomaterials,were demonstrated.The development history and current situation of azaborine chemistry are reviewed,and the recent progress of the synthesis and properties of BN-embedded fuesd aromatics are emphatically introduced.The idea of this dissertation and the research contents are sketched.Chapter ?: A novel boron-nitrogen embedded anthra[1,2-b:5,6-b']dithiophene(BN-ADT)and its derivatives were synthesized.The molecular peripheral could be modified in multifunctional way and the molecular skeleton could be extended to at least 7 conjugated rings.The monocrystalline structures,photophysical properties and electrochemical behaviors of these BN-embedded anti-fuesd aromatics were characterized,and the electron energy levels were simulated by the theoretical calculation,revealing the blue light characteristic of BN-ADT derivatives.In addition,BN-embedded fuesd aromatics were for the first time used as the host material of the luminescent layer of organic light-emitting diodes(OLEDs).Through doping with 3% 2-methyl-9,10-bis(naphthalen-2-yl)anthracene(MADN),the optimized devices displayed an external quantum efficiency(EQE)up to 1.4% with CIE coordinates of(0.16,0.16),exhibiting pure bule light.Chapter ?: The novel BN-embedded anti-fuesd aromatics with two boron atoms attached on the aromatic core were synthesized,namely boron-nitrogen embedded dibenz[a,h]anthracene(NB-DBA)series.Through the substitution at the B and N sites,a series of functional derivatives were synthesized.Based on the systematic study of the solid structures,photophysical properties and electrochemical behaviors of these molecules,along with the calculated electronic energy levels,it indicates that the electronic structures and solid state packing of BN-embedded fuesd aromatics could be effectively regulated through the variation of the aromatic cores.Chapter ?: A novel dibenzoazaboraphenalene with nitrogen-boronnitrogen zig-zag edge structure was synthesized,namely NBN-DBP.The highly region-selective bromination reaction could be achieved at the Npara position of the aromatic skeleton,and thus through the transition metal catalyzed coupling reactions,the series of ?-extended derivatives were successfully prepared.Started from different precursors,the ?-extended NBN-doped dibenzoheptazethrene(NBN-DBHZ)with two NBN-phenalene units were also synthesized by the same method,suggesting that this strategy could be a general bottom-up approach towards BN-doped zig-zag type graphene nano-ribbons.The solid structures,photophysical properties and electrochemical behaviors of these molecules were characterized systematically,by comparison with the analysis of simulative aromaticity,electron energy levels and absorption spectra,it indicates that the experimental results are in good agreement with the theoretical calculation.By oxidizing,NBN-DBP could form openshell radical cations,and futher converted into dimer molecules.The related process was systematically analyzed by near-infrared absorption spectroscopy,electron paramagnetic resonance collaborated with in-situ spectroelectrochemistry,revealing the unique chemical activity and electronic structural properties of these NBN-embedded fuesd aromatics.In conclusion,this thesis developed several efficient synthesis strategies,and obtained several series of BN-embedded fuesd aromatics and their derivatives,which enriched the family of the heteroatom doped fuesd aromatics and further provided important model compounds for the research of boron-nitrogen doped graphene and its derivatives.