Design,synthesis,controllable Functional Derivation And Optoelectronic Properties Of Non-planar Polycyclic Aromatic Hydrocarbons

Non-planar PAHs materials have been widely used in optoelectronic area due to their unique structures and properties.In recent years,Non-planar PAHs present distinct properties in synthetic chemistry,coordination chemistry,material science,supramolecular chemistry and other fields.On the one hand,the study of the nonplanar PAHs has important theoretical meaning.On the other hand,the study of the non-planar PAHs has a wide field of application with good prospects.Construction of PAHs with distinctive curved aromatic surfaces by large intramolecular tension often requires harsh reaction conditions.Therefore,the bottom-up design,simple and effictive synthesis of non-planar PAHs are important for the development of organic functional materials.To date,there are several ways to construct non-planar PAHs:(1)edge functionalization;(2)selective heteroatom doping;(3)seven-or eight-membered rings induce negative curvature;(4)five-membered rings induce positive curvature;(5)non-conventional methods.Through one or more ways,the materials with interesting structures can be constructed.Hence,there are four studies followed:(1)Bottom-up preparation of twisted graphene nanoribbons via Cu-catalyzed deoxygenative coupling.The fully armchair-edged GNRs(AGNRs)with lengths up to2.65 nm were conveniently synthesized from hexabutoxytriphenylene(HBT).The resulting AGNRs(2HBT,3HBT,and 4HBT)possess highly twisted π-scaffolds.Theoretical and spectroscopic studies manifest that butoxyls endow AGNRs with an electron-rich feature,the extension of the π-system from 2HBT to 4HBT reinforces S0 → S1 excitation,and the distortion of π-scaffold enhances fluorescence quantum yield(ФF).Particularly,4HBT has the lowest oxidation potential(Eox1 = 0.55 V vs.SCE)and displays red fluorescence with ФF of 81%.(2)Induce positive curvature molecules were synthesized synthesized by introduction of five-membered rings into polycyclic aromatic frameworks.2HBT has unsubstituted ‘bay’ which can fused five-member heterocyclic ring.The chalcogen element hybrid nano-graphenes(4S,4Se,4Te)are synthesized,and 4SO2 is synthesized by selective oxidation.Compared with 2HBT,the chalcogenidehybridized nano-graphenes tend to plane,five-membered rings induce positive curvature,and the molecule possesses a concave-convex double-bowl-shaped structure,their bowl depth are 0.46 to 0.40 ?.Since the atomic radius of tellurium is larger than sulfur and selenium,4Te molecule tends to plane.(3)Highly twisted π-Helix molecules with cyclooctatetraene cores are synthesised by coupling reaction.Saddle-shaped molecules(HBT-Cot,2S-Cot,2SeCot)with cyclooctatetraene cores were conveniently synthesized from HBT,2S and2 Se.These molecules were transformed into twisted ones by introducing cyclooctatetraene.These molecules have "X"-shaped twisted π-scaffolds with stable chiral structure,and the torsion angles between the intrasubunit are 71 o as proved by crystallographic analyses.Compared with HBT-Cot,the configuration and fluorescence properties of the heteroatom-doped 2S-Cot and 2Se-Cot were obviously changed.(4)Negatively positive curvature molecules were synthesized synthesized by introduction of eight-membered rings into polycyclic aromatic frameworks.The molecules(6Se,4Se2S)with cyclooctatetraene core are synthesized by decarboxylation coupling from 3Se and 2Se1 S.6Se has electrochromic effect,which can form cationic free radicals under oxidation and acid conditions,and change from red to blue-green.6Se shrink ring reaction from cyclooctetraene to tropone in the presence of oxidant TBHP.Crystal data suggest that 6Se possesses supramolecular assembly ability with C60 and C70.