Dibenzo[a,f]perylene Bisimide: Effects of Introducing Two Fused Rings

Perylene bisimides (PBIs) are fascinating dyes with various potential applications. To study the effects of introducing a dibenzo‐fused structure to the perylene moiety, π‐extended PBI derivatives with a dibenzo‐fused structure at both of the a and f bonds were synthesized. The twisted structure was characterized by X‐ray crystal structure analysis. In the cyclic voltammograms, the dibenzo[a,f]‐fused PBI showed a reversible oxidation wave at much less positive potential, relative to a dibenzo[a,o]‐fused PBI derivative. These data indicated that two ring fusions at both sides of a naphthalene moiety, which construct a tetracene core, effectively raise the HOMO level compared to fusion of one ring at each naphthalene moiety (two anthracene cores). The dibenzo[a,f]‐fused PBI derivative showed an absorption band at 735 nm with a shoulder band reaching 900 nm.     

非富勒烯受体DA'D型稠环单元的结构修饰及电池性能研究

近年来,设计和合成高性能非富勒烯受体(NFAs)材料已经成为太阳能电池研究领域的前沿课题。基于DA'D型稠环结构的NFAs由于具有吸光系数高、能级和带隙可调、结构易于修饰、分子可高效合成、光电学性能优异等优点而受到了越来越广泛的关注。在短短7年的时间里,能量转换效率(PCE)从3%~4%提高到18%。2019年初邹应萍等报道了一个优秀的受体分子Y6,与PM6共混制备单结电池,获得了15.7%的能量转换效率。Y6类受体材料的中心给电子单元为DA'D型稠环结构,缺电子单元(A')通过氮原子与两个给电子单元(D)并联形成稠环结构,这有助于降低前线分子轨道能级并增强吸收,同时与氮相连的两个烷基链和位于噻吩并噻吩β位的两个侧链则有助于提高溶解度及调节结晶性。自Y6问世以来,人们对分子的结构剪裁进行了深入的研究,并报道了数十种新的结构。在这些新的受体中,DA'D部分的结构裁剪对提高器件效率和太阳能电池的性能起着至关重要的作用。本文对A'、D单元和侧链结构修饰的研究进展进行了综述。通过选择几组受体,对最近报道的分子进行分类,并将它们的光学、电化学、电学和光电性质与精确的结构修饰相关联,从而对结构-性能关系进行全面概述。     

Nano palladium catalyzed C(sp3)-H bonds arylation by a transient directing strategy

Reported herein is the first example of heterogeneous palladium catalyzed C(sp³)-H bonds arylation by a transient-ligand-directed strategy.Using supported palladium(metallic state) na nopariticles as catalyst,a wide range of aryl iodides undergo the coupling with various o-methylbenzaldehyde derivatives to assemble a library of highly selective and functionalized o-benzylbenzaldehydes.The stability of the catalyst was easily recovered four runs without significant loss of activity.The XPS analysis of the catalyst before and after reaction indicated that the reaction might be carried out by a catalytic cycle starting with Pd~0.     

Electron‐Deficient Tetrabenzo‐Fused Pyracylene and Conversions into Curved and Planar π‐Systems Having Distinct Emission Behaviors

Polycyclic aromatic compounds containing fully unsaturated five‐membered ring(s) have been intensively studied because of their unique properties, which include high electron affinity and reactivity. Reported herein is an efficient route for the synthesis of tetrabenzo‐fused pyracylene, which comprises pyracylene and tetracene segments, using intramolecular oxidative C? H coupling. It was shown to possess high electron affinity and was found to undergo addition reactions with n‐butyllithium or benzyne. These reactions led to either a 1,4‐addition compound or triptycene‐type adduct with a curved or planar π‐system, respectively. Although these compounds exhibited similar sky‐blue emissions in a dilute solution, the emission band of the 1,4‐addition compound was significantly red‐shifted in the solid state and exhibited intense yellow emission attributable to the excimer, while the triptycene‐type adduct retained the intense blue color emission in the solid state.     

Ethylene sulfite based electrolyte for non-aqueous lithium oxygen batteries

Non-aqueous lithium–oxygen(Li–O_2) batteries have been considered as the superior energy storage system due to their high-energy density, however, some challenges limit the practical application of Li–O_2 batteries. One of them is the lack of stable electrolyte. In this communication, a novel electrolyte with ethylene sulfite(ES) used as solvent for Li–O_2 batteries was reported. ES solvent showed low volatility and high electrochemical stability. Without a catalyst in the air-electrode of Li–O_2 batteries, the batteries showed high specific capacity, good round-trip efficiency and cycling stability.     

Chloromethyl pivalate based electrolyte for non-aqueous lithium oxygen batteries

A novel electrolyte with chloromethyl pivalate(CP) used as solvent was first reported for non-aqueous lithium-oxygen(Li-O_2) batteries. Since there are no α-H atoms in the structure of CP, the CP based electrolyte in both superoxide radical solution and real Li-O_2 battery environment showed good chemical stability against superoxide radicals, which was confirmed by ~1H NMR and ~13C NMR measurements.Without a catalyst in the cathode of Li-O_2 batteries, the batteries showed high specific capacity and cycling stability.