Rechargeable aluminium (Al) batteries (RABs) have long‐been pursued due to the high sustainability and three‐electron‐transfer properties of Al metal. However, limited redox chemistry is available for rechargeable Al batteries, which restricts the exploration of cathode materials. Herein, we demonstrate an efficient Al–amine battery based on a quaternization reaction, in which nitrogen (radical) cations (R3N.+ or R4N+) are formed to store the anionic Al complex. The reactive aromatic amine molecules further oligomerize during cycling, inhibiting amine dissolution into the electrolyte. Consequently, the constructed Al–amine battery exhibits a high reversible capacity of 135 mAh g−1 along with a superior cycling life (4000 cycles), fast charge capability and a high energy efficiency of 94.2 %. Moreover, the Al–amine battery shows excellent stability against self‐discharge, far beyond conventional Al–graphite batteries. Our findings pave an avenue to advance the chemistry of RABs and thus battery performance.
Reduced graphene oxide (rGO)@MoS2 composites with a loose structure were prepared and added to poly(vinylidene fluoride) (PVDF) to form composites that showed superior microwave absorption and excellent electromagnetic interference shielding performances. The maximum reflection loss of the rGO@MoS2/PVDF composites, with a low filling rate (only 5.0 wt %), can reach −43.1 dB at 14.48 GHz, and the frequency bandwidth below −10 dB is 3.6–17.8 GHz (in the frequency range of 2–18 GHz) with a thickness of 1–5 mm. Furthermore, rGO@MoS2/PVDF composites with a higher filling rate (25 wt %) also exhibit outstanding electromagnetic interference shielding effectiveness, reaching a maximum at 27.9 dB. The mechanism of enhanced absorption and electromagnetic interference shielding performances were also studied in detail.
Dedicated to Professor Klaus Müllen on the occasion of his 75th birthday.Curved graphene nanoribbons (GNRs) with hybrid edge structures have recently attracted increasing attention due to their unique band structures and electronic properties as a result of their nonplanar conformation. This work reports the solution synthesis of a long and curved multi-edged GNR (cMGNR) with unprecedented cove-armchair-gulf edge structures. The synthesis involves an efficient A 2 B 2 -type Diels-Alder polymerization between a diethynyl-substituted prefused bichrysene monomer (3b) and a dicyclopenta[e,l]pyrene-5,11-dione derivative (6) followed by FeCl 3 -mediated Scholl oxidative cyclodehydrogenation of the obtained polyarylenes (P1). Model compounds 1a and 1b are first synthesized to examine the suitability and efficiency of the corresponding polymers for the Scholl reaction. The successful formation of cMGNR from polymer P1 bearing prefused bichrysene units is confirmed by FTIR, Raman, and solid-state NMR analyses. The cove-edge structure of the cMGNR imparts the ribbon with a unique nonplanar conformation as revealed by density functional theory (DFT) simulation, which effectively enhances its dispersibility in solution. The cMGNR has a narrow optical bandgap of 1.61 eV, as estimated from the UV-vis absorption spectrum, which is among the family of low-bandgap solution-synthesized GNRs. Moreover, the cMGNR exhibits a carrier mobility of ≈2 cm 2 V −1 s −1 inferred from contact-free terahertz spectroscopy.
Herein, we demonstrate a novel one‐pot synthetic method towards a series of boron‐doped polycyclic aromatic hydrocarbons (B‐PAHs, 1 a–1 o), including hitherto unknown B‐doped zethrene derivatives, from ortho‐aryl substituted diarylalkynes with high atom efficiency and broad substrate scopes. A reaction mechanism is proposed based on the experimental investigation together with the theoretical calculations, which involves a unique 1,4‐boron migration process. The resultant benchtop‐stable B‐PAHs are thoroughly investigated by X‐ray crystallography, cyclic voltammetry, UV/Vis absorption, and fluorescence spectroscopies. The blue and green organic light‐emitting diode (OLED) devices based on 1 f and 1 k are further fabricated, demonstrating the promising application potential of B‐PAHs in organic optoelectronics.
A novel synthetic strategy was developed for the construction of difficult-to-access structurally constrained boron-doped polycyclic aromatic hydrocarbons (sc-B-PAHs) via a cascade reaction from the readily available ortho-arylsubstituted diarylalkynes. This domino process involves borylative cyclization, 1,4-boron migration and successive twofold electrophilic borylation. Two types of sc-B-PAHs bearing B-doped [4]helicene (1 a-1 i) or helicene (1 n-1 t) and double [4]helicene (1 u-1 v) are constructed by this cascade reaction. Remarkably, this synthetic strategy is characterized by modest yields (20-50 %) and broad substrate scope (18 examples) with versatile functional group tolerance. The resultant sc-B-PAHs show good stability under ambient conditions and are thoroughly investigated by X-ray crystallography, UV/Vis absorption and fluorescence spectroscopy, and cyclic voltammetry. Interestingly enough, helicene 1 o forms a unique alternating p-stacked dimer of enantiomers within a helical columnar superstructure, while BN-doped double [4]helicene 1 u establishes an unprecedented p-stacked trimeric sandwich structure with a rare 2D lamellar p-stacking. The synthetic approach reported herein represents a powerful tool for the rapid generation of novel sc-B-PAHs, which are highly attractive for the elucidation of the structureproperty relationship and for potential optoelectronic applications.
The precise introduction of nonplanar pores in the backbone of graphene nanoribbon represents a great challenge. Here, we explore a synthetic strategy toward the preparation of nonplanar porous graphene nanoribbon from a predesigned dibromohexabenzotetracene monomer bearing four cove‐edges. Successive thermal annealing steps of the monomers indicate that the dehalogenative aryl‐aryl homocoupling yields a twisted polymer precursor on a gold surface and the subsequent cyclodehydrogenation leads to a defective porous graphene nanoribbon containing nonplanar [14]annulene pores and five‐membered rings as characterized by scanning tunneling microscopy and noncontact atomic force microscopy. Although the C–C bonds producing [14]annulene pores are not achieved with high yield, our results provide new synthetic perspectives for the on‐surface growth of nonplanar porous graphene nanoribbons.
The precision synthesis of helical bilayer nanographenes (NGs) with new topology is of substantial interest because of their exotic physicochemical properties. However, helical bilayer NGs bearing nonhexagonal rings remain synthetically challenging. Here we present the efficient synthesis of the first helical bilayer nonbenzenoid nanographene (HBNG1) from a tailor-made azulene-embedded precursor, which contains a novel [10]helicene backbone with two embedded heptagons. Single-crystal X-ray analysis reveals its highly twisted bilayer geometry with a record small interlayer distance of 3.2 Å among the reported helical bilayer NGs. Notably, the close interlayer distance between the two layers offers intramolecular through-space conjugation as revealed by in situ spectroelectrochemistry studies together with DFT simulations. Furthermore, the chiroptical properties of the P/M enantiomers of HBNG1 are also evaluated by circular dichroism and circularly polarized luminescence.
The research interest in azulene‐embedded polycyclic aromatic hydrocarbons (PAHs) has significantly increased recently, but the lack of efficient synthetic strategies impedes the investigation of their structure‐property relationships and further opto‐electronic applications. Here we report a modular synthetic strategy towards diverse azulene‐embedded PAHs by a tandem Suzuki coupling and base‐promoted Knoevenagel‐type condensation with good yields and great structural versatility, including non‐alternant thiophene‐rich PAHs, butterfly‐ or Z‐shaped PAHs bearing two azulene units, and the first example of a two‐azulene‐embedded double [5]helicene. The structural topology, aromaticity and photophysical properties were investigated by NMR, X‐ray crystallography analysis and UV/Vis absorption spectroscopy assisted by DFT calculations. This strategy provides a new platform for rapidly synthesizing unexplored non‐alternant PAHs or even graphene nanoribbons with multiple azulene units.
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