The application of conventional metal–organic frameworks (MOFs) as electrode materials in supercapacitors is largely hindered by their conventionally poor electrical conductivity. This study reports ...the fabrication of conductive MOF nanowire arrays (NWAs) and the application of them as the sole electrode material for solid‐state supercapacitors. By taking advantage of the nanostructure and making full use of the high porosity and excellent conductivity, the MOF NWAs in solid‐state supercapacitor show the highest areal capacitance and best rate performance of all reported MOF materials for supercapacitors, which is even comparable to most carbon materials.
Conductive metal–organic framework (MOF) nanowire arrays (NWAs) are prepared as the sole electrode material for solid‐state supercapacitors. By taking advantage of their nanostructure and making full use of the high porosity and excellent conductivity, the MOF NWAs in the solid‐state supercapacitor show the highest areal capacitance and best rate performance of all reported MOF materials.
Full-carbon electronics at the scale of several angstroms is an expeimental challenge, which could be overcome by exploiting the versatility of carbon allotropes. Here, we investigate charge ...transport through graphene/single-fullerene/graphene hybrid junctions using a single-molecule manipulation technique. Such sub-nanoscale electronic junctions can be tuned by band gap engineering as exemplified by various pristine fullerenes such as C
, C
, C
and C
. In addition, we demonstrate further control of charge transport by breaking the conjugation of their π systems which lowers their conductance, and via heteroatom doping of fullerene, which introduces transport resonances and increase their conductance. Supported by our combined density functional theory (DFT) calculations, a promising future of tunable full-carbon electronics based on numerous sub-nanoscale fullerenes in the large family of carbon allotropes is anticipated.
The assembly of spherical fullerenes, or buckyballs, into single crystals for crystallographic identification often suffers from disordered arrangement. Here we show a chiral configuration of ...decapyrrylcorannulene that has a concave 'palm' of corannulene and ten flexible electron-rich pyrryl group 'fingers' to mimic the smart molecular 'hands' for self-adaptably cradling various buckyballs in a (+)hand-ball-hand(-) mode. As exemplified by crystallographic identification of 15 buckyball structures representing pristine, exohedral, endohedral, dimeric and hetero-derivatization, the pyrryl groups twist with varying dihedral angles to adjust the interaction between decapyrrylcorannulene and fullerene. The self-adaptable electron-rich pyrryl groups, susceptible to methylation, are theoretically revealed to contribute more than the bowl-shaped palm of the corannulene in holding buckyball structures. The generality of the present decapyrrylcorannulene host with flexible pyrryl groups facilitates the visualization of numerous unknown/unsolved fullerenes by crystallography and the assembly of the otherwise close-packed spherical fullerenes into two-dimensional layered structures by intercalation.
Herein, a hetero(S,N)‐quintuple 9helicene (SNQ9H) molecule with an azacorannulene core was synthesized, currently representing the highest hetero‐helicene reported in the field of multiple ...nhelicenes. X‐ray crystallography indicated that SNQ9H includes not only a propeller‐shaped conformer SNQ9H‐1, but also an unforeseen quasi‐propeller‐shaped conformer SNQ9H‐2. Different conformers were observed for the first time in multiple n≥9helicenes, likely owing to the doping of heteroatomic sulfurs in the helical skeletons. Remarkably, the ratio of SNQ9H‐1 to SNQ9H‐2 can be regulated in situ by the reaction temperature. Experimental studies on the photophysical and redox properties of SNQ9H and theoretical calculations clearly demonstrated that the electronic structures of SNQ9H depend on their molecular conformations. The strategy of introducing heteroatomic sulfurs into the helical skeleton may be useful in constructing various conformers of higher multiple nhelicenes in the future.
Two conformers of a novel quintuple 9helicene with an azabuckybowl as the core were obtained by the deliberate introduction of sulfur heteroatoms into the helical skeleton. The structure–property relationship of different conformers was investigated through detailed experiment and theoretical calculations. The success of the sulfur‐doped strategy implies the potential of realizing higher multiple nhelicenes with various conformers.
A double–heptagon–containing C70H6 (dihept-C70H6) was isolated and unambiguously characterized in the soot of low-pressure combustion, which shares the identical heptagonal cage as dihept-C70Cl6 ...previously identified in the products of carbon arc, and thus represents the first nonclassical fullerene isolable in both carbon arc and combustion.
All previously reported C70 isomers have positive curvature and contain 12 pentagons in addition to hexagons. Herein, we report a new C70 species with two negatively curved heptagon moieties and 14 ...pentagons. This unconventional heptafullerene70 containing two symmetric heptagons, referred to as dihept‐C70, grows in the carbon arc by a theoretically supported pathway in which the carbon cluster of a previously reported C66 species undergoes successive C2 insertion via a known heptafullerene68 intermediate with low energy barriers. As identified by X‐ray crystallography, the occurrence of heptagons facilitates a reduction in the angle of the π‐orbital axis vector in the fused pentagons to stabilize dihept‐C70. Chlorination at the intersection of a heptagon and two adjacent pentagons can greatly enlarge the HOMO–LUMO gap, which makes dihept‐C70Cl6 isolable by chromatography. The synthesis of dihept‐C70Cl6 offers precious clues with respect to the fullerene formation mechanism in the carbon‐clustering process.
Beautiful curves: Double‐heptagon‐containing C70 with negative curvature was captured in the form of dihept‐C70Cl6 (see structure). Chlorination at the intersection of a heptagon and two adjacent pentagons greatly enlarges the HOMO–LUMO gap, which made dihept‐C70Cl6 isolable by chromatography. The synthesis of dihept‐C70Cl6 offers precious clues with respect to the fullerene formation mechanism in the carbon‐clustering process.
Main observation and conclusion
Because of its unsaturated bonds, C60 is susceptible to polymerize into dimers. The implications of nitrogen doping on the geometrical and electronic structure of C60 ...dimers have been ambiguous for years. A quarter‐century after the discovery of azafullerene dimer (C59N)2, we reported its single crystallographic structure in 2019. Herein, the unambiguous crystal structure information of (C59N)2 is elucidated specifically, revealing that the inter‐cage C—C single bond length of (C59N)2 is comparable with that of an ordinary C(sp3)‐C(sp3) single bond, and that the most stable conformer of (C59N)2 is gauche‐conformer with a dihedral angle of 66°. To amend the structural deviations, geometrical structure of (C59N)2 is optimized by a B3LYP‐D3BJ function, which is proved to be more consistent with its single crystal structure than those by the commonly used B3LYP function. Moreover, the calculation method is also suitable for other representative fullerene dimers, such as (C60)2 and its divalent anion. Additionally, the dissociation of (C59N)2 at 473 K under mass spectrometric conditions suggests the inter‐cage C—C bond is relatively weaker than an ordinary C—C single bond, which can be explained by the interaction energies of inter‐cages.
The structures of C60 dimer and its nitrogen doping species (C59N)2 are discussed in detail, and the differences between computational and experimental geometrics are described. An accurate calculation method is suggested to correct the structural deviation between the theoretical results and the crystallographic data for the fullerene dimers.
Curvature prevalently exists in the world of carbon materials (e.g., fullerenes, buckyl bowls, carbon nanotubes, and onions), but traditional C2-addition mechanisms fail to elucidate the mechanism ...responsible for the formation of carbon curvature starting from a pentagonal carbon ring in currently available chemical-physical processes such as combustion. Here, we show a complete series of nascent pentagon-incorporating C5–C18 that are online produced in the flame of acetylene–cyclopentadiene–oxygen and in situ captured by C60 or trapped as polycyclic aromatic hydrocarbons for clarifying the growth of the curved subunit of C20H10. A mechanism regarding C1-substitution and C2-addition has been proposed for understanding the formation of curvature in carbon materials, as exemplified by the typical curved molecule containing a single pentagon completely surrounded by five hexagons. The present mechanism, supported by the intermediates characterized by X-ray crystallography as well as NMR, has been experimentally validated for the rational synthesis of curved molecule in the commercially useful combustion process.
Carboncones, a special family of all-carbon allotropes, are predicted to have unique properties that distinguish them from fullerenes, carbon nanotubes, and graphenes. Owing to the absence of methods ...to synthesize atomically well-defined carboncones, however, experimental insight into the nature of pure carboncones has been inaccessible. Herein, we describe a facile synthesis of an atomically well-defined carboncone1,2 (C
H
) and its soluble penta-mesityl derivative. Identified by x-ray crystallography, the carbon skeleton is a carboncone with the largest possible apex angle. Much of the structural strain is overcome in the final step of converting the bowl-shaped precursor into the rigid carboncone under mild reaction conditions. This work provides a research opportunity for investigations of atomically precise single-layered carboncones having even higher cone walls and/or smaller apex angles.
The flash vacuum pyrolysis (FVP) technique is useful for preparing curved polycyclic aromatic compounds (PAHs) and caged nanocarbon molecules, such as the well-known corannulene and fullerene C60. ...However, the operating temperature of the traditional FVP apparatus is limited to ~1250 °C, which is not sufficient to overcome the high energy barriers of some reactions. Herein, we report an ultrahigh-temperature FVP (UT-FVP) apparatus with a controllable operating temperature of up to 2500 °C to synthesize fullerene C60 from a nonaromatic single carbon reactant, i.e., chloroform, at 1350 °C or above. Fullerene C60 cannot be obtained from CHCl3 using the traditional FVP apparatus because of the limitation of the reaction temperature. The significant improvements in the UT-FVP apparatus, compared to the traditional FVP apparatus, were the replacement of the quartz tube with a graphite tube and the direct heating of the graphite tube by impedance heating instead of indirect heating of the quartz tube using an electric furnace. Because of the higher temperature range, UT-FVP can not only synthesize fullerene C60 from single carbon nonaromatic reactants but sublimate some high-molecular-weight compounds to synthesize larger curved PAHs in the future.
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![Sulfur‐Doped Quintuple [9]H...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1433-7851/small "Sulfur‐Doped Quintuple [9]Helicene with Azacorannulene as Core")
