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1.  Carbon arc production of heptagon-containing fullerene[68] 
Nature Communications  2011;2:420-.
A carbon heptagon ring is a key unit responsible for structural defects in sp2-hybrized carbon allotropes including fullerenes, carbon nanotubes and graphenes, with consequential influences on their mechanical, electronic and magnetic properties. Previous evidence concerning the existence of heptagons in fullerenes has been obtained only in off-line halogenation experiments through top-down detachment of a C2 unit from a stable fullerene. Here we report a heptagon-incorporating fullerene C68, tentatively named as heptafullerene[68], which is captured as C68Cl6 from a carbon arc plasma in situ. The occurrence of heptagons in fullerenes is rationalized by heptagon-related strain relief and temperature-dependent stability. 13C-labelled experiments and mass/energy conservation equation simulations show that heptafullerene[68] grows together with other fullerenes in a bottom-up fashion in the arc zone. This work extends fullerene research into numerous topologically possible, heptagon-incorporating isomers and provides clues to an understanding of the heptagon-involved growth mechanism and heptagon-dependent properties of fullerenes.
Chemical manipulation of fullerenes has allowed the production of heptagon-containing fullerenes, but they have not been synthesised using bottom-up approaches. Here, a heptagon-containing fullerene[68] is obtained as C68Cl6 from a carbon arc plasma.
doi:10.1038/ncomms1431
PMCID: PMC3267027  PMID: 21829182
2.  Ammine(2,2′-bipyridine-κ2 N,N′)silver(I) nitrate: a dimer formed by π–π stacking and ligand-unsupported Ag⋯Ag inter­actions 
Reaction of AgNO3 and 2,2′-bipyridine (bipy) under ultrasonic treatment gave the title compound, [Ag(C10H8N2)(NH3)]NO3. The crystal structure consists of dimers formed by two symmetry-related AgI–bipy monomers connected through intra-dimer π–π stacking and ligand-unsupported Ag⋯Ag inter­actions. A crystallographic C2 axis passes through the mid-point of and is perpendicular to the Ag⋯Agi(−x + 1, y, −z + ) axis. In addition, each AgI cation is coordinated by one chelating bipy ligand and one ammine ligand, giving a trigonal coordination environment capped by the symmetry-equivalent Ag atom. Mol­ecules are assembled by Ag⋯Ag, π–π, hydrogen-bond (N—H⋯O and C—H⋯O) and weak Ag⋯π inter­actions into a three-dimensional framework. Comparing the products synthesized under different mechanical treatments, we found that reaction conditions have a significant influence on the resulting structures. The luminescence properties of the title compound are also discussed.
doi:10.1107/S010827011000377X
PMCID: PMC2855567  PMID: 20203399
3.  Tetra­aqua­tetra­kis{μ3-3,3′-[(E,E)-ethane-1,2-diylbis(nitrilo­methyl­idyne)]benzene-1,2-diolato}octa­zinc(II) N,N-dimethyl­formamide hexa­solvate 
The asymmetric unit of the title compound [Zn8(C16H12N2O4)4(H2O)4]·6C3H7NO, consists of eight ZnII cations, four tetra­valent anionic ligands, L 4− (L 4− = 3,3′-(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-yl­idene))bis­(methan-1-yl-1-yl­idene)dibenzene-1,2-bis­(olate), four coordinated water mol­ecules and six N,N-dimethyl­formamide solvate mol­ecules. The coordination complex comprises an octa­nuclear ZnII unit with its ZnII centers coordinated in two discrete distorted square-pyramidal geometries. Four ZnII atoms each coordinate to two nitro­gen atoms and two phenolate oxygen atoms from an individual L 4− ligand and one coordinated water mol­ecule. The other four ZnII atoms each bind to five phenolate oxygen atoms from three different L 4− ligands. In the crystal structure, the ZnII complex unit, coordinated water mol­ecules and dimethyl­formamide solvate mol­ecules are linked via O—H⋯O and C—H⋯O hydrogen bonds. Mol­ecules are connected by additional inter­molecular O—H⋯O and C—H⋯O hydrogen bonds, forming an extensive three dimensional framework.
doi:10.1107/S1600536809046923
PMCID: PMC2972079  PMID: 21578596
4.  4H-Cyclo­penta­[def]phenanthren-4-one 
In the title compound, C15H8O, the asymmetric unit contains four independent mol­ecules and crystallizes with aromatic π–π stacking inter­actions[centroid–centroid distances = 3.5326 (18) Å].
doi:10.1107/S1600536809030633
PMCID: PMC2970027  PMID: 21577520
5.  3-Chloro-4-hydroxy­furan-2(5H)-one 
In the title compound, C4H3ClO3, mol­ecules are linked via O—H⋯O hydrogen bonds into an infinite chain with graph-set motif C(6) along the c axis.
doi:10.1107/S1600536809028724
PMCID: PMC2977129  PMID: 21583653
6.  Benzo[a]fluoren-11-one 
The mol­ecule of the title compound, C17H10O, is nearly planar, the largest deviation from the mean plane being 0.06 Å. The crystal structure is governed by π–π inter­actions, with centroid–centroid distances ranging from .559 to 3.730 Å.
doi:10.1107/S1600536808020989
PMCID: PMC2962100  PMID: 21203182

Results 1-6 (6)