Spotlights Cite This: J. Am. Chem. Soc. 2018, 140, 1183−1183
pubs.acs.org/JACS
Spotlights on Recent JACS Publications
■
■
FUNCTIONAL BN-DOPED NANOGRAPHENES ACHIEVED IN ONLY TWO STEPS
WATER IMPROVES QUINONE-BASED LITHIUM OXIDE BATTERIES Lithium−oxygen batteries (or lithium−air) batteries are now the target of intensive research because they possesses a theoretical energy density close to gasoline, 10 times higher than current lithium ion batteries. However, lithium−oxygen batteries are plagued by unresolved problems. For example, undesirable side reactions occur during cycling, which inactivate the electrode surfaces and thus affect the attainable energy density. To solve the problems, Clare Gray and co-workers turn to quinones, a class of organic redox molecules that play an important role in photosynthesis in biological systems (DOI: 10.1021/jacs.7b11007). The researchers uses 2,5-di-tert-butyl1,4-benzoquinone (DBBQ) as mediators in lithium−oxygen batteries and find that water can stabilize the quinone anion via hydrogen-bond formation and promote the coordination of the lithium ions, improving the battery discharge voltage, rate and capacity. Furthermore, it inhibits the formation of LiO2 which reduces the side reactions by around 70%. This strategy of using water to improve lithium-ion battery performance may be applicable to other soluble redox mediators, ultimately helping to find the optimal system. Alexander Hellemans
Consisting of a monolayer of carbon atoms in a hexagonal array, graphene is transparent, conductive, and 200 times stronger than steel, and it has attracted great interest for various applications in membrane, electronic, and biomedical devices, to name a few. Doping of graphene with heteroatoms can further introduce novel electronic, magnetic, and other properties, although the synthesis of uniform materials, and therefore the tuning of these properties, remains a challenge. One potentially advantageous approach is to start from heteroatom-doped nanographenes, which can typically be accessed only via involved, multistep processes. Takuji Hatakeyama and co-workers have devised a straightforward, direct synthesis of BN-doped nanographenes in only two steps, starting from commercially available tribromobenzene and using carefully chosen Brønsted bases and boron precursors (DOI: 10.1021/jacs.7b10578). Initial triarylamine synthesis is followed by one-shot borylation of six, nine, or 11 C−H bonds to introduce two, three, or four boron atoms with yields ranging from 40 to 80%. Notably, all three materials exhibit pure deep-blue fluorescence, and the diborylated structure could be successfully implemented in an organic light-emitting diode device. The simple synthetic approach holds great promise for the design of functional materials based on BNdoped nanographenes. Katie Meihaus, Ph.D.
■
■
DEFINING THE SHAPE OF A PIECE OF THE HIV PUZZLE Bit by bit, the structures of HIV proteins are coming to light, with each offering a possible opportunity to take down the virus. Fusion between the viral envelope protein and the host cell is a critical infection step, yet some aspects of this process have remained elusive. Researchers had, based on some experimental evidence, widely believed that the transmembrane region of the gp41 domain of the viral envelope protein formed a symmetric C3 trimer, but conclusive data was lacking. To help define the transmembrane domain of the gp41 protein, Ad Bax and colleagues turn to nuclear magnetic resonance experiments that measure residual dipolar couplings, which have special properties in the case of C3 symmetry (DOI: 10.1021/jacs.7b10245). However, their results are incompatible with a trimer. Further investigation indicates that the transmembrane domain is actually monomeric. Additional analysis shows that the region is well ordered, nearly straight, alpha helical, and must be diagonal with respect to the bilayer axis. Based on the large tilt angle, Bax’s team speculates that hydrophilic amino acid side chains may interact with the polar bilayer surface and contribute to membrane destabilization, instigating fusion during HIV infection. Erika Gebel Berg, Ph.D.
NEW STRATEGY FOR TUNING BAND STRUCTURE OF GRAPHENE NANORIBBONS
The electronic band structure of a material defines its electrical conductivity. In the search for carbon-based nanomaterials with unique physical and electronic properties, the ability to strategically tune the band structure is critical. Steven Louie, Felix Fischer, and colleagues describe a new strategy for accomplishing this with bottom-up synthesized graphene nanoribbons (GNRs) (DOI: 10.1021/jacs.7b11886). The team creates a series of atomically precise nitrogen-, oxygen-, and sulfur-doped GNR materials. The heteroatom dopants are placed with trigonal planar geometry at defined positions along the edges of the nanoribbons to ensure the overlap of the heteroatom lone-pairs with the extended πsystem. The researchers determine that the heteroatom dopants induce certain changes in the band structure, and a set of structure-properties relationships for GNRs are proposed. The work broadens the scope of the dopant atoms and has significant implications on the integration of functional GNRs into advanced electronics. Christine Herman, Ph.D. © 2018 American Chemical Society
Published: January 31, 2018 1183
DOI: 10.1021/jacs.8b00835 J. Am. Chem. Soc. 2018, 140, 1183−1183
