No abstract

Analysis of 179 new Ebola virus sequences from patient samples collected in Guinea between March 2014 and January 2015 shows how different lineages evolved and spread in West Africa. Supplementary information The online version of this article (doi:10.1038/nature14594) contains supplementary material, which is available to authorized users.

No abstract

The new germandiyls 1 and 2 which sublime at 50 °C are monomeric in the solid state, in solution, and in the gas phase. They are available from germanium dichloride · 1,4‐dioxane and the appropriate lithium diamides in high yields, and react smoothly with [Ni(CO)4] to give 3 and 4. According to ab initio calculations, the π electrons in 2 are delocalized. cod = cyclooctadiene.

9,10-Dihydro-9,10-diboraanthracene (DBA) provides a versatile scaffold for the development of boron-doped organic luminophores. Symmetrically C-halogenated DBAs are obtained through the condensation of 4-bromo-1,2-bis(trimethylsilyl)benzene or 4,5-dichloro-1,2-bis(trimethylsilyl)benzene with BBr3 in hexane. Unsymmetrically C-halogenated DBAs are formed via an electrophilic solvent activation reaction if the synthesis is carried out in o-xylene. Mechanistic insight has been achieved by in situ NMR spectroscopy, which revealed C-halogenated 1,2-bis(dibromoboryl)benzenes to be the key intermediates. Treatment of the primary 9,10-dibromo-DBAs with MesMgBr yields air- and water-stable C-halogenated 9,10-dimesityl-DBAs (2-Br-6,7-Me2-DBA(Mes)2; 2,6-Br2-DBA(Mes)2; 2,3-Cl2-6,7-Me2-DBA(Mes)2; 2,3,6,7-Cl4-DBA(Mes)2). Subsequent Stille-type C-C-coupling reactions give access to corresponding phenyl, 2-thienyl, and p-N,N-diphenylaminophenyl derivatives, which act as highly emissive donor-acceptor dyads or donor-acceptor-donor triads both in solution and in the solid state. 2-Thienyl was chosen as a model substituent to show that already a variation of the number and/or the positional distribution of the donor groups suffices to tune the emission wavelength of the resulting benchtop stable compounds from 469 nm (blue) to 540 nm (green). A further shift of the fluorescence maximum to 594 nm (red) can be achieved by switching from 2-thienyl to p-aminophenyl groups. A comparison of the optoelectronic properties of selected C-substituted DBA(Mes)2 derivatives with those of the isostructural anthracene analogues unveiled the following: (i) The DBA core is a much better electron acceptor. (ii) The emission colors of DBAs fall in the visible range of the spectrum (blue to orange), while anthracenes emit exclusively in the near-ultraviolet to blue wavelength regime. (iii) DBAs show significantly higher solid-state quantum yields.

Honey was previously considered to be one of the main food sources of human pyrrolizidine alkaloid (PA) exposure in Europe. However, comprehensive analyses of honey and tea sampled in the Berlin retail market revealed unexpected high PA amounts in teas. This study comprised the analysis of 87 honey as well as 274 tea samples including black, green, rooibos, melissa, peppermint, chamomile, fennel, nettle, and mixed herbal tea or fruit tea. Total PA concentrations in tea ranged from < LOD to 5647 µg kg(-1), while a mean value of about 10 µg kg(-1) was found in honey samples. Additionally, herbal drugs were investigated to identify the source of PA in teas. Results suggest that PA in tea samples are most likely a contamination caused by co-harvesting of PA-producing plants. In some cases such as fennel, anise or caraway, it cannot be excluded that these plants are able to produce PA themselves.

Herein we show that replacing the two meso carbon atoms of the polycyclic aromatic hydrocarbon (PAH) bisanthene by boron atoms transforms a near-infrared dye into an efficient blue luminophore. This observation impressively illustrates the impact of boron doping on the frontier orbitals of PAHs. To take full advantage of this tool for the targeted design of organic electronic materials, the underlying structure-property relationships need to be further elucidated. We therefore developed a modular synthesis sequence based on a Peterson olefination, a stilbene-type photocyclization, and an Si-B exchange reaction to substantially broaden the palette of accessible polycyclic aromatic organoboranes and to permit a direct comparison with their PAH congeners.

Building bridges: The title compound forms an unprecedented polymeric structure with bridging B-H-B three-center two-electron bonds in the solid state. This organoborane serves as an efficient precursor for the preparation of boron-doped pi-conjugated polymers by hydroboration polymerization with a functionalized 1,4-diethynylbenzene (see picture). These polymers form thin films that show intense green luminescence.