Multiple lamellar {111} twins are observed in GaAs, GaP, and InAs nanowires synthesized by supercritical fluid-liquid-solid (SFLS) and solution-liquid-solid (SLS) approaches. All of these nanowires have zinc blende (cubic) crystal structure and grow predominantly in the 〈111〉 direction. The twins bisect the nanowires perpendicular to their growth direction to give them a "bamboo"-like appearance in TEM images. In contrast, Si and Ge nanowires with 〈111〉 growth direction do not exhibit {111} twins, even though this is a common twin plane with relatively low twin energy in diamond cubic Ge and Si. However, Si and Ge nanowires with 〈112〉 growth directions typically have several {111} twins extending down the length of the nanowires. Here, we present a semiquantitative model that explains the observed twinning in III-V and IV nanowires.

Here we report the solution-liquid-solid (SLS) synthesis of silicon (Si) nanowires. Nanowires are grown by trisilane (Si3H8) decomposition in a high boiling solvent, octacosane (C28H58) or squalane (C30H62), in the presence of either Au or Bi nanocrystals. To our knowledge, this is the first report of a colloidal synthetic route carried out in a solvent at atmospheric pressure that provides crystalline Si nanowires in large quantities.

High yields of crystalline Ge nanowires were synthesized for the first time in a conventional solvent of trioctylphosphine by disproportionating GeI2 in the presence of Bi nanoparticle growth seeds at 350 degrees C and atmospheric pressure.

Bismuth (Bi) nanocrystals are used for solution-liquid-solid (SLS) synthesis of crystalline InAs, GaP, GaAs, and InP nanowires at temperatures between 300 and 340°C in trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO), and trioctylamine (TOA). Bi nanocrystals are observed at the nanowire tips, confirming their role as crystallization seeds. The nanowires are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD).

The development of a short and efficient synthesis of a complex 6-azaindole, BMS-663068, is described. Construction of the 6-azaindole core is quickly accomplished starting from a simple pyrrole, via a regioselective Friedel-Crafts acylation, Pictet-Spengler cyclization, and a radical-mediated aromatization. The synthesis leverages an unusual heterocyclic N-oxide α-bromination to functionalize a critical C-H bond, enabling a highly regioselective copper-mediated Ullmann-Goldberg-Buchwald coupling to install a challenging triazole substituent. This strategy resulted in an efficient 11 step linear synthesis of this complex clinical candidate.