No abstract

Silver nanowires with adjustable diameters ranging from 20 to 500 nm have been synthesized by introducing certain control agents into the conventional polyol process. These control agents can be classified into three types: inorganic anions, metal cations, and molecules. The as-synthesized nanowires also exhibit size dependent UV-vis absorption spectra, which are meaningful to the fabrication of nanodevices. It is presumed that the control agents could influence the size of the initial nucleus and therefore the diameters of the final nanowires through forming silver salt colloids or varying the rate of silver reduction. This synthetical strategy may also provide a versatile route to prepare nanomaterials with well-defined diameters.

A cobalt-catalyzed asymmetric hydroboration of styrenes using an imidazoline phenyl picoliamide (ImPPA) ligand was first reported to deliver the valuable chiral secondary organoboronates with good functional tolerance and high enantioselectivity (up to >99% ee). This protocol is operationally simple without any activator. Particularly, this method can be applied in the asymmetric hydroboration of allylamine to afford 1,3-amino alcohol, which is a key intermediate for the synthesis of fluoxetine and atomoxetine. Furthermore, control experiments, isotopic labeling experiments, and qualitative and quantitative kinetic studies were also conducted to figure out the primary mechanism.

The polyol process including the introduction of preformed seeds and the inducement of poly(vinyl pyrrolidone) (PVP) has been developed as a powerful approach for synthesizing silver nanowires. Here, silver nanowires without other metal elements as impurities were synthesized through a silver seeding polyol process in a shielding gas atmosphere. It is demonstrated that the first seeding step is critical in obtaining silver nanowires as the principal product, and we also observe that the shielding gas atmosphere not only improves the repeatability of experiments but also affects the morphology of the final product. We obtained nanocubes with hydrogen gas shielding in a short reaction time; these would scarcely appear with argon or air shielding. Our work supplies new evidence to explain the actual growth mechanism of silver nanowires.

A highly Markovnikov-selective, iron-catalyzed hydroboration of styrenes is reported using available oxazolinylphenyl picolinamide as the ligand to afford the branched hydroboration products with up to >50/1 b/l. This reaction is operationally simple and could be carried out in gram scale.