Synthesis and characterization of a trigonal bipyramidal supramolecular cage based upon rhodium and platinum metal centers

The reaction of 4-ethynyl-pyridine with tert-butyl lithium followed by its addition to (Me3tacn)RhCl3 affords the facial octahedral complex (Me3tacn)Rh(CCPy)3, condensation of which with the square planar complex cis-(DCPE)Pt(NO3)2 results in a self-assembled trigonal bipyramidal cage with Rh(III) and Pt(II) atoms occupying the vertices.     

Ahornzucker

Ohne Zusammenfassung     

Die Bestimmung der L?vulose im Honig etc.

Ohne Zusammenfassung     

The stereospecific synthesis of spectinomycin

The first synthesis of spectinomycin, a complex and sensitive antibiotic, is described. The synthesis, which requires only four steps from known materials, has flexibility for modifying either half of the molecule.     

Synthesis and optical properties of nanorattles and multiple-walled nanoshells/nanotubes made of metal alloys

The galvanic replacement reaction between silver and chloroauric acid has been exploited as a powerful means for preparing metal nanostructures with hollow interiors. Here, the utility of this approach is further extended to produce complex core/shell nanostructures made of metals by combining the replacement reaction with electroless deposition of silver. We have fabricated nanorattles consisting of Au/Ag alloy cores and Au/Ag alloy shells by starting with Au/Ag alloy colloids as the initial template. We have also prepared multiple-walled nanoshells/nanotubes (or nanoscale Matrioshka) with a variety of shapes, compositions, and structures by controlling the morphology of the template and the precursor salt used in each step of the replacement reaction. There are a number of interesting optical features associated with these new core/shell metal nanostructures. For example, nanorattles made of Au/Ag alloys displayed two well-separated extinction peaks, a feature similar to that of gold or silver nanorods. The peak at approximately 510 nm could be attributed to the Au/Ag alloy cores, while the other peak was associated with the Au/Ag alloy shells and could be continuously tuned in the spectral range from red to near-infrared.     

Polyol synthesis of silver nanostructures: control of product morphology with Fe(II) or Fe(III) species

Adjusting the concentration of Fe(II) or Fe(III) in the polyol reduction of silver nitrate allows for the production of either nanocubes or nanowires. Reduction by ethylene glycol maintained the iron ions in the reduced Fe(II) form, which in turn reacted with and removed adsorbed atomic oxygen from the surface of silver nanoparticles. Relatively high concentrations (2.2 microM) of iron ions facilitated the growth of multiply twinned seeds to form nanowires by removing oxygen from the surface of twinned seeds and preventing their dissolution by oxidative etching. Lower concentrations (<0.44 microM) of iron ions only partially removed oxygen from the surface, resulting in selective etching of twinned seeds and accelerated formation of single-crystal nanocubes. In each case, the addition of chloride prevented rapid aggregation of seeds and facilitated their growth into discrete nanostructures.