Nonhydrolytic sol-gel processes in organic solvents have become very popular for the synthesis of metal oxide NCs. We report an affordable, high-yield, shape-control synthesis of MnO multipod nanocrystals with a quick reaction time. The reaction yields exclusively multipods; two to six pod nanocrystals are synthesized. The mechanism leading to this hierarchical nanostructure is studied in relation with an oriented attachment mechanism; all nanocrystals are found to be single crystals. The study is completed by high-resolution TEM, X-ray powder diffraction, and magnetic measurements.

Giant redox dendrimers were synthesized with ferrocenyl and pentamethylferrocenyl termini up to a theoretical number of 3(9) tethers (seventh generation). Lengthening of the tethers proved to be a reliable strategy to overcome the bulk constraint at the dendrimers periphery. These redox metallodendrimers were characterized by (1)H, (13)C, and (29)Si NMR; MALDI-TOF mass spectrometry (for the low generations); elemental analysis; UV-vis spectroscopy; dynamic light scattering (DLS); atomic force microscopy (AFM); electron-force microscopy (EFM) for half- or fully oxidized dendrimers; cyclic voltammetry; and coulometry. UV-vis spectroscopy, coulometry, and analytical data are consistent with an increasing amount of defects as the generation number increases, with this amount remaining relatively weak up to G(5). AFM shows that the dendrimers form aggregates of discrete size on the mica surface, recalling the agglomeration of metal atoms in monodisperse nanoparticles. Cyclic voltammetry reveals full chemical and electrochemical reversibility up to G(7), showing that electron transfer is fast among the flexible peripheral redox sites. Indeed, the redox stability of these new electrochromic dendrimers, i.e., a battery behavior, was established by complete chemical oxido-reduction cycles, and the blue 17-electron ferrocenium and deep-green mixed-valence Fe(III)/Fe(II) dendritic complexes were isolated and characterized. AFM studies also show the reversible dendrimer size changes from upon redox switching between Fe(II) and Fe(III), suggesting a breathing mechanism controlled by the redox potential. Considerable adsorption of high-generation dendrimers on Pt electrodes such as G(7)-Fc allows the easy formation of modified electrodes that sense the ATP anion only involving the electrostatic factor even in the absence of any other type of interaction with the redox tethers.

The reinforcement of a styrene‐butadiene rubber (SBR) by single fillers—carbon black (CB) or multiwall carbon nanotubes (MWNTs)—or by mixtures of CB and MWNTs, is investigated. The morphologies, mechanical and electrical properties of the composites, are analyzed. A significant improvement in the tensile properties is observed for samples containing a dual phase. Using atomic force (AFM) and transmission electron (TEM) microscopies, we demonstrate that the double loading improves the dispersion of the nanotubes in SBR. Electrical measurements show lower resistivity and a lower percolation threshhold for composites containing blends of fillers, which provides further evidence of better dispersion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 46: 1939–1951, 2008

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diamine yields deep-red rods which have been shown to be (crypt-K+)6Ge92-Geg4--2.5en by x-ray crystallography. The com-pound crystallizes in the PI space group with Z = 2 and a = 20.037 (2) K,b = 28.944 (2) Á, c = 14.546 (2) Á, a = 99.356 (8)°, ß = 94.077 (8)°, and y = 87.60 (1)°, V = 8312.9 (12) Á3 at 25 °C. Diffraction data were measured over four octants using a four-circle automated diffractometer and monochromatized Mo Ka radiation, and the structure was solved by direct methods and Fourier techniques. The 190 independent (nonhydrogen) atoms in the structure yielded, with anisotropic thermal parameters for germanium and potassium, R = 0.149 and Rw = 0.169 for 8409 independent observed reflections with 2 <50°. Charges on the two Geg cluster ions were assigned according to their relationship to the isoelectronic Sng4-(C4v) and BgHg2-(¿>3*). The Geg4-ion configuration is quite close to the ideal C4l,.2 with a nearly square base (3.58 and 3.64 Á diagonals and a vicinal dihedral angle & 5.3°) and 162 and 156°for the characteristic opposed faces parallel to the fourfold axis (158°i n Sng4-). The Geg2-ion exhibits essentially Civ symmetry but clearly derives from the 3/, limit, with 2.81, 2.86, and 3.17 Á for the parallel edges of the trigonal prism, 171°for the opposed faces therein, and capping atoms separated by 4.00, 4.16, and 4.22 Á. Atomization energies from SCF-MO-CNDO calculations support the charge assignment deduced geometrically, the differentiation of configurations arising almost entirely from the Geg2-ion. The observed distortion of this ion may relate to the generation of a small dipole moment. The configurational contrast between the highly polar Sng4-and Geg4-(C 4i,) and the isoelectronic but a polar Big5+ (£>3 ) is considered further.The extensive electrochemical studies of Zintl and co-workers3"6 on solutions of alkali metal alloys of posttransition elements in liquid NH3 served to identify such homopolyatomic anions as Pbg4-, Pby4-, Sng4-, Sb33-, Sb?3-, and Bis3-. In general the evaporation of ammonia from these solutions gave 1 °scan) in the four octants HKL, HKL, HKL, HKL using molybdenum radiation monochromatized with a graphite crystal (X 0.70954 Á). The reflection data were recorded in two stages, first for 7173 reflections in the range 0°<29 <30°and later, when the structure appeared solvable, for 9125 reflections with 30°<29 <50°, each group covering all four octants. During data collection the intensities of three standard reflections were checked after every 75 reflections, and these Cisar / Nonagermanide(2-j and Nonagermanide(4-) Ions Belin, Corbett,

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Multiwall carbon nanotubes were dispersed in a styrene-butadiene copolymer. The effect of nanotube concentration on the tensile characteristics of the composites was examined. Electrical properties carried out under uniaxial extension show an increase in resistivity upon gradual stretching. A second stretch performed after total release of the stress was shown to lead to a flat response in resistivity. Atomic force microscopy was used to examine orientational effects and changes in filler structure occurring upon application of an uniaxial deformation.