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A new oxyiminopyrazole-based ytterbium chelate enables NIR emission upon UV excitation in colorless single layer luminescent solar concentrators for building integrated photovoltaics., (This journal is © the Owner Societies 2012)

We describe two synthesis approaches to colloidal Cu(3)P nanocrystals using trioctylphosphine (TOP) as phosphorus precursor. One approach is based on the homogeneous nucleation of small Cu(3)P nanocrystals with hexagonal plate-like morphology and with sizes that can be tuned from 5 to 50 nm depending on the reaction time. In the other approach, metallic Cu nanocrystals are nucleated first and then they are progressively phosphorized to Cu(3)P. In this case, intermediate Janus-like dimeric nanoparticles can be isolated, which are made of two domains of different materials, Cu and Cu(3)P, sharing a flat epitaxial interface. The Janus-like nanoparticles can be transformed back to single-crystalline copper particles if they are annealed at high temperature under high vacuum conditions, which makes them an interesting source of phosphorus. The features of the Cu-Cu(3)P Janus-like nanoparticles are compared with those of the striped microstructure discovered more than two decades ago in the rapidly quenched Cu-Cu(3)P eutectic of the Cu-P alloy, suggesting that other alloy/eutectic systems that display similar behavior might give origin to nanostructures with flat, epitaxial interface between domains of two diverse materials. Finally, the electrochemical properties of the copper phosphide plates are studied, and they are found to be capable of undergoing lithiation/delithiation through a displacement reaction, while the Janus-like Cu-Cu(3)P particles do not display an electrochemical behavior that would make them suitable for applications in batteries., (© 2011 American Chemical Society)

Blends of chlorinated polyethylene and nylon-6/-6,6/-12 terpolyamide were prepared. The ratio of the two components was systematically varied within the blends. The mechanical behavior of the samples was analyzed with tensile tests and dynamical mechanical analysis showing that, for several ratios, materials with improved mechanical properties typical of thermoplastic elastomers were obtained. In such a mechanical regime, a co-continuous phase-separated morphology was clearly evidenced at the microscopic scale by 3D laser scanning confocal fluorescent microscopy (LSCFM). At blend compositions where plastic tensile behavior is observed, LSCFM reveals dispersed spheres of one component in the other., (Copyright © 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.)

A porous single-crystal collects xenon atoms from the gas phase and orients them macroscopically, as highlighted by hyperpolarized xenon NMR.

Controlled morphogenesis and shape replication are challenges for several rapidly developing fields of materials science. Indeed, although complex forms have been generated by the condensation of inorganic matter in organized media, the shaping of plastic matter on the micrometre scale is still limited to simple forms that are typically obtained as inverse replicas of channel-like cavities and colloidal crystals. Here we report the fabrication of individual plastic micro-objects that follow an elaborate design and are faithful copies of nanoporous inorganic morphotypes. The direct replica method produces an unprecedented library of curved geometrical solids made of plastics, such as cones, bicones, hollow cylinders, rings, test tubes, clubs and vases. The shape retention of the original structures on the microscale and the creation of a new nanostructure produced objects with homogeneous nanopores of 7 nm and cylindrical microcavities as large as 1 microm. This strategy of shape transcription from one material to another opens new perspectives in microfabrication, separation, anchorage and storage of chemical and biological species. Until now it has not been possible to realize such transformations.

Interlayer nanoporosity of hectorite pillared by tetraethylammonium ions is explored by hyperpolarized xenon NMR and relevant gases such as carbon dioxide revealing the adsorption capacity of the open galleries.

The mobility of a series of linear alkanes in their inclusion compound with tris(o-phenylenedioxy)spirotriphosphazene is studied by high-resolution carbon-proton magic-angle spinning solid-state NMR spectroscopy. Two different carbon-proton dipolar recoupling experiments are compared with respect to their ability to yield precise site-specific, motion-averaged dipolar coupling constants. The most accurate results are obtained by analysis of extrema positions in Lee-Goldburg cross-polarization build-up curves. We present a comprehensive collection of coupling constants, which evidence a rotational motion of the all-trans chains around the channel axis, with some further averaging due to additional fluctuations, as previously found for alkanes in other host matrices such as urea. The order parameter increases toward the inner parts of the chains, and is largely independent of chain length. Notably, chains in a TPP host are not more ordered than in urea, even though the average TPP channel diameter is reported to be smaller. Significantly decreased order is found for highly filled short-alkane samples, which is interpreted in terms of an increased rate of mutual collisions. From residual dipolar couplings as well as carbon chemical shifts, we derive similar amounts of gauche conformers. Translational motions along the channels are further studied by proton double-quantum spectroscopy, which probes guest-host dipolar couplings. The extent of local-scale lateral motion is again correlated with the sample filling, and is a weak function of temperature, as expected from a case in which highly restricted single-file diffusion should dominate the mobility. Characteristic effects of sample aging are apparent in all our experiments.

Two oligothiophenes, 4,4'-dipentoxy-2,2'-dithiophene and 4,4"-dipentoxy-2,2':5',2":5",2' ''-tetrathiophene, have been included in the nanochannels of the autoassembling host TPP (tris-o-phenylenedioxycyclotriphosphazene). The effect of the confinement on the structure and properties of the two dyes, as conformational arrangements, dynamics, and photophysical behavior, was addressed by the combination of high spinning speed solid-state NMR and time-resolved EPR spectroscopy. We compared the conformations of the dyes in their ground and photoexcited triplet states and described in detail the dynamics of the supramolecular adducts from 4 K to room temperature. Above 200 K surprisingly fast spinning rates of the dithiophene core were discovered, while the side chains show far slower reorientation motion, being in bulky gauche-rich conformations. These lateral plugs keep the planar core as appended in the space like a nanoscale gyroscope, allowing a reorientation in the motion regime of liquids and a long triplet lifetime at unusually high temperature. The nuclear magnetic properties of the guest dyes are also largely affected by the aromatic rings of the neighboring host, imparting an impressive magnetic susceptibility effect (2 ppm proton shift). The high mobility is due to the formation of a nanocage in a channel where aliphatic and aromatic functions isolate the thiophene moieties. Instead, two conformers of the tetrathiophene twisted on the central bond are stabilized by interaction with the host. They interconvert fast enough to be averaged in the NMR time scale.

Advanced 2D solid state NMR techniques reveal weak intermolecular interactions that cooperatively sustain nanostructures of high molecular mass aliphatic polymers entrapped as guests in channels formed by an aromatic host.

Ethanol associates easily with MgCl(2) to form adducts of complex architecture, but until now available characterization methods have failed to identify the pure stoichiometric compounds and their structures. To remedy this, we set about applying homonuclear and heteronuclear 2D correlated solid-state NMR spectroscopy to identify the pure compounds and the ethanol-to-magnesium coordination pattern. High spinning speed and Lee-Goldburg sequences were able to reduce the hydrogen spin-diffusion and homonuclear coupling in the crystalline solid, thus achieving high resolution also in the hydrogen domain. On this basis, the pure adducts, of interest as catalyst supports for Ziegler-Natta polymerization, were isolated for the first time. Magnesium coordination sites with given numbers of ligands and their multiplicity in the crystal cells were determined in the new-found stoichiometric complexes. Variable temperature and 2D carbon-carbon exchange NMR, as well as relaxation times in the fast motion regime, revealed the disordering phenomena generated by ethanol dynamics in the crystal. Decoding the intriguing polymorphism of the precursors permits to trace the genealogy of tailored MgCl(2) titanate granules, active as highly productive catalysts for the stereospecific polymerization of olefins.