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Foodborne pathogens like Listeria monocytogenes can cause various illnesses and pose a serious threat to public health. They produce species-specific microbial volatile organic compounds, i.e., the biomarkers, making it possible to indirectly measure microbial contamination in foodstuff. Herein, highly ordered mesoporous tungsten oxides with high surface areas and tunable pores have been synthesized and used as sensing materials to achieve an exceptionally sensitive and selective detection of trace Listeria monocytogenes. The mesoporous WO 3 -based chemiresistive sensors exhibit a rapid response, superior sensitivity, and highly selective detection of 3-hydroxy-2-butanone. The chemical mechanism study reveals that acetic acid is the main product generated by the surface catalytic reaction of the biomarker molecule over mesoporous WO 3 . Furthermore, by using the mesoporous WO 3 -based sensors, a rapid bacteria detection was achieved, with a high sensitivity, a linear relationship in a broad range, and a high specificity for Listeria monocytogenes. Such a good gas sensing performance foresees the great potential application of mesoporous WO 3 -based sensors for fast and effective detection of microbial contamination for the safety of food, water safety and public health.

A Ag-mediated C-H/P-H functionalization reaction of arylphosphine oxides with internal alkynes was described for the direct preparation of benzo[b]phosphole oxides with a high yield. An unusual aryl migration on the P-atom derived from a C-P bond cleavage and a new C-P bond formation was also observed and demonstrated to proceed via the radical process.

A series of end-to-end azido-bridged perovskite-type compounds [(CH3)nNH4-n][Mn(N3)3] (n = 1-4) were synthesized and characterized. Structural phase transitions indicating the general lattice flexibility were observed and confirmed by the crystal structures of different phases. These materials show cation-dependent magnetic ordering at up to 92 K and magnetic bistability near room temperature.

With the exploding interest in transition metal chalcogenides, sulfide minerals containing the dianion S2(2-), such as pyrite (FeS2), cattierite (CoS2), and vaesite (NiS2), have recently attracted much attention for potential applications in energy conversion and storage devices. However, the synthesis of the patronite structure (VS4, V(4+)(S2(2-))2) and its applications have not yet been clearly demonstrated because of experimental difficulties and the existence of nonstoichiometric phases. Herein, we report the synthesis of VS4 using a simple, facile hydrothermal method with a graphene oxide (GO) template and the characterization of the resulting material. Tests of various templates such as CNT, pyrene, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), and graphite led us to the conclusion that the graphitic layer plays a role in the nucleation during growth of VS4. Furthermore, the VS4/rGO hybrid was proved to be a promising functional material in energy storage devices.

We report the synthesis of KNbO(3) nanowires (NWs) with a monoclinic phase, a phase not observed in bulk KNbO(3) materials. The monoclinic NWs can be synthesized via a hydrothermal method using metallic Nb as a precursor. The NWs are metastable, and thermal treatment at ∼450 °C changed the monoclinic phase into the orthorhombic phase, which is the most stable phase of KNbO(3) at room temperature. Furthermore, we fabricated energy-harvesting nanogenerators by vertically aligning the NWs on SrTiO(3) substrates. The monoclinic NWs showed significantly better energy conversion characteristics than orthorhombic NWs. Moreover, the frequency-doubling efficiency of the monoclinic NWs was ∼3 times higher than that of orthorhombic NWs. This work may contribute to the synthesis of materials with new crystalline structures and hence improve the properties of the materials for various applications.

Squaraine dyes were loaded inside mesoporous silica nanoparticles, and the nanoparticle surfaces were then wrapped with ultrathin graphene oxide sheets, leading to the formation of a novel hybrid material. The hybrid exhibits remarkable stability and can efficiently protect the loaded dye from nucleophilic attack. The biocompatible hybrid is noncytotoxic and presents significant potential for application in fluorescence imaging in vitro.

A methodology for the design of polar, inorganic structures is demonstrated here with the packing of lambda (Λ)-shaped basic building units (BBUs). Noncentrosymmetric (NCS) solids with interesting physical properties can be created with BBUs that lack an inversion center and are likely to pack into a polar configuration; previous methods to construct these solids have used NCS octahedra as BBUs. Using this methodology to synthesize NCS solids, one must increase the coordination of the NCS octahedra with maintenance of the noncentrosymmetry of the bulk. The first step in this progression from an NCS octahedron to an inorganic NCS solid is the formation of a bimetallic BBU. This step is exemplified with the compound CuVOF(4)(H(2)O)(7): this compound, presented here, crystallizes in an NCS structure with ordered, isolated [Cu(H(2)O)(5)](2+) cations and [VOF(4)(H(2)O)](2-) anions into Λ-shaped, bimetallic BBUs to form CuVOF(4)(H(2)O)(6)·H(2)O, owing to the Jahn-Teller distortion of Cu(2+). Conversely, the centrosymmetric heterotypes with the same formula MVOF(4)(H(2)O)(7) (M(II) = Co, Ni, and Zn) exhibit ordered, isolated [VOF(4)(H(2)O)](2-) and [M(H(2)O)(6)](2+) ionic species in a hydrogen bond network. CuVOF(4)(H(2)O)(7) exhibits a net polar moment while the heterotypes do not; this demonstrates that Λ-shaped BBUs give a greater probability for and, in this case, lead to NCS structures.

Ever since Au nanoparticles were developed as X-ray contrast agents, researchers have actively sought alternative nanoparticle-based imaging probes that are not only inexpensive but also safe for clinical use. Herein, we demonstrate that bioinert tantalum oxide nanoparticles are suitable nanoprobes for high-performance X-ray computed tomography (CT) imaging while simultaneously being cost-effective and meeting the criteria as a biomedical platform. Uniformly sized tantalum oxide nanoparticles were prepared using a microemulsion method, and their surfaces were readily modified using various silane derivatives through simple in situ sol-gel reaction. The silane-modified surface enabled facile immobilization of functional moieties such as polyethylene glycol (PEG) and fluorescent dye. PEG was introduced to endow the nanoparticles with biocompatibility and antifouling activity, whereas immobilized fluorescent dye molecules enabled simultaneous fluorescence imaging as well as X-ray CT imaging. The resulting nanoparticles exhibited remarkable performances in the in vivo X-ray CT angiography and bimodal image-guided lymph node mapping. We also performed an extensive study on in vivo toxicity of tantalum oxide nanoparticles, revealing that the nanoparticles did not affect normal functioning of organs., (© 2011 American Chemical Society)

Short reaction times and morphology control in the synthesis of inorganic materials under nonthermal conditions remain a challenge. Herein we report a rapid, self-templating, and nonthermal method based on ultraviolet light to prepare metal oxide hierarchical structures. With this method, the morphology of the metal oxides was controlled readily without using templates.

A novel metal-organic replica of α-PbO(2) exhibits high capacity for capture of nerve agent surrogate.

Unsymmetrically substituted allenes (1,2-dienes) are inherently chiral and can be prepared in optically pure form. Nonetheless, to date the allene framework has not been incorporated into ligands for asymmetric catalysis. Since allenes project functionality differently than either tetrahedral carbon or chiral biaryls, they may create complementary chiral environments. This study demonstrates that optically active, C(2)-symmetric allene-containing bisphosphine oxides can catalyze the addition of SiCl(4) to meso-epoxides with high enantioselectivity. The epoxide opening likely involves generation of a Lewis acidic, cationic (bisphosphine oxide)SiCl(3) complex. The fact that high asymmetric induction is observed suggests that allenes may represent a new platform for the development of ligands and catalysts for asymmetric synthesis.

Heterostructured nanoparticles composed of metals and Fe3O4 or MnO were synthesized by thermal decomposition of mixtures of metal-oleate complexes (for the oxide component) and metal-oleylamine complexes (for the metal component). The products included flowerlike-shaped nanoparticles of Pt-Fe3O4 and Ni-Fe3O4 and snowmanlike-shaped nanoparticles of Ag-MnO and Au-MnO. Powder X-ray diffraction patterns showed that these nanoparticles were composed of face-centered cubic (fcc)-structured Fe3O4 or MnO and fcc-structured metals. The relaxivity values of the Au-MnO and Au-Fe3O4 nanoparticles were similar to those of the MnO and Fe3O4 nanoparticles, respectively. Au-Fe3O4 heterostructured nanoparticles conjugated with two kinds of 12-base oligonucleotide sequences were able to sense a complementary 24-mer sequence, causing nanoparticle aggregation. This hybridization-mediated aggregation was detected by the overall size increase indicated by dynamic light scattering data, the red shift of the surface plasmon band of the Au component, and the enhancement of the signal intensity of the Fe3O4 component in T2-weighted magnetic resonance imaging.

In this article, we have demonstrated one-step solid-phase transformation from high-quality cadmium carbonate microcrystals into highly nanoporous cadmium oxide. The high crystal quality of cadmium carbonate is critical for the successful fabrication of porous nanoarchitectures with predetermined morphology and well-controlled internal structure. This novel strategy has a good potential to prepare nanoporous materials at a large scale by using perfect monolithic carbonate crystals, and it is also useful to synthesize different nanoporous materials on metal-oxide-coated substrates. Meanwhile, this simple thermal transformation of cadmium carbonate into porous structures has further been extended to convert calcium carbonate into such porous structures.

Control of the size, shape, and structure of mesoporous transition metal oxide materials is important in their correlations with corresponding optoelectronic and photocatalytic properties. Highly ordered cubic phases of mixed-valent mesoporous molybdenum oxides have been prepared by the reduction and decomposition of aqueous molybdenum precursor solution in the presence of poly(ethylene oxide) under ultrasonic irradiation. Large-scale uniform molybdenum oxide particles with well-defined crystal-like morphologies (ball-like, rhombic dodecahedral, and cubic shapes) were synthesized and found to be controllable by modifying the molecular chain length of the polymeric additive. Molybdenum oxides with an average oxidation state of 4.8 form a cubic lattice of open mesoporous structures.

Cryptomelane-type manganese oxide octahedral molecular (OMS) sieve three-dimensional (3D) nanostructures were synthesized via facile temple-free low-temperature hydrothermal reactions. Morphologies of the cryptomelane-type OMS-2 nanoparticles with tunnel dimension of 4.6 x 4.6 A can be tuned by varying reaction temperatures. At low temperature (120 degrees C), OMS-2 dendritic nanoclusters composed of uniform single-crystal nanotetragonal prisms with square cross-sections were formed. At high temperature (180 degrees C), the morphologies of OMS-2 became spherical dandelion-like microspheres composed of uniform single-crystal OMS-2 nanoneedles. Slow oxidation of Mn(2+) by Cr(2)O(7)(-) under hydrothermal conditions is critical for the formation of the hierarchically ordered OMS-2 3D nanostructures.

The 3-alkylidene-3H-indole 1-oxide functional group found in the naturally occurring alkaloid avrainvillamide has been synthesized by a cross coupling-reductive condensation sequence and found to undergo reversible addition of oxygen- and sulfur-based nucleophiles.