Acute Aquatic Toxicity to Zebrafish and Bioaccumulation in Marine Mussels of Antimony Tin Oxide Nanoparticles.

Antimony tin oxide (Sb2O5/SnO2) is effective in the absorption of infrared radiation for applications, such as skylights. As a nanoparticle (NP), it can be incorporated into films or sheets providing infrared radiation attenuation while allowing for a transparent final product. The acute toxicity exerted by commercial Sb2O5/SnO2 (ATO) NPs was studied in adults and embryos of zebrafish (Danio rerio). Our results suggest that these NPs do not induce an acute toxicity in zebrafish, either adults or embryos. However, some sub-lethal parameters were altered: heart rate and spontaneous movements. Finally, the possible bioaccumulation of these NPs in the aquacultured marine mussel Mytilus sp. was studied. A quantitative analysis was performed using single particle inductively coupled plasma mass spectrometry (sp-ICP-MS). The results indicated that, despite being scarce (2.31 × 106 ± 9.05 × 105 NPs/g), there is some accumulation of the ATO NPs in the mussel. In conclusion, commercial ATO NPs seem to be quite innocuous to aquatic organisms; however, the fact that some of the developmental parameters in zebrafish embryos are altered should be considered for further investigation. More in-depth analysis of these NPs transformations in the digestive tract of humans is needed to assess whether their accumulation in mussels presents an actual risk to humans.

Etching suppression as a means to Pt dendritic ultrathin nanosheets by seeded growth.

2D ultrathin metal nanostructures are emerging materials displaying distinct physical and chemical properties compared to their analogues of different dimensionalities. Nanosheets of fcc metals are intriguing, as their crystal structure does not favour a 2D configuration. Thanks to their increased surface-to-volume ratios and the optimal exposure of low-coordinated sites, 2D metal nanostructures can be advantageously exploited in catalysis. Synthesis approaches to ultrathin nanosheets of pure platinum are scarce compared to other noble metals and to Pt-based alloys. Here, we present the selective synthesis of Pt ultrathin nansosheets by a simple seeded-growth method. The most crucial point in our approach is the selective synthesis of Pt seeds comprising planar defects, a main driving force for the 2D growth of metals with fcc structure. Defect engineering is employed here, not in order to disintegrate, but for conserving the defect comprising seeds. This is achieved by in situ elimination of the principal etching agent, chloride, which is present in the PtCl2 precursor. As a result of etching suppression, twinned nuclei, that are selectively formed during the early stage of nucleation, survive and grow to multipods comprising planar defects. Using the twinned multipods as seeds for the subsequent 2D overgrowth of Pt from Pt(acac)2 yields ultrathin dendritic nanosheets, in which the planar defects are conserved. Using phenylacetylene hydrogenation as a model reaction of selective hydrogenation, we compared the performance of Pt nanosheets to that of a commercial Pt/C catalyst. The Pt nanosheets show better stability and much higher selectivity to styrene than the commercial Pt/C catalyst for comparable activity.

Heterogeneous Oxysulfide@Fluoride Core/Shell Nanocrystals for Upconversion-Based Nanothermometry.

Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs) often suffer from weak luminescence, especially when their sizes are ultrasmall (less than 10 nm). Enhancing the upconversion luminescence (UCL) efficiency of ultrasmall UCNPs has remained a challenge that must be undertaken if any practical applications are to be envisaged. Herein, we present a Ln3+-doped oxysulfide@fluoride core/shell heterostructure which shows efficient UCL properties under 980 nm excitation and good stability in solution. Through epitaxial heterogeneous growth, a ∼4 nm optically inert ß-NaYF4 shell was coated onto ∼5 nm ultrasmall Gd2O2S:20%Yb,1%Tm. These Gd2O2S:20%Yb,1%Tm@NaYF4 core/shell UCNPs exhibit a more than 800-fold increase in UCL intensity compared to the unprotected core, a 180-fold increase in luminescence decay time of the 3H4 → 3H6 Tm3+ transition from 5 to 900 µs, and an upconversion quantum yield (UCQY) of 0.76% at an excitation power density of 155 W/cm2. Likewise, Gd2O2S:20%Yb,2%Er@NaYF4 core/shell UCNPs show a nearly 5000-fold increase of their UCL intensity compared to the Gd2O2S:20%Yb,2%Er core and a maximum UCQY of 0.61%. In the Yb/Er core-shell UCNP system, the observed variation of luminescence intensity ratio seems to originate from a change in lattice strain as the temperature is elevated. For nanothermometry applications, the thermal sensitivities based on thermally coupled levels are estimated for both Yb/Tm and Yb/Er doped Gd2O2S@NaYF4 core/shell UCNPs.

Magnetophoresis-Assisted Capillary Assembly: A Versatile Approach for Fabricating Tailored 3D Magnetic Supercrystals.

The fabrication and integration of sub-millimeter magnetic materials into predefined circuits is of major importance for the realization of portable devices designed for telecommunications, automotive, biomedical, and space applications but remains highly challenging. We report here a versatile approach for the fabrication and direct integration of nanostructured magnetic materials of controlled shaped at specific locations onto silicon substrates. The magnetophoresis-assisted capillary assembly of magnetic nanoparticles, either spherical or anisotropic, leads to the fabrication of high-performance Co-based permanent magnets and Fe-based supercrystals. Integrated sub-millimeter magnets as well as millimeter self-standing magnets exhibiting magnetic properties competing with NdFeB-based composites were obtained through this cost- and time-efficient process. The proof-of-concept of electromagnetic actuation of a micro-electromechanical system cantilever by means of these supercrystals highlights their potentiality as efficient integrated magnetic materials within nomadic devices.

Synthesis, Spectroelectrochemical Behavior, and Chiroptical Switching of Tris(ß-diketonato) Complexes of Ruthenium(III), Chromium(III), and Cobalt(III).

Five tris(ß-diketonato) complexes of ruthenium(III), chromium(III), and cobalt(III) [Ru(Buacac)3 (1), Ru(Oacac)3 (2), Cr(Buacac)3 (3), Cr(Oacac)3 (4), and Co(Buacac)3 (5), where Buacac = 3-butylpentane-2,4-dionato and Oacac = 3-octylpentane-2,4-dionato] with a chiral propeller-like structure have been prepared. Ligands and complexes syntheses are presented together with characterization of the compounds by 1H and 13C NMR spectroscopy, mass spectrometry, IR, UV-vis, electronic circular dichroism (ECD) spectroscopy, electrochemistry studies, and first-principles calculations. The crystal structures of 1 and 5 have also been obtained and analyzed. A comparison of the 1H NMR spectra of diamagnetic (ligands and 5) and paramagnetic (1 and 2) species is presented. Optical resolution of the five complexes has been achieved for the first time by supercritical fluid chromatography using a chiral column, giving rise to very high purity grades in all cases. ECD measurements and calculations have led to the assignment of the absolute configuration, Δ or Λ, of each enantiomer for 1-5. Spectroelectrochemical UV-vis and ECD studies have been performed on ruthenium Λ-2 and chromium Λ-4 complexes, revealing their redox-triggered chiroptical switching confirming the noninnocence character of the ß-diketonate ligands.

Simple and economic elaboration of high purity CaCO3 particles for bone graft applications using a spray pyrolysis technique.

Materials for bone grafting are a major health stake today. The existing synthetic materials only partially answer to the requirements for such uses and do not provide a real alternative solution to the classical way consisting of the reuse of natural osseous materials, known to create other problems. In the present work, we have prepared calcium carbonate powders using spray pyrolysis in the perspective to realize ideal and multi-purposed bricks to form bone graft materials, by bottom-up approaches, using classical techniques. The chemical reactions involved in the synthesis process consist in the thermal decomposition of calcium acetate. This precursor, a classical food additive, is known to be non toxic, easy to use and very cheap. Morphological and chemical characterization was conducted on the obtained materials. Depending on the pyrolysis temperature, we observed partial decomposition of calcium acetate or lime formation. An annealing step is consequently required to finalize the transformation. Finally, it appears that annealed products are pure calcite particles, having a spherical morphology and possessing a low dispersity in the micron size range. These particles exhibit an original internal structure, reinforcing and ensuring the preservation of their morphological characteristics during the sintering process. Furthermore, a porosity value compatible with drug carrier capabilities was measured on the obtained products. All these qualities allow us to consider a multi-purpose use of these particles in almost all types of bone graft materials.

Dual Photochemical Bond Cleavage for a Diarylethene-Based Phototrigger Containing both Methanolic and Acetic Sources.

In this paper, we present a novel concept for "smarter" photolabile organic compounds combining not one but two caged functions. As proof of principle, this diarylethene-based compound possesses two inhibited chemical groups (OMe and OAc) and its efficient release in different solvents is reported. In low- to medium-polarity media, both MeOH and AcOH are released, with a slight preferential uncaging of AcOH except in 1,4-dioxane, where MeOH is preferentially released. In contrast, DMSO or DMF render AcOH release strongly dominating. DFT calculations of the corresponding photoreactive conformations not only afford strong support to the observed release of MeOH and AcOH but also qualitatively explain the preferential release of acid in terms of dispersive noncovalent interactions. Finally, mechanistic aspects are discussed on the bases of the spectroscopic observations and of the TD-DFT calculations.

Crystal structure of 3-ethynyl-benzoic acid.

In the title compound, C9H6O2, the carb-oxy-lic acid group is almost in the plane of the benzene ring, making a dihedral angle of 2.49 (18)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming classical acid-acid inversion dimers, with an R 2 (2)(8) ring motif. The dimers are linked by pairs of C-H⋯O hydrogen bonds forming chains, enclosing R 2 (2)(16) ring motifs, propagating along the c-axis direction.

TiC-carbide derived carbon electrolyte adsorption study by ways of X-ray scattering analysis.

Understanding ion adsorption in nanoporous carbon electrodes is of great importance for designing the next-generation of high energy density electrical double-layer capacitors. In this work, X-ray scattering is used for investigating the impregnation of nanoporous carbons with electrolytes in the absence of applied potential. We are able to show that interactions between the carbon surface and electrolytes allow adsorption to take place in sub-nanopores, thus confirming experimentally for the first time the results predicted by molecular dynamic simulations.

Structure of the calcium pyrophosphate monohydrate phase (Ca2P2O7·H2O): towards understanding the dehydration process in calcium pyrophosphate hydrates.

Calcium pyrophosphate hydrate (CPP, Ca(2)P(2)O(7) · nH2O) and calcium orthophosphate compounds (including apatite, octacalcium phosphate etc.) are among the most prevalent pathological calcifications in joints. Even though only two dihydrated forms of CPP (CPPD) have been detected in vivo (monoclinic and triclinic CPPD), investigations of other hydrated forms such as tetrahydrated or amorphous CPP are relevant to a further understanding of the physicochemistry of those phases of biological interest. The synthesis of single crystals of calcium pyrophosphate monohydrate (CPPM; Ca(2)P(2)O(7) · H2O) by diffusion in silica gel at ambient temperature and the structural analysis of this phase are reported in this paper. Complementarily, data from synchrotron X-ray diffraction on a CPPM powder sample have been fitted to the crystal parameters. Finally, the relationship between the resolved structure for the CPPM phase and the structure of the tetrahydrated calcium pyrophosphate ß phase (CPPT-ß) is discussed.

Bis(2-meth-oxy-benzyl-ammonium) di-aqua-bis-(di-hydrogen diphosphato-κ(2) O,O')cobaltate(II) dihydrate.

The title compound, (C8H12NO)2[Co(H2P2O7)2(H2O)2]·2H2O, crystallizes isotypically with its Mn(II) analogue. It consists of alternating layers of organic cations and inorganic complex anions, extending parallel to (100). The complex cobaltate(II) anion exhibits -1 symmetry. Its Co(2+) atom has an octa-hedral coordination sphere, defined by two water mol-ecules in apical positions and two H2P2O7 (2-) ligands in equatorial positions. The cohesion between inorganic and organic layers is accomplished by a set of O-H⋯O and N-H⋯O hydrogen bonds involving the organic cation, the inorganic anion and the remaining lattice water mol-ecules.

Bis(benzyl-ammonium) di-hydrogen diphosphate.

The asymmetric unit of the title salt, 2C6H5CH2NH3 (+)·H2P2O7 (2-), contains two independent benzyl-ammonium cations and a di-hydrogen diphosphate dianion. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the cations and anions, forming a two-dimensional network parallel to (010). Within this network, weak C-H⋯O hydrogen bonds are observed.