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Iron oxide magnetic nanoparticles produced by chemical synthesis are usually composed of both magnetite and maghemite phases. Information about the phase composition is typically obtained using Mos...

Organized three-dimensional (3D) nanomaterial architectures are promising candidates for applications in optoelectronics, catalysis, or theranostics owing to their anisotropy and advanced structural features that allow tailoring their physical and chemical properties. The synthesis of such complex but well-organized nanomaterials is difficult because the interplay of interfacial strain and facet-specific reactivity must be considered. Especially the magnetic anisotropy with controlled size and morphology plays a decisive role for applications like magnetic resonance imaging (MRI) and advanced data storage. We present a solution phase seed mediated synthesis of colloidal, well dispersible iron oxide superparticles with flower- and hedgehog-like morphology starting from dispersible spherical maghemite (SPH) and nanoplate hematite (HEX) templates. In the superparticles the templates are epitaxially decorated with nanodomains and nanorods as shown by (high-resolution) transmission electron microscopy (TEM), o...

The effect of surface functionalization on the structural and magnetic properties of catechol-functionalized iron oxide magnetic (γ-Fe2O3) nanocrystals was investigated. γ-Fe2O3 nanocrystals (NCs) were synthesized from iron acetyl acetonate in phenyl ether with 1,2-tetradecanediol, oleic acid, and oleylamine. X-ray powder diffraction in combination with Mossbauer spectroscopy revealed the presence of γ-Fe2O3 (maghemite) particles only. Replacement of oleic acid (OA) with catechol-type 3,4-dihydroxyhydrocinnamic acid (DHCA) or polydentate polydopamine acrylate (PDAm) surface ligands leads to a pronounced change of the magnetic behavior of the γ-Fe2O3 nanocrystals and separated them into two distinctive magnetic entities. XPS and Mossbauer spectroscopy revealed the shell to be reduced with a magnetite (Fe3O4) contribution of up to 33% of the total mass while the core remained maghemite (γ-Fe2O3). The magnetic interaction between the maghemite core and the magnetite shell strongly reduced the anisotropy constant of the nanocrystals and the effective magnetization. Our experiments show that the surface chemistry strongly affects the phase distribution and the macroscopic magnetic properties of iron oxide nanopowders.

Multicomponent nanostructures containing purely organic or inorganic as well as hybrid organic–inorganic components connected through a solid interface are, unlike conventional spherical particles, able to combine different or even incompatible properties within a single entity. They are multifunctional and resemble molecular amphiphiles, like surfactants or block copolymers, which makes them attractive for the self-assembly of complex structures, drug delivery, bioimaging, or catalysis. We have synthesized Pd@FexO heterodimer nanoparticles (NPs) to fabricate a macroporous, hydrophobic, magnetically active, three-dimensional (3D), and template-free hybrid foam capable of repeatedly separating oil contaminants from water. The Pd domains in the Pd@FexO heterodimers act as nanocatalysts for the hydrosilylation of polyhydrosiloxane and tetravinylsilane, while the FexO component confers magnetic properties to the final functional material. Pd@FexO heterodimers were synthesized by heterogeneous nucleation and g...

Compared to conventional deposition techniques for the epitaxial growth of metal oxide structures on a bulk metal substrate, wet-chemical synthesis based on a dispersible template offers advantages such as low cost, high throughput, and the capability to prepare metal/metal oxide nanostructures with controllable size and morphology. However, the synthesis of such organized multicomponent architectures is difficult because the size and morphology of the components are dictated by the interplay of interfacial strain and facet-specific reactivity. Here we show that solution-processable two-dimensional Pd nanotetrahedra and nanoplates can be used to direct the epitaxial growth of γ-Fe2O3 nanorods. The interfacial strain at the Pd−γ-Fe2O3 interface is minimized by the formation of an FexPd “buffer phase” facilitating the growth of the nanorods. The γ-Fe2O3 nanorods show a (111) orientation on the Pd(111) surface. Importantly, the Pd@γ-Fe2O3 hybrid nanomaterials exhibit enhanced peroxidase activity compared to ...

Single crystals of several ternary alkali uranium fluorides, LiUF5, KU2F9, K7U6F31, RbUF5, RbU2F9, and RbU3F13, have been obtained in a mild hydrothermal process using UO2(CH3CO2)2(H2O)2 as the uranium source. Their crystal structures were determined by single crystal X-ray diffraction. The uranium in the starting reagent was successfully reduced from U6+ to U4+ in a dilute hydrofluoric acid environment, aided by the presence of a copper salt. All materials exhibit highly complex crystal structures that range from two-dimensional to three-dimensional. The U4+ cations are found in high (UF8 and UF9) coordination environments. The magnetic susceptibility measurements yielded effective magnetic moments of 3.01–3.83 μB for the U4+ cations. The temperature dependent magnetic susceptibility measurements confirmed that the U4+ cation exhibits a nonmagnetic singlet ground state at low temperatures. No long-range magnetic order was observed for any of the above compositions down to 2 K. Optical and thermal behavio...

A series of layered divalent metal formate compounds, [M(HCOO)2(HCONH2)2] (M = Mn (1Mn), Ni (2Ni), Cu(3Cu), Zn(4Zn), Mg(5Mg)), have been prepared by solvothermal synthesis and their room temperature (RT) and low-temperature (LT) crystal structures, and thermal and magnetic properties determined. All the compounds contain octahedral metal ions connected by four anti-anti formato ligands to form (4,4) nets with the composition of M(HCOO)2. The oxygen atoms from two coordinating formamide ligands above and below the layer complete the MO6 distorted octahedral coordination. Order-disorder phase transformations involving the formamide ligands were observed in the 1Mn, 2Ni, and 4Zn compounds. Like transitions in related formate structures with perovskite like topology, the transitions correspond to the ordering of the amine groups of the terminating formamide ligands which are disordered at ambient temperature. The magnetic properties of the three magnetic members of the series 1Mn, 2Ni, and 3Cu were investigated using microcrystalline samples, over the temperature range of 2 K-300 K under different applied fields. All compounds belong to antiferromagnetic square lattices with S = 5/2, 1, and 1/2. Exchange constants for a nearest neighbor model are presented here. Specific heat measurements indicate magnetic long-range order at lower temperatures, S = 5/2 (antiferromagnetic) and S = 1 (ferrimagnetic).

Na5[FeO3][OH] has been obtained from a redox reaction between iron metal and CdO in the presence of Na2O and NaOH at 450 °C (5 d) as red crystals. The structure has been determined from single crystal data (Pnma, Z = 8, a = 990.94(7) pm, b = 1016.41(7) pm, c = 1185.35(8) pm, wR2 = 0.050) and evaluated by MAPLE calculations. In addition, we present experimental single-crystal IR and Raman spectroscopic data to discuss aspects of the isolated [FeO3]4– complexes and non-coordinating hydroxide in comparison with the respective cobalt compounds. Additional ab-initio lattice dynamic calculations are included for comparison.

An alternative copper halide-free route to obtain highly reactive trifluoromethylcopper species has been developed via the reaction of silver fluoride and trimethyl(trifluoromethyl)silane followed by a redox transmetallation with elemental copper. The composition of the reactive intermediate was investigated by means of UV/Vis/NIR, ESR, 19F NMR spectroscopy and ESI mass spectrometry. “Trifluoromethylcopper” prepared by the oxidative transmetallation route exhibits excellent reactivity and selectivity in substitutions of iodine or bromine bond to aromatic or heterocyclic compounds for trifluoromethyl groups without any additional catalyst.

Dark red single crystals of AgCuVO4 were obtained from hydroxide fluxes in Ag-containers at 430 °C. According to X-ray diffraction data AgCuVO4 crystallizes in the orthorhombic space group Pnma (Z = 4, a = 925.5(1) pm, b = 677.8(1) pm, c = 540.1(1) pm, wR2 = 0.0753). The Pearson code (oP28) and Wyckoff sequence (dc4a) indicate that AgCuVO4 is related to the olivine-type of structure, but the first coordination sphere of AgI and CuII differ significantly from the C.N. 6 with irregular square-pyramidal [AgO5] polyhedra and distorted square-planar [CuO4] units. These differences in crystal chemistry are discussed and MAPLE as well as ECoN values are given.

Synthesis and Crystal Structure of Na10[M3O6][MO3] (M = Fe, Mn) with a Remark on the Magnetic Properties Single crystals of Na10[M3O6][MO3] (M = Mn, Fe) may be obtained via a redox reaction of CdO with the respective transition metal in the presence of Na2O and a flux as red single crystals, which are sensitive to moisture. The crystal structure (determined from IPDS data, , Z = 6) contains isolated trigonal aplanar [MO3] units and layers of [MO4] tetrahedra connected via corners to three-membered rings, which share common edges resulting in the formation of twelve-membered rings. The statistical occupancy of 21 out of 60 sodium atoms per unit cell is discussed and calculations of the Madelung Part of the Lattice Energy (MAPLE) are given. Furthermore, we report on the magnetic properties of Na10[Mn3O6][MnO3] in close relation to the structural entities.

Because dietary intake is supposed to be an important route of human exposure we quantified the dietary intake of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS), perfluorohexanoate (PFHxA), and perfluorooctane sulfonamide (PFOSA) using 214 duplicate diet samples. The study was carried out with a study population of 15 female and 16 male healthy subjects aged 16-45 years. The participants collected daily duplicate diet samples over seven consecutive days in 2005. Duplicate samples were homogenized and their ultrasonic extracts were cleaned up by SPE and subjected to HPLC-ESI-MS/MS. In addition, individual intakes were estimated based on blood levels of PFOS and PFOA using a pharmacokinetic model. Blood samples were collected once during the sampling period. The median (90th percentile) daily dietary intake of PFOS and PFOA was 1.4 ng/kg b.w. (3.8 ng/kg b.w.) and 2.9 ng/kg b.w. (8.4 ng/kg b.w.), respectively. PFHxS and PFHxA could be detected only in some samples above detection limit with median (maximum) daily intakes of 2.0 ng/kg b.w. (4.0 ng/kg b.w.) and 4.3 ng/kg b.w. (9.2 ng/kg b.w.), respectively. Because PFOSA could not be detected above the limit of detection of 0.2 ng/g f.w. this indirect route of exposure seems to be of less significance. Overall, the results of this study demonstrate that the German population is exposed to PFOS and PFOA, but the median dietary intake did not reach the recommended tolerable daily intake by far. Biomonitoring data predict an exposure in a comparable range, We suppose that, normally, food intake is the main source of exposure of the general population to PFOS and PFOA.

Rb5[SiO4][OH] crystallizes in the monoclinc space group C2/m with a = 737.3(1) pm, b = 1073.7(2) pm, c = 1207.2(2) pm, β = 106.07(2)° and Z = 4 (single crystal data; R1= 0.0681 all data). Layers of edge-connected distorted trigonal prismatic [(OH)Rb6] entities and isolated tetrahedral [SiO4] units present the main structural features of this unprecedented structure type.

The aim of this research report is to give an introduction to a specific solid state reaction applied in the field of alkali metal rich transition metal compounds. The approach is an explorative investigation of the oxidation of transition metals with CdO in the presence of alkali metal oxides and / or compounds with complex anions such as Na2SO4. Thereby, a range of unusual compounds have been obtained and structurally characterized. In particular, low valences and uncommon coordination numbers (C.N.) of the late 3d transition metals, as well as interesting varieties in the anionic part of the structures are accessible. The presented examples were selected mainly in order of their inherent aspects concerning the reactivity, structural features or electronic structures.

The new compound Rb 2 CdSiO 4 has been synthesized from Rb 2 CdO 2 and SiO 2 in the presence of excess Rb 2 O (typical molar ratio 1:1:2) under Ar atmosphere in a sealed Ag container at 330°C (40d). The twinned structure has been refined from X-ray single crystal data. Rb 2 CdSiO 4 was found to crystallize in the space group C 222 1 (No. 20) with a =1142.6(2) pm, b =1102.3(1) pm, c =1672.5(2) pm. The lattice constants were refined from X-ray powder data. The crystal structure can be described as a stuffed derivative of the α -cristobalite modification of SiO 2 .

Die neuen ternaren gemischtvalenten Bromide und Iodide des Dysprosiums und Thuliums Rb5Dy3Br12, Rb5Tm3Br12, K5Dy3I12, K5Tm3I12, Rb5Dy3I12 und Rb5Tm3I12 wurden durch metallothermische Reduktion von DyBr3, TmBr3, DyI3 bzw. TmI3 mit Kalium bzw. Rubidium in Gegenwart der entsprechenden Alkalihalogenide in verschweisten Niobampullen erhalten. Die Kristallstruktur wurde am Beispiel von K5Dy3I12 bestimmt (hexagonal, P 6 2m, Z = 1; a = 1446,7(2); c = 473,3(1) pm): Es liegen DyI6-Oktaeder vor, die uber transstandige Kanten zu Ketten verknupft werden. Magnetische Untersuchungen an rontgenreinen Proben zeigen bei hoheren Temperaturen Curie-Weiss-Verhalten, bei tiefen Temperaturen treten antiferromagnetische Kopplungen auf. New Mixed-Valence Ternary Bromides and Iodides of Dysprosium and Thulium of the Type A5M3X12 The new ternary mixed-valence bromides and iodides of dysprosium and thulium Rb5Dy3Br12, Rb5Tm3Br12, K5Dy3I12, K5Tm3I12, Rb5Dy3I12 and Rb5Tm3I12 were obtained by metallothermic reduction of DyBr3, TmBr3, DyI3 and TmI3, respectively, with potassium and rubidium in the presence of the respective alkali metal halides in sealed niobium containers. The crystal structure was determined for the example of K5Dy3I12 (hexagonal, P 6 2m, Z = 1; a = 1446.7(2), c = 473.3(1) pm): DyI6 octahedra are connected via common trans edges to chains. Magnetic measurements on X-ray pure samples show Curie-Weiss behaviour at sufficiently high temperatures. Antiferromagnetic coupling occurs at low temperatures.

Rb[NaCd3O4] presents, to the best of our knowledge, the first example of a 4d transition metal oxide in this A[(MO)4] structure type. The structure consists of a three-dimensional network of edge- and corner-linked distorted tetra­hedral [MO4] entities, with M = Na+ and Cd2+ in a 1:3 ratio sharing a common site set on Wyckoff position 8h in space group I4/m. The large cavities are occupied by A = Rb+ in an almost cubic coordination (4/m symmetry), giving rise to one-dimensional chains of face-sharing [RbO8] polyhedra along [001].

Rb7[SiO4][VO4]: an Ortho-Silicate-Vanadate(V) Rb7[SiO4][VO4] has been obtained from a redox reaction between CdO and vanadium metal in the presence of Rb2O and SiO2 at 600 °C in an Ag container as yellow-greenish transparent single crystals. The crystal structure determination (IPDS data: P21/c, a = 637.6(1) pm, b = 1039.7(1) pm, c = 2076.8(4) pm, β = 93.21(2)°, Z = 4, wR2 = 0.1319) reveals the presence of isolated complex anions, [SiO4]4— and [VO4]3—.

Synthesis of Na3FeO3, a Ternary Oxoferrate(III) with a Chain Structure Na3FeO3 has been obtained from a redox reaction between CdO and iron metal in the presence of Na2O and Na2CO3 at 650 °C as amber colored transparent single crystals. The crystal structure determination (IPDS data: P21/n, a = 579.9(1) pm, b = 1265.9(2) pm, c = 582.8(1) pm, β = 116.02(2)°, Z = 4, Rall = 0.0576) reveals the presence of [FeO2O2/2] zig-zag-chains.

A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0, Comment: 4 pages, 7 figures, + supporting information

(NMe4)2[Re3Br11(H2O)] [Re3Br9(H2O)3](H2O)2 kristallisiert aus einer bromwasserstoffsauren Losung von Re3Br9 · 2 H2O und NMe4Br als dunkel-rotbraune Einkristalle bei 0 – 5°C aus. Die Kristallstruktur wurde aus Vierkreis-Diffraktometerdaten bestimmt: monoklin; P21/m (Nr. 11); a = 967,9(3); b = 1 529,7(4); c = 1 710,9(4) pm; β = 91,66(2)°; Z = 2; R = 0,113; Rw = 0,068. In der Struktur liegen zwei unterschiedliche Clustereinheiten vor: Eine anionische, isolierte Baueinheit, [Re3Br11(H2O)]2−, sowie eine neutrale uber Kristallwasser zu Strangen gemas {[Re3Br9(H2O)3](H2O)2} verknupfte Einheit. Crystal Structure of (NMe4)2[Re3Br11(H2O)] [Re3Br9(H2O)3](H2O)2. (NMe4)2[Re3Br11(H2O)] [Re3Br9(H2O)3](H2O)2 crystallizes from hydrobromic acid solution of Re3Br9 · 2 H2O and NMe4Br at 0 – 5°C. The crystal structure (monoclinic; P21/m (Nr. 11); a = 967.9(3); b = 1 529.7(4); c = 1 710.9(4) pm; β = 91.66(2)°; Z = 2; R = 0.113; Rw = 0.068) has been determined from four-circle diffractometer data. The structure contains two different cluster units of trivalent rhenium, isolated anionic [Re3Br11(H2O)]2− units and neutral cluster units that are connected through crystal water molecules to chains{[Re3Br9(H2O)3](H2O)2}.

Simultaneous thermal analysis-mass spectrometry and time resolved X-ray powder diffraction of the thermal behaviour of such platinum-group-metal complexes as (NH 4 [PtCl 6 ], [Pd(NH 3 ) 2 Cl 2 ] or (NH 4 )3[RhCl 6 ](H 2 O), and preparative procedures, clearly reveal that the initial step to produce finely divided metal powder must be the internal redox reaction between the N 3− of the ammonium ion/ammine ligand and the noble-metal ion (M n+ ; n = 2, 3, 4). It is certainly not the decomposition to binary components followed by their decomposition to the elements or reaction to oxides as has been reported quite recently.

Thermal decomposition of the ammonium hexachlorometalates (NH4)2[MCl6] (M ≡ Pd, Re, Os, Ir, Pt), (NH4)3[RhCl6 · H2O (NH4)4[Ru2Cl10O] was investigated by means of thermogravimetry, differential thermal analysis, mass spectrometry and X-ray diffraction dependent upon temperature. All ammonium compounds produce, finally, finely divided metal powders. Nitrogen and hydrogen chloride, are released as gases attesting to the internal redox reaction M 4+ (M 3+ ) + N 3− → N 2 ±0 + M ±0 which takes place in all cases at temperatures between 300 and 450 °C depending upon the heating rates and the element M. For M ≡ Rh and Pd, stable intermediates could be detected, namely (NH4)2[Rh(NH3)Cl5] and (NH4)2[PdCl4].

The thermal decomposition of di-ammonium hexachloroplatinate ((NH4)2[PtCI6]) to metallic platinum has been investigated by time-resolved in situ XAS measurements at the CI Kand Pt Lmedge. Spectra at the CI K-edge were recorded utilizing an energy dispersive monochromator (EDM), while the Pt Lm-edge spectra were recorded using a double crystal monochromator. By analysing the energy shift of the CI K-edge a reaction intermediate has been observed at about 310°C. Fingerprinting arguments indicate that this intermediate could be cis-platin or some other platinum amine complex.

Na5[VO4][O] and Na4[VO4][OH] were obtained from reactions of V2O5 with Na2O and additional NaOH in the latter case, respectively, at 600-700 °C in sealed Ag containers under Ar atmosphere. The crystal structures have been determined from X-ray single crystal data. The structures contain isolated [VO4]3− complexes and non-coordinating oxide and hydroxide anions, respectively. Raman and infrared data is compared for both compounds and hydrogen bonding is discussed for Na4[VO4][OH].

Dimanganese(II) hydroxide vanadate was obtained from hydrothermal reactions. The crystal structure of the title compound is isotypic with that of Zn2(OH)[VO4]. Three crystallographically independent Mn2+ions are present, one (site symmetry .m.) with a distorted trigonal-bipyramidal and two (site symmetries .m. and 1) with distorted octahedral coordination spheres. These polyhedra are linked through common edges, forming a corrugated layer-type of structure extending parallel to (100). A three-dimensional framework resultsviaadditional Mn—O—V—O—Mn connectivities involving the two different tetrahedral [VO4] units (each with point-group symmetry .m.). O—H...O hydrogen bonds (one bifurcated) between the OH functions (both with point-group symmetry .m.) and the [VO4] units complete this arrangement.

Rb2NaMnO4 has been obtained from a redox reaction in silver crucibles. The crystal structure contains isolated [MnO4] units, which are slightly distorted from ideal tetra­hedral symmetry. Rb2NaMnO4 crystallizes isotypic with Cs2NaVO4 and Cs2NaAsO4.

Cs4K2CuSi2O8: Synthesis, Crystal Structure, UV-Vis-IR Data Cs4K2CuSi2O8 may be obtained via a redox reaction of KCuO2 in the presence of Cs2O and SiO2 with the container material (Cu) at 450 °C as blue single crystals which are sensitive to moisture. Powder samples were obtained by annealing intimate mixtures of the binary oxides under an inert gas atmosphere (Ar) in sealed Ag containers at 500 °C. The crystal structure contains isolated trimeric anions of [O2SiO2CuO2SiO2]6–. Cu2+ in square-planar coordination share trans-edges with [SiO4] tetrahedra. Spectroscopic investigations focus on the bonding situation of the [CuO4] unit (AOM) and characteristic vibrational modes of the silicate.

In the crystal structure of [NdCl(NO3)2(tetraglyme)] (triclinic, P1, Z = 2, a = 7.814(1); b = 7.9832(9); c = 15.322(2) A; α = 87.38(1); β = 84.88(1); γ = 79.83(1)°), neodymium is ten coordinate with two transoid chelating nitrate ligands, a chlorine and the five oxygen atoms of the tetraglyme ligand in an irregular array.

Crystal Structure and Absorptionspectrum of Cs4CuSi2O7, EPR Spectra of K6CuSi2O8 and A4CuSi2O7 (A = Rb, Cs), a Comparison with Egyptian Blue, CaCuSi4O10 Cs4CuSi2O7 is obtained by annealing intimate mixtures of Cs2O, CuO and SiO2 in sealed Ag containers at 500 °C as a greenish-blue powder which is sensitive to moisture. The crystal structure (triclinic, P1) contains chains of [CuSi2O7] with Cu2+ in square-planar coordination. The absorption and EPR spectra of Cs4CuSi2O7, K6CuSi2O8 and Rb4CuSi2O7 are discussed in terms of the Angular-Overlap-Model (AOM) and compared with Egyptian blue, CaCuSi4O10.