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Abstract

The scandium-rich indide Sc50Pt13.47In2.53 was obtained by induction melting of the elements and subsequent annealing. The structure of Sc50Pt13.47In2.53 has been refined from single-crystal X-ray diffractometer data: Fm 3¯, a = 1774.61(3) pm, wR2 = 0.0443, 1047 F2 values and 35 variables. Sc50Pt13.47In2.53 is isopointal with the intermetallic phases Sc50Co12.5In3.5, Sc50Rh13.3In2.7, Sc50Ir13.6In2.4, Ag7+xMg26−x and Ga4.55Mg21.85Pd6.6 (Pearson code cF264 and Wyckoff sequence ih 2 fecba). Two of the eight crystallographic sites in the structure show mixed occupancies: M1 (≡Pt20.70In10.30) and M2 (≡Pt30.76In20.24). The structure contains four basic polyhedra: M2@Sc8 cubes, Pt1@Sc10 sphenocorona and slightly distorted M1@Sc12 and In3@Sc12 icosahedra. The polyhedra are condensed via common scandium corners and edges. The various Sc–Sc distances range from 302–334 pm and are indicative of substantial Sc–Sc bonding, stabilizing the Sc50Pt13.47In2.53 structure.

Abstract

The title compounds are difunctionalized acetylenic building blocks, which can serve as electrophilic dienophiles and dipolarophiles in [4+2] and azide-iodoalkyne [3+2] cycloaddition reactions, which, however, require strong thermal activation. In their crystal structures, they are self-complementary tectons, which are arranged in polymeric chains maintained by very short intermolecular Csp–I···O=P halogen bonds.

Abstract

Single crystals of La5Ir1.73In4.27 were grown from a sample of the starting composition 47La: 17Ir: 36 In by arc-melting, followed by a long annealing sequence in a muffle furnace. La5Ir1.73In4.27 crystallizes with the Lu5Ni2In4-type structure, space group Pbam, which was refined from single-crystal X-ray diffractometer data: a = 834.0(2), b = 1862.2(4), c = 385.31(8) pm, wR2 = 0.0278, 1165 F 2 values and 37 variables. The 4h iridium site shows a small degree of Ir/In mixing. Geometrically one can describe the La5Ir1.73In4.27 structure as a simple 4:1 intergrowth variant of CsCl and AlB2-related slabs. The iridium and indium atoms form a one-dimensional meandering [Ir1.73In4.27]δ polyanion (292 pm Ir–In and 327 pm In–In) which is embedded in a lanthanum matrix.

Abstract

N,N′,N″-Triaminoguanidinium chloride (TAG-Cl) reacts with cyclopentanone or cyclohexanone to afford 8-(2-cyclopentylidenehydrazinyl)-6,7,9,10-tetraazaspiro[4.5]decan-8-ylium and 3-(2-cyclohexylidenehydrazinyl)-1,2,4,5-tetraazaspiro[5,5]undecan-3-ylium salts, respectively, i. e., two arms of the TAG ion were engaged in spiroaminal formation and the NH2 group of the third arm underwent imine-forming condensation. Ring-opening reactions of the cyclopentanone derived spiroaminal with aldehydes, aryl ketones, aromatic or aliphatic isocyanates give access to a variety of unsymmetrically substituted derivatives of the TAG ion.

Abstract

γ-Sm(BO2)3 was obtained via a high-pressure/high-temperature approach in a multi-anvil apparatus at 10 GPa and 1673 K. It crystallizes in the orthorhombic space group Pca21 (no. 29) with the lattice parameters a = 18.3088(8), b = 4.4181(2), and c = 4.2551(2) Å. The compound was analysed by means of X-ray diffraction and vibrational spectroscopy. The structure is isotypic to that of the already known meta-oxoborates γ-RE(BO2)3 (RE = La−Nd) and built up of a highly condensed borate framework containing three-, four-, six-, and ten-membered rings. Next to neodymium, samarium represents the second rare earth element that forms the α-, β-, and γ-modification of the four known rare earth meta-oxoborate structure types.

Abstract

The synthesis of 2,2′-(Imidazo[1,5-a]pyridine-1,3-diyl)bis(2-hydroxy-1H-indene-1,3(2H)-dione) (11) is achieved by reaction of imidazo[1,5-a]pyridine (7) with two equivalents of ninhydrin (1) at room temperature. The structure of this new 1,3-bis-adduct 11 is evidenced from HRMS and NMR spectral data and confirmed by single-crystal X-ray crystallography. Employment of equimolar amounts of 1 and 7 gave a separable mixture of the respective 1- and 3-monomeric adducts (9, 10).

Abstract

In this study, radon concentration measurements and chemical analyses of groundwater samples were performed in four sampling locations of Bartın Province of Western Black Sea Region, Turkey. 222Rn analysis was carried out in groundwater samples with liquid scintillation counting system in accordance with ASTM D5072 standard. The pH, total hardness, alkalinity and dissolved oxygen parameters of the groundwater samples were also determined. The radon concentrations for the water samples ranged between <3.00 Bq/L–12.03 Bq/L. Thirty eight percentage of the samples slightly exceeded the permissible limit of 11.1 Bq/L specified by USEPA for drinking waters. The annual effective doses of groundwater samples were calculated in the range of 7.41–30.74 μSv/y for ingestion of water (Ew.Ig), and in the range of 7.31–30.31 μSv/y for inhalation of radon released from water (Ew.Ih). The total calculated annual effective doses due to ingestion and inhalation were found to be below the limit value of 100 μSv/y specified by the World Health Organization (WHO). The radioactivity measurement results significantly varied for three sampling points but not for one sampling point on two different measurement dates, which is attributed to the differences in geological structure. The chemical analysis results, except for total hardness in two sampling points, were within the permissible limits specified by international standards.

Abstract

The design of organic/inorganic nanoparticles hybrids provides the great potential for the fabrication of γ-ray sensor systems. Herein, structural and dosimetric properties of the gamma irradiated poly vinyl acetate (PVAc) doped with cadmium telluride quantum dots (CdTe QDs) and graphene oxide (GO) nanoflakes have been investigated. Thioglycolic acid (TGA) capped water-soluble CdTe QDs and (GO) nanoflakes are synthesized and characterized. Then, CdTe QDs/GO/PVAc sensors were formed by post-depositing CdTe and GO over polymer matrix. The photophysical interactions between nanoparticles and organic polymer have been investigated using ohmic contact detectors with two gold coated electrodes. Real time dose rate information of the sensors such as sensitivity, repeatability, and the linearity of dose rate response were assessed. A wider photoelectric response range and wider gamma harvesting range were observed in the resultant hybrid gamma sensor at a standard bias voltage with respect to non-hybrid CdTe QDs/PVAc sensors.

Abstract

The suitability of perrhenate (Re(VII)) to act as an analog for pertechnetate (Tc(VII)) was tested using solvent extraction and the carrier/tracer systems 99Tc(VII)/99mTc(VII) and 185/187Re/186/188Re(VII). Perrhenate is often used as a non-radioactive analogue of pertechnetate, but scarce data is available for the comparison of these metals for liquid-liquid extraction applications. Results show that neither Tc(VII) nor Re(VII) extraction is influenced by pH in the 2–8 range. The anion extractant also separates electrolyte anions, with increasing extraction following the order Cl < NO3  ≪ ClO4 , resulting in a decreased Tc(VII) and Re(VII) extraction in presence of salt. In particular, the extraction of Re and Tc is suppressed in presence of NaCl at concentrations higher than 1 mM. While Tc extraction is larger than that of Re in absence of electrolyte, they are statistically identical in presence of enough electrolyte. Furthermore, tetraphenylphosphonium chloride (Ph4PCl) is a stronger extractant than iodonitrotetrazolium chloride (INT).

Abstract

Potassium cobalt hexacyanoferrate(II) [K2CoFe(CN)6] is an extremely selective ion exchanger for cesium ions. To examine the atomic level background for the selectivity a computational structural study using DFT modelling was carried out for K2CoFe(CN)6 and for products where Cs has replaced K in the elemental cube cages closest to the surface. In the K-form compound the potassium ions are not in the center of the Co–Fe–CN elementary cube cages closest to the surface but locate about 140 pm from the cube center towards the surface. When cesium ions are exchanged to these potassium ions they locate much deeper from the surface, being only about 70 pm upwards from the cube center. This apparently leads to much stronger bonding of cesium compared to potassium. Once taken up into the outermost cube cages on the surface of the crystallites cesium ions are not able to penetrate further since they are much larger than the electron window between the cubes. Furthermore, they are not able to return to the solution phase either leading to a practically irreversible sorption.