High-pressure synthesis of rock salt LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions

Metastable LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions with rock salt crystal structure have been synthesized by solid state reaction of ZnO with LiMeO2 complex oxides at 7.7 GPa and 1350-1450 K. Structure, phase composition, thermal stability and thermal expansion of the recovered samples have been studied by X-ray diffraction with synchrotron radiation. At ambient pressure rock salt LiMeO2-ZnO solid solutions are kinetically stable up to 670-800 K depending on the composition.Comment: 11 pages, 3 figures, 1 tabl

(1R,2R,3R,4S,5S)-3-Methyl-8-oxa­bicyclo­[3.2.1]oct-6-ene-2,4-diyl diacetate

The mol­ecule of the title compound, C12H16O5, has crystallographically imposed mirror symmetry with the mirror plane passing through the endocyclic O atom and the mid-point of the double bond. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming chains running along the a axis

3-exo-Chloro-8-oxabicyclo­[3.2.1]oct-6-ene-2,4-diol chloro­form 0.33-solvate

The title compound, 3C7H9ClO3·CHCl3, crystallizes with mol­ecules of 3-exo-chloro-8-oxabicyclo­[3.2.1]oct-6-ene-2,4-diol (A) and chloro­form in a 3:1 ratio, in the space group R3m. Mol­ecules of A straddle a crystallographic mirror plane, whereas the chloro­form mol­ecules (C and H atoms) lie additionally on the threefold axis. The mol­ecules of A are linked into right- and left-helical chains by means of O—H⋯O hydrogen bonds, thus forming columns running along the c axis. Six inter­penetrated columns form a channel in which the solvent mol­ecules (chloro­form) are located

Aryl oligogermanes as ligands for transition metal complexes

The ligand properties of a series of aryl oligogermanes R3Ge‐GeAr3, 3‐7 (Me3Ge‐GePh3 (3), Me3Ge‐Ge(pTol)3 (4), Ph3Ge‐GePh3 (5), (C6F5)3Ge‐GePh3 (6), Ph3Ge‐GeMe2GePh3 (7)), for the synthesis of transition metal carbonyl complexes such as R3Ge‐GeAr2(R’C6H4‐η6)M(CO)3 (M = Cr, 3a‐7a; M = Mo, 3b; M = W, 3c) were investigated. The target complexes were obtained in moderate yields using several different synthetic approaches. The physicochemical properties of these new derivatives were investigated by IR, UV/vis, NMR spectroscopy, electrochemistry and DFT calculations. The molecular structures of 3c, 4a and 5a were studied by single crystal X‐ray diffraction analysis. A comparative analysis of donor‐ and acceptor properties of aryl oligogermanes as ligands for transition metal carbonyl complexes is reported

Antioxidative vs cytotoxic activities of organotin complexes bearing 2,6-di-tert-butylphenol moieties

Copyright © 2018 John Wiley & Sons, Ltd. Two series of organotin(IV) complexes with Sn–S bonds on the base of 2,6-di-tert-butyl-4-mercaptophenol (L1SH) of formulae Me2Sn(L1S)2 (1); Et2Sn(L1S)2 (2); Bu2Sn(L1S)2 (3); Ph2Sn(L1S)2 (4); (L1)2Sn(L1S)2 (5); Me3Sn(L1S) (6); Ph3Sn(L1S) (7) (L1 = 3,5-di-tert-butyl-4-hydroxyphenyl), together with the new ones [Me3SnCl(L2)] (8), [Me2SnCl2(L2)2] (9) (L2 = 2-(N-3′,5′-di-tert-butyl-4′-hydroxyphenyl)-iminomethylphenol) were used to study their antioxidant and cytotoxic activity. Novel complexes 8, 9 of MenSnCl4 − n (n = 3, 2) with Schiff base were synthesized and characterized by 1H, 13C NMR, IR and elemental analysis. The crystal structures of compounds 8 and 9 were determined by X-ray diffraction analysis. The distorted tetrahedral geometry around the Sn center in the monocrystals of 8 was revealed, the Schiff base is coordinated to the tin(IV) atom by electrostatic interaction and formation of short contact Sn–O 2.805 Å. In the case of complex 9 the distorted octahedron coordination of Sn atom is formed. The antioxidant activity of compounds as radical scavengers and reducing agents was proved spectrophotometrically in tests with stable radical DPPH, reduction of Cu2+ (CUPRAC method) and interaction with superoxide radical-anion. Moreover, compounds have been screened for in vitro cytotoxicity on eight human cancer cell lines. A high activity against all cell lines with IC50 values 60–160 nM was determined for the triphenyltin complex 7, while the introduction of Schiff base decreased the cytotoxicity of the complexes. The influence on mitochondrial potential and mitochondrial permeability for the compounds 8 and 9 has been studied. It is shown that studied complexes depolarize the mitochondria but don't influence the calcium-induced mitochondrial permeability transition

Molecular recognition of organic vapors by adamantylcalix[4]arene in QCM sensor using partial binding reversibility

The parameters of stability, guest binding reversibility, and Gibbs energy of guest inclusion were determined for clathrates of adamantylcalix[4]arene (1), These data provide a new insight into the structure-property relationships in vapor sensor applications of clathrate-forming hosts. A thin layer of 1, used in the quartz mierobalance (QCM) sensor, demonstrates a selectivity for organic vapors, which depends on the regeneration technique after the guest binding. Complete regeneration of 1 on the sensor surface was reached through the exchange of bound guest with ethanol vapor, which forms an unstable clathrate with 1. The efficiency of the used regeneration technique was proved by comparing the QCM data with the isotherms of guest vapor sorption by guest-free host 1 and with the data of simultaneous thermogravimetry and differential scanning calorimetry for the saturated clathrates of 1. In sensor, the extent of host regeneration without guest exchange depends on the guest molecular structure. This extent, or guest-binding reversibility parameter, being determined in a combination with the sensor responses of completely regenerated 1 to guest vapors, increases the recognition capability of single sensor device. Using this technique, 13 of 15 studied guests were discriminated. The structural hints on the suitable sensor properties of 1 were found in the determined X-ray monocrystal data for clathrate of this host with toluene. © 2008 American Chemical Society

Cathodoluminescence of zinc oxide crystals grown from melt under high pressure in the presence of ytterbium oxide

International audienceA mixture of poly-and single crystals of zinc and ytterbium (2 at.%) oxides were grown from the melt at high temperature (1430 °C) and high pressure (3.8 GPa). The crystals were transparent under examination with naked eye. The diameter of crystals was in the range from 0.005 to 2 mm. X-ray diffraction confirmed the presence of individual zinc and ytterbium oxides in the recovered samples. No change in zinc oxide lattice parameters was observed compared to pristine zinc oxide. Cathodoluminescence spectra of the mixture were recorded at 77 and 293 K. The collected spectra exhibit UV, green and nearinfrared bands due to exciton recombination, presence of oxygen vacancies and ytterbium ions in ZnO crystals, respectively