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Distortion of polyhedra is frequently used in the structure–property analysis of inorganic materials. The commonly used Baur distortion index (BDI) loses efficacy in dealing with equi-length polyhedra. This work provides an online calculator to characterize the polyhedral distortion on the basis of the best fitted idealized polyhedron (BFIP) method. This method can determine any subtle change between distorted and corresponding idealized polyhedra. It works by fitting an idealized oriented polyhedron of user-selected type to a collection of center and vertex coordinates on an orthonormal basis. The input only needs the coordinates of the center and ligand atoms. It can be accessed at http://bfip.crystalstructure.cn. The function is demonstrated using a distorted MgO6 octahedron. Examples of the application and comparison with the BDI are given, including a tetrahedron, octahedron, eight-vertex triangular dodecahedron/cube and cuboctahedron.

International audience; Crystal structures can strongly deviate from bulk states when confined into nanodomains. These deviations may deeply affect properties and reactivity and then call for a close examination. In this work, we address the case where extended crystal defects spread through a whole solid and then yield an aperiodic structure and specific reactivity. We focus on iron boride, α-FeB, whose structure has not been elucidated yet, thus hindering the understanding of its properties. We synthesize the two known phases, α-FeB and β-FeB, in molten salts at 600 and 1100 °C, respectively. The experimental X-ray diffraction (XRD) data cannot be satisfactorily accounted for by a periodic crystal structure. We then model the compound as a stochastic assembly of layers of two structure types. Refinement of the powder XRD pattern by considering the explicit scattering interference of the different layers allows quantitative evaluation of the size of these domains and of the stacking faults between them. We, therefore, demonstrate that α-FeB is an intergrowth of nanometer-thick slabs of two structure types, β-FeB and CrB-type structures, in similar proportions. We finally discuss the implications of this novel structure on the reactivity of the material and its ability to perform insertion reactions by comparing the reactivities of α-FeB and β-FeB as reagents in the synthesis of a model layered material: Fe2AlB2. Using synchrotron-based in situ X-ray diffraction, we elucidate the mechanisms of the formation of Fe2AlB2. We highlight the higher reactivity of the intergrowth α-FeB in agreement with structural relationships.

The reactivity of alkali–manganese(ii) and alkali trifluoroacetates towards amorphous SiO2 was studied in the solid-state with an eye towards the synthesis of alkali fluorosilicates.

YBa2Cu3O6+δ (YBC) oxygen deficient perovskite was synthesized by an auto-combustion method and was studied as potential cathode for Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC). Synchrotron X-ray thermodiffraction in air shows a phase transition from orthorhombic Pmmm to tetragonal P4/mmm space groups at ~ 425 °C. The chemical compatibility with Ce0.9Gd0.1O1.95 (GDC) electrolyte was investigated in air where certain reactivity was observed above 800 °C. However, the main phase is Ba(Ce1-xYx)O3, a good ionic conductor. The catalytic performance in air was obtained by electrochemical impedance spectroscopy (EIS) measurements on YBC/GDC/YBC symmetrical cells. The area specific resistance (ASR) values change from 13.66 to 0.14 Ω cm2 between 500 and 800 °C, with activation energy (Ea) of 0.41 eV. The results suggest potential applications of YBC as IT-SOFC cathode.

Iboga alkaloids are a group of monoterpenoid indole alkaloids with promising and intriguing biological activities. Ibogaine is the representative member of the series and has become widely known as a potent atypical psychedelic with promising effects to treat substance use disorder. Nowadays, an efficient and scalable enantioselective total synthesis of ibogaine and related iboga alkaloids is still lacking, so direct extraction from natural sources or semi-synthetic schemes are the methods of choice to obtain them in a preparative scale. In particular, ibogaine can be obtained either by a low yielding direct isolation from Tabernanthe iboga or using a semi-synthetic procedure from voacangine, an iboga alkaloid occurring in a higher yield in the root bark of Voacanga africana. In this work, we describe an optimized process to obtain voacangine from V. africana root bark as a precursor of the iboga scaffold. Using a direct acetone-based extraction procedure (0.5 kg of root bark), voacangine was isolated in ∼0.8% of root bark dried weight, while the major alkaloids isolated from the bark were identified as iboga-vobasinyl dimers (∼3.7%) such as voacamine and voacamidine. Since these alkaloids contain the voacangine moiety in their structure, the cleavage of the dimers was further optimized, affording an extra amount of voacangine in ∼50% isolated molar yield. In this manner, the total amount of voacangine obtained by application of the whole procedure to the plant material (extraction and dimer cleavage) could almost duplicate the content originally found in the root bark.

Four novel alkali-manganese(II) trifluoroacetates were synthesized, and their potential as self-fluorinating precursors to layered perovskites A2MnF4 (A = K, Rb, and Cs) was demonstrated. Na2Mn(tfa)4, K4Mn2(tfa)8, Rb4Mn2(tfa)8·0.23H2O, and Cs3Mn2(tfa)7(tfaH) (tfa = CF3COO- and tfaH = CF3COOH) were grown as single crystals, and their crystal structures solved using X-ray diffraction. Chemically pure K4Mn2(tfa)8, Rb4Mn2(tfa)8·0.23H2O, and Cs3Mn2(tfa)7(tfaH) were also prepared in polycrystalline form as confirmed by thermal analysis and powder X-ray diffraction. Thermolysis of these powders yielded the isostructural series K2MnF4, Rb2MnF4, and Cs2MnF4 at low temperatures (≈200-300 °C). Trifluoromethyl groups belonging to the trifluoroacetato ligands served as the fluorine source, thereby eliminating the need for external fluorinating agents. K2MnF4 and Rb2MnF4 were obtained as single-phase powders, whereas Cs2MnF4 crystallized along with CsMnF3. Access to polycrystalline Cs2MnF4 coupled to Rietveld analysis enabled elucidation of the crystal structure of this ternary fluoride, which had remained elusive. Findings presented in this article expand the synthetic accessibility of polycrystalline A2MnF4 fluorides, for which a scarce number of routes is available in the literature.

The synthesis of eight novel Zn(II), Co(II), Cu(II), Ni(II) and Pt(II) complexes (2–9) derived from the ONNO tetradentate coumarin Schiff-Base donor ligands, L1 and the novel L2, was performed. All compounds were characterized by analytical, spectrometry and spectroscopy techniques. Complexes 2–4 were also characterized by DFT calculations and the structures of 5 and 6 were determined by single-crystal X-ray diffraction analysis. A cytotoxicity study was carried out through an MTT assay in the carcinogenic cell line HeLa and the noncarcinogenic cell lines HFF-1 and HaCaT. The results indicated that among all the evaluated compounds, 2 and 6 presented the best anticarcinogenic potential against HeLa cells with an IC50 of 3.5 and 4.1 µM, respectively. In addition, classical molecular dynamics simulations were performed on the synthesized coordination compounds bound to G4 DNA architectures in the scope of shedding light on their inhibition mode and the most conserved interactions that may lead to the biological activity of the compounds.

Heteropolynuclear metal organic frameworks (MOFs) of the general formula [Ln2Ni3(oda)6(H2O)6]·xH2O (oda = oxydiacetate, Ln = +3 rare earth ion) were synthesized and characterized. Most of them bear a honeycomb structure with 1D channels containing 11 to 14 crystallization water molecules per formula unit. The size of the channels and the number of crystallization water molecules they contain decrease as the Ln ionic radii become smaller along the series from La to Tm. In addition, the water content changes reversibly with temperature and relative humidity conditions. Accordingly, the as-synthesized [Tm2Ni3(oda)6(H2O)6]·11H2O picks up water when exposed to a 100% relative humidity atmosphere to become [Tm2Ni3(oda)6(H2O)6]·14H2O. Computational calculations show the formation of a hydrogen bond network in which layers of water molecules are arranged and associated primarily to the polar groups of the framework walls, anticipating good proton conduction along the [001] channels. Furthermore, higher confinement of water molecules in the smaller channels could favor the water molecules' mobility. Indeed, the proton conductivity of [Tm2Ni3(oda)6(H2O)6]·14H2O is 2.43 × 10−3 S cm−1 at 70 °C, similar to that of standard conductive MOF-based materials reported. A vehicular carrier mechanism by means of H3O+ species diffusing along the 1D channels of the porous structure seems to be operative, with a high activation energy value of 1.46 eV.

A new synthetic route to access pristine and rare-earth-doped BaFBr nanocrystals is described. Central to this route is an organic–inorganic hybrid precursor of formula Ba5(CF2BrCOO)10(H2O)7 that serves as a dual-halogen source. Thermolysis of this precursor in a mixture of high-boiling point organic solvents yields spherical BaFBr nanocrystals (≈20 nm in diameter). Yb:Er:BaFBr nanocuboids (≈26 nm in length) are obtained following the same route. Rare-earth-doped nanocrystals display NIR-to-visible photon upconversion under 980 nm excitation. The temperature-dependence of the green emission from Er3+ may be exploited for optical temperature sensing between 150 and 450 K, achieving a sensitivity of 1.1 × 10−2 K−1 and a mean calculated temperature of 300.9 ± 1.5 K at 300 K. The synthetic route presented herein not only enables access to unexplored upconverting materials but also, and more importantly, creates the opportunity to develop solution-processable photostimulable phosphors based on BaFBr.

Enantioselective synthesis of ampelomin B and epi-ampelomin B, D, and E was accomplished starting from toluene, through a chemoenzymatic sequence, in which stereoselective hydrogenation, Mitsunobu reaction, and regio- and stereoselective nucleophilic opening of an epoxide were used as the main transformations. Structural revision and absolute configuration of the natural compounds were carried out.

In this work, we report a novel polymorph of AgBiW2O8, which was synthesized by a simple arc melting method. The structural details of this compound were determined by X-ray powder diffraction, and elemental composition was confirmed with ICP-AES. β-AgBiW2O8 adopts the scheelite structure type with tetragonal space group I41/a and lattice parameters a = b = 5.3019(3) and c = 11.678(2) A. Structural details and optical properties are discussed in detail. Diffuse reflectance spectroscopy (DRS) measurements of β-AgBiW2O8 showed light absorption profile extended to the visible region, which suggests the material has a smaller band gap energy than Bi2WO6, as expected due to contribution of Ag d-orbitals to the electronic structure.

A modified synthesis procedure allowed lapachol acetate (acetic acid 3-(3-methyl-but-2-en­yl)-1,4-dioxo-1,4-di­hydro- naphthalen-2-yl ester) to be obtained in high yield and its crystal structure is reported for the first time 80 years after its first synthesis. The lapachol acetate mol­ecular conformation is very similar to that of reported lapachol mol­ecules and other derivatives. The monoclinic P21/n crystal structure packs through weak inter­molecular π–π and C—H⋯O inter­actions as described by Hirshfeld surface analysis., Lapachol acetate [systematic name: 3-(3-methyl­but-2-en­yl)-1,4-dioxonaph­thalen-2-yl acetate], C17H16O4, was prepared using a modified high-yield procedure and its crystal structure is reported for the first time 80 years after its first synthesis. The full spectroscopic characterization of the mol­ecule is reported. The mol­ecular conformation shows little difference with other lapachol derivatives and lapachol itself. The packing is directed by inter­molecular π–π and C—H⋯O inter­actions, as described by Hirshfeld surface analysis. The former inter­actions make the largest contributions to the total packing energy in a ratio of 2:1 with respect to the latter.

A new type of organic–inorganic hybrid precursor to mixed-halide optical materials is described by using Ba5(CF2ClCOO)10·7H2O as an example. This heterohaloacetate belongs to the family of extended inorganic hybrids in which metal connectivity in three dimensions is achieved via metal–organooxygen–metal bridges. Thermolysis in the solid state and in solution yield crystalline BaFCl at temperatures below 300 °C. Chlorodifluoromethyl groups act as chlorine and fluorine source, making the organic moiety a de facto single-source precursor for the anionic portion of the target mixed halide. Solution thermolysis in the presence of Yb3+–Er3+ sensitizing–activator pairs yields rare-earth-doped BaFCl nanocrystals capable of NIR-to-visible photon upconversion. Analyses of the composition, morphology, structure, and luminescence of these nanocrystals demonstrate that heterohalocetates serve as dual halogen sources for mixed-halide optical materials. Findings presented in this article enlarge the synthetic toolbox to...

New bond valence R0 parameters were derived for alkali– and alkaline-earth–oxygen pairs encountered in metal−organic compounds. A total of 7693 metal−oxygen bond lengths were extracted from structures deposited in the Cambridge Structural Database (CSD) and containing at least one carboxylate ligand bound to the metal. One hundred structures were individually analyzed for each metal. R0 values were computed using two different approaches: geometric mean and graphical fitting. In both cases, the bond valence parameter b was fixed at 0.37 A. R0 values obtained using a geometric mean approach were 1.744 (Na–O), 2.094 (K–O), 2.228 (Rb–O), 2.412 (Cs–O), 1.661 (Mg–O), 1.933 (Ca–O), 2.090 (Sr–O), and 2.265 A (Ba–O). These parameters yielded more accurate metal bond valence sums (BVS) and lower root-mean square deviations (RMSD) than those computed using R0 values currently available in the literature,1 which had been derived from the structures of inorganic oxides. The most significant improvement was observed for sodium (this work mean BVS = 1.01 v.u., RMSD = 0.116 v.u.; literature mean BVS = 1.18 v.u., RMSD = 0.226 v.u.; v.u.: valence units) and magnesium (this work mean BVS = 2.00 v.u., RMSD = 0.038 v.u.; literature mean BVS = 2.18 v.u., RMSD = 0.100 v.u.). More accurate bond valence sums and lower variances were also observed when the new set of R0 values was applied to metal–organic compounds featuring oxygenated ligands such as ethers, ketones, aldehydes, alcohols, and esthers. These parameters should be applicable to the structural and crystal-chemical analysis of metal−organic compounds ranging from coordination complexes to organic−inorganic extended hybrids.

Single-phase oxygen stoichiometric LaMnO3 and doped La0.8A0.2MnO3 (A = Ca, Sr, Ba) perovskites have been prepared by a simple one-step auto-combustion method. Cation-deficient LaMnO3+δ and La0.8A0.2MnO3+δ were obtained by calcination of the former samples in air at 750 °C. The samples were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, temperature-programmed oxygen desorption, and N2 physisorption in order to apply them as catalysts in the complete catalytic oxidation of acetone as a model volatile organic compound. The studied phases show the expected orthorhombic and rhombohedral perovskite crystal structures. Catalytic experiments performed with all the samples show measurable activity already at 100 °C. At 200 °C, doped La0.8A0.2MnO3 samples show higher activity than undoped LaMnO3, with increasing conversion with larger A-cation size. Calcined samples also show higher activity than as-prepared ones making La0.8Ba0.2MnO3+δ the best catalyst at this temperature. All doped samples show >95% acetone conversion at T ≥ 250 °C with a weak dependence on the sample processing or A cation doping. The collected evidence confirms that the most important factors for the catalytic activity of these oxides are the Mn4+/Mn3+ molar ratio on the surface of the samples and the cation-deficiency of the bulk perovskite structure. In addition, increasing the symmetry of the bulk crystal structure appears to have an additional favourable effect. Despite the observation of the presence of surface carbonates, we show that it is possible to use the as-prepared samples without further thermal treatment with good results in the oxidation of acetone.

Zero-trans edible fats attractive to be used for shortenings or margarines were designed solely from rice bran oil (RBO). For this purpose, RBO was fully hydrogenated, blended with the original oil at different percentages, and finally, blends were interesterified by an enzyme-catalyzed process. The interesterification process reduced the concentration of trisaturated and triunsaturated triglycerides and increased the concentration of medium saturation degree molecules, thus increasing their compatibility and causing the moderation of the melting point, as compared with blends. Conversely to blends, products showed a high tendency to crystallize under the β’ polymorph, which is the preferred one for products destined for many edible applications. Results demonstrated that the proper combination of different technologies (total hydrogenation, blending and interesterification) is a versatile and useful technology for designing zero-trans fats from RBO, attractive for the confection of shortenings or margarines for different applications depending on the proportion of each component in the starting blend. This strategy offers an attractive alternative for the diversification of RBO utilization, a valuable vegetable oil still underexploited, providing attractive fats useful for structuring different type of foods.

El presente estudio esta referido a la caracterizacion de materiales arqueologicos de cuentas y ceramicas, provenientes de los sitios arqueologicos “Iglesia Colonial” y “Pampa La Cruz” de Huanchaco, respectivamente. Las cuentas de “Iglesia Colonial” fueron registradas en contextos funerarios del Periodo Chimu Inca (1450-1532 d.C.) y Colonial Temprano (1532-1650 d.C.). La importancia de estudiar este sitio radica en entender como se dio la ocupacion humana entre la transicion Inca y la llegada de los Espanoles a la costa norte del Peru. En el sitio “Pampa La Cruz” fueron descubiertas tumbas conteniendo cuentas y vasijas de ceramica con la tecnica decorativa del “negativo”. En este trabajo fragmentos de ceramica de este sitio fueron investigados, su composicion mineralogica fue determinada cualitativa y cuantitativamente. Esta informacion contribuiria a identificar la posible fuente de arcillas utilizadas para la preparacion de las vasijas, lo que, a su vez, podria ayudar a determinar si es que las vasijas provenian de varios lugares, o si los mismos pobladores del sitio las procesaban. La caracterizacion de las muestras fue realizada por la tecnica de difraccion de rayos X. Las medidas fueron analizadas a partir del modelamiento de la intensidad de difraccion experimental, aplicando el metodo de Rietveld, a fin de determinar cuantitativamente el porcentaje en peso de las componentes minerales cristalinas de las muestras. Palabras clave: cuenta, ceramica, arcilla, difraccion de rayos X, metodo de Rietveld.

An experimental investigation of the structure and crystal-chemistry of the triple perovskite BaSr2MgTa2O9 is reported. Polycrystalline BaSr2MgTa2O9 was synthesized via solid-state reaction and its structure quantitatively probed at 10 and 300 K using neutron diffraction. Monoclinic (A2/m, a0 b ¯ – b–) and trigonal structural models (P 3 ¯ c1, a–a–a–) were fit to diffraction data. The former was found to correctly reproduce experimental intensities, while the latter failed to do so. This difference is attributed to the ability of the monoclinic model to accurately reflect octahedral tilting. BaSr2MgTa2O9 features corner-sharing MgO6 and TaO6 octahedra with barium and strontium cations occupying cubooctahedral holes. Barium and strontium are disordered over the A site, whereas B site cations magnesium and tantalum are ordered. Chemical substitution of strontium for barium in Ba3MgTa2O9 induces tilting of MgO6 and TaO6 octahedra in two directions and geometric distortions of MgO6 octahedra.

Oil shales from Mangrullo Formation (Uruguay) was assessed as a potential fuel for energy production. The assessment is based on a comprehensive characterization of the material from a thermal perspective. Co-combustion of this type of fuel with biomass waste can enhance the combustion performance and decrease hazardous gas emissions. The low heating value (3.2 MJ kg) of the Uruguayan oil shale indicates that it could be mixed with biomass to obtain better results. Stratified sampling of drill cores was used to obtain a representative sample. The morphological and structural characteristics of the oil shale were studied by X-ray diffraction and scanning electron microscopy. Chemical composition (hydrocarbons and minerals) of oil shales was investigated by X-ray diffraction, X-ray fluorescence, proximate and ultimate analysis and Fourier transform infrared spectroscopy. Rock Eval analysis was performed to measure richness and maturity of the Uruguayan oil shale, the results of the TOC content (8.93%) and the hydrogen index (525 mg HC/ g TOC) indicated that it constitutes an excellent source rock. The kinetic of the combustion and thermal properties of oil shale were studied. The activation energy of the different reaction stages was calculated using the Flynn-Wall-Ozawa model, then we obtained the pre-exponencial factor and the reaction order optimizing the theoretical model using the experimental data. Results indicated that the combustion of the oil shale exhibits multiple reaction stages with activations energies that varies between 152.2 and 316.4 kJ mol.

The crystal structure of divainillin (systematic name: 6,6′-dihydroxy-5,5′-dimethoxy-[1,1′-biphenyl]-3,3′-dicarbaldehyde), C16H14O6, was determined from laboratory powder X-ray diffraction data using the software EXPO2013 (direct methods) and WinPSSP (direct-space approach). Divanillin molecules crystallize in the orthorhombic space group Pba2 (No. 32), with two molecules per unit cell (Z′ = 1 \over 2). Each divanillin molecule, with twofold symmetry, is linked through strong alcohol–aldehyde hydrogen bonds to four equivalent molecules, defining a three-dimensional hydrogen-bonding network, with rings made up of six divanillin units (a diamond-like arrangement). Each molecule is also connected through π–π interactions to a translation-equivalent molecule along c. Four consecutive molecules stacked along [001] belong to four different three-dimensional hydrogen-bonding networks defining a quadruple array of interpenetrating networks. This complex hydrogen-bonding array is proposed as an explanation for the aging process experienced by divanillin powders.

Considering the importance of quinolones due to their broad spectrum of biological activities, the crystal structure of the title compound, C22H21NO3·0.5C7H16, has been determined. Two enantiomers of the benzazepinoquinoline molecule and one molecule of heptane form the asymmetric unit of this centrosymmetric triclinic (P\overline{1}) crystal. All the molecules in the crystal present disorder. Substitutional disorder is observed for the benzazepine molecules, where a minority conformer of the R enantiomer replaces the main conformer of the S enantiomer and vice versa. Positional disorder is found for the heptane solvent molecule, which occupies a void left by the independent enantiomers of both conformers.

We describe a novel pericyclic/anionic cascade reaction on tropolonic substrates that combines a Diels-Alder reaction, an oxa-Michael addition, and an acyloin rearrangement to afford tricyclic α-hydroxy-β-methoxyketones. Spectroscopic, crystallographic, and mechanistic studies indicate that the process requires stabilization of reaction intermediates through intramolecular H-bonding to take place, and suggest that the conjugate addition step involves a catalytic cycle with initial formation of an ammonium enolate and sustained by an alkoxide ion pair. Given the rich functionality and structural complexity generated in a single step, the process could be exploited in the preparation of natural product-like compound libraries.

The preparation of oxyfluoroborate glasses and glass–ceramics doped with Yb3+ and Er3+ with improved luminescent properties is reported. Glasses with compositions (100 − x − y) (MO·2B2O3) + xPbF2 + y(YbF3:ErF3) (% in mol), where M is Sr, Ba, Ca, x = 10–40% and y = 0, 1 or 5% were prepared by the melt/quenching technique. Glass crystallization was studied using thermal analysis and X-ray diffraction techniques. Optical absorption and infrared up-conversion were studied on both glasses and glass–ceramics. The incorporation of a fluoride compound into the borate glass resulted to depend on the ionic radius of the glass modifier: as it increases, glasses become more stable against crystallization. On the other hand, alkali–fluoride compounds such as BaF2 and SrF2 can be crystallized from these systems by selecting an appropriate proportion between their components. Furthermore, the up-conversion response can be tuned by changing the glass modifiers (Sr, Ba and Ca) of the borate matrix, which also influence the type of fluoride crystallized compound. The strontium glass–ceramics have the highest luminescence response due to the crystallization of SrF2 compound in the system SrO–B2O3–PbF2. Meanwhile, the lowest luminescence signal was obtained for samples in the system BaO–B2O3–PbF2 where the Pb1.33Ba2.66B11FO20 phase crystallizes. With this strategy, new materials with improved luminescence properties that can be used as up converters, were obtained.

Using the flexible ligand oxydiacetic acid (H2oda), ten new heteropolynuclear compounds with general formula [Ln2Zn3(oda)6]·xH2O (Ln = lanthanide ion, oda = oxydiacetate) were synthesized and structurally characterized. They were prepared by the direct reaction of oda in aqueous solution with stoichiometric amounts of Zn and Ln salts, followed by slow organic solvent diffusion. Two different structures were obtained: the larger lanthanides Pr, Nd, Eu and Tb gave compounds belonging to the hexagonal system, space group P6/mcc; whereas, the smaller ones, Ho, Er, Yb and Y formed cubic systems, space group Fdc. In the case of Dy, the two polymorphs were obtained by slight variations in the synthetic conditions. The phase change observed is discussed in comparison with previously reported [Ln2M3(oda)6]·xH2O compounds (M = bivalent metal ion). Luminescence studies were also carried out. Compounds containing Eu and Tb showed the most intense luminescence, also bearing relatively long lifetimes for the excited state deactivation. The luminescence profiles of both Dy systems are independent of the hexagonal or cubic arrangements, due to the similar environment of the Ln having the same point symmetry.

Speciosins constitute a group of natural compounds that have never been synthesized enantioselectively. We propose to introduce chirality by the use of enantiopure 3-halo-cis-1,2-cyclohexadienediols of microbial origin. The introduction of the alkynylic side chain by Sonogashira's methodology was successful, thus confirming a valuable strategy for the asymmetric preparation of speciosins.

The reaction of Cu(CH3COO)2·H2O and Cu(ClO4)2·6H2O with bis(3,5-dimethylpyrazol-1-yl)methane ligand (L) yielded complexes [Cu(CH3COO)2(L)] (1) and [Cu(L)2(H2O)](ClO4)2 (2), which were isolated as air-stable solids. The complexes were characterized by electrical conductivity; thermogravimetric analysis; cyclic voltammetry; and Raman, infrared and ultraviolet/visible spectroscopy. The structure of 2 was determined by single-crystal X-ray diffraction analysis. Graphite electrodes modified with each of the complexes were used to detect dopamine using differential pulse voltammetry. In the presence of ascorbic acid and uric acid, the highest sensitivity (2.01 μA μM− 1 cm− 2) and the lowest detection limit (0.5 μM) were obtained with the electrode modified with 1. The linearity of the signal, the sensitivity and the detection limit were significantly improved when the solution contained polystyrenesulfonate (PSS−), demonstrating the synergistic effect between the complexes modifying the electrode surface and the PSS− in solution.

Alkali–manganese(II) trifluoroacetates were synthesized, and their potential as single-source precursors for the solid-state and solution-phase synthesis of AMnF3 fluoroperovskites (A = Na, K, Rb, Cs) was demonstrated. Crystals of Na2Mn2(tfa)6(tfaH), K2Mn2(tfa)6(tfaH)2·H2O, Rb2Mn2(tfa)6·H2O, and CsMn(tfa)3 (tfa = trifluoroacetato) were grown via solvent evaporation and their crystal structures solved using single-crystal X-ray diffraction (XRD). Chemical purity was confirmed using thermal analyses (TGA/DTA) and Rietveld analysis of powder XRD patterns. Thermal decomposition of Na2Mn2(tfa)6(tfaH), K2Mn2(tfa)6(tfaH)2·H2O, Rb2Mn2(tfa)6·H2O, and CsMn(tfa)3 in both the solid state and solution phase yielded crystalline, single-phase NaMnF3, KMnF3, RbMnF3, and CsMnF3 fluoroperovskites, respectively. Nanocrystals (

The reaction of CrCl36H2O with the ligand bis(3,5-dimethylpyrazol-1-yl)methane (L) yielded the cationic complex [(Cr(L)(H2O)2Cl2]+, which crystallized as the chloride trihydrate [(Cr(L)(H2O)2Cl2]Cl·3H2O. The chromium complex was characterized by elemental analysis, electrical conductivity, Infrared and Ultraviolet/Visible spectroscopy. The crystal structure determination using single-crystal X-ray diffraction showed a chromium center in a distorted octahedral coordination sphere. In the crystal, the packing was directed by O H⋯(O,Cl) hydrogen bonds and weak C H⋯O interactions to build a monoclinic P21/c supramolecular structure. The complex showed excellent properties as an initiator for the ring opening polymerization of є-caprolactone (CL) under solvent-free conditions. The obtained polymer showed high crystallinity (89.9%) and a decomposition temperature above 475 °C. In addition, the new complex was evaluated against epimastigotes from Trypanosoma cruzi (T. cruzi) strains. The results indicated that this complex has a high activity against this parasite with a minimum inhibitory concentration 50 (MIC50) of 1.08 μg/mL. Interestingly, this compound showed little effect on erythrocytes, indicating that it is not cytotoxic. These results provide interesting contributions to the design of metal complexes by using simple and accessible ligands with activity against T. cruzi and with potential applications in the polymerization of CL.

The enantioselective preparation of three protected β-amino-γ-hydroxyesters from benzoic acid is described. The employed synthetic methodology involves the ipso, ortho cis-dihydroxylation of benzoic acid by the mutant strain Ralstonia eutropha B9, followed by a selective halonium induced beta lactamization. Modification of this novel β-lactam structure by the appropriate sequence of reactions allows for the selective preparation of the aforementioned β-amino-γ-hydroxyesters in a diastereodivergent manner. The overall transformation results in a selective formal aminohydroxylation of the diene moiety of the initial cis-cyclohexadienediol. The synthesized products are important building blocks and will allow for the selective preparation of aminoacids, inosamines and alkaloids from benzoic acid.

Fil: de la Sovera, Victoria. Universidad de la Republica. Facultad de Quimica. Departamento de Quimica Organica; Uruguay

The absolute configuration of the title compound, determined as 4S,5R,6S on the basis of the synthetic pathway, was confirmed by single-crystal X-ray diffraction. The mol­ecule is formed by a substituted six-membered cyclo­hexene ring adopting an envelope conformation and substituted by carbonyl, methyl and hydroxyl groups. The supra­molecular structure is mainly built by a combination of O—H⋯O and weaker C—H⋯O hydrogen bonds., The mol­ecule of the title keto carbasugar, C7H10O4, is formed by a cyclo­hexene skeleton with an envelope conformation, substituted by carbonyl, methyl and hydroxyl groups. The crystal structure is controlled mainly by a combination of strong O—H⋯O and weak C—H⋯O hydrogen bonds, forming nearly perpendicular chains running parallel to the [110] and [-110] directions. This perpendicularity is caused by a tetra­gonal pseudosymmetry influenced by the similarity between the a and b axes, the value of 90.9770 (10)° of the β angle and the action of a 21 screw axis, which transform each chain into its corresponding nearly orthogonal one.

A concise and stereoselective de novo synthesis of the protected oxidized sugar (5 R )-3,4:5,6-di- O -isopropylidene- d - ribo -hexos-5-ulo-5,2-furanose is described. The synthetic sequence involves a stereoselective proline-catalyzed aldol reaction of an orthogonally protected l -glyceraldehyde derivative and 2,2-dimethyl-1,3-dioxan-5-one, to obtain 5- O -acetyl-6- O -benzyl-1,3-isopropylidene- l -psicose as a key intermediate, and the final product in 5 steps and 38% yield.

The absolute configuration,i.e.(3aR,3′aR,7aS,7′aS), of the title compound, C18H26O4, synthesizedviaa palladium-catalyzed homocoupling reaction, was determined on the basis of the synthetic pathway and was confirmed by X-ray diffraction. The homocoupled molecule is formed by two chemically identical moieties built up from two five- and six-membered fused rings. The supramolecular assembly is controlled mainly by C—H...O interactions that lead to the formation of hydrogen-bonded chains of molecules along the [001] direction, while weak dipolar interactions and van der Waals forces hold the chains together in the crystal structure.

Owing to their potential as single-source precursors for compositionally complex materials, there is growing interest in the rational design of multimetallic compounds containing fluorinated ligands. In this work, we show that chemical and structural principles for a materials-by-design approach to bimetallic trifluoroacetates can be established through a systematic investigation of the crystal-chemistry of their monometallic counterparts. A(CF3COO)2·nH2O (A = Mg, Ca, Sr, Ba, Mn) monometallic trifluoroacetates were employed to demonstrate the feasibility of this approach. The crystal-chemistry of monometallic trifluoroacetates was mapped using variable-temperature single-crystal X-ray diffraction, powder X-ray diffraction, and thermal analysis. The evolution with temperature of the previously unknown crystal structure of Mg(CF3COO)2·4H2O was found to be identical to that of Mn(CF3COO)2·4H2O. More important, the flexibility of Mnx(CF3COO)2x·4H2O (x = 1, 3) to adopt two structures, one isostructural to Mg(CF3COO)2·4H2O, the other isostructural to Ca3(CF3COO)6·4H2O, enabled the synthesis of Mg–Mn and Ca–Mn bimetallic trifluoroacetates. Mg0.45Mn0.55(CF3COO)2·4H2O was found to be isostructural to Mg(CF3COO)2·4H2O and exhibited isolated metal–oxygen octahedra with Mg2+ and Mn2+ nearly equally distributed over the metal sites (Mg/Mn: 45/55). Ca1.72Mn1.28(CF3COO)6·4H2O was isostructural to Ca3(CF3COO)6·4H2O and displayed trimers of metal–oxygen corner-sharing octahedra; Ca2+ and Mn2+ were unequally distributed over the central (Ca/Mn: 96/4) and terminal (Ca/Mn: 38/62) octahedral sites.