Griselda Polla

Conformational polymorphism on imatinib mesylate: grinding effects.

Crystal structures of polymorphs α and β of imatinib mesylate were obtained. Thermal behavior and grinding effects were studied by X-ray powder diffraction and differential scanning calorimetry techniques. Molecules in forms α and β exhibit significant conformational differences due to dissimilar intramolecular interactions, which stabilize their molecular conformations. In spite of that, both crystal structures present a dimer-chain arrangement. Dimers are mainly determined by hydrogen bonding interactions and some weak π-π interactions. Connections between dimers are provided by mesylate ions to determine chains of dimers. Neighboring chains are linked by very weak interactions: C-H···π interactions in form α and π-π interactions in form β. At room temperature, thermal disorder was observed in the mesylate ion in form α, which could be removed at low temperatures (-123°C). Form β was found to be the more stable form at room temperature. Both polymorphs exhibit a tendency to generate amorphous material by grinding, which can be converted to a crystalline phase by either temperature or aging. When amorphous crystallization is kinetically studied at room temperature, form β is obtained after a week. Conversely, when the crystallization is activated by temperature, the final obtained crystal form depends on the starting material, proving the importance of seeding.

Gel growth and characterization of bismuth oxalate single crystals

Abstract The simultaneous growth of Bi 2 ( C 2 O 4 ) 3 ·7 H 2 O and Bi 2 ( C 2 O 4 ) 3 · H 2 C 2 O 4 single crystals, by two different techniques (slow evaporation from solution and gel growth) is reported. The work includes a comprehensive characterization for both compounds, performed on the much better gel grown specimens, as well as single crystal and powder X-ray data and a thorough study of the thermal behaviour. Dominant hillocks giving rise to vicinal faces in Bi 2 ( C 2 O 4 ) 3 · H 2 C 2 O 4 are described, and a tentative explanation for their existence is given.

The Zn2+ salt of pamidronate: a role for water in the metal-cation binding properties of bisphosphonates.

Pamidronate (3-ammonium-1-hydroxypropylidene-1,1-bisphosphonate) is used clinically in the treatment of diseases affecting bone tissue. In the salt zinc pamidronate dihydrate, Zn(2+).2C(3)H(10)NO(7)P(2)(-).2H(2)O, pamidronate is a zwitterion with an overall charge of -1. The carbon chain adopts a trans conformation, separating maximally the positively charged N atom from the negative phosphonate groups. The Zn(2+) ion lies on an inversion center and is surrounded by a sixfold coordination sphere provided by two bidentate chelating zwitterions and two water molecules. The bidentate O.Zn.O bond angle is 92.70 (7) degrees, while the O.O bite distance is 3.018 (3) A.

The dehydration of CuSr2(HCOO)6 · 8H2O: A crystallographic study

Abstract The isothermal dehydration of CuSr2(HCOO)6 · 8H2O single crystals as well as powdered material has been followed by several techniques, mainly X-ray diffraction and optical microscopy. Evidence was found of a two-stage process, with an early appearance of an amorphous state (attributed to internal dissolution) and further recrystallization of the stable phases. One of these (CuSr(HCOO)4, monoclinic, Pc, Z = 2, a = 7.345(10) A, b = 8.692(15) A, c = 6.702(10)A, β = 97.25(5)°) has not been reported so far in the literature. When dehydration takes place near room temperature, the remaining product (Sr(HCOO)2) bears a topotactic relationship to the parent matrix ((hk0)//(hk0)′; 〈0k0〉//〈0k0〉′). A striking metric match between both (hk0) sections, as well as the absence of any common structural motive, suggest an inner epitactic growth as the most probable mechanism for the transformation.

EMPLEO DE ESPECTROSCOPIA RAMAN, DIFRACCIÓN DE RAYOS X Y MICROSCOPIA ELECTRÓNICA PARA EL ANÁLISIS DE PIGMENTOS EN CERÁMICAS VAQUERÍAS

* M. Fabiana Bugliani, ConiCet-Museo Etnografico J. B. Ambrosetti, Universidad de Buenos Aires, Argentina, email: fbugliani@gmail.com ** Claudia Di Lello, CiCpBA-Museo de La Plata-FCnym-Unlp, email: cdilello@fenym.unlp.edu.ar *** Eleonora Freire, CNEA, Buenos Aires, Argentina, email: freire@tandar.cnea.gov.ar **** Griselda Polla, CNEA, Buenos Aires, Argentina, email: grispoll@cnea.gov.ar ***** Alicia Petragalli, CNEA, Buenos Aires, Argentina, email: petra@tandar.cnea.gov.ar ****** Maria Reinoso, CNEA, Buenos Aires, Argentina, email: reinoso@cnea.gov.ar ******* Emilia B. Halac, CNEA, Buenos Aires, Argentina, email: halac@cnea.gov.ar

Aripiprazole salts. I. Aripiprazole nitrate.

The crystal structure of aripiprazole nitrate (systematic name: 4-(2,3-dichlorophenyl)-1-{4-[(2-oxo-1,2,3,4-tetrahydroquinolin-7-yl)oxy]butyl}piperazin-1-ium nitrate), C(23)H(28)Cl(2)N(3)O(2)(+)·NO(3)(-) or AripH(+)·NO(3)(-), is presented and the molecule compared with the aripiprazole molecules reported so far in the literature. Bond distances and angles appear very similar, except for a slight lengthening of the C-NH distances involving the protonated N atom, and the main differences are to be found in the molecular spatial arrangement (revealed by the sequence of torsion angles) and the intermolecular interactions (resulting from structural elements specific to this structure, viz. the nitrate counter-ions on one hand and the extra protons on the other hand as hydrogen-bond acceptors and donors, respectively). The result is the formation of [100] strips, laterally linked by weak π-π and C-Cl...π interactions, leading to a family of undulating sheets parallel to (010).

1-(9H-Carbazol-4-yloxy)-3-{[2-(2-methoxyphenoxy)ethyl]amino}propan-2-ol hemihydrate: a carvedilol solvatomorph.

In the title racemic hemihydrated solvatomorph of carvedilol (carv), C(24)H(26)N(2)O(4)·0.5H(2)O, the asymmetric unit contains two independent organic moieties and one water molecule. Within this 2(carv)·H(2)O unit, the molecular components are strongly linked by hydrogen bonds and the unit acts as the basic building block for the crystal structure. Interactions parallel to (10 ̅1) generate hydrogen-bonded layers which are further linked by much weaker C-H···N/O interactions. The conformations of the organic molecules, as well as the hydrogen-bonding interactions connecting them, are compared with other related structures in the literature.

Correlation between magnetic and transport properties of phase-separated La0.5Ca0.5MnO3

Abstract The effect of low-magnetic fields on the magnetic and electrical transport properties of polycrystalline samples of the phase-separated compound La0.5Ca0.5MnO3 is studied. The results are interpreted in the framework of the field-induced ferromagnetic fraction enlargement mechanism. A fraction expansion coefficient αf, which relates the ferromagnetic fraction f with the applied field H, was obtained. A phenomenological model to understand the enlargement mechanism is worked out.

Chemical incorporation of halogens in high TC superconductors: II:Atmospheric degradation of La1.8Sr0.2Cu O4−σ−12 yCly

Powdered and sintered samples of nominal composition La1.8Sr0.2CuO4−σ and the partially chlorinated compounds La1.8Sr0.2CuO4−σ−12 yCly for 0.1<y<1 do not behave in the same way under ambient conditions. Sintered pellets of the chlorinated materials degrade in a humid atmosphere and La(OH)3 and Cl2Sr.6H2O are detected by X-rays diffraction, while no degradation is observed in any of the other samples. In these sintered pellets adsorption isotherms show the presence of mesopones (diameter between 15 A and 250 A) in which condensation of water vapor can take place. The capillary condensation hypothesis offers the most reasonable explanation for the enhancement of degradation observed only in the sintered partially chlorinated samples.

ESTUDIO DE PIGMENTOS EN ALFARERÍA ESTILO NEGRO SOBRE ROJO DE QUEBRADA DE HUMAHUACA, JUJUY, ARGENTINA

En las piezas ceramicas Negro sobre Rojo de la Quebrada de Humahuaca pueden observarse atributos tecnologicos que aportan informacion sobre su variabilidad local y cronologica. En este trabajo se realiza el analisis de pigmentos sobre muestras ceramicas procedentes de dicha region, mediante diversas tecnicas arqueometricas. Algunas de uso ya comun, como la microscopia optica y la difraccion de rayos X, y otras de mas reciente aplicacion, como la espectroscopia Raman y la microscopia electronica de barrido con espectroscopia de energia dispersiva. La aplicacion combinada de diversas tecnicas y la discusion del caso con los distintos especialistas permitio establecer interpretaciones significativas a partir de los resultados obtenidos.