The polymorphism of copper-oxinate crystal

Summary a) Polymorphs Copper-oxinate dihydrate has three different crystal forms, namely, α-, γ-, Β-form. The γ-form is an intermediate crystal form in the course of the α → Β transformation in aqueous suspension. They gave three anhydrous polymorphs respectively, that is, the α′-,γ′- and Β′-forms by the dehydration and they are all transformed into the most stable anhydride (Β∼-form). The Β′-form is also precipitated directly from the solution at about boiling temperature. The relationships among the various crystal forms are also discussed. b) Crystal structure The cell dimensions of the γ-form dihydrated crystal are assumed to be a=13.10 ?. b=8.33 ?, c=9.49 ? and Β=106‡. The Β′-form anhydride has the following lattice Constants a=12.25 ?, b=3.78 ?, c=14.95 ? and Β=98.6‡ with the space group P2/c(C _2h ⁴ ).

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Zusammenfassung a) Polymorphismus Kupferoxynat-Dihydrat hat drei verschiedene Kristall-formen, n?mlich die Alpha-, Gamma- und Beta-form. Die Gamma-Form ist eine intermedi?re Kristallform im Verlauf der Umwandlung von der Alpha- in die Beta-Form in w?\riger Suspension. Diese Umwandlungen ergeben 3 polymorphe Anhydrite, n?mlich die Alpha-, Gamma- und Beta-Form durch Dehydrierung, und sie alle gehen über in die stabilste Anhydritdibeta-Form. Die Beta-Form f?llt auch direkt aus der L?sung etwa bei der Siedetemperatur aus. Die Beziehung zwischen den verschiedenen Kristallformen wird ebenfalls diskutiert. b) Kristallstrukturen Die Parameter der Elementarzelle der Gamma-Form des dihydrierten Kristalls werden zu α=13,10 ?, b=8,3 ?, c=9,49 ? und Β=106‡ festgestellt. Die Beta-Form des Anhydrits hat die folgenden Gitterkonstanten α=12,2 ?, b=3,38 ?, c=14,95 ? und Β=98,6‡ und die Raumgruppe P2/c(C _2h ^7/4 ).

     

The association between the CASP5 rs7939842 polymorphism and the risk of rheumatoid arthritis in Chinese Han individuals

BackgroundThe association between inflammatory cysteinyl aspartate protease-5 (CASP5) and the susceptibility to rheumatoid arthritis (RA) remains unclear. This study examined whether the CASP5 rs7939842 polymorphism affects RA risk in Chinese Han individuals.MethodsThis study recruited 805 RA patients and 1095 healthy controls to investigate the association between the CASP5 rs7939842 polymorphism and RA risk. Genotype was examined using the 48-Plex SNPscan? Kit. Plasma CASP5 levels were determined using enzyme-linked immunosorbent assays, and CASP5 gene expression was detected by quantitative polymerase chain reaction in 40 RA patients and 40 healthy controls.ResultThe CASP5 rs7939842 polymorphism G allele is a putative risk factor for RA. After stratified analyses, this polymorphism increased the risk of RA among CRP-, ACPA-, RF-, and ESR-positive individuals, as well as individuals with DAS28 ≥ 3.20 and functional class III + IV. Furthermore, the plasma CASP5 levels and CASP5 mRNA expression were higher in RA patients than in healthy controls.ConclusionThe CASP5 rs7939842 polymorphism appears to be associated with an elevated risk of RA in Chinese Han individuals. Blood CASP5 protein and mRNA levels were significantly higher in RA patients than in healthy controls.     

The thermodynamic rules governing polymorphism of beryllium oxide

A thermodynamic analysis of qualitative and quantitative rules governing polymorphism of BeO was performed. Equations for the temperature dependences of its polarization and isobaric heat capacity in the low-temperature neighborhood of the wurtzite polymorph-rutile polymorph transition point were suggested. Equations describing the curvature of the line of this transition and mutual correlation of the temperature dependences of the thermodynamic characteristics of beryllium oxide were obtained.     

The lyotropic polymorphism of two pharmacologically active molecules

The two drugs considered are amiodarone hydrochloride (AC), used in heart therapy and palmitoyl timolol malonate (PTM), a prodrug of timolol and a medicament for glaucoma. These crystalline compounds are poorly soluble in water at room temperature, but form transparent phases, which are sols or gels, much more concentrated than the critical micellar concentration (CMC), when the crystals are heated in the presence of water to temperatures from 50 to 80 degrees C and cooled to room temperature. These transparent pseudo-solutions were also obtained by dissolution in chloroform, followed by rapid solvent evaporation and addition of water. A lamellar phase was also observed, with its classical textures: myelin forms, oily streaks and polygonal fields. Two transparent and isotropic phases, one more concentrated than the lamellar phase and the other one less concentrated, are presumed to be inverse sponges. The water-rich phase, mainly studied with amiodarone, formed a milky cloud on further dilution and a model has been proposed. From these two examples, some remarks of a geometrical kind are presented on the rich polymorphism of certain water-lipid systems.     

The lyotropic polymorphism of two pharmacologically active molecules

The two drugs considered are amiodarone hydrochloride (AC), used in heart therapy and palmitoyl timolol malonate (PTM), a prodrug of timolol and a medicament for glaucoma. These crystalline compounds are poorly soluble in water at room temperature, but form transparent phases, which are sols or gels, much more concentrated than the critical micellar concentration (CMC), when the crystals are heated in the presence of water to temperatures from 50 to 80 degrees C and cooled to room temperature. These transparent pseudo-solutions were also obtained by dissolution in chloroform, followed by rapid solvent evaporation and addition of water. A lamellar phase was also observed, with its classical textures: myelin forms, oily streaks and polygonal fields. Two transparent and isotropic phases, one more concentrated than the lamellar phase and the other one less concentrated, are presumed to be inverse sponges. The water-rich phase, mainly studied with amiodarone, formed a milky cloud on further dilution and a model has been proposed. From these two examples, some remarks of a geometrical kind are presented on the rich polymorphism of certain water-lipid systems.     

The polymorphism of ice: five unresolved questions

Our recent discovery of three new phases of ice has increased the total number of known distinct polymorphs of ice to fifteen. In this Perspective article, we give a brief account of previous work in the field, and discuss some of the particularly interesting open questions that have emerged from recent studies. These include (i) the effectiveness of acid and base dopants to enable hydrogen-ordering processes in the ices, (ii) the comparison of the calorimetric data of some of the crystalline phases of ice and low-density amorphous ice, (iii) the disagreement between the experimental ice XV structure and computational predictions, (iv) the incompleteness of some of the hydrogen order/disorder pairs and (v) the new frontiers at the high and negative pressure ends of the phase diagram.     

The genetic haptoglobin polymorphism: relevance of paternity assessment

A practical method for haptoglobin subtyping is described utilizing fast sample preparation by means of batch adsorption to DEAE-cellulose and subsequent isoelectric focusing of reductively cleaved samples. The expanded haptoglobin polymorphism leads to an increase of the theoretical paternity exclusion rate to approximately 33%. Hence, the system appears to be highly attractive for paternity assessment.     

Fifty-nine bp repeat polymorphism in the uncommon intron 36 of the human mucin gene MUC5B

A variable number of tandem repeat (VNTR) polymorphism within the intron 36 of the human mucin gene MUC5B, which is mapped to chromosome 11 band p15.5, have been identified using Southern blotting experiments. This polymorphism can be easily assayed by polymerase chain reaction (PCR) to detect linkage of inherited disorder. Five alleles were observed in 86 unrelated individuals due to 3-8 direct perfect repeats of 59 bp. This repeat has the particularity to begin at the end of the preceding exon. Southern blot experiments revealed the locus specificity of the repeat. The sequence of the repeat unit does not match the consensus sequence of Chi-related minisatellites.     

Kinetic insights into the role of the solvent in the polymorphism of 5-fluorouracil from molecular dynamics simulations

We investigate the fundamental factors controlling polymorphism in 5-fluorouracil by performing molecular dynamics simulations of solutions of the compound in water, nitromethane, and wet nitromethane. Analysis of the effect of solvent on the initial aggregation of 5-fluorouracil molecules shows that the strong binding of water to the 5-fluorouracil molecule hinders the formation of the doubly hydrogen-bonded dimer and, by default, promotes close hydrophobic F...F interactions that are a feature of the unusual (Z' = 4) structure of form I. In contrast, doubly hydrogen-bonded dimers are observed to form readily in solution in dry nitromethane, consistent with the crystallization of the doubly hydrogen-bonded ribbon structure of form II from this solvent. When nitromethane is doped with water, the water forms hydrogen bonds to the solute, interfering with the formation of the doubly hydrogen-bonded dimers, which is consistent with the crystallization of form I from this hygroscopic solvent when it is not dried. Overall, the molecular dynamics simulations provide an atomistic picture of how solvent-solute interactions can significantly affect the initial association of 5-fluorouracil molecules to the extent that they determine the polymorphic outcome of the crystallization.     

Isotopomeric polymorphism

The complex formed between 4-methylpyridine and pentachlorophenol (4MPPCP) crystallizes in a triclinic space group. If the same complex is synthesized from deuterated pentachlorophenol (4MPPCP-d1), it crystallizes in an entirely different monoclinic polymorph. Solid-state NMR of samples synthesized with a full range of deuteration levels, crystallized from solution or the melt, and in the presence or absence of seeds confirms that the isotopomers indeed have different thermodynamically stable crystal structures. The phenomenon is apparently due to very different hydrogen bond strengths between the two polymorphs.     

Structure and polymorphism of complex phosphates prepared from fluxes of the Na2O-P2O5-Fe2O3-Nb2O5 system

The phase formation of complex phosphates in the Na₂O-P₂O₅-Fe₂O₃-Nb₂O₅ flux system was studied in the ranges of sodium-to-phosphorus ratios of 0.7–1.2 and iron-to-niobium ratios of 0.9–2.7. The crystallization region and crystallization conditions for the compounds of composition Na_3?2x Fe_2-x Nb_x(PO₄)₃ (0.8 ≤ x < 1.2) were found. These compounds can be prepared in two (hexagonal and monoclinic) polymorphs. Single-crystal X-ray diffraction experiments were carried out for hexagonal NaFeNb(PO₄)₃ (space group $R\bar 3$ c, a = 8.590 Å, c = 22.013 Å). The polymorphism in Na_3-2x Fe_2-x Nb_x(PO₄)₃ complex phosphates is considered as dependent on the preparation parameters.     

The effect of phenyltin chlorides on the phase polymorphism of dipalmitoylphosphatidylcholine

The effects of diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT) on polymorphic phase behaviour of aqueous dispersions of a dipalmitoylphosphatidylcholine (DPPC) bilayer were investigated by means of ³¹P NMR. It is suggested that DPhT induces interdigitated gel phase formation and TPhT induces hexagonal phase formation. The toxic activities of DPhT and TPhT seem to be connected with their ability to induce changes in the membrane structure. Copyright © 2001 John Wiley & Sons, Ltd.