Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Powder Diffraction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed2001

Liquid ammonia mediated metathesis: synthesis of binary metal chalcogenides and pnictides.

Addition of stoichiometric amounts of low valent metal halides to liquid ammonia solutions of disodium chalcogenide (Na(2)E; E = S, Se, Te) afforded a range of both crystalline (PbE (E = S, Se, Te), TlE (E = S, Se), Tl(5)Te(3), Ag(2)E (E = S, Se, Te)) and X-ray amorphous (MS (M = Ni, Cu, Zn, Cd, Hg), M(2)E(3) (M = Ga, In; E = S, Se, Te), HgE (E = Se, Te), CuE (E = S, Se, Te), Cu(2)S) metal chalcogenides in good yield (95%). Reactions between metal halides and sodium pnictides (Na(3)Pn; Pn = As, Sb) in liquid ammonia also afforded X-ray amorphous material (M(3)Pn(2), M = Zn, Cd; MPn, M = Fe, Co, Ni) in good yield (95%). Isolation of the metal chalcogenides and pnictides was achieved through washing with CS(2) and distilled water. All reactions were complete within 36 h. Products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDXA), electron probe analysis, FT-IR spectroscopy, Raman spectroscopy, microanalysis, and band gap measurements. Annealing amorphous material at 250-300 degrees C for 48 h induced sufficient crystallinity for analysis by X-ray powder diffraction.

Journal Article↗
PubMed2002

Decomposition of silver carbonate; the crystal structure of two high-temperature modifications of Ag(2)CO(3).

High-resolution powder diffraction was used to study the thermal transformation of silver carbonate. A sample of Ag(2)CO(3) was heated in a capillary under 4.5 atm CO(2) pressure. The decomposition temperature of silver carbonate to silver oxide is thereby increased, allowing high-resolution synchrotron X-ray powder diffraction patterns of the two high-temperature phases of Ag(2)CO(3) to be collected. The structure of the low-temperature (lt) phase was confirmed, and the structures of the two high-temperature phases were determined by direct methods and refined using the Rietveld method: lt-Ag(2)CO(3) (295 K) P2(1)/m, z = 2, a = 4.8521(2) A, b = 9.5489(4) A, c = 3.2536(1) A, beta = 91.9713(3) degrees; beta-Ag(2)CO(3) (453 K) P31c, z = 6, a = 9.1716(4) A, c = 6.5176(3) A; alpha-Ag(2)CO(3) (476 K) P6 macro 2m, z = 3, a = 9.0924(4) A, c = 3.3249(1) A. In addition, thermal expansion properties, anisotropic microstrain distributions, and thermal transformations of the three silver carbonate phases and silver oxide are described.

Journal Article↗
PubMed2005

Synthesis and structure of the framework scandium methylphosphonates ScF(H2O)CH3PO3 and NaSc(CH3PO3)2.0.5H2O.

Two framework scandium methylphosphonates have been prepared hydrothermally and their structures solved. ScF(H(2)O)CH(3)PO(3) is a non-porous solid built up from -ScF- chains linked by methylphosphonate groups. The ScO(4)F(2) octahedra are completed by a coordinated water molecule. NaSc(CH(3)PO(3))(2).0.5H(2)O was solved ab initio from high-resolution synchrotron X-ray powder diffraction data. It has a fully connected, negatively charged scandium phosphonate framework where ScO(6) octahedra share vertices with PO(3)CH(3) groups. The solid contains charge balancing sodium cations, coordinated by a water molecule, which may be reversibly removed and adsorbed. The structure of the perdeuterated, dehydrated solid has been refined against neutron powder diffraction data collected at 2.5 K, showing the CD(3) groups in a fully staggered orientation with respect to the phosphonate oxygen atoms.

Journal Article↗
PubMed1999

Anti-Inflammatory Dinuclear Copper(II) Complexes with Indomethacin. Synthesis, Magnetism and EPR Spectroscopy. Crystal Structure of the N,N-Dimethylformamide Adduct.

Veterinary anti-inflammatory Cu(II) complexes of indomethacin (1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid = IndoH), of the general formula [Cu(2)(Indo)(4)L(2)] (L = N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-methylpyrrolidone (NMP), and water), were studied by zero-field and X-band EPR spectroscopies, electronic spectroscopy, magnetic measurements, and X-ray powder diffraction. The complexes are similar to Cu(II) acetate monohydrate, with a strong antiferromagnetic exchange interaction, J, ranging from -141 to -152 cm(-)(1). Variable temperature magnetic susceptibility data for all of the complexes are similar, with the exception of a [Cu(2)(Indo)(4)(H(2)O)(2)] complex, which displays an unusual increase in magnetic moment with decreasing temperature from 50 to 10 K. The X-ray powder diffraction patterns of the DMF and DMA dimers show that they are isostructural. Two isostructural H(2)O complexes were synthesized from different methods yet displayed different variable temperature magnetic susceptibity data. All of the [Cu(2)(Indo)(4)L(2)] complexes crystallize in the triclinic space group P&onemacr;. Single-crystal X-ray diffraction analysis of the DMF complex, [Cu(2)(Indo)(4)(DMF)(2)].1.6(DMF), shows that it is similar to the previously reported [Cu(2)(Indo)(4)(DMSO)(2)] with a Cu-Cu bond length of 2.630(1) Å, Cu-O(RCOO) of 1.960(4)-1.967(4) Å, and Cu-O(DMF) of 2.143(5) Å and crystal parameters a = 10.848(3) Å, b = 13.336(6) Å, c = 16.457(4) Å, alpha = 104.67(3) degrees, beta = 100.94(2) degrees, and gamma = 107.16(3) degrees. The X-ray structure of the DMF dimer does not exhibit strong intermolecular interactions due to the hydrophobic nature of the exterior. This may be important in facilitating its dissolution in micelles and transport through membranes.

Journal Article↗
PubMed2000

Comparison of two heat-pressed all-ceramic dental materials.

OBJECTIVES: The processing route for two heat-pressed all-ceramic materials (Empress and OPC) is virtually identical. The purpose of this study was to determine the mechanical properties of both materials and determine if significant differences exist between them. METHODS: X-ray powder diffraction of the ceramics before and after processing was carried out to identify the crystal phases present. The mechanical properties of both materials were tested. Specimens were tested for hardness, fracture toughness (indentation method) and flexural strength (biaxial method). The results were statistically evaluated and tested for differences using a Mann-Whitney test. Secondary electron imaging of both materials was carried out before and after processing. RESULTS: X-ray powder diffraction revealed that OPC changes as a result of heat-pressing from being a complex mixture of crystalline oxides to a glass-ceramic. In contrast Empress is a glass-ceramic before and after processing. X-ray diffraction identified leucite as the main crystalline phase in both ceramics. The biaxial flexural strength of OPC was 153.6 (17.8) MPa and for Empress was 134.4 (11.5) MPa. The hardness of OPC was 7.28 (0.62) GPa and for Empress was 6.94 (0.79) GPa. Indentation fracture toughness of OPC was 1.36 (0.29) MPam0.5 and for Empress was 1.33 (0.08) MPam0.5. Secondary electron images show Empress to be the same before and after processing while OPC is clearly very different. Empress also appears to have a higher glass content compared with OPC. SIGNIFICANCE: The results of X-ray diffraction show that Empress is pre-cerammed whilst OPC is not. Statistical analysis revealed that no significant difference exists between the two materials for any of the mechanical properties tested at a 95% (p < 0.05) confidence level. It was concluded that no difference exists between the two materials on completion of processing.

Aluminum Silicates↗
PubMed1998

Synthesis of Nanoporous Cubic In(CN)(3) and In(1)(-)(x)()Ga(x)()(CN)(3) and Corresponding Inclusion Compounds.

Anhydrous In(CN)(3) and In(1)(-)(x)()Ga(x)()(CN)(3) phases with empty Prussian-blue-type structures have been prepared via low-temperature solution methods utilizing molecular templating agents. Quantitative X-ray powder diffraction was used to refine the In(CN)(3) cubic structure in which In is octahedrally surrounded by an average of three C and three N atoms. The symmetry is Pm&thremacr;m, a = 5.627(1) Å, and the In-(C,N) and C-N bond lengths are 2.251(1) and 1.125(1) Å, respectively. The compound reversibly incorporates krypton atoms into the empty cavities to form In(CN)(3).Kr, which is readily identified by powder diffraction. Similar inclusion systems with n-hexane in the porous framework are also synthesized. In(1)(-)(x)()Ga(x)()(CN)(3) solid solutions are formed by suitable combinations of the binary systems and have lattice constants adjustable between 5.293 Å for Ga(CN)(3) and 5.627(1) Å for In(CN)(3). The variation of the lattice parameters with composition obeys Vegard's Law.

Journal Article↗
PubMed2002

Compatibility studies between carbamazepine and tablet excipients using thermal and non-thermal methods.

Proper formulation is an important aspect of any dosage form design. As a part of preformulation studies, differential scanning calorimetry (DSC) was used to investigate the physicochemical compatibility between Carbamazepine and various excipients commonly used in tablet manufacturing, supported by Fourier transform infrared (FTIR) and x-ray powder diffraction (XRPD) studies. Compatibility studies were conducted on samples kept at room temperature and at an elevated temperature of 55 degrees C for 3 weeks. Carbamazepine was found to be compatible with all lactose-based components, such as Granulac 230, Flowlac 100, and Microcelac 100. Differential scanning calorimetry studies indicated incompatibility with mannitol, microcrystalline cellulose, starch, and stearic acid. However, XRPD and FTIR studies implied that all the above excipients are compatible with Carbamazepine. X-ray powder diffraction demonstrated incompatibility with stearic acid for samples stored at 55 degrees C for 3 weeks, indicative of formation of a solid solution. Thus, DSC being a thermal method of analysis should not be used singly to detect any inherent incompatibility. It has to be supported sufficiently by other non-thermal techniques, such as XRPD and FTIR.

Anticonvulsants↗
PubMed2005

Layered and pillared metal carboxyethylphosphonate hybrid compounds.

A series of carboxyethylphosphonate hybrid materials has been prepared: Mn(II)(O3PCH2CH2COOH) *H2O (1), Mn(III)(OH)(O3PCH2CH2COOH)*H2O (2), Al3(III)(OH)3(O3PCH2CH2CO2)2 *3H2O (3) and Cr2(III)(OH)3(O3PCH2CH2CO2) *3H2O (4). Compounds 1 and 2 were synthesized from Mn(III)(CH3COO)3 *2H2O under hydrothermal, or refluxing treatments, respectively. The crystal structures of the manganese-bearing solids have been solved ab initio from laboratory X-ray powder diffraction data and refined by the Rietveld method. 1 crystallises in a orthorhombic cell and 2 in monoclinic symmetry. Both solids have inorganic 2D layered structures with the acid carboxylic groups pointing towards the interlayer space, and the layers linked only through hydrogen bonds. The inorganic layers of these compounds are formed by manganese atoms in distorted octahedral environments linked together by the phosphonate groups. The crystal structure of 3 has been solved ab initio from synchrotron X-ray powder diffraction data. This solid shows a pillared structure with the phosphonate and carboxylate groups cross-linking the inorganic layers. These layers contain chains of aluminium octahedra running parallel to each other. 4 is amorphous and the IR-UV-VIS spectra suggest a framework with Cr(III) cations in octahedral environments. Thermal, spectroscopic and magnetic data for manganese and chromium compounds as well as the structural details of these solids are discussed.

Journal Article↗
PubMed1998

One- and Two-Coordinate Detectors in BINP.

One- and two-coordinate detectors with proportional chambers developed at the Budker Institute of Nuclear Physics (BINP) are presented. The parallax-free 10 MHz one-coordinate OD-3.1 and OD-3.2 detectors are used in synchrotron radiation powder diffraction and SAXS experiments. The two-coordinate DED-3 detector with a multiwire proportional chamber (MWPC) is used in Laue diffraction. The latest modification of this detector, DED-5, with a working area of 384 x 384 mm, is briefly described. The micro-strip detector prototype MSGC-100 has passed test synchrotron radiation experiments and the next modification (MSGC-500), with 500 channels for high energy, is under construction. The one-coordinate MWPC OD-160 detector, with an angle aperture of 160 degrees and a count rate of 3.3 GHz, is under construction. It will be used for high-resolution powder diffraction. Two types of gas chamber will be used: L for low energies (5-30 keV) and H for high energies (30-70 keV). A 16 degrees section with an H-chamber has been produced and tested on the synchrotron radiation beamline.

Journal Article↗
PubMed1985

Structure and polymorphism of 1,2-dioleoyl-3-acyl-sn-glycerols. Three- and six-layered structures.

Triacylglycerols, which usually contain at least one unsaturated fatty acid, are the most important forms of stored biological lipids in teleosts, mammals, and most plants. Since the physical properties of such mixed-chain triacylglycerols are poorly understood, a systematic study of such compounds has been initiated. Stereospecific 1,2-dioleoyl-3-acyl-sn-glycerols were synthesized with even carbon saturated fatty acyl chains of 14-24 carbons in length. Their polymorphic behavior was examined by differential scanning calorimetry and X-ray powder diffraction. The thermal behavior revealed from one to four major polymorphic transitions depending upon saturated chain length. Plots of enthalpy of fusion and entropy vs. carbon number for melting of the most stable polymorph were linear throughout the series with slopes of 1.0 kcal/mol per carbon atom and 2.6 cal/(mol K) per carbon atom, respectively. These slopes indicate that the saturated chains are packed in a well-ordered tightly packed lattice. When the compounds were rapidly cooled to 5 degrees C, X-ray powder diffraction revealed strong beta' (ca. 3.8 and 4.2 A) reflections and weak beta (ca. 4.6 A) reflections. The beta subcell reflections intensified when the compounds were heated to within 5 degrees C of the melting temperature of the highest melting polymorph. Evidence of an alpha phase was not seen on 30-min X-ray exposures for any of the compounds. In the proposed packing arrangement the saturated and unsaturated chains are segregated into layers. The stable form of all compounds exhibits a triple layer packing mode in which a bilayer of oleoyl chains is segregated from an interdigitated layer of saturated chains.(ABSTRACT TRUNCATED AT 250 WORDS)

Calorimetry↗
PubMed2002

Cystine: a promoter of the growth and aggregation of calcium oxalate crystals in normal undiluted human urine.

PURPOSE: Many variables are known to be associated with the formation of calcium oxalate stones. We noted that on analysis a number of patients with calcium oxalate calculi also had cystine in the stones. Some but not all of these patients showed urinary cystine excretion slightly above the normal limits, resembling heterozygous carriers. This finding raised the question of whether some recurrent stone formers may be at risk for calcium oxalate calculi when they excrete cystine in above normal concentrations. MATERIALS AND METHODS: Pooled urine obtained from 3 pairs of age and sex matched controls was independently analyzed. Each urine sample was divided into spun and filtered, and ultrafiltered urine. A Multisizer II (Coulter Electronics Ltd, Beds, England) was used to measure particle number, diameter and volume. The metastable limit of each specimen was determined. Promotion activity was measured in spun and filtered, and ultrafiltered urine using 3 concentrations of cystine (80, 160 and 320 micromol./l.). Results were confirmed by measuring the incorporation of (14)C-oxalate into the crystals. Scanning electron microscopy was performed to study further the agglomerates as well as exclude cystine crystals. Each experiment was repeated 6 times. Crystalline material was collected for x-ray powder diffraction analysis. RESULTS: The urine metastable limit did not change with increasing cystine concentrations. Particle diameter increased significantly from 10.6 microm in ultrafiltered urine alone to 11.6 and 13.5 microm (p < 0.05) at 160 and 320 micromol/l. cystine, respectively. In addition, particle volume also increased proportionally in a dose response manner to cystine concentration. The dose of 320 micromol/l. cystine increased the crystal growth rate 52%. 14C-oxalate experiments confirmed these results. Scanning electron microscopy at 500x magnification revealed no cystine crystals in any experiments performed. Furthermore, x-ray powder diffraction analysis of samples revealed that experimentally determined parameters matched reference values for calcium oxalate trihydrate but not for cystine, again confirming absent cystine in the samples. CONCLUSIONS: Adding cystine to undiluted human urine resulted in the marked enhancement of calcium oxalate crystal precipitation. When considered with the finding of cystine in calcium oxalate stones in the noncystinuric population, this result implies that urinary cystine may be a risk factor for calcium oxalate calculi. Cystine was not observed in any calcium oxalate crystals, suggesting that the mechanism of crystal formation was a salting out effect.

Calcium Oxalate↗
PubMed2001

Solid state properties of pure UC-781 and solid dispersions with polyvinylpyrrolidone (PVP K30).

The purpose of this study was to elucidate the physical structure of solid dispersions of the antiviral agent UC-781 (N-[4-chloro-3-(3-methyl-2-butenyloxy)phenyl]-2-methyl-3-furancarbothioamide) with polyvinylpyrrolidone (PVP K30). Solid dispersions were prepared by coevaporating UC-781 with PVP K30 from dichloromethane. The physicochemical properties of the dispersions were evaluated in comparison with the physical mixtures by differential scanning calorimetry (DSC), X-ray powder diffraction, and FT-IR spectroscopy. We investigated the single crystal structure of pure UC-781. The data from single crystal analysis showed that UC-781 crystallized with orthorhombic symmetry in the space group Pcab. Its cell parameters were found to be; a = 8.1556(7) A,b = 17.658(2) A and c = 23.609(2) A; the unit cell was made up of eight molecules of UC-781. The molecules formed intermolecular hydrogen bonds between NH and thio groups, and were packed in a herringbone-like structure. The data from X-ray powder diffraction showed that crystalline UC-781 was changed into the amorphous state by co-evaporating it with PVP K30. From differential scanning calorimetry analysis, UC-781 peaks were observed in the DSC curves of all physical mixtures, while no peaks corresponding to the drug could be observed in the solid dispersions with the same drug composition up to the concentration of 50% w/w. The data from FT-IR spectroscopy showed the distortions and disappearance of some bands from the drug, while other bands were too broad or significantly less intense compared with the physical mixtures of the crystalline drug in PVP K30. Furthermore, the results from IR spectroscopy demonstrated that UC-781 interacted with PVP K30 in solid dispersions through intermolecular H-bonding.

Anilides↗
PubMed1977

Polymorphism and H-bonding of 2-[1(2H)-oxo-2-phthalazinyl]methylbenzoic acid.

The three crystalline and one amorphous forms of the title compound, so far isolated, have been characterized by differential scanning calorimetry, thermomicroscopy, infrared spectroscopy and X-ray powder diffraction. From I was obtained by solidification of the melt at 200 degrees; form II by crystallization from water/ethanol 1/1; form III by grinding of II; the amorphous form by rapid cooling of the melt or by evaporation to dryness of a chloroform solution. From II melts of about 200 degrees and immediately crystallizes into form I, which melts at 210 degrees. Form III transforms into I at 165 degrees. The infrared spectra of form I is different from that of forms II and III, while each form has a different X-ray powder diffraction. From consideration of the infrared functional absorption bands, it can be derived that form I is a dimer with H-bonds between the carboxylic groups, forms II and III are monomers with intramolecular H-bond between the carboxylic group and the hydrazide carbonyl, displaying different crystal packings, and the amorphous form is a mixture of both monomers and dimers, the latters in greater amount.

Benzoates↗
PubMed2005

Temperature effects on the hydrogen-bond patterns in 4-piperidinecarboxylic acid.

A temperature-controlled X-ray powder diffraction experiment, complemented with TGA and DSC analysis, allowed us to follow changes in the molecular conformation and hydrogen-bond patterns of 4-piperidinecarboxylic acid. The presence of three phases is confirmed. Phase 1 represents the monohydrated form of 4-piperidinecarboxylic acid, which exists from room temperature to 359 K, where dehydration occurs. Phase 2 measured at 363 K corresponds to an anhydrous form of the acid. At ca 458 K the onset of a second, more gradual transition is observed, which ends at around 543 K. Phase 3 measured at 543 K is a high-temperature anhydrous form of the acid. The structures of phases 2 and 3 were solved from synchrotron powder diffraction data by simulated annealing using the DASH program and refined by the Rietveld method. The phase changes are accompanied by modification of the hydrogen-bond patterns and of the torsional orientation of the terminal carboxylate group. This group makes a 49 degrees rotation about the C1-C2 bond during the first transition.

Calorimetry, Differential Scanning↗
PubMedDate not supplied

In vitro and in vivo evaluation of a new Opaque system for metal ceramic restorations.

This study made an in vitro comparison of the shear strength in a corrosive solution, the scanning electron microscopy of the processing steps, and the x-ray powder diffraction analyses of a newly developed opaque system (Biopaque) with a traditional opaque-system (Opaque P). Clinically, two traditional opaque systems (Opaque P and Vita-VMK-Paint-On 88 opaque) were compared to Biopaque over a 4-year period. A total of 218 metal ceramic units were placed for 29 patients. One hundred ten were veneered with Biopaque, 50 with Opaque P, and 58 with Vita-VMK-Paint-On 88. The technical failure rate of the metal ceramic restorations was 9.6%, and the biological failure rate 5.5%. There was no significant difference of the shear strength in a corrosive solution between Biopaque and the traditional opaque system (Opaque). The x-ray powder diffraction analyses revealed that only the base paste of Biopaque was a newly developed material. In this study, the new opaque system (Biopaque) showed the same in vitro and in vivo results as the other conventional opaque systems. However, at least 5 years of clinical evaluation are necessary before this new opaque system can be completely recommended.

Adult↗
PubMed1998

Detoxified glutaraldehyde cross-linked pericardium: tissue preservation and mineralization mitigation in a subcutaneous rat model.

BACKGROUND AND AIM OF THE STUDY: Glutaraldehyde is considered a promoter of calcification by the action of toxic aldehyde group residuals from cross-linking. Post-fixation treatment with homocysteic acid (HA), besides bonding aldehyde groups and neutralizing toxicity, should enhance biocompatibility due to the strongly electronegative sulfonic group. The aim of this investigation was to evaluate HA efficacy on tissue preservation and dystrophic calcification mitigation in glutaraldehyde cross-linked bovine pericardium (BP) using a subcutaneous rat model. METHODS: Four samples of BP, two with glutaraldehyde-HA and two with glutaraldehyde treatment, were implanted in each of 24 male Sprague-Dawley rats. Three rats were killed at 14 days, eight at 28 days, eight at 56 days and five at 84 days. Unimplanted glutaraldehyde-HA- and glutaraldehyde-treated samples served as controls. All samples were studied by gross examination, mammography, light transmission and scanning electron microscopy, and atomic absorption spectroscopy. The nature of mineralization was investigated by coupling techniques of scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. RESULTS: No histological and ultrastructural differences were found between glutaraldehyde-HA- and glutaraldehyde-treated BP, whether implanted or unimplanted. In both groups, calcification progressed with time, but significantly less after glutaraldehyde-HA treatment than after glutaraldehyde alone and at all time intervals (14.63 +/- 21.34 versus 43.17 +/- 15.99 at 28 days, p = 0.003; 56.42 +/- 40.20 versus 90.59 +/- 32.90 at 56 days, p = 0.008; 91.68 +/- 67.68 versus 156.23 +/- 17.85 at 84 days, p = 0.01). Differences were evident by mammography and histology (von Kossa stain). Electron microprobe analysis in both groups showed the composition of calcified nuclei to be calcium phosphate, stoichiometrically close to apatite (Ca5(PO4)3(OH)). The occurrence of crystallized apatite was supported by X-ray powder diffraction findings, the amount of crystallized apatite being higher in glutaraldehyde-treated samples. CONCLUSIONS: Post-fixation treatment with HA preserves BP structural properties and significantly mitigates mineralization of long-term subcutaneous implants.

Animals↗
PubMed2005

Solid state characterization of mometasone furoate anhydrous and monohydrate forms.

Mometasone furoate is a potent glucocorticoid anti-inflammatory agent. Its anhydrous Form 1 and monohydrate form were characterized by X-ray crystallography, X-ray powder diffraction at ambient and elevated temperature, thermal analysis, FT-IR, and dynamic moisture adsorption. In Form 1, mometasone furoate molecules pack tightly with molecules interlocked in a space group of P2(1)2(1)2(1). The monohydrate form crystallizes in space group P1. The unit cell of the monohydrate contains one water molecule and one mometasone furoate molecule. The water molecules form channels along the a axis and mometasone furoate molecules pack in layers in the same direction. Dehydration was observed between 60 and 100 degrees C by thermogravimetric analysis with a heating rate of 10 degrees C/min. It corresponds to a broad endotherm over the same temperature range in the differential scanning calorimetry with the same heating rate. Variable temperature X-ray powder diffraction reveals that a new anhydrous form (Form 2) was fully produced above 90 degrees C. This crystalline form was converted to Form 1 after being heated above 150 degrees C; and was totally converted to the monohydrate after 1 day at 23 degrees C, 45% RH.

Anti-Inflammatory Agents↗
PubMed2004

Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine.

The ternary piroxicam (Pir; 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide) complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with various amino acids (AA) such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized by elemental analyses, molar conductance, IR, UV-Vis, magnetic moment, diffuse reflectance and X-ray powder diffraction. The UV-Vis spectra of Pir and the effect of metal chelation on the different interligand transitions are discussed in detailed manner. IR and UV-Vis spectra confirm that Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its carboxylic group, in addition PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its carboxylic and amino groups. All the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. The molar conductance data reveal that most of these chelates are non electrolytes, while Fe(III)-Pir-Gly, Co(II)-, Ni(II)-, Cu(II)- and Zn(II)-Pir-PhA chelates were 1:1 electrolytes. X-ray powder diffraction is used as a new tool to estimate the crystallinity of chelates as well as to elucidate their geometrical structures.

Chelating Agents↗