Crystal Structure Data for Efavirenz (Sustiva™) by Combined Synchrotron X-Ray Diffraction and Electron Microscopy Techniques

2001 ◽  
Vol 7 (S2) ◽  
pp. 630-631
Author(s):  
Z. G. Li ◽  
R. L. Harlow ◽  
W. Marshell ◽  
C. M. Foris ◽  
D. Murphy ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Crystal Form ◽  
Transcriptase Inhibitor ◽  
Process Conditions ◽  
X Ray Diffraction ◽  
Synthetic Process ◽  
X Ray ◽  
Cell Parameters ◽  
Solvate Form ◽  
Diffraction Patterns

Efavirenz (Sustiva™) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) for the treatment of HrV-infected patients and has been in the market since 1998. Efavirenz exists as three different polymorphs (Forms I, II, III) and a nonstochiometric heptane solvate (Form IV). The current synthetic process for Efavirenz yields Form IV which is converted to the desired Form I polymorph by heating. One of the concerns for any drug substance is whether a consistent crystal form is produced in order to insure consistent physical and chemical properties, as well as to safeguard pharmacokinetic profiles. The sensitivity and resolution of single-crystal x-ray diffraction, the traditional method employed to determine unit cell parameters of drug compounds in development, are limited for Efavirenz Form IV because of the small crystallite size of the material. Furthermore, Efavirenz Form IV materials, depending on the process conditions, have slightly different powder diffraction patterns in terms of intensity when collected on standard in-house diffractometers.

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

X-ray diffraction patterns for BaR2PdO5 (R=Nd, Sm, Eu, and Gd)

1996 ◽  
Vol 11 (1) ◽  
pp. 9-12
Author(s):  
W. Wong-Ng
Keyword(s):  
Materials Characterization ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
The Eu

Calculated patterns for the BaR2PdO5 series, in which X is Pd and R=Nd, Sm, Eu, or Gd, have been prepared for materials characterization until experimental patterns can be determined. These compounds are isostructural to the superconductor related “brown phases” BaLa2CuO5 and BaNd2CuO5, which are tetragonal with space group P4/mbm, Z=4. The cell parameters of the Eu and Gd compounds were derived from the La and Nd analogs. The calculated patterns of these four compounds compared well to an experimental pattern of BaNd2CuO5.

Synthesis and properties of double gadolinium tellurites

2021 ◽  
Vol 103 (3) ◽  
pp. 67-73
Author(s):  
A.A. Toibek ◽  
◽  
K.T. Rustembekov ◽  
D.A. Kaikenov ◽  
M. Stoev ◽  
...  
Keyword(s):  
Phase Analysis ◽  
Solid Phase ◽  
Heat Capacities ◽  
Ceramic Technology ◽  
Phase Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Temperature Range ◽  
Diffraction Patterns

For the first time, double gadolinium tellurites of the composition GdMIITeO4.5 (MII — Sr, Ba) were synthesized by the solid-phase method. The solid-phase synthesis of samples was carried out from decrepitated gadolinium (III) and tellurium (IV) oxides, strontium, and barium carbonates according to the standard ceramic technology. The synthesis was carried out in the temperature range of 800-1100 °C. The samples obtained were confirmed by X-ray phase analysis. X-ray phase analysis was carried out on an Empyrean instrument in the XRDML Pananalitical format. The intensity of the diffraction maxima was estimated on a 100-point scale. X-ray diffraction patterns indexing of the powder of gadolinium tellurites — alkaline earth metals studied were carried out by the homology method. The reliability and correctness of the results of indexing the X-ray diffraction patterns are confirmed by the good agreement between the experimental and calculated values of the interplanar distances (d) and the agreement between the values of the X-ray and pycnometric densities. It was found that compounds GdSrTeO4.5 and GdBaTeO4.5 crystallize in the monoclinic system and have the unit cell parameters, namely GdSrTeO4.5 — a = 12.7610, b = 10.4289, c = 8.6235 Å, V° = 1141.83 Å3, β = 95.77°, Z = 5, ρrent. = 3.22, ρpikn. = (3.10±0.09) g/cm3; GdBaTeO4.5 — a = 15.7272, b = 15.8351, c = 7.1393 Å, V° = 1769.72 Å3, β = 95.53°, Z = 8, ρrent = 3.71, ρpick = (3.61±0.10) g/cm3. Using the Landiya method, the standard heat capacities of the compounds were estimated from the calculated values of the standard entropies, and the temperature dependences of the heat capacities of the gadolinium tellurites synthesized were determined in the temperature range of 298–850 K.

scholarly journals Bi3+ and Eu3+ Activated Luminescent Behaviors in Non-Stoichiometric LaO0.65F1.7 Structure

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2326
Author(s):  
Sungjun Yang ◽  
Sangmoon Park
Keyword(s):  
Optical Materials ◽  
Emission Spectra ◽  
Lattice Energy ◽  
Host Lattice ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
Cation Sites

Optical materials composed of La1-p-qBipEuqO0.65F1.7 (p = 0.001–0.05, q = 0–0.1) were prepared via a solid-state reaction using La(Bi,Eu)2O3 and NH4F precursors at 1050 °C for two hours. X-ray diffraction patterns of the phosphors were obtained permitting the calculation of unit-cell parameters. The two La3+ cation sites were clearly distinguished by exploiting the photoluminescence excitation and emission spectra through Bi3+ and Eu3+ transitions in the non-stoichiometric host lattice. Energy transfer from Bi3+ to Eu3+ upon excitation with 286 nm radiation and its mechanism in the Bi3+- and Eu3+-doped host structures is discussed. The desired Commission Internationale de l’Eclairage values, including emissions in blue-green, white, and red wavelength regions, were obtained from the Bi3+- and Eu3+-doped LaO0.65F1.7 phosphors.

Preparation and preliminary X-ray diffraction studies of a new crystal form of L-asparaginase from Escherichia coli

1999 ◽  
Vol 55 (9) ◽  
pp. 1616-1617
Author(s):  
I. Polikarpov ◽  
R. T. de Oliveira ◽  
J. Abrahão-Neto
Keyword(s):  
Escherichia Coli ◽  
Synchrotron Radiation ◽  
Crystal Form ◽  
Asymmetric Unit ◽  
Chemotherapeutic Drug ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Synchrotron Radiation Diffraction

L-Asparaginase is an enzyme which hydrolyzes asparagine to produce aspartic acid and ammonia. It is an effective chemotherapeutic drug, especially in the treatment of acute lymphoblastic leukaemia in children. The enzyme from Escherichia coli was crystallized in a new crystal form with space group C2, unit-cell parameters a = 76.3 (0), b = 134.6 (2), c = 64.8 (7) Å, β = 110.5 (1)° and a dimer in the asymmetric unit. Synchrotron-radiation diffraction data have been collected to 1.95 Å resolution.

Structure analysis of CaTi1−xSnxO3 (x = 0.0–1.0) solid solutions

2014 ◽  
Vol 29 (3) ◽  
pp. 254-259 ◽  
Author(s):  
Naoki Takani ◽  
Hisanori Yamane
Keyword(s):  
Solid State ◽  
Solid Solutions ◽  
Solid State Reaction ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
Perovskite Type ◽  
Perovskite Type Structure

CaTi1−xSnxO3 (x = 0.0–1.0) solid solutions were prepared by solid-state reaction at 1450 °C. Rietveld refinement of their powder X-ray diffraction patterns revealed that all the solid solutions crystallized in orthorhombic cells with the perovskite-type structure, the space group Pbnm. The refined unit-cell parameters linearly increased with nominal tin contents x.

scholarly journals SpaB, an atypically adhesive basal pilin from the lactobacillar SpaCBA pilus: crystallization and X-ray diffraction analysis

2019 ◽  
Vol 75 (12) ◽  
pp. 731-737 ◽  
Author(s):  
Abhin Kumar Megta ◽  
Airi Palva ◽  
Ingemar von Ossowski ◽  
Vengadesan Krishnan
Keyword(s):  
Lactobacillus Rhamnosus ◽  
Crystal Form ◽  
Data Sets ◽  
Structural Factors ◽  
Lysine Methylation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Dual Functional ◽  
Anomalous Signal

The SpaB pilin is recognized as the basal subunit of the sortase-dependent SpaCBA pilus, which is known to be produced by the Gram-positive Lactobacillus rhamnosus GG, a gut-adapted commensal advocated to have health benefits. Despite seeming to function as an archetypal basal pilin by serving as the terminal subunit in pilus assembly, SpaB also assumes an atypical role as a mucoadhesive protein. To shed light on the structural factors that contribute to this dual functional behaviour, a recombinant form of the L. rhamnosus GG SpaB pilin was produced and purified for crystallization and X-ray diffraction experiments. The crystallization of SpaB remained particularly challenging until the implementation of a three-pronged crystallization approach involving C-terminal tail truncation, surface lysine methylation and magnesium additives. Ultimately, hexagonal crystals of SpaB were produced and were able to diffract to a resolution of 2.4 Å. This crystal form belonged to space group P6522 or P6122, with unit-cell parameters a = b = 51.53, c = 408.22 Å, α = β = 90.0, γ = 120.0°. Obtaining an interpretable electron-density map via single-wavelength anomalous diffraction (SAD) using iodide-derivative data sets did not succeed owing to the weak anomalous signal. As an alternative, attempts to provide phases by molecular replacement using the iodide-SAD data from SpaB and a collection of distant homology models (<28% sequence identity) are in progress.

Synthesis, crystal structure, and X-ray diffraction data of lithium m-phenylenediamine sulfate Li2(C6H10N2)(SO4)2

2021 ◽  
pp. 1-5
Author(s):  
Junyan Zhou ◽  
Congcong Chai ◽  
Munan Hao ◽  
Xin Zhong
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Structural Phase ◽  
Measured Temperature ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Anisotropic Expansion ◽  
Diffraction Patterns

A new organic–inorganic hybrid lithium m-phenylenediamine sulfate (LPS), Li2(C6H10N2)(SO4)2, was synthesized under aqueous solution conditions. The X-ray powder diffraction study determined that the title compound crystallized in a monoclinic system at 300 K, with unit-cell parameters a = 7.8689(6) Å, b = 6.6353(5) Å, c = 11.8322(10) Å, β = 109.385(3) °, V = 582.77(8) Å3. Indexing of the diffraction patterns collected from 100 to 600 K reveals that LPS has no structural phase transition within the measured temperature range, and the volume expansion coefficient is approximately 2.79 × 10−5 K−1. The crystal structure was solved based on the single-crystal diffraction data with space group P21/m. Lithium and SO42− are found to form quasi-two-dimensional anti-fluorite [LiSO4] layers stacking along the c-axis, with m-phenylenediamine molecules inserted in the anti-fluorite layers and forming hydrogen bonds to the SO42−. This explains a moderate anisotropic expansion in LPS.

Powder-Pattern: A System of Programs for Processing and Interpreting Powder Diffraction Data

1982 ◽  
Vol 26 ◽  
pp. 63-72 ◽  
Author(s):  
Nikos P. Pyrros ◽  
Camden R. Hubbard
Keyword(s):  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Pure Phase ◽  
Diffraction Patterns ◽  
Better Than ◽  
Good Agreement

The production of standard x-ray diffraction patterns at NBS imposes special requirements in the data processing of powder patterns. The patterns should be complete and have an overall accuracy of better than 0.01 degree two theta. To ensure completeness all the observable peaks should be indexed. To make certain that the sample is a pure phase, weak peaks have to be identified as well.The indexing of all the peaks implies that the cell constants must be known and there should be a good agreement between all the calculated and observed peak positions. In practice this is achieved by a least-squares refinement of the unit cell parameters. This serves as a test of the assumed unit cell and also as an interpretation of the observed peaks. Finally, an attempt is made to identify the space group. This step also requires the identification of weak peaks. The agreement of a known space group with the observed reflections further confirms the purity of the sample.

Powder diffraction investigations of naphthalenesulfonic acids and their complexes with DMAN

2004 ◽  
Vol 19 (4) ◽  
pp. 378-384
Author(s):  
A. Rafalska-Lasocha ◽  
M. Grzywa ◽  
B. Włodarczyk-Gajda ◽  
W. Lasocha
Keyword(s):  
Powder Diffraction ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Acid Hydrate ◽  
M 12 ◽  
Diffraction Patterns

The X-ray diffraction patterns of two organic acids 1-naphthalenesulfonic acid dihydrate and 2-naphthalenesulfonic acid hydrate were measured at room temperature. Complexes of these acids with 1,8-bis(dimethylamino)naphthalene (DMAN) were synthesized, purified and investigated by means of X-ray powder diffraction. 1-Naphthalenesulfonic acid dihydrate as well as its complex with 1,8-bis(dimethylamino)naphthalene crystallize in the monoclinic system with unit cell parameters refined to a=0.91531(8) nm, b=0.7919(1) nm, c=0.8184(1) nm, β=101.618(9)° space group P21/m (11) and a=1.7781(4) nm, b=2.0122(4) nm, c=1.2337(2) nm, β=96.54(3)°, space group C2/m (12), respectively. 2-Naphthalenesulfonic acid hydrate crystallizes in the orthorhombic system with a=2.2749(3) nm, b=0.7745(1) nm, c=0.591 36(9) nm, space group Pnma, whereas its complex with 1,8-bis(dimethylamino)naphthalene crystallizes in the triclinic system a=1.3969(6) nm, b=1.4292(5) nm, c=1.1741(6) nm, α=90.93(3)°, β=98.14(3)°, γ=113.93(3)°, space group P-1 (2).

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