scholarly journals Preparation and Solid-State Characterization of Eltrombopag Crystal Phases

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 65
Author(s):  
Vincenzo Mirco Abbinante ◽  
Massimo Zampieri ◽  
Giuseppe Barreca ◽  
Norberto Masciocchi
Keyword(s):  
Free Acid ◽  
Variable Temperature ◽  
Intermediate Species ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Crystal Phases ◽  
The Stability ◽  
Solid State Characterization

Eltrombopag, of C25H22N4O4 chemical formula, is a drug used against thrombocytopenia, marketed worldwide under different tradenames in the form of its bis-olamine salt. The free acid (CAS no. 496775-61-2) is an intermediate species used for the final drug isolation and is reported to crystallize in more than 20 distinct crystal forms, including a large number of hydrates and solvates. Their identification, and, ultimately, their quantification in industrial lots require the usage of accurately measured X-ray powder diffraction pattern, as well as the assessment of the metrical features (crystal symmetry and lattice parameters), nowadays accessible by powerful crystallographic software. Here, the complete indexing of 13 monophasic samples, prepared using literature or newly tailored crystallization methods, jointly to simultaneous thermogravimetric and calorimetric analyses and to variable temperature X-ray diffraction studies, provide a clear picture of the stability fields of the different crystal phases and their mutual interconversion processes, leading, in a few cases, to new and unexpected crystalline polymorphs or solvates of the pristine unsolvated Form I.

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.

Synthesis and characterization of the pentazolate anion cyclo-N5ˉ in (N5)6(H3O)3(NH4)4Cl

Science ◽  
2017 ◽  
Vol 355 (6323) ◽  
pp. 374-376 ◽  
Author(s):  
Chong Zhang ◽  
Chengguo Sun ◽  
Bingcheng Hu ◽  
Chuanming Yu ◽  
Ming Lu
Keyword(s):  
Thermal Analysis ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Decomposition Temperature ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Onset Decomposition Temperature ◽  
The Stability

Pentazole (HN5), an unstable molecular ring comprising five nitrogen atoms, has been of great interest to researchers for the better part of a century. We report the synthesis and characterization of the pentazolate anion stabilized in a (N5)6(H3O)3(NH4)4Cl salt. The anion was generated by direct cleavage of the C–N bond in a multisubstituted arylpentazole using m-chloroperbenzoic acid and ferrous bisglycinate. The structure was confirmed by single-crystal x-ray diffraction analysis, which highlighted stabilization of the cyclo-N5ˉ ring by chloride, ammonium, and hydronium. Thermal analysis indicated the stability of the salt below 117°C on the basis of thermogravimetry-measured onset decomposition temperature.

The Effects of Substrate-Induced Strains on the Charge-Ordering Transition in Nd0.5Sr0.5MnO3 Thin Films

1999 ◽  
Vol 602 ◽  
Author(s):  
W. Prellier ◽  
Amlan Biswas ◽  
M. Rajeswari ◽  
T. Venkatesan ◽  
R.L. Greene
Keyword(s):  
Thin Films ◽  
Variable Temperature ◽  
Charge Ordering ◽  
Laser Deposition ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
X Ray ◽  
Post Annealing ◽  
Ordering Transition

AbstractWe report the growth and characterization of Nd0.5Sr0.5MnO3 thin films deposited by the Pulsed Laser Deposition (PLD) technique on [100]-oriented LaAlO3 substrates. X-ray diffraction (XRD) studies show that the films are [101]-oriented, with a strained and quasi-relaxed component, the latter increasing with film thickness. A post-annealing under oxygen leads to a quasi-relaxed film with a metallic behavior. We also observe that transport properties are strongly dependent on the thickness of the films. Variable temperature XRD down to 100 K suggests that this is caused by substrate-induced strain on the films.

Structural characterization of p-benzosemiquinone radical in a solid state: the radical stabilization by a low-barrier hydrogen bond

2006 ◽  
Vol 62 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
Krešimir Molčanov ◽  
Biserka Kojić-Prodić ◽  
Mario Roboz
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Variable Temperature ◽  
Organic Radical ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Packings ◽  
Dynamical Disorder ◽  
Benzenoid Ring

Semiquinone (p-benzosemiquinone), a transient organic radical, was detected in the solid state by EPR spectroscopy revealing four symmetrically equivalent protons. A variable-temperature X-ray diffraction analysis (293 and 90 K) and EPR data support a dynamical disorder of the proton. A low-barrier O—H···O hydrogen bond stabilizes the radical. The C—O bond length is 1.297 (4) Å, corresponding to a bond order of ca 1.5. The geometry of the radical implies an electron delocalization throughout the benzenoid ring. Two polymorphs of semiquinone, monoclinic and triclinic, were observed and their structures determined. Their crystal packings were compared with those of quinhydrone polymorphs.

The Study and Characterization of a Novel Structure of 1,3,5-Benzenetricarboxylic Acid

2013 ◽  
Vol 830 ◽  
pp. 202-206
Author(s):  
Hai Yan Tan ◽  
Cheng Liu ◽  
Jin Ping Wu
Keyword(s):  
Relevant Information ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Novel Structure ◽  
Ft Ir ◽  
Benzenetricarboxylic Acid ◽  
The Stability ◽  
Lamella Structure

A novel ten-interpenetrating structure of 1,3,5-benzenetricarboxylic acid was grown under solvothemal condition after heated it 16 hours. It was characterized by FT-IR, HNMR, X-ray diffraction, HRTEM. HRTEM obtain the relevant information of structural morphologies. The result of HRTEM showsed this material owned special lamella structure. X-ray diffraction showed the crystal of the new structure is of monoclinic system, space groupP1 with a=26.5039(17), b=16.4121(17),c=26.550(2)Å,α=90.00, β=91.533(2), γ=90.00, V=11544.4(17)Å3, Z=8, Dc=1.451g/cm3,μ=0.126mm-1,F(000)=5184, R=0.0891 and w (R)=0.1819 for 11318 observed reflection with I>2(I),hydrogen bond contributed to the stability of the structure. The fluorescence spectra indicated that the title compound had two stronger emission peak at 346nm and 400nm. Keywords:1, 3, 5-benzenetricarboxylic acid; novel structure; ten-interpenetrating

Synthesis and characterization of a series of 4-methyl-1-[2-aryl-1-diazenyl]-1,4-diazepanes and 1,4-di-[2-aryl-1-diazenyl]-1,4-diazepanes

2004 ◽  
Vol 82 (12) ◽  
pp. 1725-1735 ◽  
Author(s):  
Shasta Lee Moser ◽  
Keith Vaughan
Keyword(s):  
Nmr Assignments ◽  
Diazonium Salt ◽  
Variable Temperature ◽  
2D Nmr ◽  
Diazonium Salts ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Compounds ◽  
C Nmr

1-Methylhomopiperazine was coupled with a series of diazonium salts to afford the 4-methyl-1-[2-aryl-1-diazenyl]-1,4-diazepanes (6), a new series of triazenes. These compounds are, in the main, stable crystalline solids (some of the series are stable oils), and they have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and mass spectrometry. NMR assignments were determined by 2D NMR and variable-temperature NMR experiments and by comparison with model compounds. A second series of new compounds, namely, 1,4-di-[2-aryl-1-diazenyl]-1,4-diazepanes (5), were prepared by coupling unsubstituted homopiperazine (1,4-diazepane) with 2 molar equivalents of the diazonium salt and were similarly characterized. The crystal and molecular structure of the parent member of this bis-triazene series (5, X = H) has been determined by single-crystal X-ray diffraction analysis.Key words: triazene, bis-triazene, diazenyl, bis-diazenyl, diazonium salt, NMR, diazepane.

Characterization of Silver Doped Hydroxyapatite Prepared by EDTA Chelate Decomposition Method

2012 ◽  
Vol 1418 ◽  
Author(s):  
Kubra Celik ◽  
Celaletdin Ergun ◽  
Huseyin Kizil
Keyword(s):  
Decomposition Method ◽  
Bacterial Activity ◽  
Gram Negative Bacteria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Antimicrobial Sensitivity ◽  
Second Phases ◽  
The Stability ◽  
Antimicrobial Sensitivity Test

ABSTRACTIn this study, Ag doped hydroxyapatite (HA) samples prepared by EDTA chelate decomposition method were characterized with X-Ray Diffraction Spectroscopy (XRD), Scanning Electron Microscopy (SEM) and antimicrobial sensitivity test. Hydroxyapatite (Ca10(PO)6(OH)2) and NaCaPO4 (rhenanite) phases were observed while Ag was present in the form of Ag2O. Results showed that microstructurally controlled HA-based composites with NaCaPO4 interphase can be prepared, which significantly enhances sinterability of hydroxyapatite at 1100° C without formation of any undesired second phases, such as tricalcium phosphate (TCP) known to decrease the stability of HA. The antibacterial sensitivity was tested with E.Coli gram-negative bacteria. The radius of circle enclosing the sample increases with increasing Ag content in the structure as an indication of the region of non-bacterial activity.

Formation and characterization of ohmic contacts to n–AlGaAs using Pd/AuGe/Ag/Au

1993 ◽  
Vol 8 (5) ◽  
pp. 1045-1051 ◽  
Author(s):  
L.R. Zheng ◽  
D.J. Lawrence ◽  
T.N. Blanton
Keyword(s):  
Liquid Phase ◽  
Ohmic Contacts ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sequential Deposition ◽  
The Stability ◽  
Ion Backscattering ◽  
Liquid Phase Reaction

Sequential deposition of Pd/AuGe/Ag/Au and rapid thermal annealing at 450 to 550 °C were employed to form a shallow ohmic contact to n–Alx Ga1−x As. Contact resistivity was in the range of (0.7–1) × 10−5 at x = 0.3 to (2–4) × 10−5 ohm-cm2 at x = 0.55. Limited interfacial reaction was verified by ion backscattering and x-ray diffraction techniques and attributed to the stability of Au–Ag solid solutions against underlying substrates. Contacts form at 450 to 500 °C, possibly via solid-state reaction, whereas liquid phase reaction may take place at 550 °C.

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