scholarly journals Synthesis of Two Novel Azilsartan Cocrystals: Preparation, Physicochemical Characterization and Solubility Studies

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 739
Author(s):  
Lei Gao ◽  
Xian-Rui Zhang
Keyword(s):  
Water Solubility ◽  
Physicochemical Characterization ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
One Dimensional ◽  
X Ray ◽  
Solubility Study ◽  
Solution Crystallization

Azilsartan is a novel angiotension II receptor blocker primarily used to treat high blood pressure. This is not a formulation-friendly molecule largely due to the inherent water-solubility pitfalls. In this paper, two novel cocrystals of azilsartan (AZ) were studied (AZ-BIP, AZ-BPE; BIP = 4,4′-bipyridine, BPE = trans-1,2-bis (4-pyridyl) ethylene) by solution crystallization. The structures of these two cocrystals were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), including the single-crystal structure determination of AZ-BIP and AZ-BPE. In the cocrystals AZ-BIP (2:1) and AZ-BPE (2:1), two AZ molecules and one coformer formed a sandwich structure through N-H…N interactions. These sandwich structures were extended into a one-dimensional structure through O-H…N hydrogen bonds. The equilibrium solubility study demonstrated that the AZ-BIP and AZ-BPE cocrystals both showed higher solubility than azilsartan in water.

Formalism for the determination of intermediate stress gradients using X-ray diffraction

2009 ◽  
Vol 42 (2) ◽  
pp. 192-197 ◽  
Author(s):  
Thomas Gnäupel-Herold
Keyword(s):  
Lattice Strain ◽  
Narrow Line ◽  
X Ray Diffraction ◽  
Beam Spot ◽  
Strain Measurements ◽  
One Dimensional ◽  
X Ray ◽  
Stress Gradients ◽  
Shaped Beam

A method is outlined that allows the determination of one-dimensional stress gradients at length scales greater than 0.2 mm. By using standard four-circle X-ray diffractometer equipment and simple aperture components, length resolutions down to 0.05 mm in one direction can be achieved through constant orientation of a narrow, line-shaped beam spot. Angle calculations are given for the adjustment of goniometer angles, and for the effective azimuth and tilt of the scattering vector for general angle settings in a four-circle goniometer. The latter is necessary for the computation of stresses from lattice strain measurements.

Salts of purine alkaloids caffeine and theobromine with 2,6-dihydroxybenzoic acid as coformer: structural, theoretical, thermal and spectroscopic studies

2021 ◽  
Vol 77 (11) ◽  
Author(s):  
Mateusz Gołdyn ◽  
Anna Komasa ◽  
Mateusz Pawlaczyk ◽  
Aneta Lewandowska ◽  
Elżbieta Bartoszak-Adamska
Keyword(s):  
Hydrogen Bonds ◽  
Water Solubility ◽  
Theoretical Calculations ◽  
Spectroscopic Studies ◽  
X Ray Diffraction ◽  
Dihydroxybenzoic Acid ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Purine Alkaloids ◽  
Vis Spectroscopy

The study of various forms of pharmaceutical substances with specific physicochemical properties suitable for putting them on the market is one of the elements of research in the pharmaceutical industry. A large proportion of active pharmaceutical ingredients (APIs) occur in the salt form. The use of an acidic coformer with a given structure and a suitable pK a value towards purine alkaloids containing a basic imidazole N atom can lead to salt formation. In this work, 2,6-dihydroxybenzoic acid (26DHBA) was used for cocrystallization of theobromine (TBR) and caffeine (CAF). Two novel salts, namely, theobrominium 2,6-dihydroxybenzoate, C7H9N4O2 +·C7H5O4 − (I), and caffeinium 2,6-dihydroxybenzoate, C8H11N4O2 +·C7H5O4 − (II), were synthesized. Both salts were obtained independently by slow evaporation from solution, by neat grinding and also by microwave-assisted slurry cocrystallization. Powder X-ray diffraction measurements proved the formation of the new substances. Single-crystal X-ray diffraction studies confirmed proton transfer between the given alkaloid and 26DHBA, and the formation of N—H...O hydrogen bonds in both I and II. Unlike the caffeine cations in II, the theobromine cations in I are paired by noncovalent N—H...O=C interactions and a cyclic array is observed. As expected, the two hydroxy groups in the 26DHBA anion in both salts are involved in two intramolecular O—H...O hydrogen bonds. C—H...O and π–π interactions further stabilize the crystal structures of both compounds. Steady-state UV–Vis spectroscopy showed changes in the water solubility of xanthines after ionizable complex formation. The obtained salts I and II were also characterized by theoretical calculations, Fourier-transform IR spectroscopy (FT–IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis.

Using Ultrathin-Film, Modulated Composites to Control the Reaction Mechanism of Ternary Compound Formation

1991 ◽  
Vol 238 ◽  
Author(s):  
Loreli Fister ◽  
David C. Johnson
Keyword(s):  
Ternary Compound ◽  
Reaction Pathway ◽  
Experimental Parameter ◽  
Ultrathin Film ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Compound Formation ◽  
One Dimensional ◽  
X Ray ◽  
Made In

ABSTRACTA predictable, controllable approach to the synthesis of ternary compounds through known intermediates is presented. Thin and ultrathin film superlattices were made in the Mo-Se, Cu-Se and Mo-Cu systems. Differential scanning calorimetry, low- and high-angle x-ray diffraction were used to assess the interdiffusion and nucleation reactions between elemental layers in these one-dimensional crystals. The experimental parameter modulation distance was used to influence the interfacial reactions. The results from each binary system were then used to predict the reaction pathway in the synthesis of a ternary compound, Cu2Mo6Se8. Superlattices with two different lengthscales were investigated. In the first, only one intermediate, MoSe2 which typically crystallizes at ∼200'C, is observed prior to the crystallization of Cu2Mo6Se8. In the second, no crystalline intermediates are observed below 6000 C.

Study of an Energetic-oxidant Co-crystal: Preparation, Characterisation, and Crystallisation Mechanism

2017 ◽  
Vol 67 (5) ◽  
pp. 510 ◽  
Author(s):  
Han Gao ◽  
Wei Jiang ◽  
Jie Liu ◽  
Gazi Hao ◽  
Lei Xiao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Diffraction Spectrum ◽  
Solvent Evaporation Method ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Scanning Electron

<p>An energetic co-crystal consisting of the most promising military explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and the most well-known oxidant applied in propellants ammonium perchlorate has been prepared with a simple solvent evaporation method. Scanning electron microscopy revealed that the morphology of co-crystal differs greatly from each component. The X-ray diffraction spectrum, FTIR, Raman spectra, and differential scanning calorimetry characterisation further prove the formation of the co-crystal. The result of determination of hygroscopic rate indicated the hygroscopicity was effectively reduced. At last, the crystallisation mechanism has been discussed.</p>

scholarly journals Insights into the multistep transformation of titanate nanotubes into nanowires and nanoribbons

2016 ◽  
Vol 34 (4) ◽  
pp. 691-702 ◽  
Author(s):  
Agnieszka Baszczuk ◽  
Marek Jasiorski ◽  
Beata Borak ◽  
Jerzy Wódka
Keyword(s):  
Treatment Duration ◽  
Hydrothermal Reaction ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Transmission Electron ◽  
Morphology And Structure ◽  
Different Types ◽  
Increasing Temperature

AbstractDifferent types of titanate one-dimensional nanostructured materials were synthesized and characterized using scanning and transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The results presented in this work unquestionably showed dependence of morphology and structure of the titanate nanopowders on parameters of hydrothermal synthesis. It was found that nanotubes, nanowires and nanoribbons are three unavoidable kinetic products of hydrothermal reaction. Moreover, increasing temperature of reaction or hydrothermal treatment duration results in acceleration of nanotube-nanowire-nanoribbon transformation. However, the sequence of titanate morphology transformation is invariable. The detailed studies further revealed that the crystal structure of hydrothermally prepared nanotubes and nanowires are indistinguishable but the determination of the exact structure is practically impossible. Because of higher crystallinity, the structure of nanoribbons can be established. It was shown that it corresponds to the monoclinic layered trititanic acid H2Ti3O7 and is isostructural with sodium derivatives Na2_xHxTi3O7.nH20 (with x near 2).

Structure determination of the silver carboxylate dimer [Ag(O2C20H39)]2, silver arachidate, using powder X-ray diffraction methods

2012 ◽  
Vol 27 (2) ◽  
pp. 99-103 ◽  
Author(s):  
Peter W. Stephens ◽  
James A. Kaduk ◽  
Thomas N. Blanton ◽  
David R. Whitcomb ◽  
Scott T. Misture ◽  
...  
Keyword(s):  
Density Functional ◽  
Structural Model ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
One Dimensional ◽  
X Ray ◽  
Cell Dimensions ◽  
Silver Carboxylate ◽  
Pseudo Potential

High-resolution powder X-ray diffraction and density functional plane wave pseudo-potential techniques have been used to obtain an optimized structural model of silver arachidate, [Ag(O2C(CH2)18CH3]2. The unit cell is triclinic, space group P-1 with cell dimensions of a = 4.1519(10) Å, b = 4.7055(10) Å, c = 53.555(4) Å, α = 89.473(15)°, β = 87.617(5)° and γ = 76.329(5)°. The structure is characterized by an 8-membered ring dimer of Ag atoms and carboxyl groups joined by four-member Ag–O rings with fully extended zigzag side chains, giving rise to one-dimensional chains along the b-axis.

Ab Initio Structure Determination of Quasicrystals via Single Crystal X-Ray Diffraction

2003 ◽  
Vol 805 ◽  
Author(s):  
Hiroyuki Takakura ◽  
Akiji Yamamoto ◽  
Marc de Boissieu ◽  
Taku J Sato ◽  
An Pang Tsai
Keyword(s):  
Single Crystal ◽  
Ab Initio ◽  
Structure Determination ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Higher Dimensional ◽  
Icosahedral Quasicrystals ◽  
Ab Initio Structure

ABSTRACTA standard approach for structure solution of ordinary crystals begins with solving the phase problem. We show that a similar procedure can be taken even in the case of quasicrystals using single crystal X-ray diffraction by applying an ab initio structure determination method called the low density elimination method. The first picture of the occupation domains, which must be specified in a higher-dimensional structure determination of quasicrystals, is obtained from a phase-reconstructed density. We present six-dimensional densities determined by this method and give their interpretation for several different types of icosahedral quasicrystals.

scholarly journals Two Novel Palbociclib-Resorcinol and Palbociclib-Orcinol Cocrystals with Enhanced Solubility and Dissolution Rate

Pharmaceutics ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 23
Author(s):  
Chenxin Duan ◽  
Wenwen Liu ◽  
Yunwen Tao ◽  
Feifei Liang ◽  
Yanming Chen ◽  
...  
Keyword(s):  
Water Solubility ◽  
Cancer Drug ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Dissolution Rates ◽  
Intrinsic Dissolution ◽  
X Ray ◽  
Enhanced Solubility

Palbociclib (PAL) is an effective anti-breast cancer drug, but its use has been partly restricted due to poor bioavailability (resulting from extremely low water solubility) and serious adverse reactions. In this study, two cocrystals of PAL with resorcinol (RES) or orcinol (ORC) were prepared by evaporation crystallization to enhance their solubility. The cocrystals were characterized by single crystal X-ray diffraction, Hirshfeld surface analysis, powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared and scanning electron microscopy. The intrinsic dissolution rates of the PAL cocrystals were determined in three different dissolution media (pH 1.0, pH 4.5 and pH 6.8), and both cocrystals showed improved dissolution rates at pH 1.0 and pH 6.8 in comparison to the parent drug. In addition, the cocrystals increased the solubility of PAL at pH 6.8 by 2–3 times and showed good stabilities in both the accelerated stability testing and stress testing. The PAL-RES cocrystal also exhibited an improved relative bioavailability (1.24 times) than PAL in vivo pharmacokinetics in rats. Moreover, the in vitro cytotoxicity assay of PAL-RES showed an increased IC50 value for normal cells, suggesting a better biosafety profile than PAL. Co-crystallization may represent a promising strategy for improving the physicochemical properties of PAL with better pharmacokinetics.

scholarly journals History of protein crystallography in China

2007 ◽  
Vol 362 (1482) ◽  
pp. 1035-1042 ◽  
Author(s):  
Zihe Rao
Keyword(s):  
Protein Crystallography ◽  
Three Dimensional ◽  
Porcine Insulin ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Crystallography ◽  
Subsequent Determination ◽  
History Of

China has a strong background in X-ray crystallography dating back to the 1920s. Protein crystallography research in China was first developed following the successful synthesis of insulin in China in 1966. The subsequent determination of the three-dimensional structure of porcine insulin made China one of the few countries which could determine macromolecular structures by X-ray diffraction methods in the late 1960s and early 1970s. After a slow period during the 1970s and 1980s, protein crystallography in China has reached a new climax with a number of outstanding accomplishments. Here, I review the history and progress of protein crystallography in China and detail some of the recent research highlights, including the crystal structures of two membrane proteins as well as the structural genomics initiative in China.

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