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Angewandte Chemie (International Ed. in... Jul 2018The absolute configuration of active pharmaceutical ingredients (APIs) was determined by generating salts of the active pharmaceutical ingredient (API) with counterions...
The absolute configuration of active pharmaceutical ingredients (APIs) was determined by generating salts of the active pharmaceutical ingredient (API) with counterions of known chirality, and determining the crystal structures by X-ray powder diffraction. This approach avoids the (often tedious) growth of single crystals, and is successful with very limited quantities of material (less than 1 mg). The feasibility of the method is demonstrated on five examples, and its limitations are discussed as well.
Topics: Models, Molecular; Molecular Conformation; Pharmaceutical Preparations; Powder Diffraction; X-Rays
PubMed: 29409149
DOI: 10.1002/anie.201713168 -
Acta Crystallographica. Section C,... Mar 2016We have identified a new compound in the glycine-MgSO4-water ternary system, namely glycine magnesium sulfate trihydrate (or Gly·MgSO4·3H2O) {systematic name:...
We have identified a new compound in the glycine-MgSO4-water ternary system, namely glycine magnesium sulfate trihydrate (or Gly·MgSO4·3H2O) {systematic name: catena-poly[[tetraaquamagnesium(II)]-μ-glycine-κ(2)O:O'-[diaquabis(sulfato-κO)magnesium(II)]-μ-glycine-κ(2)O:O']; [Mg(SO4)(C2D5NO2)(D2O)3]n}, which can be grown from a supersaturated solution at ∼350 K and which may also be formed by heating the previously known glycine magnesium sulfate pentahydrate (or Gly·MgSO4·5H2O) {systematic name: hexaaquamagnesium(II) tetraaquadiglycinemagnesium(II) disulfate; [Mg(D2O)6][Mg(C2D5NO2)2(D2O)4](SO4)2} above ∼330 K in air. X-ray powder diffraction analysis reveals that the trihydrate phase is monoclinic (space group P21/n), with a unit-cell metric very similar to that of recently identified Gly·CoSO4·3H2O [Tepavitcharova et al. (2012). J. Mol. Struct. 1018, 113-121]. In order to obtain an accurate determination of all structural parameters, including the locations of H atoms, and to better understand the relationship between the pentahydrate and the trihydrate, neutron powder diffraction measurements of both (fully deuterated) phases were carried out at 10 K at the ISIS neutron spallation source, these being complemented with X-ray powder diffraction measurements and Raman spectroscopy. At 10 K, glycine magnesium sulfate pentahydrate, structurally described by the `double' formula [Gly(d5)·MgSO4·5D2O]2, is triclinic (space group P-1, Z = 1), and glycine magnesium sulfate trihydrate, which may be described by the formula Gly(d5)·MgSO4·3D2O, is monoclinic (space group P21/n, Z = 4). In the pentahydrate, there are two symmetry-inequivalent MgO6 octahedra on sites of -1 symmetry and two SO4 tetrahedra with site symmetry 1. The octahedra comprise one [tetraaquadiglcyinemagnesium](2+) ion (centred on Mg1) and one [hexaaquamagnesium](2+) ion (centred on Mg2), and the glycine zwitterion, NH3(+)CH2COO(-), adopts a monodentate coordination to Mg2. In the trihydrate, there are two pairs of symmetry-inequivalent MgO6 octahedra on sites of -1 symmetry and two pairs of SO4 tetrahedra with site symmetry 1; the glycine zwitterion adopts a binuclear-bidentate bridging function between Mg1 and Mg2, whilst the Mg2 octahedra form a corner-sharing arrangement with the sulfate tetrahedra. These bridged polyhedra thus constitute infinite polymeric chains extending along the b axis of the crystal. A range of O-H...O, N-H...O and C-H...O hydrogen bonds, including some three-centred interactions, complete the three-dimensional framework of each crystal.
Topics: Coordination Complexes; Glycine; Hydrogen Bonding; Magnesium Sulfate; Neutrons; Powder Diffraction; X-Ray Diffraction
PubMed: 26942430
DOI: 10.1107/S2053229616001200 -
Journal of Visualized Experiments : JoVE Jan 2017In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C...
In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline at the Advanced Photon Source. The DAC program at 13-BM-C is part of the Partnership for Extreme Xtallography (PX^2) project. BX-90 type DACs with conical-type diamond anvils and backing plates are recommended for these experiments. The sample chamber should be loaded with noble gas to maintain a hydrostatic pressure environment. The sample is aligned to the rotation center of the diffraction goniometer. The MARCCD area detector is calibrated with a powder diffraction pattern from LaB6. The sample diffraction peaks are analyzed with the ATREX software program, and are then indexed with the RSV software program. RSV is used to refine the UB matrix of the single crystal, and with this information and the peak prediction function, more diffraction peaks can be located. Representative single crystal diffraction data from an omphacite (Ca0.51Na0.48)(Mg0.44Al0.44Fe0.14Fe0.02)Si2O6 sample were collected. Analysis of the data gave a monoclinic lattice with P2/n space group at 0.35 GPa, and the lattice parameters were found to be: a = 9.496 ±0.006 Å, b = 8.761 ±0.004 Å, c = 5.248 ±0.001 Å, β = 105.06 ±0.03º, α = γ = 90º.
Topics: Crystallography, X-Ray; Diamond; Powder Diffraction; Pressure; Synchrotrons
PubMed: 28117811
DOI: 10.3791/54660 -
Physical Review Letters May 2004For solving the atomic structure of organic molecules such as small proteins which are difficult to crystallize, the use of a jet of doped liquid helium droplets...
For solving the atomic structure of organic molecules such as small proteins which are difficult to crystallize, the use of a jet of doped liquid helium droplets traversing a continuous high energy electron beam is proposed as a means of obtaining electron diffraction patterns (serial crystallography). Organic molecules (such as small proteins) within the droplet (and within a vitreous ice jacket) may be aligned by use of a polarized laser beam. Iterative methods for solving the phase problem are indicated. Comparisons with a related plan for pulsed x-ray diffraction from single proteins in a molecular beam are provided.
Topics: Electrons; Helium; Membrane Proteins; Powder Diffraction; X-Ray Diffraction
PubMed: 15169448
DOI: 10.1103/PhysRevLett.92.198102 -
ChemSusChem Sep 2015The ability to directly track the charge carrier in a battery as it inserts/extracts from an electrode during charge/discharge provides unparalleled insight for...
The ability to directly track the charge carrier in a battery as it inserts/extracts from an electrode during charge/discharge provides unparalleled insight for researchers into the working mechanism of the device. This crystallographic-electrochemical information can be used to design new materials or modify electrochemical conditions to improve battery performance characteristics, such as lifetime. Critical to collecting operando data used to obtain such information in situ while a battery functions are X-ray and neutron diffractometers with sufficient spatial and temporal resolution to capture complex and subtle structural changes. The number of operando battery experiments has dramatically increased in recent years, particularly those involving neutron powder diffraction. Herein, the importance of structure-property relationships to understanding battery function, why in situ experimentation is critical to this, and the types of experiments and electrochemical cells required to obtain such information are described. For each battery type, selected research that showcases the power of in situ and operando diffraction experiments to understand battery function is highlighted and future opportunities for such experiments are discussed. The intention is to encourage researchers to use in situ and operando techniques and to provide a concise overview of this area of research.
Topics: Electric Power Supplies; Electrodes; Powder Diffraction; Structure-Activity Relationship
PubMed: 26223736
DOI: 10.1002/cssc.201500152 -
Acta Crystallographica Section B,... Jun 2022Experimental and computational studies of ammonium carbamate have been carried out, with the objective of studying the elastic anisotropy of the framework manifested in...
Ab initio simulations of α- and β-ammonium carbamate (NH·NHCO), and the thermal expansivity of deuterated α-ammonium carbamate from 4.2 to 180 K by neutron powder diffraction.
Experimental and computational studies of ammonium carbamate have been carried out, with the objective of studying the elastic anisotropy of the framework manifested in (i) the thermal expansion and (ii) the compressibility; furthermore, the relative thermodynamic stability of the two known polymorphs has been evaluated computationally. Using high-resolution neutron powder diffraction data, the crystal structure of α-ammonium carbamate (ND·NDCO) has been refined [space group Pbca, Z = 8, with a = 17.05189 (15), b = 6.43531 (7), c = 6.68093 (7) Å and V = 733.126 (9) Å at 4.2 K] and the thermal expansivity of α-ammonium carbamate has been measured over the temperature range 4.2-180 K. The expansivity shows a high degree of anisotropy, with the b axis most expandable. The ab initio computational studies were carried out on the α- and β-polymorphs of ammonium carbamate using density functional theory. Fitting equations of state to the P(V) points of the simulations (run athermally) gave the following values: V = 744 (2) Å and bulk modulus K = 16.5 (4) GPa for the α-polymorph, and V = 713.6 (5) Å and K = 24.4 (4) GPa for the β-polymorph. The simulations show good agreement with the thermoelastic behaviour of α-ammonium carbamate. Both phases show a high-degree of anisotropy; in particular, α-ammonium carbamate shows unusual compressive behaviour, being determined to have negative linear compressibility (NLC) along its a axis above 5 GPa. The thermodynamically stable phase at ambient pressure is the α-polymorph, with a calculated enthalpy difference with respect to the β-polymorph of 0.399 kJ mol; a transition to the β-polymorph could occur at ∼0.4 GPa.
Topics: Carbamates; Carbon Dioxide; Neutrons; Powder Diffraction; Powders
PubMed: 35702963
DOI: 10.1107/S2052520622002645 -
Journal of Pharmaceutical and... Jan 2018Spurious/Falsely-labeled/Falsified/Counterfeit (SFFC)drugs have become a major threat to public health, especially in rural areas of developing countries.The goal of... (Review)
Review
Spurious/Falsely-labeled/Falsified/Counterfeit (SFFC)drugs have become a major threat to public health, especially in rural areas of developing countries.The goal of this review is to provide an overview of rapid detection technologies for counterfeits recently reported, such as Near Infrared Spectroscopy, Near Infrared Chemical Imaging, Raman Spectroscopy, X-Ray Fluorescence, X-RayPowder Diffraction, Ion Mobility Spectrometry, Ion MobilityMass Spectrometry,Isotope Ratio Mass Spectrometry and visual analytical methods The advantages of each of these detection methods are introduced. Examples of characterization of SFFC drugs using the detection technology mentioned are presented. In addition, new characteristics and trends of SFFC drugs are listed and the solution is discussed.
Topics: Counterfeit Drugs; Developing Countries; Limit of Detection; Powder Diffraction; Spectrum Analysis
PubMed: 28844368
DOI: 10.1016/j.jpba.2017.08.016 -
Drugs in R&D Sep 2017The identification of different (pseudo) polymorphs of an active pharmaceutical ingredient in dry powder formulations is of importance during development and entire... (Comparative Study)
Comparative Study
BACKGROUND
The identification of different (pseudo) polymorphs of an active pharmaceutical ingredient in dry powder formulations is of importance during development and entire product lifecycle, e.g., quality control. Whereas determination of polymorphic differences of pure substances is rather easy, in dry powder formulations, it is generally difficult and the difficulties increase particularly, if the substance of interest is present only in low concentrations in the formulation. Such a formulation is Spiriva inhalation powder (Boehringer Ingelheim), which contains only 0.4 w/w% of the active pharmaceutical ingredient tiotropium bromide monohydrate in a matrix of α-lactose monohydrate as excipient.
METHODS
In this study, identification of 0.4 w/w% tiotropium bromide in the dry powder formulation was examined by X-ray powder diffraction (XRPD) using a synchrotron radiation source and the results were compared with the conventional laboratory XRPD measurements.
RESULTS
The detection limit of tiotropium bromide by the laboratory XRPD was around 2-5 w/w%, and hence, detection of 0.4 w/w% tiotropium bromide was impossible. The synchrotron XRPD was capable to detect significantly lower level of tiotropium bromide by at least an order of magnitude.
CONCLUSION
Four different polymorphic forms of tiotropium bromide present at 0.4 w/w% concentration in lactose powder blends were unambiguously identified by the synchrotron XRPD method.
Topics: Bronchodilator Agents; Excipients; Lactose; Powder Diffraction; Powders; Synchrotrons; Tiotropium Bromide; X-Ray Diffraction
PubMed: 28905245
DOI: 10.1007/s40268-017-0196-6 -
Analytical Chemistry Jun 2020Understanding the transitions between polymorphs is essential in the development of strategies for manufacturing and maximizing the efficiency of pharmaceuticals....
Understanding the transitions between polymorphs is essential in the development of strategies for manufacturing and maximizing the efficiency of pharmaceuticals. However, this can be extremely challenging: crystallization can be influenced by subtle changes in environment, such as temperature and mixing intensity or even imperfections in the crystallizer walls. Here, we highlight the importance of in situ measurements in understanding crystallization mechanisms, where a segmented flow crystallizer was used to study the crystallization of the pharmaceuticals urea: barbituric acid (UBA) and carbamazepine (CBZ). The reactor provides highly reproducible reaction conditions, while in situ synchrotron powder X-ray diffraction (PXRD) enables us to monitor the evolution of this system. UBA has two polymorphs of almost equivalent free-energy and so is typically obtained as a polymorphic mixture. In situ PXRD analysis uncovered a progression of polymorphs from UBA III to the thermodynamic polymorph UBA I, where different positions along the length of the tubular flow crystallizer correspond to different reaction times. Addition of UBA I seed crystals modified this pathway such that only UBA I was observed throughout, while transformation from UBA III into UBA I still occurred in the presence of UBA III seeds. Information regarding the mixing-dependent kinetics of the CBZ form II to III transformation was also uncovered in a series of seeded and unseeded flow crystallization runs, despite atypical habit expression. These results illustrate the importance of coupling controlled reaction environments with in situ XRD to study the phase relationships in polymorphic materials.
Topics: Barbiturates; Carbamazepine; Crystallization; Pharmaceutical Preparations; Powder Diffraction; Urea
PubMed: 32365293
DOI: 10.1021/acs.analchem.0c00860 -
Inorganic Chemistry Sep 2004The crystal structure of a new hybrid product comprised of two rigid building blocks, namely dirhodium(II) tetraacetate, [Rh(2)(O(2)CCH(3))(4)] (1), and...
The crystal structure of a new hybrid product comprised of two rigid building blocks, namely dirhodium(II) tetraacetate, [Rh(2)(O(2)CCH(3))(4)] (1), and 2,6-diselenaspiro[3.3]heptane, Se(2)C(5)H(8) (2), has been solved ab initio using laboratory source X-ray powder diffraction (XRPD) data. The rigid body refinement approach has been applied to assist in finding an adequate model and to reduce the number of the refined parameters. Complex [Rh(2)(O(2)CCH(3))(4).mu(2)-Se(2)C(5)H(8)-Se,Se'] (3) conforms to the triclinic unit cell with lattice parameters of a = 8.1357(4), b = 8.7736(4), and c = 15.2183(8) A, alpha = 77.417(3), beta = 88.837(3), and gamma = 69.276(4) degrees, V = 989.66(8) A(3), and Z = 2. The centrosymmetric P space group was selected for calculations. The final values of the reduced wR(p), R(p), and chi(2) were calculated at 0.0579, 0.0433, and 5.95, respectively. The structure of 3 is a one-dimensional zigzag polymer built on axial Rh...Se interactions at 2.632(6) A. The 2,6-diselenaspiro[3.3]heptane ligand acts as a bidentate linker bridging dirhodium units via both selenium atoms. The geometrical parameters of individual groups for rigid body refinement have been obtained from X-ray powder data for dirhodium(II) tetraacetate (1) and from single-crystal X-ray diffraction for diselenium molecule 2. The crystal structures of 1 and 2 are reported here for the first time. For 1 indexing based on XRPD data has resulted in the triclinic unit cell P with lattice parameters of a = 8.3392(7), b = 5.2216(5), and c = 7.5264(6) A, alpha = 95.547(10), beta = 78.101(6), and gamma = 104.714(13) degrees, V = 309.51(5) A(3), and Z = 1. The final values were wR(p) = 0.0452, R(p) = 0.0340, and chi(2) = 1.99. The 1D polymeric motif built on axial Rh.O interactions of the centrosymmetric dirhodium units has been confirmed for the solid-state structure of 1. Compound 2,6-diselenaspiro[3.3]heptane (2) conforms to the monoclinic space group P2(1)/c with the unit cell parameters of a = 5.9123(4), b = 19.6400(13), and c = 5.8877(4) A, beta = 108.5500(10) degrees, V = 648.15(8) A(3), and Z = 4.
Topics: Copper; Crystallography, X-Ray; Models, Chemical; Molecular Structure; Organometallic Compounds; Polymers; Powder Diffraction; Rhodium; Selenium
PubMed: 15332807
DOI: 10.1021/ic049497u