Theobromine cocrystals with monohydroxybenzoic acids – synthesis, X-ray structural analysis, solubility and thermal properties

CrystEngComm ◽  
2019 ◽  
Vol 21 (38) ◽  
pp. 5721-5732 ◽  
Author(s):  
Mateusz Gołdyn ◽  
Daria Larowska ◽  
Weronika Nowak ◽  
Elżbieta Bartoszak-Adamska
Keyword(s):  
Thermal Properties ◽  
Structural Analysis ◽  
Active Pharmaceutical Ingredient ◽  
Polar Solvents ◽  
X Ray ◽  
Purine Alkaloid

Theobromine, a compound from the purine alkaloid group, is much less soluble in polar solvents than its analogues, i.e. caffeine and theophylline, that is why it was used as an active pharmaceutical ingredient (API) model in cocrystal preparation.

Transition Metal Complexes of Diazenes, XXXVIII [1] Activation of Aromatic C-Cl Bonds in the Oxidative Addition of ortho-Chlorophenyldiazenes to Chlorotris(triphenylphosphine)rhodium

1996 ◽  
Vol 51 (11) ◽  
pp. 1555-1558 ◽  
Author(s):  
Uwe R. Aulwurm ◽  
Falk Knoch ◽  
Horst Kisch
Keyword(s):  
Structural Analysis ◽  
Transition Metal ◽  
Dimethyl Sulfoxide ◽  
Transition Metal Complexes ◽  
Oxidative Addition ◽  
Trans Position ◽  
Polar Solvents ◽  
X Ray ◽  
Reaction Proceeds ◽  
Cyclometalated Complexes

Refluxing a slightly acidic n-BuOH solution of RhCl(PPh3)3 and 2-chloro-, 2,4-dichloro-, or 2,4,6-trichloroazobenzene affords cyclometalated complexes (1) via loss of one phosphine ligand and oxidative addition of the ortho -C-Cl bond. X-ray structural analysis indicates a trans-position of the two triphenylphosphine ligands. The reaction proceeds only in polar solvents like alcohols or dimethyl sulfoxide but not in toluene. In the presence of air or oxygen a hydrido complex was formed as a by-product.

RNA polymerase: Preparation and structural analysis of helical polymers

1984 ◽  
Vol 42 ◽  
pp. 152-153
Author(s):  
E. Loren Buhle ◽  
Pamela Rew ◽  
Ueli Aebi
Keyword(s):  
Structural Analysis ◽  
Rna Polymerase ◽  
Molecular Level ◽  
X Ray Diffraction ◽  
Helical Polymers ◽  
X Ray ◽  
E Coli ◽  
The Past ◽  
Ordered Arrays ◽  
Low Ionic Strength

While DNA-dependent RNA polymerase represents one of the key enzymes involved in transcription and ultimately in gene expression in procaryotic and eucaryotic cells, little progress has been made towards elucidation of its 3-D structure at the molecular level over the past few years. This is mainly because to date no 3-D crystals suitable for X-ray diffraction analysis have been obtained with this rather large (MW ~500 kd) multi-subunit (α2ββ'ζ). As an alternative, we have been trying to form ordered arrays of RNA polymerase from E. coli suitable for structural analysis in the electron microscope combined with image processing. Here we report about helical polymers induced from holoenzyme (α2ββ'ζ) at low ionic strength with 5-7 mM MnCl2 (see Fig. 1a). The presence of the ζ-subunit (MW 86 kd) is required to form these polymers, since the core enzyme (α2ββ') does fail to assemble into such structures under these conditions.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

The crystal and molecular structure of tris(pentamethylenedithiocarbamate) chromium(III)-chloroform (1 : 2)

1981 ◽  
Vol 46 (1) ◽  
pp. 6-19 ◽  
Author(s):  
Viktor Kettman ◽  
Ján Garaj ◽  
Jaroslav Majer
Keyword(s):  
Molecular Structure ◽  
Structural Analysis ◽  
Crystal And Molecular Structure ◽  
Analysis Method ◽  
Complex Molecules ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Cell Dimensions ◽  
Crustal Density ◽  
Unit Cell Dimensions

The crystal and molecular structure of [Cr(S2CN(CH2)5)3].2 CHCl3 was found by the X-ray structural analysis method. The value R 0.090 was found for 1 131 observed independent reflections. The substance crystallizes in a space group of symmetry P212121 with the following unit cell dimensions: a = 0.8675 (6), b = 1.815(2), c = 2.155(3) nm. The experimentally observed crustal density was 1.48 Mgm-3 and the value calculated for Z = 4 was 1.51 Mgm-3. The CrS6 coordination polyhedron has the shape of a trigonally distorted octahedron, where the D3 symmetry is a approximately retained. The degree of trigonal distortion expressed as the projection of the chelate S-Cr-S angle onto the plane perpendicular to the C3 pseudo axis is Φ = 41.7° (Φ = 60° for an octahedron). The skeleton of the structure formed by the complex molecules contains channels filled with chloroform molecules. The specific type of complex-chloroform interaction consists of the formation of hydrogen bonds of the chloroform protons with the fully occupied pπ-orbitals of the sulphur atoms in the coordination polyhedra. The low stability and crystal decomposition can be explained by loss of chloroform from the channels.

Reactivity of Sodium Hexaethyl-2,4-dicarba-nido-hexaborate(1-)

1999 ◽  
Vol 64 (6) ◽  
pp. 977-985 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Hans-Jörg Schanz ◽  
Wolfgang Milius ◽  
Catherine McCammon
Keyword(s):  
Mössbauer Spectroscopy ◽  
Nmr Spectroscopy ◽  
Structural Analysis ◽  
Hydrogen Atom ◽  
Mossbauer Spectroscopy ◽  
Sandwich Complex ◽  
X Ray ◽  
Bromo Derivative ◽  
Boron Tribromide ◽  
C Nmr

Sodium hexaethyl-2,4-dicarba-nido-hexaborate(1-) (6), available from hexaethyl-2,4-dicarba- nido-hexaborane(8) (4) by deprotonation, reacts with deuterated methanol, CD3OD, to give back 4 without H/D exchange of the B-H-B hydrogen atom. The reaction of 6 with diethylboron chloride, Et2BCl, affords hexaethyl-2,4-dicarba-closo-hexaborane(6) (7), the first example of a peralkylated carborane of this type. In contrast, the reaction of 6 with boron tribromide, BBr3, leads mainly to 2,3,4,5,6,7-hexaethyl-2,4-dicarba-closo-heptaborane(7) (8), together with the corresponding 1-bromo derivative (9) and the closo-carborane 7 as side products. The reaction of two equivalents of 6 with FeCl2 gives the air-stable sandwich complex bis[hexaethyl-2,4-dicarba-nido-hexaborate(1-)]iron 10 which was characterised by X-ray structural analysis. All products were characterised by 1H, 11B and 13C NMR spectroscopy, and 57Fe Mössbauer spectroscopy was used to study 10.

scholarly journals X-Ray Structural Analysis of Molten KF–KX(X=Cl, Br, and I) Systems

1987 ◽  
Vol 1987-7 (1) ◽  
pp. 165-174
Author(s):  
Yoshihiro OKAMOTO
Keyword(s):  
Structural Analysis ◽  
X Ray

scholarly journals Light-induced [2 + 2] Cycloaddition of 6-Methoxy-2-naphthonitrile to 2-Chloroacrylonitrile

1999 ◽  
Vol 23 (1) ◽  
pp. xiv-xiv
Author(s):  
Nader A. Al-Jalal ◽  
Robin G. Pritchard ◽  
Charles A. McAuliffe
Keyword(s):  
Structural Analysis ◽  
X Ray

6-Methoxy-2-naphthonitrile undergoes photocycloaddition to 2-chloroacrylonitrile to give [2 + 2] cyclobutane adducts (1a and 1b), the structure of one of which (1a) has been unambiguously confirmed by an X-ray structural analysis.

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