93 research outputs found
On the Application of Strong Magnetic Fields during Organic Crystal Growth
We investigate the effect of crystal growth within a magnetic field for three polymorphic pharmaceuticals, using an experiment where the magnetic field can be varied in strength without altering other crystallization conditions. In the case of carbamazepine, fields above 0.6 T produce metastable form I, and for flufenamic acid, there is an increased propensity to crystallize metastable form I around 1 T. In contrast, the magnetic field has no effect on the crystallization of mefenamic acid, a closely related molecule. The growth of the metastable β polymorph of coronene within a magnetic field at ambient temperature is difficult to reproduce but has been seen as a minor component, consistent with this transformation to the more stable form being facile, depending on the particle size. Calculations of the diamagnetic susceptibility tensors of the polymorphs and their morphologies provide semiquantitative estimates of how the diamagnetic susceptibilities of crystallites differ between polymorphs and explain why mefenamic acid crystallization is unaffected. As the onset of crystallization of carbamazepine and coronene, as defined by changes in turbidity, occur at lower temperatures and hence greater supersaturations in certain ranges of magnetic field strength, this suggests that the field causes precipitation of the metastable form through Ostwald’s rule of stages
An Experimental and Computational Study into the Crystallisation Propensity of 2nd Generation Sulflower
Racemic Conglomerate Formation via Crystallization of Metaxalone from Volatile Deep Eutectic Solvents
Crystal structure and Hirshfeld surface analysis of (E)-3-(3-iodophenyl)-1- (4-iodophenyl)prop-2-en-1-one
Lamotrigine ethanol monosolvate
Lamotrigine is an active pharmaceutical ingredient used as a treatment for epilepsy and psychiatric disorders. Single crystals of an ethanolate solvate, C9H7Cl2N5·C2H5OH, were produced by slow evaporation of a saturated solution from anhydrous ethanol. Within the crystal structure, the lamotrigine molecules form dimers through N—H...N hydrogen bonds involving the amine N atoms in the ortho position of the triazine group. These dimers are linked into a tape motif through hydrogen bonds involving the amine N atoms in the para position. The ethanol and lamotrigine are present in a 1:1 ratio in the lattice with the ethyl group of the ethanol molecule exhibiting disorder with an occupancy ratio of 0.516 (14):0.484 (14)
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Metastable crystalline phase formation in deep eutectic systems revealed by simultaneous synchrotron XRD and DSC
The phase behaviour of various deep eutectic systems was analysed using concurrent synchrotron powder X-ray diffraction and differential scanning calorimetry. Deep eutectic systems containing the pharmaceuticals metacetamol, 2-ethoxybenzamide or benzamide as binary mixtures with phenol revealed new crystalline phases melting either before or with crystals of phenol, highlighting their lower stabilities. Furthermore, in the phenol:2-ethoxybenzamide system it was shown that multiple metastable phases can form, highlighting the potential for the separation of a hierarchy of crystal structures with differing stabilities from eutectic systems. Through these experiments, we strengthen the idea that eutectic systems can be described by understanding the formation and stabilities of metastable co-crystalline structures. These novel results lead to a deeper understanding of the structure and thermodynamics of deep eutectic solvents, with relevance for analagous systems across materials science
Crystal structures of three functionalized chalcones:4'-di-methyl-amino-3-nitro-chalcone, 3-di-methyl-amino-3'-nitrochalcone and 3'-nitro-chalcone
Crystal structure and Hirshfeld analysis of 3'-bromo-4-methylchalcone and 3'-cyano-4- methylchalcone
Clean WateR3: Integrating Research and Extension to Help Specialty Crop Growers Reduce, Remediate, and Recycle Water
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