News
12.11.2020
Publications of the Polymorphism and Calorimetry Unit
Dr. Rafel Prohens, responsible for the CCiTUB's Polymorphism and Calorimetry Unit, has published different articles in the last months in the
Crystal Growth & Design magazine. Mr. Rafael Barbas and Mrs. Dafne de Sande, of the same Unit, also collaborate in the articles, as well as researchers from the Universities of Leeds, Bradford and Manchester from United Kingdom and from the Center for Intelligent Research in Crystal Engineering (CIRCE) of Palma de Mallorca.
The publications are the following:
"Solid-State Competitive Destabilization of Caffeine Malonic Acid Cocrystal: Mechanistic and Kinetic Investigations"
Magazine: Crystal Growth & Design
The summary of the article is:
"The main objective of this research is to investigate both the mechanism and the kinetics of solvent-free destabilization of the model caffeine/malonic acid cocrystal (CA/MO 2:1) in the presence of oxalic acid (OX) as a structural competitor to malonic acid (MO). Competitive destabilization of CA/MO and subsequent formation of caffeine/oxalic acid (CA/OX) take place at temperatures significantly below their melting points. The destabilization mechanism was found to be mediated by sublimation of both CA/MO and OX. During CA/MO destabilization, free CA could not be detected, and direct transformation to the CA/OX cocrystal was observed. The destabilization kinetics follow Prout–Tompkins nucleation and the crystal growth model with an activation energy of 133.91 kJ/mol, and subsequent CA/OX growth kinetics follow Ginstling–Brounshtien and three-dimensional diffusion models with an activation energy range of 130.45–132.57 kJ/mol".
More information [+]
"Mechanistic Understanding of Competitive Destabilization of Carbamazepine Cocrystals under Solvent Free Conditions"
Magazine: Crystal Growth & Design
The summary of the article is:
"Mechanistic understanding of competitive destabilization of carbamazepine:nicotinamide and carbamazepine:saccharin cocrystals under solvent free conditions has been investigated. The crystal phase transformations were monitored using hot stage microscopy, variable-temperature powder X-ray diffraction, and sublimation experiments. The destabilization of the two cocrystals occurs via two distinct mechanisms: vapor and eutectic phase formations. Vapor pressure measurements and thermodynamic calculations using fusion and sublimation enthalpies were in good agreement with experimental findings. The mechanistic understanding is important to maintain the stability of cocrystals during solvent free green manufacturing".
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"New Cocrystal of Ubiquinol with High Stability to Oxidation"
Magazine: Crystal Growth & Design
The summary of the article is:
"A new cocrystal of the essential nutrient ubiquinol that is highly resistant to air oxidation has been designed and discovered in a cocrystal screening. Hydroxybenzoic acids and phenols have been selected as the coformers with the aim to transfer their molecular antioxidant properties to the cocrystal and protect ubiquinol from oxidation. The new cocrystal ubiquinol/3,4-dihydroxybenzoic acid shows a remarkably high stability under standard stress conditions, which offers alternative strategies of formulation for an important industrial problem".
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