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Updated: Aug 9, 2026

Crystallization of Membrane Proteins in Lipidic Mesophases
Published on: March 28, 2011
Polymorphism on leflunomide: stability and crystal structures
Daniel Vega1, Alicia Petragalli, Daniel Fernández
1Unidad de Actividad Física, Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires, Argentina.
Abstract:
Two polymorphs of Leflunomide were found and studied (form I and II). Both of them were characterized by X-ray powder diffraction and thermal analysis. Single crystals were obtained and both structures were solved. Forms I and II crystallize in the space group P2(1)/c with two and one independent molecules per asymmetric unit, respectively. Thermodynamic stability of the two forms is assessed by differential scanning calorimetry. The cohesion in the crystal of form I (the more stable) is provided by both by H bonding as well as pi...pi interactions, while in form II it is given only by the former. The independent molecules in form I adopt different conformations thus allowing for a larger number of intermolecular interactions.
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