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Crystallization of (±)-Modafinil in Gel: Access to Form I, Form III, and Twins

2006; American Chemical Society; Volume: 6; Issue: 8 Linguagem: Inglês

10.1021/cg060203k

1528-7505

Morgan Pauchet, Thomas Morelli, Servane Coste, Jean-Jacques Malandain, Gérard Coquerel,

Crystallography and molecular interactions

Single crystals of (±)-modafinil have been grown in gel medium obtained from the hydrolysis and condensation of tetramethoxysilane (TMOS). Three different crystal morphologies have been highlighted, corresponding to two modifications and a twin. The first polymorphic form was found to match with the known monoclinic form I (P21/a, Z' = 2, a = 14.502 Å, b = 9.678 Å, c = 20.844 Å, and β = 110.17°). The determination of the second form allowed us to validate the previously predicted form III (orthorhombic Pna21, Z' = 2, a = 14.510 Å, b = 9.710 Å, c = 19.569 Å). The analysis of the twinned bodies and the structural similarities between form I and form III allowed us to identify the twin law: a stacking fault of (001)form I leading to a form III like interface. The analysis of the structures also suggested possible multitwinning.