Serendipitous isolation of a disappearing conformational polymorph of succinic acid challenges computational polymorph prediction.

Blagden, Nicholas and Singh, Ishwar and Lucaioli, Paolo (2018) Serendipitous isolation of a disappearing conformational polymorph of succinic acid challenges computational polymorph prediction. CrystEngComm . ISSN 1466-8033

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Serendipitous isolation of a disappearing conformational polymorph of succinic acid challenges computational polymorph prediction
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Abstract

A conformational polymorph () of succinic acid was discovered in an attempt to purify a leucine dipeptide by cocrystallization from a methanol solution in the presence of various impurities, such as trifluoroacetic acid. The new -form was found to have crystallized concomitantly with the most stable  form. In light of this situation, a crystal structure prediction study was undertaken to examine the polymorph landscape. These studies reveal that the  polymorph is thermodynamically competitive with the other observed polymorphs; having a more stable folded conformation than the planar crystalline conformation in the  form, but being stabilized less by the intermolecular interactions. Simulations and experiment show that the folded conformation is dominant in solution, but that trapping long-lived crystals of the new metastable polymorph may be challenging. Thus the  polymorph provides a stringent test of theories for predicting which thermodynamically plausible structures may be practically important polymorphs.

Additional Information:Currently Advance Article 26.6.8 PPS - okay for pre-print or post-print with 12 months embargo
Keywords:Metastable polymorphs, crytstal prediction
Subjects:F Physical Sciences > F170 Physical Chemistry
F Physical Sciences > F131 Crystallography
Divisions:College of Science > School of Pharmacy
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ID Code:32310
Deposited On:26 Jun 2018 21:19

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