Stable Polymorphs Crystallized Directly under Thermodynamic Control in Three-Dimensional Nanoconfinement: A Generic Methodology

Abstract

. (2011) 'Stable polymorphs crystallized directly under thermodynamic control in three-dimensional nanocon nement : a generic methodology.', Crystal growth design., 11 (2). pp. 363-366. Further information on publisher's website:https://doi.org/10.1021/cg101200fPublisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Crystal growth design, copyright c American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see https://doi.org/10.1021/cg101200fAdditional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThermodynamic control of crystallization has been achieved to produce stable polymorphs directly by using 3D nano-confinement in microemulsions. The theoretical basis for thermodynamic control of crystallization using 3D nano-confinement is outlined. Our approach leap-frogs the usual metastable polymorph pathway because crystallization becomes governed by the ability to form stable nuclei, rather than critical nuclei. The generality of this approach is demonstrated by crystallizing the stable polymorph of three 'problem' compounds from microemulsions under conditions yielding metastable forms in bulk solution. The polymorphic compounds are mefenamic acid (2-[(2,3-(dimethylphenyl)amino] benzoic acid), glycine (aminoethanoic acid) and the highly polymorphic 5-methyl-2-[(2-nitrophenyl) amino]-3-thiophenecarbonitrile, commonly known as ROY because of its red, orange and yellow polymorphs. Application of this methodology should prevent another Ritonavir-type disaster, whereby a marketed drug transforms into a more stable form, reducing its bioavailability and effectiveness. The lowest energy nuclei selectively grow in our approach. Consequently this also provides a generic method for producing higher crystallinity materials, which may prove beneficial for crystallizing proteins and inorganic nanocrystals.Statement of urgency and brief summary of significant findings. We believe the paper fulfills the requirements of urgency for a Communication because it details for the first time a generic method to obtain thermodynamic control of crystallization. This enables stable polymorphs to be crystallized directly, to prevent another Ritonavir-type disaster. The methodology used selectively grows the lowest energy crystal nuclei, so it can also produce materials with higher crystallinity, which may prove of use for a wide range of crystalline materials, including potential...

Computer simulation of epitaxial nucleation of a crystal on a crystalline surface

“…Understanding crystallization is important for a wide variety of applications, in areas as diverse as pharmaceuticals, 1 the food industry, 2 atmospheric science, 3 and protein crystallization. 4 The first stage of crystallization is nucleation, the formation of a microscopic crystal nucleus.…”

Crystallization of Mefenamic Acid from Dimethylformamide Microemulsions: Obtaining Thermodynamic Control through 3D Nanoconfinement

“…These conditions corresponded to the lowest supersaturations at which crystallization was still possible in the microemulsions, with the mean initial supersaturation ratios,   sat initial c c , ranging from ≈3.0 to 3.8. The mean hydrophilic core radii of these microemulsions had previously been determined to be 1.6 nm [3]. Mostly (>60% †) Form II nanocrystals, with some Form I nanocrystals after 24 h. Form II macrocrystals typically develop over weeks to months.…”

“…This presents a unique opportunity for generic thermodynamic control of crystallization in microemulsions [3]. In particular, thermodynamic control is achievable under conditions where crystallization is only just possible in microemulsions, since this corresponds to the case where only the largest droplets with the highest supersaturations can form (near) stable nuclei of (typically) only the stable polymorph [3], see Figure 1b.…”

“…In particular, thermodynamic control is achievable under conditions where crystallization is only just possible in microemulsions, since this corresponds to the case where only the largest droplets with the highest supersaturations can form (near) stable nuclei of (typically) only the stable polymorph [3], see Figure 1b. The stable polymorph would usually be the only form able to produce (near) stable nuclei under these conditions because of the following considerations.…”

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