Rosbottom, I, Ma, CY orcid.org/0000-0002-4576-7411, Turner, T orcid.org/0000-0003-3776-2044 et al. (5 more authors) (2017) Influence of Solvent Composition on the Crystal Morphology and Structure of p-Aminobenzoic Acid Crystallised from Mixed Ethanol and Nitromethane Solutions. Crystal Growth & Design, 17 (8). pp. 4151-4161. ISSN 1528-7483
Abstract
The crystallization of α-p-aminobenzoic acid (pABA) from mixed solutions in ethanol (EtOH) and nitromethane (NMe) is reported. From solutions with compositions >60 wt % NMe, the known α-polymorph of pABA appears. In contrast, crystals prepared from mixed solvent with <60 wt % NMe reveal the presence of a previously unknown NMe solvate, which crystallizes concomitantly with the α-form. The crystal structure of this new form has been determined and is compared with the previously known structure of the α-polymorph. The crystal structure of the NMe solvate has similar synthonic interactions with respect to α-pABA, in particular, the OH···O H-bonded dimers and the NH···O H-bonds between the pABA molecules. However, the π–π stacking interactions between the phenyl ring groups are found to be much more offset and do not form a continuous chain through the structure, as found in α-pABA. The synthonic interactions in the NMe solvate structure are generally weaker than those found in α-pABA, and the lattice energy is calculated to be significantly lower, suggesting the solvate structure is metastable with respect to α-pABA. The impact of NMe on the morphology of α-pABA crystals, together with molecular modelling results suggest that this solvent is able to disrupt the π–π stacking interactions that dominate growth along the needle (b-axis) direction of α-pABA, and are intimately linked to the ultimate formation of the solvate.
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Copyright, Publisher and Additional Information: | © 2017 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. | ||||
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Institution: | The University of Leeds | ||||
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) | ||||
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Depositing User: | Symplectic Publications | ||||
Date Deposited: | 23 Aug 2017 12:29 | ||||
Last Modified: | 08 Aug 2019 16:38 | ||||
Status: | Published | ||||
Publisher: | American Chemical Society | ||||
Identification Number: | https://doi.org/10.1021/acs.cgd.7b00425 |