Journal ArticleDOI
Recurrence of carboxylic acid-pyridine supramolecular synthon in the crystal structures of some pyrazinecarboxylic acids.
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X-ray crystal structures of pyrazinic acid 1 and isomeric methylpyrazine carboxylic acids 2-4 are analyzed to examine the occurrence of car boxylic acid-pyridine supramolecular synthon V in these heterocyclic acids.Abstract:
X-ray crystal structures of pyrazinic acid 1 and isomeric methylpyrazine carboxylic acids 2-4 are analyzed to examine the occurrence of carboxylic acid-pyridine supramolecular synthon V in these heterocyclic acids. Synthon V, assembled by (carboxyl)O-H...N(pyridine) and (pyridine)C-H...O(carbonyl) hydrogen bonds, controls self-assembly in the crystal structures of pyridine and pyrazine monocarboxylic acids. The recurrence of acid-pyridine heterodimer V compared to the more common acid-acid homodimer I in the crystal structures of pyridine and pyrazine monocarboxylic acids is explained by energy computations in the RHF 6-31G* basis set. Both the O-H.N and the C-H...O hydrogen bonds in synthon V result from activated acidic donor and basic acceptor atoms in 1-4. Pyrazine 2,3- and 2,5-dicarboxylic acids 10 and 11 crystallize as dihydrates with a (carboxyl)O-H...O(water) hydrogen bond in synthon VII, a recurring pattern in the diacid structures. In summary, the carboxylic acid group forms an O-H...N hydrogen bond in pyrazine monocarboxylic acids and an O-H...O hydrogen bond in pyrazine dicarboxylic acids. This structural analysis correlates molecular features with supramolecular synthons in pyridine and pyrazine carboxylic acids for future crystal engineering strategies.read more
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Journal ArticleDOI
Pharmaceutical Co-Crystals
TL;DR: This review addresses how crystal engineering has been applied to active pharmaceutical ingredients, API's, with emphasis upon how pharmaceutical co-crystals, a long known but little explored alternative to the four traditionally known forms of API, can be generated in a rational fashion.
Journal ArticleDOI
Building co-crystals with molecular sense and supramolecular sensibility
TL;DR: In this article, the authors provide an overview of some modular and transferable strategies for the synthesis of binary and ternary supermolecules and co-crystals based upon a hierarchy of intermolecular interactions, notably hydrogen bonds.
Journal ArticleDOI
Crystal engineering of the composition of pharmaceutical phases
R. D. Bailey Walsh,Michael W. Bradner,S. Fleischman,L. A. Morales,Brian Moulton,Naír Rodríguez-Hornedo,Michael J. Zaworotko +6 more
TL;DR: It has become clear that a wide array of multiple component pharmaceutical phases, so called pharmaceutical co-crystals, can be rationally designed using crystal engineering, and the strategy affords new intellectual property and enhanced properties for pharmaceutical substances.
Journal ArticleDOI
Hierarchy of Supramolecular Synthons: Persistent Carboxylic Acid···Pyridine Hydrogen Bonds in Cocrystals That also Contain a Hydroxyl Moiety
TL;DR: In this paper, the authors evaluate the hierarchy of supramolecular heterosynthons that involve two of the most relevant functional groups in the context of active pharmaceutical ingredients, carboxylic acids and alcohols, in competitive environments.
Journal ArticleDOI
Tape and layer structures in cocrystals of some di- and tricarboxylic acids with 4,4′-bipyridines and isonicotinamide. From binary to ternary cocrystals
TL;DR: In this paper, a modular expansion of carboxylic acid dimer in neutral cocrystals with pyridine type bases is shown, which results in a ternary cocrystal 12 sustained via O−H⋯N and O−O− hydrogen bonds, and the length of bipyridinium cation plays a role in the overall structure.
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Journal ArticleDOI
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