Shishkina SV, Shaposhnyk AM, Konovalova IS, Dyakonenko VV, Vaksler YO. Concomitant polymorphs of 2-imino-2H-chromene-3-carboxylic acid amide: experimental and quantum chemical study.
ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2024;
80:27-37. [PMID:
38205837 DOI:
10.1107/s2052520623010193]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 11/24/2023] [Indexed: 01/12/2024]
Abstract
2-Iminocoumarin-3-carboxamide (2-imino-2 H-chromene-3-carboxylic acid) is a perspective compound for use in the pharmaceutical industry. This compound crystallized from several solvents as two concomitant polymorphic forms. The monoclinic polymorph, crystallized initially, is formed due to strong N-H...O hydrogen bonds, weak C-H...O and C-H...N(π) hydrogen bonds, and stacking interactions of `head-to-head' type. The triclinic polymorphic form obtained due to slow evaporation of the same solution is formed due to only strong intermolecular interactions, N-H...O hydrogen bonds of two types, and stacking interactions of two types. Analysis of pairwise interaction energies showed that the monoclinic structure is columnar while the triclinic one is layered. Calculations in a periodic approximation of their lattice energies confirmed that the monoclinic polymorphic crystals are metastable as compared to the stable triclinic polymorph. Further quantum chemical modeling of possible structure deformations proved that both concomitant polymorphs can not be transformed into a new polymorphic form under external influence.
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