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Electrostatic properties of the pyrimethamine–2,4‐dihydroxybenzoic acid cocrystal in methanol studied using transferred electron‐density parameters
Author(s) -
Faroque Muhammad Umer,
Noureen Sajida,
Ahmed Maqsood,
Tahir Muhammad Nawaz
Publication year - 2018
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229617017788
Subject(s) - cocrystal , methanol , pyrimethamine , electron , electron density , chemistry , physics , organic chemistry , molecule , biology , quantum mechanics , plasmodium falciparum , malaria , hydrogen bond , immunology
The crystal structure of the cocrystal salt form of the antimalarial drug pyrimethamine with 2,4‐dihydroxybenzoic acid in methanol [systematic name: 2,4‐diamino‐5‐(4‐chlorophenyl)‐6‐ethylpyrimidin‐1‐ium 2,4‐dihydroxybenzoate methanol monosolvate, C 12 H 14 ClN 4 + ·C 7 H 5 O 4 − ·CH 3 OH] has been studied using X‐ray diffraction data collected at room temperature. The crystal structure was refined using the classical Independent Atom Model (IAM) and the Multipolar Atom Model by transferring electron‐density parameters from the ELMAM2 database. The Cl atom was refined anharmonically. The results of both refinement methods have been compared. The intermolecular interactions have been characterized on the basis of Hirshfeld surface analysis and topological analysis using Bader's theory of Atoms in Molecules. The results show that the molecular assembly is built primarily on the basis of charge transfer between 2,4‐dihydroxybenzoic acid and pyrimethamine, which results in strong intermolecular hydrogen bonds. This fact is further validated by the calculation of the electrostatic potential based on transferred electron‐density parameters.