Premium
Cocrystals of the antimalarial drug 11‐azaartemisinin with three alkenoic acids of 1:1 or 2:1 stoichiometry
Author(s) -
Nisar Madiha,
Wong Lawrence W.-Y.,
Sung Herman H.-Y.,
Haynes Richard K.,
Williams Ian D.
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/s2053229618006320
Subject(s) - cocrystal , maleic acid , fumaric acid , chemistry , stoichiometry , hydrogen bond , crystal engineering , molecule , stereochemistry , crystallography , organic chemistry , polymer , copolymer
The stoichiometry, X‐ray structures and stability of four pharmaceutical cocrystals previously identified from liquid‐assisted grinding (LAG) of 11‐azaartemisinin (11‐Aza; systematic name: 1,5,9‐trimethyl‐14,15,16‐trioxa‐11‐azatetracyclo[10.3.1.0 4,13 .0 8,13 ]hexadecan‐10‐one) with trans ‐cinnamic (Cin), maleic (Mal) and fumaric (Fum) acids are herein reported. trans ‐Cinnamic acid, a mono acid, forms 1:1 cocrystal 11‐Aza:Cin ( 1 , C 15 H 23 NO 4 ·C 9 H 8 O 2 ). Maleic acid forms both 1:1 cocrystal 11‐Aza:Mal ( 2 , C 15 H 23 NO 4 ·C 4 H 4 O 4 ), in which one COOH group is involved in self‐catenation, and 2:1 cocrystal 11‐Aza 2 :Mal ( 3 , 2C 15 H 23 NO 4 ·C 4 H 4 O 4 ). Its isomer, fumaric acid, only affords 2:1 cocrystal 11‐Aza 2 :Fum ( 4 ). All cocrystal formation appears driven by acid–lactam R 2 2 (8) heterosynthons with short O—H…O=C hydrogen bonds [O…O = 2.56 (2) Å], augmented by weaker C=O…H—N contacts. Despite a better packing efficiency, cocrystal 3 is metastable with respect to 2 , probably due to a higher conformational energy for the maleic acid molecule in its structure. In each case, the microcrystalline powders from LAG were useful in providing seeding for the single‐crystal growth.