Varying degrees of homostructurality in a series of cocrystals of antimalarial drug 11-azaartemisinin with salicylic acids

Monalisa Roy, Keyao Li, Madiha Nisar, Lawrence W.Y. Wong, Herman H.Y. Sung, Richard K. Haynes, Ian D. Williams

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The X-ray structures of three new 1:1 pharmaceutical cocrystals of 11-aza-artemisinin (11-Aza; systematic name: 1,5,9-trimethyl-14,15,16-trioxa-11-aza-tetra-cyclo-[10.3.1.04,13.08,13]hexa-decan-10-one, C15H23NO4) with bromo-substituted salicylic acids [namely, 5-bromo-(5-BrSalA, C7H5BrO3), 4-bromo-(4-BrSalA, C7H5BrO3) and 3,5-di-bromo-salicylic acid (3,5-Br2SalA, C7H4Br2O3)] are reported. All the structures are related to the parent 11-Aza:SalA cocrystal (monoclinic P21) reported previously. The 5-BrSalA analogue is isostructural with the parent, with lattice expansion along the c axis. The 4-BrSalA and 3,5-Br2SalA cocrystals retain the highly preserved 21 stacks of the mol-ecular pairs, but these pack with a varying degree of slippage with respect to neighbouring stacks, altering the close contacts between them, and represent two potential alternative homostructural arrangements for the parent com-pound. Structure redeterminations of the bromo-salicylic acids 5-BrSalA, 4-BrSalA and 3,5-Br2SalA at 100 K show that the packing efficiency of the cocrystals need not be higher than the parent coformers, based on specific-volume calculations, attributable to the strong O-H...O=C hydrogen bonds of 2.54 A˚ in the cocrystals.
Original languageEnglish
Pages (from-to)262-270
Number of pages9
JournalActa Crystallographica Section C: Structural Chemistry
Volume77
DOIs
Publication statusPublished - 01 Jun 2021

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