The X-ray structures of three new 1:1 pharmaceutical cocrystals of 11-azaartemisinin (11-Aza; systematic name: 1,5,9-trimethyl-14,15,16-trioxa-11-azatetracyclo[10.3.1.04,13.08,13]hexadecan-10-one, C15H23NO4) with bromo-substituted salicylic acids [namely, 5-bromo- (5-BrSalA, C7H5BrO3), 4-bromo- (4-BrSalA, C7H5BrO3) and 3,5-dibromosalicylic 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 molecular 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 compound. Structure redeterminations of the bromosalicylic 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 Å in the cocrystals.
11-氮杂青蒿素(11-Aza;系统名:1,5,9-三甲基-14,15,16-三氧杂-11-氮杂四环[10.3.1.04,13.系统名称:1,5,9-三甲基-14,15,16-三氧杂-11-氮杂十四烷环[10.3.1.04,13.08,13]十六烷-10-酮,C15H23NO4)与溴代水杨酸[即 5-溴-(5-BrSalA,C7H5BrO3)、4-溴-(4-BrSalA,C7H5BrO3)和 3,5-二溴水杨酸(3,5-Br2SalA,C7H4Br2O3)]。所有这些结构都与之前报告的 11-Aza:SalA 母共晶(单斜 P21)有关。5-BrSalA 类似物与母体结构相同,晶格沿 c 轴扩展。4-BrSalA 和 3,5-Br2SalA 共晶体高度保留了分子对的 21 层堆积,但这些堆积相对于相邻堆积有不同程度的滑动,改变了它们之间的紧密接触,代表了母体化合物的两种潜在同结构排列。在 100 K 下对溴水杨酸 5-BrSalA、4-BrSalA 和 3,5-Br2SalA 的结构重新测定表明,根据比容计算,共晶体的堆积效率不必高于母体共形物,这归因于共晶体中 2.54 Å 的强 O-H...O=C 氢键。