An experimental screen has been carried out for salts and co-crystals of quinoline (C9H7N) and fumaric acid (C4H4O4), including solution-based co-crystallisation from a variety of solvents, solvent-assisted and solvent-free co-grinding, and direct co-crystallisation of the starting materials. Characterised products include the previously published 1 : 1 salt, C9H8N+·C4H3O4−, and a new 2 : 1 quinoline/fumaric acid co-crystal, (C9H7N)2·C4H4O4. Attempts to influence the crystallisation outcome by addition of 6-methylquinoline yielded a second co-crystal, also with an inherent 2 : 1 quinoline/fumaric acid ratio, as a solid solution containing ca. 75% 6-methylquinoline and 25% quinoline. The corresponding co-crystal with pure 6-methylquinoline, (C10H9N)2·C4H4O4, was prepared, but the analogous structure with pure quinoline could not be obtained. Energy minimisation using dispersion-corrected density functional theory (DFT-D) calculations suggests that the hypothetical polymorph of the 2 : 1 quinoline/fumaric acid co-crystal derived from the structure of the 2 : 1 6-methylquinoline/fumaric acid co-crystal is ca. 8 kJ mol−1 less stable than the structure that is actually observed.
已经针对
喹啉(
C9H7N)和
富马酸(
C4H4O4)的盐类和共晶体进行了实验筛选,方法包括多种溶剂的溶液共晶化、溶剂辅助和无溶剂共研磨,以及起始材料的直接共晶化。表征的产物包括之前发表的1:1盐
C9H8N+·
C4H3O4−和一种新的2:1
喹啉/
富马酸共晶体( )2· 。通过添加
6-甲基喹啉来影响结晶结果的尝试,获得了第二种共晶体,仍然具有固有的2:1
喹啉/
富马酸比例,作为一种含有约75%
6-甲基喹啉和25%
喹啉的固体溶液。对应的纯
6-甲基喹啉共晶体(
C10H9N)2· 也已制备,但无法获得纯
喹啉的类似结构。使用经色散修正的密度泛函理论(DFT-D)计算的能量优化结果表明,从2:1
6-甲基喹啉/
富马酸共晶体的结构推导出的假设多晶型,稳定性比实际观察到的结构低约8 kJ mol−1。