Odiase Isaac, Nicholson Catherine E, Ahmad Ruksanna, Cooper Jerry, Yufit Dmitry S, Cooper Sharon J
Department of Chemistry, Durham University, South Road, Durham DH1 3LE, England.
Centre for Process Innovation, Wilton Centre, Wilton, Redcar TS10 4RF, England.
Acta Crystallogr C Struct Chem. 2015 Apr;71(Pt 4):276-83. doi: 10.1107/S2053229615004283. Epub 2015 Mar 14.
Four new cocrystals of pyrimidin-2-amine and propane-1,3-dicarboxylic (glutaric) acid were crystallized from three different solvents (acetonitrile, methanol and a 50:50 wt% mixture of methanol and chloroform) and their crystal structures determined. Two of the cocrystals, namely pyrimidin-2-amine-glutaric acid (1/1), C4H5N3·C6H8O4, (I) and (II), are polymorphs. The glutaric acid molecule in (I) has a linear conformation, whereas it is twisted in (II). The pyrimidin-2-amine-glutaric acid (2/1) cocrystal, 2C4H5N3·C6H8O4, (III), contains glutaric acid in its linear form. Cocrystal-salt bis(2-aminopyrimidinium) glutarate-glutaric acid (1/2), 2C4H6N3(+)·C6H6O4(2-)·2C6H8O4, (IV), was crystallized from the same solvent as cocrystal (II), supporting the idea of a cocrystal-salt continuum when both the neutral and ionic forms are present in appreciable concentrations in solution. The diversity of the packing motifs in (I)-(IV) is mainly caused by the conformational flexibility of glutaric acid, while the hydrogen-bond patterns show certain similarities in all four structures.
嘧啶 - 2 - 胺与丙烷 - 1,3 - 二羧酸（戊二酸）的四种新型共晶体从三种不同溶剂（乙腈、甲醇以及甲醇与氯仿的50:50重量比混合物）中结晶析出，并确定了它们的晶体结构。其中两种共晶体，即嘧啶 - 2 - 胺 - 戊二酸（1/1），C₄H₅N₃·C₆H₈O₄，（I）和（II），是多晶型物。（I）中的戊二酸分子具有线性构象，而在（II）中它是扭曲的。嘧啶 - 2 - 胺 - 戊二酸（2/1）共晶体，2C₄H₅N₃·C₆H₈O₄，（III），含有线性形式的戊二酸。共晶体 - 盐双（2 - 氨基嘧啶鎓）戊二酸盐 - 戊二酸（1/2），2C₄H₆N₃(+)·C₆H₆O₄(2-)·2C₆H₈O₄，（IV），与共晶体（II）从相同溶剂中结晶析出，这支持了在溶液中中性和离子形式都以可观浓度存在时共晶体 - 盐连续统的观点。（I） - （IV）中堆积模式的多样性主要由戊二酸的构象灵活性引起，而氢键模式在所有四种结构中显示出一定的相似性。
