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首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >Structural changes of hexamethylenetetramine and undecanedioic acid co-crystal (HMT-C11) as a function of the temperature
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Structural changes of hexamethylenetetramine and undecanedioic acid co-crystal (HMT-C11) as a function of the temperature

机译：六亚甲基四胺和十一碳二酸共晶体（HMT-C11）的结构变化与温度的关系

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摘要

HMT-C11 belongs to the family of adducts formed by the cocrystallization of N-4(CH2)(6) molecules ( hexamethylenetetramine or HMT) and aliphatic dicarboxylic acids HOOC(CH2)(n-2)COOH with 5 less than or equal to n less than or equal to 13 (Cn). The adducts exhibit a layered structure in which the packing between HMT and Cn is determined by strong hydrogen bonds. The compounds in this family studied so far present thermotropic structural phase transitions and, depending on the chain length, disordered, twinned and modulated phases. The structure refinement of HMT-C11 based on X-ray diffraction experiments indicates three distinct phases from the melting point down to liquid nitrogen temperature: phase I is not crystalline; phase II is disordered ( stacking fault) and its average structure is described in space group Bmmb; phase III is partially disordered and its symmetry is P2(1)/c. The systematic study of the structure evolution of phase III upon cooling revealed that the disorder has a dynamic character (anharmonicity). The main structural change observed from 293 K down to 93 K is the increase of the tilting angle of the C11 chains relative to the layer plane and the rotation of the HMT molecules. Both HMT and C11 behave like rigid bodies in the temperature range investigated. The quality of the refinements leads to a conclusive model for the O-H...N hydrogen bonds linking HMT and C11. [References: 36]
机译：HMT-C11属于由N-4（CH2）（6）分子（六亚甲基四胺或HMT）与脂肪族二羧酸HOOC（CH2）（n-2）COOH共结晶而形成的加合物家族，其中5小于或等于5 n小于或等于13（Cn）。加合物显示出层状结构，其中HMT和Cn之间的堆积由强氢键决定。迄今为止，该家族中的化合物都呈现出热致结构相变，并且取决于链长，它们是无序，孪生和调制相。基于X射线衍射实验的HMT-C11的结构细化表明，从熔点到液氮温度，共有三个不同的相：I相为非结晶态; I相为非结晶态; I相为非结晶态。第二阶段是无序的（堆垛层错），其平均结构在空间群Bmmb中描述。阶段III部分无序，其对称性为P2（1）/ c。对第三相在冷却后的结构演变的系统研究表明，该疾病具有动态特征（非谐性）。从293 K下降到93 K的主要结构变化是C11链相对于层平面的倾斜角的增加以及HMT分子的旋转。在研究的温度范围内，HMT和C11的行为都像刚体。细化的质量导致连接HMT和C11的O-H ... N氢键的结论模型。 [参考：36]

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