Polymorphism and Structure in a Pentamorphic Guest−Host Material: The Tris(5-acetyl-3-thienyl) Methane (TATM) Inclusion Compound with 1,3-Dichloropropane

In this work, we describe the preparation and structural properties of five polymorphs of the 1G:2H,
1,3-dichloropropane/tris (5-acetyl-3-thienyl) methane (TATM) inclusion compound. A number of different preparative
methods were used to give products whose structures were solved by single-crystal X-ray diffraction. In addition,
solid-state 13C NMR spectroscopy and powder X-ray diffraction (PXRD) were used for bulk phase identification. On
the basis of the unit cell parameters determined from single crystal X-ray diffraction experiments, the PXRD results
were used to resolve the products as being from either pure or mixed phases. In four of the five forms, the host
TATM molecules have similar torsional conformations and share a common layered motif. The guest molecules are
disordered and reside in cages or channels that are formed from the stacking of these layers. In the fifth form, the
conformation of the TATM host molecules differ significantly, and the disordered guests reside in a pronounced
zigzag channel. Apparently, slightly different conformations for the host and the flexile guest give structures that
differ little in energy. The results suggest that minor changes in synthetic procedures can have a profound effect on
the structure of the resulting crystalline product. Some of the structures presented here are closely related to other
structures previously reported for TATM inclusion compounds with a variety of guests, suggesting that this may be
a particularly rich area for studying polymorphism.

本研究中，我们对1G:2H，1,3-二氯丙烷/三(5-乙酰-3-噻吩基)甲烷（TATM）包合物的五种同质异构体的制备及其结构特性进行了详细描述。通过多种不同的制备方法，我们得到了结构通过单晶X射线衍射解析的产品。此外，固态13C核磁共振光谱和粉末X射线衍射（PXRD）被用于识别块体相。基于单晶X射线衍射实验确定的晶胞参数，PXRD结果被用于解析产物是否为纯净相或混合相。在五种形态中的四种中，宿主TATM分子具有相似的扭转构象，并共享一个共同的层状结构单元。客体分子呈无序排列，位于由这些层堆积形成的笼或通道中。在第五种形态中，TATM宿主分子的构象显著不同，无序的客体分子位于一个明显的之字形通道中。显然，宿主分子与柔性客体分子之间略微不同的构象产生了在能量上差异微小的结构。结果表明，合成过程中的细微变化可以对最终结晶产物的结构产生深远影响。所展示的一些结构与其他先前报道的具有各种客体的TATM包合物的结构密切相关，这表明这可能是研究同质异构性的一个特别丰富的领域。