Mechanochemical synthesis via grinding of trimesic acid (TA, C9H6O6) and 4-chlorophenyl diphenyl phosphate (4CDP, C18H14ClO4P) (liquid at room temperature) in a 1:1 ratio resulted in the formation of an inclusion type of cocrystal. The crystallization of this phase via slow evaporation at low temperature (276–277 K) from methanol resulted in a rare `stairstep morphology' during the process of crystal growth. This morphology was not observed after crystallization of the compound from other solvents like toluene, dichloromethane, acetone, hexane and isooctane, and hence this was characteristically observed in methanol only. The characterization from single-crystal X-ray diffraction revealed the formation of a cocrystal with five molecules of TA and two molecules of 4CDP in the asymmetric unit. The trimesic acid molecules form hydrogen-bonded dimers resulting in hexagonal rings, and these rings are stacked through π–π intermolecular interactions to make a hexagonal honeycomb-like structure. The phosphate molecules, 4CDP, were found to be trapped as guests in these hexagonal channels. The similarity in the packing of trimesic acid is compared in the cocrystal and the free acid quantitatively via
Xpac analysis, which establishes the relationship of a `2D supramolecular construct' between them. This signifies a unique type of arrangement in which the voids created by the trimesic acid moiety do not undergo distortion by the inclusion of the guest molecules. The quantitative analysis of the intermolecular interactions using Hirshfeld surfaces and fingerprint plots deciphers the role of both strong O—H...O hydrogen bonds and weak intermolecular interactions in the crystal packing.
以 1:1 的比例研磨三美酸(TA,C9H6O6)和 4-氯苯基二苯基磷酸酯(4CDP,C18H14ClO4P)(室温下为液态)进行机械化学合成,形成了一种包涵型共晶体。通过在低温(276-277 K)下从甲醇中缓慢蒸发结晶,在晶体生长过程中形成了罕见的 "台阶形态"。该化合物从甲苯、二氯甲烷、丙酮、己烷和异辛烷等其他溶剂中结晶出来后,并没有观察到这种形态,因此只有在甲醇中才能观察到这种特征。单晶 X 射线衍射表征显示,在不对称单元中形成了由五个 TA 分子和两个 4CDP 分子组成的共晶体。三肟酸分子形成氢键二聚体,形成六角环,这些环通过π-π分子间相互作用堆叠成六角蜂窝状结构。研究发现,磷酸分子 4CDP 作为客体被困在这些六边形通道中。通过 Xpac 分析,定量比较了共晶体和游离酸中三美酸填料的相似性。
Xpac分析定量比较了三聚氰酸和游离酸的堆积相似性,从而确定了它们之间的 "二维超分子结构 "关系。这意味着一种独特的排列方式,即三聚氰酸分子产生的空隙不会因为客体分子的加入而发生变形。利用 Hirshfeld 表面和指纹图谱对分子间相互作用进行的定量分析,揭示了强 O-H...O 氢键和弱分子间相互作用在晶体堆积中的作用。