Nearly Isostructural Polymorphs of Ethynylbenzene: Resolution of ⋮CH···π(arene) and Cooperative ⋮CH···π(C⋮C) Interactions by Pressure Freezing

In ethynylbenzene, elevated pressure favors cooperative ⋮CH···π(C⋮C) hydrogen bonds compared to ⋮CH···π(arene) and leads to the ordered polymorph nearly isostructural form with the crystals frozen by cooling. The high-pressure polymorph is more resistant to polymerization than the liquid and, in this respect, is a manifestation of Le Chatelier principle explained at the microscopic level for this compound. A new type of the polymorphic relation has been described.

在乙烯基苯中，高压条件有利于协同的⋮CH···π(C⋮C)氢键的形成，相较于⋮CH···π(芳烃)氢键，进而导致有序的准同构多晶形态，该形态通过冷却晶化而成。高压下的多晶形态相较于液态物质，对聚合反应具有更高的抵抗性，这在某种程度上体现了勒夏特列原理在微观层面的解释。一种新型的多晶关系已被描述。