In weakly bound materials such as water, one of the three primitive Frank-Kasper (FK) phases, the Z phase, is long absent due to the relatively unstable framework. The Z phase in clathrate hydrate, which is known as the HS-I structure, has now been found by precise tuning of the molecular guest structure. In the crystal structure, the never stabilized combination water cage of two 15-hedra and two 14-hedra formed with its original symmetries, providing sufficient gas capacity to the 12-hedral cages. With the discovery of the final FK clathrate hydrate, guest design now enables engineering of weak interactions in any mix of the three, illuminating how to leverage properties of clathrates in the broadest sense.

中文翻译：

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笼形水合物最终原始 Frank-Kasper 相的发现


在水等弱结合材料中，由于相对不稳定的骨架，三种原始弗兰克-卡斯帕（FK）相之一的Z相长期不存在。笼形水合物中的 Z 相（即 HS-I 结构）现已通过分子客体结构的精确调节被发现。在晶体结构中，两个15面体和两个14面体的从未稳定的组合水笼以其原始的对称性形成，为12面体笼提供了足够的气体容量。随着最终的 FK 笼形水合物的发现，客体设计现在可以对三者的任意组合中的弱相互作用进行工程设计，阐明了如何在最广泛的意义上利用笼形化合物的特性。