title: Dense Semi-Clathrates at High Pressure: A Study of the Water-tert-Butylamine System.
abstract: In situ high-pressure crystallization and diffraction techniques have been applied to obtain two very structurally distinct semi-clathrates of the tert-butylamine-water system with hydration numbers 5.65 and 5.8, respectively, thereby considerably reducing a notable hydration gap between the monohydrate and the 71/4 -hydrate that results when crystallization space is explored by temperature alone. Both structures can be considered as an intriguing solid-state example of hydrophobic hydration, in which the water network creates wide tert-butylamine-filled channels stabilized by cross-linking hydrogen bonds. The existence of interconnected channels might also add low hydration structures to a list of potential targets for hydrogen storage. A detailed analysis of the topology of host water and host-guest interactions is reported and extended to those of other hydrates of the compound. This analysis offers new insight into properties of the tert-butylamine-water system and provides some clues as to the occurrence of the sizable number of hydrates of this compound.
authors.affiliation: GZG, Abt. Kristallographie, Georg-August-Universität Göttingen, Goldschmidtstr. 1, 37077, Göttingen, Germany.
authors.forename: Rubén
authors.initials: R
authors.lastname: Granero-García
authors.affiliation: GZG, Abt. Kristallographie, Georg-August-Universität Göttingen, Goldschmidtstr. 1, 37077, Göttingen, Germany.
authors.forename: Andrzej
authors.identifier: http://orcid.org/0000-0001-5995-9900
authors.initials: A
authors.lastname: Falenty
authors.affiliation: GZG, Abt. Kristallographie, Georg-August-Universität Göttingen, Goldschmidtstr. 1, 37077, Göttingen, Germany.
authors.forename: Francesca P A
authors.initials: FP
authors.lastname: Fabbiani
keywords: clathrates; crystal engineering; high-pressure chemistry; polymorphism