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.

Studying weak interactions in crystals at high pressures: when hardware matters

“…From a data completeness point of view, this provides the same number of reflections in a narrower 2 range. Ag K radiation is therefore becoming popular for high-pressure X-ray diffraction studies (Saouane et al, 2013;Saouane & Fabbiani, 2015;Granero-García et al, 2017). The number of independent reflections for data collection (1) was 1.6 times greater than for (2) (893 vs 550), as a result of using a shorter wavelength.…”

Formation of Crystalline Hydrates by Nonionic Chaotropes and Kosmotropes: Case of Piperidine

“…Nevertheless, the core structure of the water framework is typical for the hydrate clathrates with bigger cages occupied and smaller cages empty. Under elevated pressure, two additional hydrates of tert -butylamine ( 5.65 and 5.80 ) are observed . There are also known multicomponent clathrate hydrate systems, analogous to the sII type, with tert -butylamine, H 2 S, and Xe molecules, which are also examples of an O-disordered framework clathrate.…”

“…Under elevated pressure, two additional hydrates of tert-butylamine (5.65 and 5.80) are observed. 86 There are also known multicomponent clathrate hydrate systems, analogous to the sII type, with tert-butylamine, H 2 S, and Xe molecules, 87 which are also examples of an O-disordered framework clathrate. Furthermore, some spectroscopic observation on ordinary 88,89 or gamma irradiated 90 tert-butylamine-water clathrate-like systems are known as well.…”

Hydrate vs Anhydrate under a Pressure-(De)stabilizing Effect of the Presence of Water in Solid Forms of Sulfamethoxazole

“…However, it is worth noting that during the tableting process via compaction of APIs can also be subjected to nonambient pressure, a stimulus known to efficiently affect the crystal structure. Exposing crystals to high pressure can lead to solid-state phase transitions, , crystal amorphization, chemical reactions in the solid state, or even pressure-induced solvation. , In rare cases pressure has even led to an increase in the solubility of the investigated crystals. , Therefore, pressure can be a powerful tool used in the search of new crystal forms of the APIs, but it also should be considered in the study of their stability to avoid unintentional solid-state transformations during the tablet manufacturing process. , Similarly to the solubility, the pressure stability of a drug substance can be modified (increased or decreased) by introducing foreign molecules or ions into the crystal structure and formation of multicomponent crystals . The destabilizing effect of a second component was observed for glycine and its cocrystal with glutaric acid, as well as for dl -alanine and dl -alaninium semioxalate monohydrate, where the introduction of the second component led to the disruption of homosynthones.…”

“…34,35 In rare cases pressure has even led to an increase in the solubility of the investigated crystals. 36,37 Therefore, pressure can be a powerful tool used in the search of new crystal forms of the APIs, but it also should be considered in the study of their stability to avoid unintentional solid-state transformations during the tablet manufacturing process. 38,39 Similarly to the solubility, the pressure stability of a drug substance can be modified (increased or decreased) by introducing foreign molecules or ions into the crystal structure and formation of multicomponent crystals.…”