Dehydration of a crystal hydrate at subglacial temperatures

Abstract

Water is one of the most important substances on our planet1. It is ubiquitous in its solid, liquid and vaporous states and all known biological systems depend on its unique chemical and physical properties. Moreover, many materials exist as water adducts, chief among which are crystal hydrates (a specific class of inclusion compound), which usually retain water indefinitely at subambient temperatures2. We describe a porous organic crystal that readily and reversibly adsorbs water into 1-nm-wide channels at more than 55% relative humidity. The water uptake/release is chromogenic, thus providing a convenient visual indication of the hydration state of the crystal over a wide temperature range. The complementary techniques of X-ray diffraction, optical microscopy, differential scanning calorimetry and molecular simulations were used to establish that the nanoconfined water is in a state of flux above −70 °C, thus allowing low-temperature dehydration to occur. We were able to determine the kinetics of dehydration over a wide temperature range, including well below 0 °C which, owing to the presence of atmospheric moisture, is usually challenging to accomplish. This discovery unlocks opportunities for designing materials that capture/release water over a range of temperatures that extend well below the freezing point of bulk water.

Enhanced Electrocatalytic Performances by Spatially Confined Aqueous Electrolytes

“…It is apparent that the oxygen atoms are stationary within the limiting domain space during extreme experimental conditions, but the protons are observed to easily diffuse through the oxygen lattice, which is indicative of the recently discovered superionic phase in water (see Figure 2c). Alan C. Eaby et al [20] from the University of Stellenbosch, South Africa, and the University of Poznan, Poland, described a porous organic crystal that reversibly adsorbs water into a 1 nm wide channel at relative humidity above 55 %. The ease of water passage through T1 was assessed by mean square displacement (MSD) analysis.…”

Polymorphism and π Stacking Affect Thermal Expansion Behavior in Halogen-Bonded Cocrystals Based on 1,4-Diiodoperchlorobenzene

“…Controlling the three-dimensional self-assembly of organic molecules into a solid-state structure remains challenging for crystal engineers and materials scientists. The extended solid-state structure, as well as the intermolecular forces sustaining the solid have a direct influence on the properties of the material. − Π-stacking interactions, , for example, play a role in protein folding and binding of small molecules, affect conductivity in organic semiconductors, , and can be used to drive molecular recognition. , One property affected by solid-state structure and intermolecular forces is thermal expansion (TE); the response of a material to temperature change. Stronger intermolecular interactions, such as halogen and hydrogen bonds, are typically less affected by temperature than weaker interactions, such as π stacking.…”

Enhanced Hydrogen Bonds of the (H2O)n (n = 4–8) Clusters Confined in Uranyl Peroxide Cluster Na20(UO2)20(O2)30

“…Water plays a crucial role in biological and chemical systems as the matrix of life, and hydrogen bond, especially its strength, is vital to the exhibited properties of water. − Chaplin et al suggested that if the strength of hydrogen bonds in water is 7% stronger, the freezing temperature would increase to the average surface temperature (15 °C) of Earth, while the water would boil at a normal human body temperature if it is 22% weaker . Hence, large numbers of studies have been performed to explore the strength of hydrogen bonds.…”