Dynamic Gas-Inclusion in a Single Crystal

Dehydration of a crystal hydrate at subglacial temperatures

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.

Elastic Organic Crystals of π-Conjugated Molecules: New Concept for Materials Chemistry

It is generally believed that organic single crystals composed of a densely packed arrangement of anisotropic, organic small molecules are less useful as functional materials due to their mechanically inflexible and brittle nature, compared to polymers bearing flexible chains and thereby exhibiting viscoelasticity. Nevertheless, organic crystals have attracted much attention because of their tunable optoelectronic properties and a variety of elegant crystal habits and unique ordered or disordered molecular packings arising from the anisotropic molecular structures. However, the recent emergence of flexible organic crystal materials showing plasticity and elasticity has considerably changed the concept of organic single crystals. In this review, the author summarizes the state-of-the-art development of flexible organic crystal materials, especially functional elastic organic crystals which are expected to provide a foothold for the next generation of organic crystal materials.

Ab initio powder X-ray diffraction structural analysis of bispidine based 1D coordination polymers: insights into their guest responsive behaviour

The first ab initio synchrotron powder XRD structure solution of a desolvated 1D bispidine coordination polymer (CP) is reported, providing valuable insights into the stability, dynamic and guest responsive behavior of a new class of CPs.

Solvatochromism as a probe to observe the solvent exchange process in a 1-D porous coordination polymer with 1-D solvent accessible channels

A one-dimensional porous coordination polymer possessing pleochroic and solvatochromic properties produces an unexpected double V-shaped discolouration of the crystal upon solvent exchange with acetonitrile and nitromethane. Modelling shows that the origin of this effect is preferential sorption at two faces of the crystal.

Selective adsorption of chlorinated volatile organic compound vapours by microcrystalline 1D coordination polymers

Microcrystalline 1D coordination polymers 1–3Pwd are able to adsorb vapours of chlorinated volatile organic compounds (Cl-VOCs), displaying interesting selectivity patterns, as demonstrated by ¹H-NMR and X-ray diffraction analyses.