The majority of research into metal-organic frameworks (MOFs) focuses on their crystalline nature. Recent research has revealed solid-liquid transitions within the family, which we use here to create a class of functional, stable and porous composite materials. Described herein is the design, synthesis, and characterisation of MOF crystal-glass composites, formed by dispersing crystalline MOFs within a MOF-glass matrix. The coordinative bonding and chemical structure of a MIL-53 crystalline phase are preserved within the ZIF-62 glass matrix. Whilst separated phases, the interfacial interactions between the closely contacted microdomains improve the mechanical properties of the composite glass. More significantly, the high temperature open pore phase of MIL-53, which spontaneously transforms to a narrow pore upon cooling in the presence of water, is stabilised at room temperature in the crystal-glass composite. This leads to a significant improvement of CO 2 adsorption capacity.

Porous materials are widely used in industry for applications that include chemical separations and gas scrubbing. These materials are typically porous solids, though the liquid state can be easier to manipulate in industrial settings. The idea of combining the size-and shape-selectivity of porous domains with the fluidity of liquids is a promising one and porous liquids composed of functionalized organic cages have recently attracted attention. Here, we describe an ionic-liquid, porous, tetrahedral coordination cage. Complementing the gas-binding observed in other porous liquids, this material also encapsulates non-gaseous guestsshape-and size-selectivity was observed for a series of alcohol isomers. Three gaseous guests, chlorofluorocarbons CFC-11, CFC-12, and CFC-13, were also shown to be taken up by the liquid coordination cage with an affinity increasing with their size. We hope that these findings will lead to the synthesis of other porous liquids whose guest-uptake properties may be tailored to fulfil specific functions. Recent work has shown that persistent cavities can be engineered into liquids, lending them permanent porosity. These new materials were initially proposed by James in 2007 1 , who recognised three distinct types of them. The simplest of these, Type I permanently porous liquids, consist of rigid hosts with empty cavities that are liquid in their neat state 2,3 , without requiring an additional solvent for fluidity 4-7. Metalorganic frameworks (MOFs) have also been observed to form liquid phases that are inferred to be porous 8,9 , although the high temperatures required preclude guest binding. Previously reported examples of porous liquids have included surface-modified hollow silica spheres 2 and hollow carbon spheres 3 , crown ether-functionalised organic cages 5 , and dispersions 4, 6 or slurries 7 of porous framework materials in ionic liquids. To date, applications of these materials have focussed on gas storage and separation 2,10,11. However, we are not aware of the binding of guest molecules larger than carbon dioxide or methane inside the cavities of porous liquids, restricting the potential application of these

To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In comparison, high internal surface areas are readily achieved in crystalline materials, such as metal-organic frameworks (MOFs). It has recently been discovered that a new family of melt quenched glasses can be produced from MOFs, though they have thus far have lacked the accessible and intrinsic porosity of their crystalline precursors. Here, we report the first glasses that are permanently, and reversibly porous toward incoming gases, without post synthetic treatment. We characterized the structure of these glasses using a range of experimental techniques, and demonstrate pores in the 4-8 angstrom range. The discovery of MOF-glasses with permanent accessible porosity reveals a new category of porous glass materials, that are potentially elevated beyond conventional inorganic and organic porous glasses, by their diversity and tunability.

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To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In contrast, high internal surface areas are readily achieved in crystalline materials, such as metal-organic frameworks (MOFs). It has recently been discovered that a new family of melt quenched glasses can be produced from MOFs, though they have thus far lacked the accessible and intrinsic porosity of their crystalline precursors. Here, we report the first glasses that are permanently and reversibly porous toward incoming gases, without post-synthetic treatment. We characterize the structure of these glasses using a range of experimental techniques, and demonstrate pores in the range of 4 – 8 Å. The discovery of MOF glasses with permanent accessible porosity reveals a new category of porous glass materials that are elevated beyond conventional inorganic and organic porous glasses by their diversity and tunability.