No abstract

Like wringing out a sponge, a metal–organic framework loaded with structure‐changing light‐responsive groups can squeeze out captured CO2. Because of the groups being structurally integral, there is oscillation between native and excited states. Pairing with CO2 capture from coal‐based power generation could reduce the parasitic energy load of adsorbent regeneration.

Aging in super glassy polymers such as poly(trimethylsilylpropyne) (PTMSP), poly(4‐methyl‐2‐pentyne) (PMP), and polymers with intrinsic microporosity (PIM‐1) reduces gas permeabilities and limits their application as gas‐separation membranes. While super glassy polymers are initially very porous, and ultra‐permeable, they quickly pack into a denser phase becoming less porous and permeable. This age‐old problem has been solved by adding an ultraporous additive that maintains the low density, porous, initial stage of super glassy polymers through absorbing a portion of the polymer chains within its pores thereby holding the chains in their open position. This result is the first time that aging in super glassy polymers is inhibited whilst maintaining enhanced CO2 permeability for one year and improving CO2/N2 selectivity. This approach could allow super glassy polymers to be revisited for commercial application in gas separations.

Metal organic frameworks (MOFs) are hybrid crystalline materials, exhibiting high specific surface areas, controllable pore sizes and surface chemistry.

Biological fluoride ion channels are sub-1-nanometer protein pores with ultrahigh F − conductivity and selectivity over other halogen ions. Developing synthetic F − channels with biological-level selectivity is highly desirable for ion separations such as water defluoridation, but it remains a great challenge. Here we report synthetic F − channels fabricated from zirconium-based metal-organic frameworks (MOFs), UiO-66-X (X = H, NH 2 , and N + (CH 3 ) 3 ). These MOFs are comprised of nanometer-sized cavities connected by sub-1-nanometer-sized windows and have specific F − binding sites along the channels, sharing some features of biological F − channels. UiO-66-X channels consistently show ultrahigh F − conductivity up to ~10 S m −1 , and ultrahigh F − /Cl − selectivity, from ~13 to ~240. Molecular dynamics simulations reveal that the ultrahigh F − conductivity and selectivity can be ascribed mainly to the high F − concentration in the UiO-66 channels, arising from specific interactions between F − ions and F − binding sites in the MOF channels.

Further deployment of Metal-Organic Frameworks in applied settings requires their ready preparation at scale. Expansion of typical batch processes can lead to unsuccessful or low quality synthesis for some systems. Here we report how continuous flow chemistry can be adapted as a versatile route to a range of MOFs, by emulating conditions of lab-scale batch synthesis. This delivers ready synthesis of three different MOFs, with surface areas that closely match theoretical maxima, with production rates of 60 g/h at extremely high space-time yields.

A new concept is described for methane and hydrogen storage materials involving the incorporation of magnesium-decorated fullerenes within metal-organic frameworks (MOFs). The system is modeled using a novel approach underpinned by surface potential energies developed from Lennard-Jones parameters. Impregnation of MOF pores with magnesium-decorated Mg(10)C(60) fullerenes, denoted as Mg-C(60)@MOF, places exposed metal sites with high heats of gas adsorption into intimate contact with large surface area MOF structures. Perhaps surprisingly, given the void space occupied by C(60), this impregnation delivers remarkable gas uptake, according to our modeling, which predicts exceptional performance for the Mg-C(60)@MOF family of materials. These predictions include a volumetric methane uptake of 265 v/v, the highest reported value for any material, which significantly exceeds the U.S. Department of Energy target of 180 v/v. We also predict a very high hydrogen adsorption enthalpy of 11 kJ mol(-1) with relatively little decrease as a function of H(2) filling. This value is close to the calculated optimum value of 15.1 kJ mol(-1) and is achieved concurrently with saturation hydrogen uptake in large amounts at pressures under 10 atm.

A porous treasure: Porous aromatic framework PAF‐1 (see picture, blue structure) has been lithiated, giving a reduced framework with an increased gas storage capacity compared to native PAF‐1 (by 22, 71, and 320 % for H2, CH4, and CO2, respectively). The reduced framework was examined spectroscopically, and the potential hydrogen storage capacity was calculated.