Enantioselective adsorption of ibuprofen and lysine in metal-organic frameworks

This study reveals the efficient enantiomeric separation of bioactive molecules in the liquid phase. Chiral structure HMOF-1 separates racemic mixtures whereas heteroselectivity is observed for scalemic mixtures of ibuprofen using non-chiral MIL-47 and MIL-53. Lysine enantiomers are only separated by HMOF-1. These separations are controlled by the tight confinement of the molecules

Separation of amyl alcohol isomers in ZIF-77

The separation of pentanol isomer mixtures is shown to be very efficient using the nanoporous adsorbent zeolitic imidazolate framework ZIF-77. Through molecular simulations, we demonstrate that this material achieves a complete separation of linear from monobranchedand these from dibranchedisomers. Remarkably, the adsorption and diffusion behaviors follow the same decreasing trend, produced by the channel size of ZIF-77 and the guest shape. This separation based on molecular branching applies to alkanes and alcohols and promises to encompass numerous other functional groups

Simulation Study of Structural Changes in Zeolite RHO

Flexibility in zeolite RHO manifests itself in its ability to adopt one of two structures, depending on composition and applied external conditions. In this work, structural changes of dehydrated zeolite RHO of composition vertical bar Na6Cs3 vertical bar[Al9Si39O96] and pure silica were investigated by molecular dynamics (MD) and Monte Carlo methods using the force field by Nicholas et al. (J. Am. Chem. Soc. 1991, 113, 4792). The structure was found, depending on temperature, to be stable in the acentric form (space group I (4) over bar 3m) below similar to 300 K and in the centric form (Im (3) over barm) above, in qualitative agreement with experimental findings from the literature. Additionally, the structure may remain in the centric form in metastable conditions at all temperatures and exhibits a negative thermal expansion (NTE) of -(13 +/- 3) X 10(-6) K-1. Calculated X-ray diffraction patterns match the experimental ones closely, confirming the assignments to space groups made on the basis of lattice sizes. Modifications on the force field were investigated and other established force fields probed. A detailed knowledge and control over the behavior of this structure should lead to more reliable predictions on applications like separation of gases