A breakthrough in chemical separation made by a joint research team of the Politecnico di Milano (Technical University of Milan) and the University of Jyvδskylδ was published in the latest issue of Science.
The chemical separations using porous solids mostly rely on size selection, meaning that compounds too large to squeeze through the pores are excluded. The work by the research group describes a class of ionic solids that can selectively capture certain fluorocarbons dynamically.
The crystals comprise dicationic hydrocarbon chains capped at each end by positive ammonium groups, with negative iodide ions to balance the charge.
Although structurally nonporous, the solids spontaneously stretch to accommodate iodine-capped fluorocarbon chains, which form robust intermolecular halogen bonds with iodides at each end. In other words, the solids used behave like a sponge that can absorb a specific molecule. This encapsulation is highly selective for the fluorocarbon, with a chain length scaled to the lattice dication. Moreover, the process is reversible, with the guests liberated by heating, offering potential for use in industrial fluorocarbon separations.
The members of the team are Professor Kari Rissanen and Adjunct Professor Manu Lahtinen from JYU, and Professors Pierangelo Metrangolo and Giuseppe Resnati from the Politecnico di Milano.
- Metrangolo et al. Nonporous Organic Solids Capable of Dynamically Resolving Mixtures of Diiodoperfluoroalkanes. Science, 2009; 323 (5920): 1461 DOI: 10.1126/science.1168679
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