Selective Separation of Polyaromatic Hydrocarbons by Phase Transfer of Coordination Cages

Abstract

Here we report a new supramolecular strategy for the selective separation of specific polycyclic aromatic hydrocarbons (PAHs) from mixtures. The use of a triethylene glycol-functionalized formylpyridine subcomponent allowed the construction of an FeII4L4 tetrahedron 1 that was capable of transferring between water and nitromethane layers, driven by anion metathesis. Cage 1 selectively encapsulated coronene from among a mixture of eight different types of PAHs in nitromethane, bringing it into a new nitromethane phase by transiting through an intermediate water phase. The bound coronene was released from 1 upon addition of benzene, and both the cage and the purified coronene could be separated via further phase separation.

Design and Applications of Water-Soluble Coordination Cages

“…The subsequent addition of excess tetrabutylammonium sulfate induces the spontaneous precipitation of the sulfate salt of the cage in a water-soluble form. 90 , 91 …”

Cavity-based applications of metallo-supramolecular coordination cages (MSCCs)

“…This property of the cage was employed for selectively encapsulating coronene from a mixture of PAHs ( perylene, pyrene, anthracene, chrysene, phenanthrene, triphenylene and corannulene) through phase transfer of the cage. 52 In 2014 Nitschke and co-workers synthesized a tetrahedral, face-capped MSCC Fe II 4 L 4 cage II″ f Fe from a C 3 -symmetric triamine ligand, 2-formylpyridine and an iron salt by self-assembly and presented its host-guest chemistry (Fig. 6c).…”

Functional Material Systems Based on Soft Cages

“…The cage cavity selectively encapsulates guest molecules, and may exert intermolecular interactions towards its guests; the exterior functional group determines cage solubility and may form linkages to achieve functional composite materials, and the node not only provide chelating effects but also may provide active center for catalytic reactions. Because of the rich functions in even one cage molecule, they are increasingly employed in building functional materials such as in CO 2 or other gas adsorption, [1] ion encapsulation (anti corrosion), [2] catalysis, [3] multiphase sorting or transportation, [4] biomedicine, [5] Surface Enhanced Raman Scattering (SERS) active substrates, [6] or in polymeric composites with controlled release, [7] antibacterial, [8] or self‐healing properties (Figure 1). [9] …”