Superphanes: Old Yet New Binding–Agents for Highly Selective Recognition of Fluoride by Size–Sieving Effect
Superphanes, namely percyclophanes,
have been widely investigated for the sake of their aesthetically pleasing
structures with high symmetry, intriguing physical and chemical properties and
synthetic challenges. Nonetheless, the host–guest chemistry of superphanes
remains to be an unmet challenge. Herein, we delineate the design, preparation,
characterization, and host–guest chemistry of an unprecedented superphane 15,
which was evidenced by mass spectroscopy, NMR spectroscopy, X–ray
crystallography, and DFT calculations. 15 features six bridges between
two benzene planes, up to 18 Csp–H hydrogen–bonding donors
well–distributed around the near–closed inner cavity in three dimensions. These allow 15 to exhibit exclusive selectivity towards F– against
Cl–, Br–, I–, N3–, SCN–,
NO3–, ClO4–, SO42–
and HP2O73– due to the size–sieving effect.
This contribution opens up new opportunities for design and synthesis of new supramolecular hosts for anions of interest with high selectivity.