posted on 2023-12-07, 18:06authored byKrzysztof
M. Bąk, Igor Marques, Heike Kuhn, Kirsten E. Christensen, Vítor Félix, Paul D. Beer
Despite their hydrophobic
surfaces with localized π-holes
and rigid well-defined architectures providing a scaffold for preorganizing
binding motifs, fullerenes remain unexplored as potential supramolecular
host platforms for the recognition of anions. Herein, we present the
first example of the rational design, synthesis, and unique recognition
properties of novel fullerene-functionalized halogen-bonding (XB)
heteroditopic ion-pair receptors containing cation and anion binding
domains spatially separated by C60. Fullerene spatial separation
of the XB donors and the crown ether complexed potassium cation resulted
in a rare example of an artificial receptor containing two anion binding
sites with opposing preferences for hard and soft halides. Importantly,
the incorporation of the C60 motif into the heteroditopic
receptor structure has a significant effect on the halide binding
selectivity, which is further amplified upon K+ cation
binding. The potassium cation complexed fullerene-based receptors
exhibit enhanced selectivity for the soft polarizable iodide ion which
is assisted by the C60 scaffold preorganizing the potent
XB-based binding domains, anion−π interactions, and the
exceptional polarizability of the fullerene moiety, as evidenced from
DFT calculations. These observations serve to highlight the unique
properties of fullerene surfaces for proximal charged guest binding
with potential applications in construction of selective molecular
sensors and modulating the properties of solar cell devices.