Guest encapsulation underpins the functional properties of self-assembled capsules yet identifying systems capable of strongly binding small organic molecules in solution remains a challenge. Most coordination capsules rely on the hydrophobic effect to ensure effective solution-phase association. In contrast, we show that using non-interacting anions in apolar solvents can maximize favorable interactions between a cationic Pd2 L4 host and charge-neutral guests resulting in a dramatic increase in binding strength. With quinone-type guests, association constants in excess of 108 m-1 were observed, comparable to the highest previously recorded constant for a metallosupramolecular capsule. Modulation of optoelectronic properties of the guests was also observed, with encapsulation either changing or switching-on luminescence not present in the bulk phase.
Keywords: coordination capsules; host-guest systems; non-coordinating anions; quinones; self-assembly.
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