Hetero-Coencapsulation within a Supramolecular Cage: Moving away from the Statistical Distribution of Different Guests

Abstract

Beside sensing and delivery, another peculiar property arising from confinement in discrete molecular hosts comes from the possibility to have in close proximity, and in defined position, two different molecules (hetero-coencapsulation). This phenomenon can be tuned considering steric and electronic properties of the guests. In this work, a study on the parameters affecting homo- and hetero-coencapsulation processes within a supramolecular cage is reported. In particular, different benzoate guests were bound within a supramolecular cage containing two metal-binding sites and the experimental binding thermodynamics measured. Unexpectedly, from competition experiments it was observed that the maximum concentration of hetero-coencapsulation is achieved if a weakly binding guest is used to partially displace a strongly binding guest.

Keywords: anion recognition; guests coencapsulation; molecular cages; supramolecular chemistry.