Multicomponent, Multicavity Metallacages That Contain Different Binding Sites for Allosteric Recognition

Abstract

The encapsulation of different guest molecules by their different recognition domains of proteins leads to selective binding, catalysis, and transportation. Synthetic hosts capable of selectively binding different guests in their different cavities to mimic the function of proteins are highly desirable but challenging. Here, we report three ladder-shaped, triple-cavity metallacages prepared by multicomponent coordination-driven self-assembly. Interestingly, the porphyrin-based metallacage is capable of heteroleptic encapsulation of fullerenes (C60 or C70) and coronene using its different cavities, allowing distinct allosteric recognition of coronene upon the addition of C60 or C70. Owing to the different binding affinities of the cavities, the metallacage hosts one C60 molecule in the central cavity and two coronene units in the side cavities, while encapsulating two C70 molecules in the side cavities and one coronene molecule in the central cavity. The rational design of multicavity assemblies that enable heteroleptic encapsulation and allosteric recognition will guide the further design of advanced supramolecular constructs with tunable recognition properties.

Selective recognition and enrichment of C70 over C60 using an anthracene-based nanotube

“…On the other hand, fullerenes can be regarded as electron-decient guests in the hostguest interaction. The electron-rich aromatic units, such as porphyrins, [16][17][18] anthracene, 19,20 and nanographene 21 can be used as building blocks to achieve the complementary charge interactions with fullerenes. As a result, several fullerene-selective receptors with various geometric-shape cavities have been reported (Scheme 1a), including molecular cages, 22 coordination capsules, 23 deep cavitands, 24 and so on.…”