Synthesis and characterisation of an integratively self-sorted [Fe₄L₆]⁸⁺ tetrahedron

Isolating metal-organic cage structures which incorporate more than one distinct ligand has been challenging due to competing pressures from narcissistic and social sorting phenomena. Here we report the first example of exclusive formation of a single tetrahedral product from a reaction mixture containing two different bidentate ligands. Exclusive formation of the tetrahedron, which incorporates one unique metal vertex, relies on a triamine to orientate the heteroditopic ligand. Inclusion of perchlorate counterions during the self-assembly process is also found to be a requirement if social sorting is to be avoided. The C₃-symmetric structure is characterised by HR-MS, NMR spectroscopy and X-ray crystallography, and provides proof of principle for use of heteroditopic ligands in classical M₄L₆ supramolecular structures, opening exciting possibilities for their use in separation, storage and catalysis applications.