Non-statistical assembly of multicomponent [Pd2ABCD] cages

Self-assembled hosts, inspired by biological receptors and catalysts, show application potential in sustainable synthesis, energy conversion and medicine. Implementing multiple functionalities in the form of distinguishable building blocks, however, is difficult without risking narcissistic self-sorting or a statistical mess. Here we report a systematic series of integratively self-assembled heteroleptic cages in which two square-planar PdII cations are bridged by four different bis-pyridyl ligands, A, B, C and D, via synergistic effects to exclusively form a single isomer—the lantern-shaped cage [Pd2ABCD]. This self-sorting goal—forming just one out of 55 possible structures—is reached under full thermodynamic control and can be realized progressively (by combining progenitors, such as [Pd2A2C2] with [Pd2B2D2]), directly from ligands and PdII cations or by mixing all four corresponding homoleptic cages. The rational design of complex multicomponent assemblies that enables the modular incorporation of diverse chemical moieties will advance their applicability in functional nanosystems. Metal-mediated self-assembly of organic building blocks is a powerful strategy to generate complex supramolecular objects. The non-statistical combination of multiple different components, however, has been a major challenge. Now integrative self-sorting of low-symmetry multicomponent cages has been achieved by combining shape complementarity and selective backbone interactions under thermodynamic control.