Solvent-Controlled Separation of Integratively Self-Sorted Pd₂L^A ₂L^B ₂ Coordination Cages

The integrative implementation of multiple different components into metallosupramolecular self-assemblies requires sophisticated strategies to avoid the formation of statistical mixtures. Previously, the key focus was set on thermodynamically driven reactions of simple homoleptic into complex heteroleptic structures. Using Pd₂L^A ₂L^B ₂-type coordination cages, we herein show that integrative self-sorting can be reversed by a change of solvent (from DMSO to MeCN) to favor narcissistic re-segregation into coexisting homoleptic species Pd₂L^A ₄ and Pd₃L^B ₆. Full separation ("unsorting") back to a mixture of the homoleptic precursors was finally achieved by selective precipitation of Pd₃L^B ₆ with anionic guest G¹ from MeCN, keeping pure Pd₂L^A ₄ in solution. When a mixture of homoleptic Pd₃L^B ₆ and heteroleptic Pd₂L^A ₂L^B ₂ is exposed to a combination of two different di-anions (G¹ and G²) in DMSO, selective guest uptake gives rise to two defined coexisting host-guest complexes. A joint experimental and deep theoretical investigation via liquid-state integral equation theory of the reaction thermodynamics on a molecular level accompanied by solvent distribution analysis hints at solvent expulsion from Pd₂L^A ₄ to favor the formation of Pd₂L^A ₂L^B ₂ in DMSO as the key entropic factor for determining the solvent-specific modulation of the cage conversion equilibrium.