Solvent‐Dependent Self‐Assembly Behaviour and Speciation Control of Pd 6 L 8 Metallo‐supramolecular Cages

The C 3 ‐symmetric chiral propylated host‐type ligands (±)‐ tris (isonicotinoyl)‐ tris (propyl)‐cyclotricatechylene ( L1 ) and (±)‐ tris (4‐pyridyl‐4‐benzoxy)‐ tris (propyl)‐cyclotricatechylene ( L2 ) self‐assemble with Pd II into [Pd 6 L 8 ] 12+ metallo‐cages that resemble a stella octangula. The self‐assembly of the [Pd 6 ( L1 ) 8 ] 12+ cage is solvent‐dependent; broad NMR resonances and a disordered crystal structure indicate no chiral self‐sorting of the ligand enantiomers in DMSO solution, but sharp NMR resonances occur in MeCN or MeNO 2 . The [Pd 6 ( L1 ) 8 ] 12+ cage is observed to be less favourable in the presence of additional ligand, than is its counterpart, where L=(±)‐ tris (isonicotinoyl)cyclotriguaiacylene ( L1 a ). The stoichiometry of reactant mixtures and chemical triggers can be used to control formation of mixtures of homoleptic or heteroleptic [Pd 6 L 8 ] 12+ metallo‐cages where L= L1 and L1 a .