Solvent‐Dependent Self‐Assembly Behaviour and Speciation Control of Pd6L8 Metallo‐supramolecular Cages

The C₃‐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 Pd₆L₈]¹²⁺ metallo‐cages that resemble a stella octangula. The self‐assembly of the Pd₆( 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 MeNO₂. The Pd₆( 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 Pd₆L₈]¹²⁺ metallo‐cages where L= L1 and L1 a .