Length Ratio-Driven Configurational Modulation of Heteroleptic Pd₆L₆L'₆ Cages

Biomolecular configurational modulation is essential for maintaining the stability and functionality of biological systems. Drawing inspiration from this natural phenomenon, we present a strategy to modulate the configurations of heteroleptic Pd₆L₆L'₆ cages by systematically varying the ligand length ratio (r). Although theoretical analysis suggests that these Pd₆L₆L'₆ assemblies could adopt up to 48 possible configurational isomers, we successfully modulated the thermodynamic preference between two dominant configurations (Type-A and Type-B) by implementing energetic differentiation through careful optimization of r. Specifically, the system exclusively forms Type-A cages at r = 1.0, whereas Type-B becomes the predominant configuration when r ≥ 1.4. Control experiments demonstrate that the introduction of bulky steric groups does not induce configuration changes. This research offers valuable insights and serves as a useful reference for the design and configurational modulation of heteroleptic cages.