Synthesis of a Pd2L4 Hydrazone Molecular Cage Through Multiple Reaction Pathways

Molecular cages are preorganized molecules with a central cavity, typically formed through the reaction of their building blocks through chemical bonds. This requires, in most cases, forming and breaking reversible bonds during the cage formation reaction pathway for error correction to drive the reaction to the cage product. In this work, we focus on both Pd-ligand and hydrazone bonds implemented in the structure of a Pd₂L₄ hydrazone molecular cage. As the cage contains two different types of reversible bonds, we envisaged a cage formation comparative study by performing the synthesis of the cage through three different reaction pathways involving the formation of Pd-ligand bonds, hydrazone bonds, or a combination of both. The three reaction pathways produce the cage with yields ranging from 73% to 79%. Despite the complexity of the reaction, the cage is formed in a high yield, even for the reaction pathway that involves the formation of 16 bonds. This research paves the way for more sophisticated cage designs through complex reaction pathways.