Pathway Engineering in Pd‐Based Supramolecular Cage Synthesis via Inner‐Outer Steric Synergy

For artificial supramolecular architectures designed to mimic biological systems, achieving different pathway synthesis is challenging due to the requirement of multiple stable and interconvertible intermediates. Here, we propose a novel “inner‐outer steric synergy” strategy and investigate controllable pathway engineering for the synthesis of specific structures. Firstly, three structures (Ring‐Pd2LA2, Bowl‐Pd2LA3 or Cage‐Pd2LA4) with interconversion properties were selectively formed by assembling externally modified ligand LA with Pd(II). Furthermore, Ring‐Pd2LA2 can further assemble with the ligand LB with inner steric hindrance to generate heteroleptic trans‐Pd2LA2LB2 cage, while Bowl‐Pd2LA3, as an intermediate, can assemble with LB to form Pd2LA3LB. It is noteworthy that Ring‐Pd2LA2, Bowl‐Pd2LA3, and Cage‐Pd2LA4 can interconvert under specific conditions, enabling the synthesis of Pd2LA3LB and trans‐Pd2LA2LB2 through 10 and 16 pathways, respectively. This research not only introduces a novel strategy for constructing heteroleptic cages but also demonstrates the achievement of pathway engineering.