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

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Artificial supramolecular architectures aim to mimic biological systems.
• Synthesizing diverse structures with multiple interconvertible intermediates is challenging.
• Controlling reaction pathways is crucial for targeted assembly.

Purpose of the Study:

• To introduce a novel
• inner-outer steric synergy
• strategy for supramolecular synthesis.
• To investigate controllable pathway engineering for specific structure formation.
• To demonstrate the synthesis of heteroleptic cages with multiple pathways.

Main Methods:

• Assembly of externally modified ligand L^A with Palladium(II) ions.
• Selective formation of Ring-Pd₂L^A ₂, Bowl-Pd₂L^A ₃, and Cage-Pd₂L^A ₄ structures.
• Further assembly with ligand L^B (possessing inner steric hindrance) to create heteroleptic complexes.
• Investigation of interconversion conditions between different Pd₂L^A _x structures.

Main Results:

• Three interconvertible structures (Ring-Pd₂L^A ₂, Bowl-Pd₂L^A ₃, Cage-Pd₂L^A ₄) were selectively synthesized.
• Heteroleptic cages trans-Pd₂L^A ₂L^B ₂ and Pd₂L^A ₃L^B were formed via controlled assembly.
• Interconversion between Ring-, Bowl-, and Cage-Pd₂L^A _x structures was achieved.
• Synthesis of specific heteroleptic cages was realized through 10 and 16 distinct pathways.

Conclusions:

• The "inner-outer steric synergy" strategy enables precise control over supramolecular assembly.
• This approach facilitates the construction of complex heteroleptic cages.
• Demonstrates successful pathway engineering for targeted synthesis in supramolecular chemistry.