Chiral Self-Sorting in Pd₆ L₁₂ Metal-Organic Cages

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Chiral self-sorting is a key phenomenon in supramolecular chemistry, influencing the assembly of complex molecular architectures.
• Metal-organic cages (MOCs) offer versatile platforms for studying self-sorting due to their tunable structures and predictable assembly.
• Axially chiral ligands are crucial building blocks for creating chiral supramolecular structures.

Purpose of the Study:

• To investigate chiral self-sorting in the formation of Pd6L12-type metal-organic cages.
• To determine the outcome of self-assembly when using racemic mixtures of axially chiral bis-pyridyl ligands.
• To explore the potential for diastereoselective self-assembly and the formation of specific enantiomers or meso isomers.

Main Methods:

• Coordination-driven self-assembly of palladium(II) ions with racemic mixtures of axially chiral bis-pyridyl ligands.
• Formation of Pd6L12-type metal-organic cages.
• Analysis of the self-sorting behavior and resulting cage structures.

Main Results:

• The system exhibited high-fidelity chiral social self-sorting, deviating from a statistical mixture.
• Diastereoselective self-assembly occurred, favoring specific heterochiral cage formation.
• A racemic mixture of D3-symmetric heterochiral cages, [Pd6(L6R/6S)12]12+/[Pd6(L6S/6R)12]12+, was predominantly formed.

Conclusions:

• Chiral self-sorting in Pd6L12-type MOCs can be highly diastereoselective.
• The observed self-sorting leads to the preferential formation of specific heterochiral assemblies.
• This finding advances the understanding of chiral recognition and control in supramolecular chemistry.