Discrete Quadruple Stacks Formed in a Nanosized Metallorectangle

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Metallorectangles are nanoscale coordination cages with potential applications in host-guest chemistry.
• Janus-di-imidazolylidene ligands offer unique coordination geometries for constructing complex metallosupramolecular architectures.

Purpose of the Study:

• To synthesize a novel iridium-based nanosized metallorectangle.
• To investigate its host-guest properties with various planar aromatic molecules.
• To elucidate the binding mechanism and dynamics of co-encapsulated guests.

Main Methods:

• Synthesis of an iridium-cornered metallorectangle using a quinoxalinophenanthrophenazine-connected Janus-di-imidazolylidene ligand and 4,4'-bipyridine.
• Host-guest complexation studies with planar molecules: pyrene, triphenylene, perylene, coronene, and N,N'-dimethyl-naphthalenetetracarboxy-diimide (NTCDI).
• Analysis of binding stoichiometry and cooperativity using spectroscopic methods, including variable temperature 1H NMR spectroscopy.

Main Results:

• Successful synthesis of an iridium-cornered nanosized metallorectangle.
• Demonstration of host-guest complexation with planar aromatic molecules.
• Observation of a strongly positive cooperative 1:2 stoichiometric binding model for coronene and NTCDI.
• Formation of a heteroguest inclusion system with coronene and NTCDI.
• Characterization of the exchange dynamics of co-encapsulated guests.

Conclusions:

• The synthesized iridium metallorectangle acts as an effective host for planar molecules.
• The positive cooperative binding highlights the potential for selective guest encapsulation.
• The study provides insights into the dynamic behavior of heteroguest inclusion systems within metallosupramolecular hosts.