Metal-organic frameworks exhibiting strong anion-pi interactions

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Coordination polymers are versatile materials for adsorption, guest/anion recognition, and sensing.
• Existing ligands often exhibit weak donor properties, limiting their use in coordination frameworks.
• Anion-pi interactions, crucial for host-guest chemistry, are observed in biomolecules and protein structures.

Purpose of the Study:

• To develop a novel ligand with efficient donor properties for transition metal ions.
• To investigate enhanced anion-pi interactions for coordination polymer applications.
• To design geometrically rigid anion receptors for host-guest chemistry.

Main Methods:

• A novel one-pot synthesis involving inverse electron demand Diels-Alder cycloaddition.
• Development of unsubstituted pyridazino[4,5-d]pyridazine ligand.
• Analysis of ligand's electron-deficiency and LUMO energy levels.

Main Results:

• Pyridazino[4,5-d]pyridazine exhibits efficient donor properties and pronounced anion-pi interaction capabilities.
• The ligand's electron-deficient nature (LUMO energy -1.591 eV) enhances anion binding.
• N-coordination to Lewis acids further influences the ligand's anion binding properties.

Conclusions:

• Pyridazino[4,5-d]pyridazine is a promising ligand for creating advanced coordination polymers.
• The ligand's unique electronic properties facilitate robust anion recognition and sensing.
• This work opens new avenues for functionalizing hydrophobic crystal cavities and designing novel anion receptors.