A 2,6-diamidopyridine-based macrocyclic aromatic amide receptor with cascade ion pair recognition

Area of Science:

• Supramolecular Chemistry
• Host-Guest Chemistry
• Synthetic Receptor Design

Background:

• Ion-pair receptors are crucial in supramolecular chemistry for binding both cations and anions.
• Their ability to recognize multiple ion types is key for various applications.
• Developing selective and multifunctional receptors remains an active research area.

Purpose of the Study:

• To synthesize a novel cascade macrocyclic ion-pair receptor.
• To investigate its selectivity for anions, particularly fluoride.
• To explore its capacity for cation binding in the absence of dedicated sites.

Main Methods:

• Synthesis of a macrocyclic structure using 2,6-amidopyridine building blocks and aromatic spacers.
• Evaluation of anion binding selectivity, focusing on fluoride ions.
• Investigation of cation binding mechanisms, specifically for tetraethylammonium cations.

Main Results:

• The synthesized receptor demonstrated high selectivity for fluoride ions at its diamide binding sites.
• The receptor successfully bound tetraethylammonium cations, despite lacking intrinsic cation-binding domains.
• This cation binding was attributed to cascade electrostatic interactions initiated by the bound fluoride.

Conclusions:

• A novel cascade macrocyclic ion-pair receptor with dual anion and cation binding capabilities has been successfully synthesized.
• The receptor exhibits remarkable selectivity for fluoride anions.
• The study highlights a unique mechanism for cation recognition mediated by anion binding.