Fluoride-facilitated deuterium exchange from DMSO-d6 to polyamide-based cryptands

Area of Science:

• Supramolecular Chemistry
• Analytical Chemistry
• Structural Chemistry

Background:

• Hexaamido cryptands are macrocyclic compounds known for their ability to encapsulate guest ions.
• Fluoride ion recognition and binding are crucial in various chemical and biological processes.
• Understanding the interactions within host-guest complexes is key to designing new functional materials.

Purpose of the Study:

• To investigate the interaction between hexaamido cryptand fluoride receptors and fluoride ions.
• To verify deuterium exchange between the receptor and solvent.
• To elucidate the structural basis of fluoride encapsulation.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy (19F and 2H) was used to monitor deuterium exchange.
• Fast Atom Bombardment (FAB) mass spectrometry was employed for structural characterization.
• Single-crystal X-ray diffraction was utilized to determine the precise coordination geometry.

Main Results:

• Multiple deuterium exchange between DMSO-d6 and amide hydrogens was confirmed.
• FAB mass spectral studies supported the formation of receptor-fluoride complexes.
• Structural analysis revealed a tricapped trigonal prism coordination geometry around the encapsulated fluoride ion.
• Hydrogen bonding interactions between the fluoride ion and six amide and three phenyl hydrogens were identified.

Conclusions:

• The hexaamido cryptand receptors effectively bind and encapsulate fluoride ions.
• Deuterium exchange provides evidence for the dynamic interaction between the receptor and solvent.
• The determined coordination geometry highlights the specific hydrogen bonding network involved in fluoride recognition.