Biasing hydrogen bond donating host systems towards chemical warfare agent recognition

Area of Science:

• Supramolecular Chemistry
• Anion Recognition
• Chemical Sensing

Background:

• Hydrogen bonding is crucial for molecular recognition in organic solvents.
• Developing selective hosts for anions and neutral organophosphorus compounds remains a challenge.
• Chemical warfare agents (CWAs) require sensitive and selective detection methods.

Purpose of the Study:

• To evaluate neutral and negatively charged host molecules for binding anions and neutral organophosphorus species.
• To investigate the role of hydrogen bonding in host-guest interactions.
• To assess the potential for selective CWA detection and binding.

Main Methods:

• Synthesis and evaluation of neutral ditopic and negatively charged monotopic host molecules.
• Binding studies in organic solvent using urea, thiourea, and boronic acid functional groups.
• Affinity measurements for chloride, dihydrogen phosphate, DMMP, PMP, and GD (soman).

Main Results:

• Urea and thiourea groups showed high affinity for both anions and neutral guests via hydrogen bonding.
• Negative charge on host molecules decreased anion affinity but maintained high stability for host-GD complexes.
• Host affinity for neutral CWA GD was greater than for anionic guests, indicating charge-based selectivity reversal.

Conclusions:

• Host molecules functionalized with urea and thiourea groups demonstrate effective anion and neutral guest binding.
• Charge repulsion can be exploited to achieve selectivity for neutral CWAs over anionic species.
• These findings present a promising strategy for developing selective sensors and capture agents for CWAs.