Binding thiourea derivatives with dimethyl methylphosphonate for sensing nerve agents

Area of Science:

• Chemical sensing
• Materials science
• Computational chemistry

Background:

• Organophosphonate nerve agents pose significant threats, necessitating the development of sensitive detection methods.
• Thiourea derivatives have shown promise as receptors for sensing chemical agents.

Purpose of the Study:

• To design and evaluate novel thiourea derivatives as efficient substrates for sensing organophosphonate nerve agents.
• To investigate the relationship between molecular structure, binding energies, and receptor efficiency.

Main Methods:

• Density-functional theory (DFT) calculations to determine binding energies and geometries of DMMP-thiourea complexes.
• Synthesis of four new thiourea derivatives (TU10-TU13).
• Quartz crystal microbalance (QCM) and real-time diffuse reflectance IR spectroscopy for experimental analysis.

Main Results:

• A strong correlation was observed between calculated binding energies and experimental receptor efficiencies for most thiourea derivatives.
• Deviations from the correlation were explained by analyzing molecular geometries and intermolecular double hydrogen bonding.
• TU13 exhibited high efficiency in QCM and IR analyses, attributed to potential unfolded geometries facilitating double H-bonding.

Conclusions:

• Intermolecular double hydrogen bonding is crucial for stable complex formation and efficient sensing of organophosphonate nerve agents.
• Molecular flexibility, influenced by substituents like methylene linkages, plays a significant role in receptor performance.
• Computational and experimental methods combined provide a comprehensive understanding of sensor-analyte interactions.