Pushing the Limits of Characterising a Weak Halogen Bond in Solution

Area of Science:

• Chemical Physics
• Molecular Biophysics
• Supramolecular Chemistry

Background:

• Characterizing weak, non-covalent interactions in solution is difficult due to low affinity and short complex lifetimes.
• Sensitive spectroscopic methods often struggle to detect and analyze these subtle forces accurately.
• Understanding these interactions is crucial for various fields, including drug design and materials science.

Purpose of the Study:

• To develop and demonstrate a robust strategy for the experimental investigation of weak chemical forces in solution.
• To accurately determine the geometric and thermodynamic properties of weak interactions, such as halogen bonds.
• To provide a foundation for the improved understanding and application of weak forces in chemistry and biology.

Main Methods:

• Utilizing the entropic benefits of intramolecular interactions within a cooperatively folding system.
• Employing Nuclear Overhauser Effect (NOE) and Residual Dipolar Coupling (RDC)-based ensemble analyses for precise orientation descriptions.
• Deriving thermodynamic constants (ΔG, ΔH, ΔS) through variable temperature chemical shift analysis.

Main Results:

• Successfully characterized the weak halogen bond between an aryl iodide and an ether oxygen (0.6 kJ/mol).
• Accurate geometric and thermodynamic data were obtained for the weak interaction.
• Demonstrated the methodology's effectiveness for weak halogen bonds and related forces.

Conclusions:

• A reliable methodology for experimentally investigating weak halogen bonds and other weak forces in solution has been established.
• This approach enables a deeper understanding of these interactions.
• The findings pave the way for the strategic application of weak forces in chemical and biological systems.