Parallel water/aromatic interactions of non-coordinated and coordinated water

Area of Science:

• Chemical Physics
• Crystallography
• Computational Chemistry

Background:

• Water-aromatic interactions are crucial in various chemical and biological systems.
• Understanding these interactions is key to predicting molecular behavior in condensed phases.

Purpose of the Study:

• To investigate the parallel interactions between water molecules and aromatic rings.
• To compare non-coordinated and metal-coordinated water interactions.
• To quantify the strength of these interactions using computational methods.

Main Methods:

• Analysis of crystal structures from the Cambridge Structural Database (CSD).
• Quantum chemical calculations to determine interaction energies.
• Comparison of parallel and OH/π interaction geometries.

Main Results:

• CSD data indicates a preference for parallel water-aromatic contacts over OH/π interactions.
• Coordination of water to metal ions significantly strengthens these interactions.
• Coordinated water molecules favor a 'parallel-down' orientation.
• Calculated interaction energies reached up to -14.89 kcal/mol for parallel-down aqua complexes.

Conclusions:

• Parallel water-aromatic interactions are important and prevalent in crystal structures.
• Metal coordination enhances water-aromatic binding, with parallel-down orientation being particularly strong.
• These findings highlight the significance of parallel orientations in water-benzene interactions.