Effect of microhydration on the guanidinium···benzene interaction

Area of Science:

• Computational chemistry
• Physical chemistry
• Molecular interactions

Background:

• Guanidinium cation and benzene interactions are crucial in various chemical and biological systems.
• Understanding solvation effects is key to predicting molecular behavior.

Purpose of the Study:

• To investigate the impact of microhydration on guanidinium-benzene interactions.
• To analyze structural and energetic changes induced by water molecules.

Main Methods:

• Ab initio calculations were employed.
• Four distinct structural arrangements of guanidinium-benzene were studied.
• Up to six water molecules were systematically added to these complexes.

Main Results:

• Water inclusion decreases energy differences between T-shaped and parallel guanidinium-benzene structures.
• Parallel complexes can become more stable than T-shaped ones with added water.
• Stability changes are primarily driven by the arrangement of hydrating water molecules, not direct cation-π modulation.
• The position of water molecules in solvation shells (first vs. second) influences structural stability.

Conclusions:

• Microhydration alters the preferred binding geometry of guanidinium to benzene.
• The study highlights the significant role of the solvation shell structure in determining complex stability.
• While dispersion forces increase in parallel structures, their overall impact on interaction energy is minor.