Polarizable continuum model associated with the self-consistent-reaction field for molecular adsorbates at the...

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Surface Science

Background:

• Understanding interfacial molecule behavior is crucial for various chemical and physical processes.
• The dielectric polarizable continuum model (DPCM) is a key tool for simulating molecular environments.
• Accurate computation of adsorbate-solvent interactions requires advanced theoretical methods.

Purpose of the Study:

• To develop a novel self-consistent-reaction field (SCRF) computation procedure for interfacial molecules.
• To investigate the influence of molecular structure on adsorbate-solvent interactions at the air/water interface.
• To analyze the orientation behavior of specific benzonitrile and phenol derivatives at the air/water interface.

Main Methods:

• Extended dielectric polarizable continuum model for quantum-continuum calculations.
• Analysis of electrostatic and non-electrostatic energies (including cavitation energy).
• Investigated three molecules: 2,6-dimethyl-4-hydroxy-benzonitrile, 3,5-dimethyl-4-hydroxy-benzonitrile, and p-cyanophenol.

Main Results:

• Hydroxyl groups of 2,6-dimethyl-4-hydroxy-benzonitrile and p-cyanophenol orient towards the water phase.
• The hydroxyl group of 3,5-dimethyl-4-hydroxy-benzonitrile exhibits an opposite orientation.
• Cavitation energy is identified as the primary factor for the reversed orientation of 3,5-dimethyl-4-hydroxy-benzonitrile.

Conclusions:

• The orientation of interfacial molecules is governed by a balance between electrostatic and cavitation energies.
• The developed SCRF method accurately explains experimental sum frequency generation (SFG) measurements.
• Computational insights provide a theoretical basis for understanding molecular behavior at interfaces.