DFT Model of Elemental Sulfur in Sulfolane Solutions

Area of Science:

• Computational Chemistry
• Materials Science
• Spectroscopy

Background:

• Elemental sulfur exists in various molecular forms, influencing its solution properties.
• Understanding sulfur's behavior in solvents like sulfolane is crucial for chemical processes.
• Electronic spectroscopy is a key tool for analyzing molecular transformations.

Purpose of the Study:

• To investigate the structure and properties of elemental sulfur in sulfolane.
• To elucidate the molecular forms and aggregation behavior of sulfur in solution.
• To correlate spectral changes with sulfur concentration and molecular structure.

Main Methods:

• Density Functional Theory (DFT) methods, specifically PBE1PBE/6-311+G(d,p) approximation.
• Polarizable continuum model (integral equation formalism variant) for solvation effects.
• Time-Dependent DFT (TD-DFT) calculations for optical properties (UV absorption).

Main Results:

• Elemental sulfur (S8) forms a Sl-S8-Sl solvate in sulfolane.
• Stable (S8)n clusters form in concentrated sulfur solutions.
• Increased cluster size (n) reduces the extinction coefficient of the main UV absorption band (~50,000 cm-1).

Conclusions:

• The study provides a theoretical model for elemental sulfur's spectral behavior in sulfolane.
• The findings suggest a minor contribution of the S12 molecular form.
• This research enhances the analysis of sulfur transformation processes using electronic spectroscopy.