Solvent effects on the redox properties of thioethers

Area of Science:

• Electrochemistry
• Physical Organic Chemistry
• Supramolecular Chemistry

Background:

• Understanding redox potentials is crucial for predicting chemical reactivity.
• Solvent effects play a significant role in modulating electronic properties of molecules.
• Thioanisole derivatives are relevant in various chemical transformations.

Purpose of the Study:

• To investigate the influence of various solvents on the one-electron reduction potential of radical cations of thioanisole, benzyl methyl sulfide, and 2-hydroxyethyl benzyl sulfide.
• To quantitatively evaluate solvent effects using the Kamlet-Taft relationship.
• To determine the dominant solvent properties influencing the observed redox potentials.

Main Methods:

• Cyclic voltammetry was employed to measure one-electron reduction potentials in multiple solvents.
• Pulse radiolysis was used for comparative measurements in water.
• Kamlet-Taft parameters were utilized to analyze solvent effects.

Main Results:

• Redox potentials are highly sensitive to solvent properties, with sensitivity increasing with charge localization.
• The Kamlet-Taft equation accurately describes solvent effects on the redox properties of the studied compounds.
• Solvent dipolarity/polarizability (π*) was identified as the major contributing factor, while hydrogen bond donating ability (α) had minor importance.
• Linear correlations were observed between π* and reduction potential, as well as solvent dipole moment and peak potential.

Conclusions:

• Solvent effects on the redox potentials of thioanisole radical cations are predominantly governed by nonspecific solvation.
• Dipolar/polarizability interactions are the key drivers of solvent sensitivity in these systems.
• The findings provide valuable insights into controlling and predicting the electrochemical behavior of sulfur-containing organic molecules.