Molecular and Supramolecular Interactions in Systems with Nitroxide-Based Radicals

Area of Science:

• Computational chemistry
• Physical chemistry
• Materials science

Background:

• Nitroxide radicals are stable chemical probes used for detecting nanoscale details via electron paramagnetic resonance (EPR) spectroscopy.
• Understanding solvent effects on EPR spectral parameters is crucial for accurate interpretation in multi-component systems.
• First-principle methods offer a powerful approach to rationalize these complex interactions.

Purpose of the Study:

• To systematically investigate and rationalize the influence of solvent effects on the spectral parameters of nitroxide radicals using computational methods.
• To compare the accuracy of explicit solvent modeling with implicit solvent models (polarization continuum approximation).
• To explore the interaction energetics of nitroxide radicals with host molecules like cyclodextrins and cucurbiturils.

Main Methods:

• Utilizing state-of-the-art Density Functional Theory (DFT) calculations.
• Designing computational models that balance chemical realism with necessary idealization.
• Investigating explicit solvent molecule configurations and comparing with vacuum and continuum solvent models.
• Calculating interaction energy profiles for radical encapsulation within toroidal molecules.

Main Results:

• DFT calculations provide insights into how solvent molecules, such as dichloromethane, affect the EPR spectra of TEMPO radicals.
• Explicit solvent modeling offers a more detailed understanding compared to continuum approximations.
• The study models the interaction energy profiles of nitroxide radicals with β-cyclodextrin and cucurbit[6]uril.

Conclusions:

• The computational approach provides valuable rationales for interpreting the spectroscopy and energetics of nitroxide radicals in various chemical environments.
• This work contributes to the understanding of nitroxide radical behavior in soft chemistry applications.
• The findings aid in the rational design and application of nitroxide radicals as probes in complex systems.