The Diels-Alder Reaction as a Mechanistic Probe for Vibrational Strong Coupling

Area of Science:

• Chemical Kinetics
• Physical Chemistry
• Spectroscopy

Background:

• Vibrational Strong Coupling (VSC) is a phenomenon that can potentially alter chemical reaction kinetics.
• The precise mechanisms by which VSC influences reactions, including factors like reaction polarity and intramolecular vibrational redistribution (IVR), remain incompletely understood.
• The Diels-Alder (DA) reaction offers a versatile platform for studying VSC due to its diverse reaction partners.

Purpose of the Study:

• To investigate the impact of VSC on the kinetics of the Diels-Alder reaction.
• To explore how different VSC conditions, including solvent coupling and direct vibrational mode coupling, affect reaction rates.
• To establish the Diels-Alder reaction as a model system for probing VSC chemistry.

Main Methods:

• Utilized fixed-width cavities and UV-vis spectroscopy to measure reaction rate constants.
• Studied the Diels-Alder reaction between 1,3-diphenylisobenzofuran (DPIBF) and various dienophiles under VSC.
• Investigated VSC effects with six different solvents, cooperative solvent coupling, alcohol solvent coupling, and direct vibrational mode coupling.

Main Results:

• No substantial changes in reaction rate constants were observed across all explored VSC conditions.
• The study systematically examined solvent effects, hydrogen bonding influences, and direct vibrational coupling.
• The Diels-Alder reaction proved amenable to VSC studies under the tested conditions.

Conclusions:

• Vibrational strong coupling, under the conditions tested, did not significantly alter the kinetics of the Diels-Alder reaction.
• The Diels-Alder reaction serves as a valuable platform for future mechanistic studies of VSC.
• Further experimental and theoretical investigations are encouraged to fully elucidate VSC's influence on chemical reactivity.