Energy transfer mediated by asymmetric hydrogen-bonded interfaces

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Organometallic Chemistry

Background:

• Ruthenium(ii) polypyridyl complexes are vital in photochemistry and catalysis.
• Ferrocene derivatives are widely used in supramolecular chemistry and sensing.
• Proton-coupled electron transfer (PCET) is a key mechanism in biological and chemical systems.

Purpose of the Study:

• To investigate the interaction between amidine-appended ferrocene derivatives and Ru(ii) complexes.
• To elucidate the mechanism of excited state quenching in these supramolecular assemblies.
• To explore the role of proton motion in energy transfer processes.

Main Methods:

• Formation of supramolecular assemblies between ferrocene derivatives and Ru(ii) complexes.
• Steady-state and time-resolved spectroscopic techniques (e.g., absorption, emission, transient absorption).
• Kinetic isotope effect (KIE) studies to probe proton involvement.

Main Results:

• Supramolecular assemblies were successfully formed.
• Metal-to-ligand charge transfer excited states of Ru(ii) complexes were quenched.
• Proton-coupled energy transfer (PCEnT) was identified as the primary quenching mechanism.
• Kinetic isotope effects confirmed the involvement of proton motion.

Conclusions:

• Proton motion is an effective mediator of energy transfer (EnT) in addition to electron transfer (ET).
• PCEnT is a significant pathway for deactivation of excited states in Ru(ii) supramolecular systems.
• This study expands the understanding of proton-coupled processes in photochemistry and supramolecular assemblies.