Interfacial Dynamics within an Organic Chromophore-Based Water Oxidation Molecular Assembly

Area of Science:

• Photochemistry
• Materials Science
• Catalysis

Background:

• Investigating photoinduced electron transfer is key to understanding artificial photosynthesis and solar energy conversion.
• Molecular assemblies offer a platform to control electron transfer pathways for catalytic applications.

Purpose of the Study:

• To investigate photoinduced electron injection, intra-assembly electron transfer, and back-electron transfer in a single-site molecular assembly.
• To elucidate the electronic coupling and energy transfer dynamics within a covalently linked chromophore-catalyst system on a metal-oxide surface.

Main Methods:

• Utilizing density functional theory (DFT) calculations to model the electronic structure and interactions within the assembly.
• Employing ultrafast spectroscopy to track electron transfer dynamics on ps-ns timescales.

Main Results:

• DFT calculations revealed strong electronic coupling and enhanced low-energy absorptions due to intraligand charge transfer (ILCT) transitions.
• Ultrafast spectroscopy demonstrated ps-ns electron injection from the terthiophene chromophore into the metal-oxide conduction band.
• Rapid (<35 ps) intra-assembly electron transfer from the ruthenium catalyst to the chromophore was observed, followed by microsecond back-electron transfer.

Conclusions:

• The study successfully characterized the electron transfer cascade in a novel molecular assembly for water oxidation.
• The findings highlight the potential of rationally designed molecular assemblies for efficient light-driven catalytic processes.