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Proton-coupled electron transfer with photoexcited metal complexes
1Departement Chemie, Universität Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland.
Accounts of Chemical Research
|February 14, 2013
Summary
This study explores excited-state proton-coupled electron transfer (PCET) in d(6) metal complexes, investigating photoinduced electron and proton transfer reactions. Researchers examined how metal complex structure and reaction conditions influence PCET, including concerted vs. sequential pathways.
Area of Science:
- Inorganic Chemistry
- Photochemistry
- Physical Chemistry
Background:
- Proton-coupled electron transfer (PCET) is vital in enzymatic reactions like water oxidation and CO2 reduction.
- Research is expanding from ground-state to excited-state PCET, particularly in d(6) metal complexes.
- Understanding excited-state PCET is key to designing artificial systems for energy conversion.
Purpose of the Study:
- To investigate excited-state proton-coupled electron transfer (PCET) in d(6) metal complexes.
- To explore photoinduced electron and proton transfer reactions and their mechanisms.
- To understand the influence of molecular structure and reaction conditions on PCET pathways.
Main Methods:
- Utilized luminescence spectroscopy and transient absorption spectroscopy to monitor rapid reactions.
- Employed short laser pulses to trigger and study excited-state PCET.
- Synthesized and studied various metal complexes (Ir(III), Ru(II), Re(I)) and molecular dyads/triads.
Main Results:
- Demonstrated photoinduced electron and proton transfer from excited metal complexes to acceptors like benzoquinone and phenols.
- Investigated both unidirectional and bidirectional PCET, mimicking enzymatic processes.
- Explored the competition between concerted proton-electron transfer (CPET) and sequential ET/PT steps.
- Observed the effect of solvent hydrogen-bonding on photogenerated charge carrier lifetimes.
Conclusions:
- Excited-state PCET in d(6) metal complexes can be triggered and studied using advanced spectroscopic techniques.
- Molecular design allows for control over PCET directionality and mechanism (CPET vs. sequential).
- Factors like reaction free energy, electronic structure, and solvent interactions significantly impact PCET efficiency and pathways.
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