Direct Observation of the Photoreduction Products of Mn(NDI-bpy)(CO)3XCO 2 Reduction Catalysts Using Femtosecond Transient IR Spectroscopy
- Northwestern Univ., Evanston, IL (United States)
- Hamad Bin Khalifa Univ. (HBKU), Doha (Qatar)
The electrochemical reduction of the Mn(bpy)(CO)3X CO2 reduction catalyst is thought to proceed by the initial reduction of MnI to Mn0. Here, we have covalently attached a naphthalenediimide radical anion (NDI•–) chromophore to the 4-, 5-, or 6-position of the bpy via a phenyl bridge to produce Mn(NDI•–-bpy)(CO)3X, where X = Br, CH3CN, or DMF, and have used femtosecond and nanosecond transient IR spectroscopy to directly observe the intermediates produced by two electron-transfer reactions following selective photoexcitation of NDI•– to its lowest excited doublet state, 2*NDI•–. In complexes where NDI•– is attached at the 4- or 5-position of bipyridine, only the reaction Mn(2*NDI•–-bpy)(CO)3X → Mn(NDI-bpy•–)(CO)3X is observed, whereas in the complex where NDI•– is attached to the 6-position of bipyridine, the reaction sequence Mn(2*NDI•–-bpy)(CO)3X → Mn(NDI-bpy•–)(CO)3X → Mn0(NDI-bpy)(CO)3 is observed. Additionally, in the complexes with an NDI•– bound to the 6-position of bipyridine, Mn0(NDI-bpy)(CO)3 exhibits a lifetime that is ~105 times longer than those in complexes with an NDI•– bound at the four- or five-position of the bipyridine.
- Research Organization:
- Univ. of Texas, Austin, TX (United States). Energy Frontier Research Center (EFRC); Northwestern Univ., Evanston, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
- Grant/Contract Number:
- FG02-99ER14999; SC0001059
- OSTI ID:
- 1566528
- Journal Information:
- Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 11 Vol. 123; ISSN 1932-7447
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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