Direct Observation of the Photoreduction Products of Mn(NDI-bpy)(CO)3X CO2 Reduction Catalysts Using Femtosecond Transient IR Spectroscopy

Jose F. Martinez, Nathan T. La Porte, Ryan M. Young, Alessandro Sinopoli, Muhammad Sohail, Michael R. Wasielewski

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The electrochemical reduction of the Mn(bpy)(CO)3X CO2 reduction catalyst is thought to proceed by the initial reduction of MnI to Mn0. 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. Moreover, 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.

Original languageEnglish
Pages (from-to)6416-6426
Number of pages11
JournalJournal of Physical Chemistry C
Volume123
Issue number11
DOIs
Publication statusPublished - Mar 21 2019

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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