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Impact of Ligand Substitutions on Multielectron Redox Properties of Fe Complexes Supported by Nitrogenous Chelates
- Source :
- ACS Omega, ACS Omega, Vol 3, Iss 11, Pp 14766-14778 (2018)
- Publication Year :
- 2018
- Publisher :
- American Chemical Society, 2018.
-
Abstract
- Redox flow batteries (RFBs) have recently been recognized as a potentially viable technology for scalable energy storage. To take full advantage of RFBs, one possible approach for achieving high energy densities is to maximize a number of redox events by utilizing charge carriers capable of multiple one-electron transfers within the electrochemical window of solvent. However, past efforts to develop more efficient electrolytes for nonaqueous RFBs have mostly been empirical. In this manuscript, we shed light on design principles by theoretically investigating the effects of systematically substituting pyridyl moieties with imine ligands within a series of Fe complexes with some experimental validation. We found that such replacement is an effective strategy for reducing the molecular weight-to-charge ratios of these complexes. Simultaneously, calculations suggest that the reduction potentials and ligand-based redox activity of such substituted N-heterocyclic Fe compounds might be maintained within their +4 → -1 charge states. Additionally, by theoretically examining the role of coordination geometry, vis-à-vis reducing the number of redox noninnocent ligands within the first coordination sphere, we have demonstrated that Fe complexes with one such ligand were also capable of supporting multielectron reduction events and exhibited reduction potentials similar to their parent analogs supported by two or three of the same multidentate ligands. However, some differences in redox nature within the lower (+2 → -1) charge states were also noticed. Specifically, complexes containing two bidentate ligands, or one tridentate ligand, exhibited ligand-based reductions, whereas compounds with one bidentate ligand exhibited metal-centered reductions. The current results pave the way toward the design of the next-generation of Fe complexes with lower molecular weights and greater stored energy for redox flow batteries.
- Subjects :
- High energy
010405 organic chemistry
Ligand
Chemistry
General Chemical Engineering
Design elements and principles
General Chemistry
Electrolyte
010402 general chemistry
01 natural sciences
Combinatorial chemistry
Redox
Article
0104 chemical sciences
lcsh:Chemistry
Solvent
lcsh:QD1-999
Chelation
Electrochemical window
Subjects
Details
- Language :
- English
- ISSN :
- 24701343
- Volume :
- 3
- Issue :
- 11
- Database :
- OpenAIRE
- Journal :
- ACS Omega
- Accession number :
- edsair.doi.dedup.....a2f9c1e3b8176eeaad238c7db7cbdae0