Leveraging coordination chemistry in the design of bipolar energy storage materials for redox flow batteries

Skavenborg, Mathias Lander  Lander; McPherson, James N.; Pasadakis-Kavounis, Alexandros; Hjelm, Johan; Waite, T. David; McKenzie, Christine J.

doi:10.1039/d1se01966j

Cited by 4 publications

(11 citation statements)

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“…On the basis that the Zn(psq) 2 is electrochemically silent at these potentials, we conclude that neither redox event is due to the potentially redox noninnocent quinoline moiety of the psq ligand. 18 Thus, consistent with the observation of two redox couples, the EPR spectroscopy and the contrast to the CV of [Cu(psq)-(MeCN)](PF 6 ) (Figure 5, green), we can dismiss the possible exchange of one or both of the chloride ligands in [CuCl(psq)] 2 with MeCN. Reversibility is completely absent for [Cu(psq)(MeCN)](PF 6 ) in the presence of the noncoordinating electrolyte.…”

Section: ■ Introductionsupporting

confidence: 83%

“…The formation of exclusively 1:1 Cu:psq complexes (Scheme ) contrasts to the propensity for formation of bis-homoleptic complexes for M(II) ions (M = Co and Zn) even when the supply of psq is limited to one equivalent or less per metal ion. This difference likely arises from steric preference induced by the Jahn–Teller Cu(II) ion.…”

Section: Results and Discussionmentioning

confidence: 99%

“…17 Pyridine-2-ylsulfonyl(quinoline-8-yl)amide (psq) (Scheme 2a) is a new tridentate ligand, which produces bis-homoleptic octahedral Co(II/III) and Zn(II) complexes (Scheme 2c). 18 In these structures, the psq adopts a planar conformation very close to those furnished by its carboxamide pincer analogue in Zn(bpq) 2 , 19 Ni(Me-bpq) 2 , 20 Ni(Mebpq)(4-methoxyphenyl)ethynyl), 20 S1), which is analogous to [CuCl(psq)] 2 , also crystallizes from the solution. The isolation of an aquo complex from acetonitrile and a dehydrated dimer from a 50% aqueous solution is counterintuitive and suggests that TFE has a strong influence on the solution-state speciation (eqs 1 and 2).…”

Section: ■ Introductionmentioning

confidence: 82%

“…The pro-ligand N-(quinoline-8-yl)pyridine-2sulfonamide (Hpsq) was made according to literature procedures. 18 ESI-MS spectra were recorded on a nano spray Bruker microOTOFQ II in positive ionization mode, and mMass version 5.5.0 was used for visualization of the obtained data. IR spectra were recorded on an Agilent Cary 603 FTIR.…”

Section: ■ Conclusionmentioning

confidence: 99%

“…These include a macrocyclic ligand, an acyclic dinucleating ligand, and a salen-type ligand . Pyridine-2-ylsulfonyl(quinoline-8-yl)amide (psq) (Scheme a) is a new tridentate ligand, which produces bis-homoleptic octahedral Co(II/III) and Zn(II) complexes (Scheme c) . In these structures, the psq adopts a planar conformation very close to those furnished by its carboxamide pincer analogue in Zn(bpq) 2 , Ni(Me-bpq) 2 , Ni(Me-bpq)(4-methoxyphenyl)ethynyl), and [Cu(bpq)(MeCN)(ClO 4 )] (Scheme b).…”

Section: Introductionmentioning

confidence: 99%

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Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O₂ Reduction

et al. 2023

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Heteroleptic copper complexes of an asymmetrical pincer ligand containing a central anionic sulfonamide donor (pyridine-2-yl-sulfonyl)(quinolin-8yl)-amide (psq), which contains a central anionic sulfonamido donor have been prepared. Meridional κ 3 -N,N″,N‴ binding with the co-ligands acetate, chloride, or acetonitrile (MeCN), trans to the central sulfonamido N-donor, is revealed by the Xray crystal structures of [Cu(OAc)(psq)(H 2 O)], [CuCl(psq)] 2 , and [Cu(psq)-(MeCN)](PF 6 ). Either overall distorted square pyramidal or octahedral geometries of the copper atom are satisfied by coordinated water in the case of the acetate complex or interactions with periphery sulfonamido oxygen atoms on adjacent molecules in the dimeric chloride and 1D polymeric acetonitrile complexes. The cyclic voltammogram (CV) of [Cu(OAc)(psq)(H 2 O)] shows a quasi-reversible Cu II /Cu I reduction at −0.930 V (vs Fc + /Fc 0 , MeCN), and an irreversible Cu II /Cu I reduction for [Cu(psq)(MeCN)](PF 6) is seen at −0.838 V. This signal is split into two quasi-reversible redox processes on the addition of 2,2,2-trifluoroethanol (TFE). This suggests that TFE pushes a solution equilibrium toward a dimeric acetate complex analogous to [CuCl(psq)] 2 , which shows two quasi-reversible waves at −0.666 V and −0.904 V vs Fc + /Fc 0 consistent with its dimeric solid-state structure. A comparison of the CVs of [Cu(OAc)(psq)(H 2 O)] under either a N 2 or an O 2 atmosphere revealed that this complex catalyzes turnover electro-reduction of O 2 to H 2 O 2 and H 2 O. The rate of reaction increases on addition of a weak organic acid, and a coulombic efficiency of 48% for H 2 O 2 was determined by iodometric titration. We propose that a Cu I complex formed on electroreduction binds O 2 to yield an intermediate superoxide complex. On electron and proton transfer to this species, a bifurcated route back to the O 2 -activating Cu I complex is feasible with either release of H 2 O 2 or O−O cleavage resulting in the liberation of H 2 O. The Cu I complex is regenerated by subsequent reduction and protonation to close the cycle.

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Section: ■ Introductionsupporting

confidence: 83%

Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 82%

Section: ■ Conclusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O₂ Reduction

et al. 2023

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Recent Advances in Redox Flow Batteries Employing Metal Coordination Complexes as Redox-Active Species

Liu,

Li,

Jia

et al. 2024

Electrochem. Energy Rev.

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Redox flow batteries (RFBs) that employ sustainable, abundant, and structure-tunable redox-active species are of great interest for large-scale energy storage. As a vital class of redox-active species, metal coordination complexes (MCCs) possessing the properties of both the organic ligands and transition metal ion centers are attracting increasing attention due to the advantages of multielectron charge transfer, high structural tailorability, and reduced material crossover. Herein, we present a critical overview of RFBs that employ MCCs as redox-active materials in both aqueous and nonaqueous mediums. The progress is comprehensively summarized, including the design strategies, solubility characteristics, electrochemical properties, and battery cycling performance of MCCs. Emphasis is placed on the ligand selection and modification strategies used to tune the critical properties of MCCs, including their redox potential, solubility, cycling stability, and electron transfer redox reactions, to achieve stable cycled RFBs with a high energy density. Furthermore, we discuss the current challenges and perspectives related to the development of MCC-based RFBs for large-scale energy storage implementations. Graphical abstract

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Dimeric Copper(I) Complex with a Disulfonamide-Bridged Core

Skavenborg,

Møller,

McKenzie

2024

Inorg. Chem.

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has produced the first sulfonamidato-bridged dicopper(I) complex, {Cu[κ 4 -(μ-κN:κN-psq)]} 2 containing the rhombic Cu(I) 2 N 2 core. The single crystal X-ray structure of this complex shows that two anionic psq ligands straddle the metal atoms via bridging sulfonamide N atoms to give a Cu•••Cu distance of 2.9593(8) Å. When it is dissolved in chloroform [Cu(psq)] 2 activates C−Cl bonds as demonstrated through the rapid formation of [CuCl-(psq)] 2 . While the solid orange compound is stable for weeks under N 2 . Acetonitrile solutions of [Cu(psq)] 2 are rapidly oxidized in air. A 1D-carbonato-bridged coordination polymer, {Cu 2and the bis-homoleptic complex [Cu(κ 3psq)(κ 2 -psq)] are concurrently isolated in high yield without evidence of ligand oxidation with H 2 O 2 detected as a side product. This implicit O 2 activation was harnessed in the oxidation of phenol substrates. 2,6-Di-tert-butylphenol is catalytically converted to the coupled dione product with 100% yield. If a para-blocked phenol is used, the reaction become stoichiometric and an O 2 -derived hydroperoxide group is installed into the ortho position. In contrast, nitrophenol is not oxidized and the result is metal-based oxidation and isolation of [Cu(OC 6 H 4 NO 2 )(psq)] 2 . This is rationalized by this more acidic phenol acting as a proton donor, rather than a H atom donor to a putative O 2 adduct.

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Leveraging coordination chemistry in the design of bipolar energy storage materials for redox flow batteries

Abstract: Tuned by the ligand field, some single metal atoms in coordination complexes can offer two redox processes with a large potential difference, a key characteristic of symmetrical redox flow batteries...

Cited by 4 publications

References 53 publications

Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O₂ Reduction

Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O₂ Reduction

Recent Advances in Redox Flow Batteries Employing Metal Coordination Complexes as Redox-Active Species

Dimeric Copper(I) Complex with a Disulfonamide-Bridged Core

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Leveraging coordination chemistry in the design of bipolar energy storage materials for redox flow batteries

Abstract: Tuned by the ligand field, some single metal atoms in coordination complexes can offer two redox processes with a large potential difference, a key characteristic of symmetrical redox flow batteries...

Cited by 4 publications

References 53 publications

Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O2 Reduction

Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O2 Reduction

Recent Advances in Redox Flow Batteries Employing Metal Coordination Complexes as Redox-Active Species

Dimeric Copper(I) Complex with a Disulfonamide-Bridged Core

Contact Info

Product

Resources

About

Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O₂ Reduction

Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O₂ Reduction