Metal complex redox materials and methods

Abstract

The present disclosure generally relates to metal complex redox materials for various uses, such as in electrochemical batteries and redox flow batteries. A redox material is a chemical species that, in some embodiments, can undergo a reversible electrochemical reduction-oxidation process. In some cases, the redox material may comprise a metal. In certain cases, the redox material may include an amino poly dentate functionalized ligand. Such redox complexes have a variety of uses, such as electrolytes in electrochemical devices, for example, in flow batteries. The redox material may include iron complexed to the ligand, or other metals, including manganese and chromium as non-limiting examples. One non-limiting example is iron complexed with an amino alkyl alcohol (e.g., forming alkoxide) ligand, e.g., acting as an anolyte. Other aspects are generally directed to electrolytes containing such redox materials, methods of making or using such redox materials, kits involving such redox materials, or the like.

Description

[0001] METAL COMPLEX REDOX MATERIALS AND METHODS

[0002] RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 759,919, filed February 18, 2025, entitled “Metal Complex Redox Materials and Methods,” by Sullivan, et al., incorporated herein by reference in its entirety.

[0004] FIELD

[0005] The present disclosure generally relates to redox materials for various uses, such as in electrochemical batteries and redox flow batteries.

[0006] BACKGROUND

[0007] As dispatchable fossil fuel power generation is replaced with intermittent solar and wind energy, energy storage is needed to stabilize the grid and time-shift renewable generation to meet demand. This has economic, reliability, and emission implications. Lithium-ion batteries currently dominate new installations due to their manufacturing at scale and operational knowhow, in part from the electric vehicle market. However, lithium-ion systems have fire safety concerns, supply chain constraints, and short duration configuration, limiting their value in the booming grid market. Thus, alternative solutions are needed to address electric grid sustainability at scale.

[0008] Aqueous flow batteries are a promising technology for stationary grid energy storage. Unlike conventional solid-state batteries (i.e., lithium ion), these systems decouple power (kW) and capacity (kWh) components. Redox active species are dissolved in water to serve as the anolyte (liquid anode) and catholyte (liquid cathode) and stored in electrolyte reservoirs. These electrolytes are pumped through a power cell stack where the species are reduced and oxidized at current collector surfaces (the anode and cathode) while separated by a membrane, charging and discharging electricity to and from the grid. Although numerous specific systems exist, flow battery archetypes are intrinsically more scalable and fire-safe for stationary applications.

[0009] Vanadium flow batteries are the most mature flow battery technology, having been heavily researched by NASA in the 1970s and deployed commercially since the early 2000s. However, their commercial progress has been stunted by their performance limitations and lithium-ion battery competition. Additionally, the raw vanadium electrolyte materials have a

[0010] #14802252vlvolatile supply chain with economics that are not able to compete with lithium-ion products. Thus, lower cost electrolyte materials are needed for widespread market impact.

[0011] SUMMARY

[0012] The present disclosure generally relates to metal complex redox materials for various uses, such as in electrochemical batteries and redox flow batteries. The subject matter of the present disclosure involves, in some cases, interrelated products, alternative solutions to a particular problem, and / or a plurality of different uses of one or more systems and / or articles.

[0013] For instance, some aspects are generally directed to metal complex redox materials comprising amino polydentate functionalized ligands, for example, for use as an anolyte or catholyte in redox flow battery, or for other applications. The ligands, in some cases, may be able to bind to metal to form redox-active metal complexes. In one set of embodiments, the metal complex may include a transition metal, e.g., iron. Other metal complex compounds are contemplated as well, including manganese or chromium as non-limiting examples.

[0014] In one set of embodiments, the complex may comprise amino polydentate functionalized ligands, e.g., functionalized with alkyl alcohols (forming alkoxides). Other amino polydentate functionalized ligands are contemplated as well, including those functionalized with carboxylic acids (forming carboxylates) or phosphonic acids (forming phosphonates) as non-limiting examples.

[0015] The complex, in some embodiments, may have an overall anionic charge, for example, -1, -2, -3, -4, or -5. In some embodiments, e.g., when bearing an overall negative charge, such metal complexes may serve various purposes. These include, as a non-limiting example, pairing with proton or cation ion-exchange membranes. In addition, in certain embodiments, such anolytes may potentially improve system energy density, power density, and / or cycling stability in certain applications, such as in batteries or other electrochemical devices.

[0016] One aspect is generally directed at an electrochemical device. In one set of embodiments, the electrochemical device comprises an anode or an anode compartment containing an anolyte; a cathode or a cathode compartment containing a catholyte; and a membrane or separator between the anode compartment and the cathode compartment; wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:

[0017] #14802252vl

[0018] "

[0019] >>

[0020]

[0021] wherein each L independently is an organic linker, and each b is independently selected with at least one b selected from the group consisting of::

[0022]

[0023] wherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

[0024] In another set of embodiments, the electrochemical device comprises an anode or an anode compartment containing an anolyte; a cathode or a cathode compartment containing a catholyte; and a membrane or separator between the anode compartment and the cathode compartment; wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:

[0025] >

[0026]

[0027] #14802252vlwherein each L independently is an organic linker, and each b is independently selected with at least one b selected from the group consisting of:

[0028]

[0029] wherein the is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

[0030] In yet another set of embodiments, the electrochemical device, comprises an anode or an anode compartment containing an anolyte; a cathode or a cathode compartment containing a catholyte; and a membrane or separator between the anode compartment and the cathode compartment; wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:

[0031] #14802252vl >

[0032]

[0033] wherein each L independently is an organic linker, and each b is independently selected with at least one b selected from the group consisting of:

[0034]

[0035] wherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

[0036] In still another set of embodiments, the electrochemical device comprises an anode or an anode compartment containing an anolyte; a cathode or a cathode compartment containing a catholyte; and a membrane or separator between the anode compartment and the cathode

[0037] #14802252vlcompartment; wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:

[0038]

[0039] wherein each L independently is an organic linker, and each b independently is selected from the group consisting of:

[0040]

[0041] #14802252vlwherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

[0042] In still another set of embodiments, the electrochemical device comprises an anode or an anode compartment containing an anolyte; a cathode or a cathode compartment containing a catholyte; and a membrane or separator between the anode compartment and the cathode compartment; wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:

[0043]

[0044] wherein each L independently is an organic linker, and each b is independently selected and each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen, and wherein at least one L comprises a structure selected from the group consisting of:

[0045]

[0046] wherein the is a point of connection to the N in the core structure.

[0047] In another set of embodiments, the electrochemical device comprises an anode or an anode compartment containing an anolyte; a cathode or a cathode compartment containing a catholyte; and a membrane or separator between the anode compartment and the cathode compartment; wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:

[0048] >

[0049] " "

[0050]

[0051] wherein each L independently is an organic linker, and each b is independently selected and each

[0052] #14802252vlb comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen, and wherein at least one L comprises an alkyl alcohol group, a carboxylic acid group, a sulfonate group, or an ether group.

[0053] In still another set of embodiments, the electrochemical device, comprises an anode or an anode compartment containing an anolyte; a cathode or a cathode compartment containing a catholyte; and a membrane or separator between the anode compartment and the cathode compartment; wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:

[0054]

[0055] wherein each L independently is an organic linker, and each b is independently selected and each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen.

[0056] In another aspect, the present disclosure encompasses methods of making one or more of the embodiments described herein, for example, iron complexes with amino polyalkyl alcohol (e.g., forming alkoxides) ligands, or other compounds such as any of those described herein, including iron complexes with amino polycarboxlic acid (e.g., forming carboxylates) ligands or amino polyphosphonic acid (e.g., forming phosphonates) ligands. In still another aspect, the present disclosure encompasses methods of using one or more of the embodiments described herein, for example, iron complexes with amino polyalkyl alcohol (e.g., forming alkoxides) ligands, or other compounds such as any of those described herein, including iron complexes with amino polycarboxlic acid (e.g., forming carboxylates) ligands or amino polyphosphonic acid (e.g., forming phosphonates) ligands.

[0057] Other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments of the disclosure when considered in conjunction with the accompanying figures.

[0058] BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Non-limiting embodiments of the present disclosure will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is

[0060] #14802252vllabeled in every figure, nor is every component of each embodiment of the disclosure shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure. In the figures:

[0061] Figs. 1A-1B illustrate a non-limiting example of a battery charging and discharging, in accordance with one embodiment;

[0062] Fig. 2 is a schematic of a flow battery, in another embodiment;

[0063] Fig. 3 illustrates various ligands, in accordance with one set of embodiments;

[0064] Fig. 4 illustrates various ligands for polyamino polydentate ligands, in another set of embodiments;

[0065] Fig. 5 illustrates various pKa values, in yet other embodiments;

[0066] Fig. 6 illustrates various alkyl alcohol binding substituents, in certain embodiments; Fig. 7 illustrates various carboxylic acid binding substituents, in some embodiments; Fig. 8 illustrates various phosphonic acid binding substituents, in certain embodiments; Fig. 9 illustrates certain linkers with potential binding sites, in some embodiments; Fig. 10 illustrates binding substituents and linkers, in still other embodiments;

[0067] Fig. 11 illustrates various sulfonate binding substituents, in certain embodiments;

[0068] Fig. 12 illustrates certain sulfonate binding substituents, in some embodiments;

[0069] Fig. 13 show various ligands comprising various binding substituents, in some embodiments;

[0070] Figs. 14A-14F shows various UV-Vis spectra for certain metal complexes, in accordance with certain embodiments;

[0071] Figs. 15A-15F shows various cyclic voltametry (CV) spectra for certain metal complexes, in accordance with certain embodiments;

[0072] Figs. 16A-16J show vairous charge-discharge curvers of various compounds, in some embodiments;

[0073] Figs. 17A-17D illustrate synthetic routes for various iron complexes, in other embodiments;

[0074] Figs. 18A-18B illustrate redox behavior for various iron complexes, in other embodiments; and

[0075] Figs. 19A-19D illustrate reversible charge-dicharge behavior over tens of cycles, in still other embodiments.

[0076] #14802252vlDETAILED DESCRIPTION

[0077] The present disclosure generally relates to metal complex redox materials for various uses, such as in electrochemical batteries and redox flow batteries. A redox material is a chemical species that, in some embodiments, can undergo a reversible electrochemical reduction-oxidation process. In some cases, the redox material may comprise a metal. In certain cases, the redox material may include an amino poly dentate functionalized ligand. Such redox complexes have a variety of uses, such as electrolytes in electrochemical devices, for example, in flow batteries. The redox material may include iron complexed to the ligand, or other metals, including manganese and chromium as non-limiting examples. One non-limiting example is iron complexed with an amino alkyl alcohol (e.g., forming alkoxide) ligand, e.g., acting as an anolyte. Other aspects are generally directed to electrolytes containing such redox materials, methods of making or using such redox materials, kits involving such redox materials, or the like.

[0078] In certain aspects, redox materials such as those described herein may be used as electrolytes in various redox-driven electrochemical devices, such as batteries, fuel cells, supercapacitors, or the like. In some cases, the electrochemical device may be a battery, such as a flow battery. A flow battery may be a battery having liquids present on separate sides of a membrane (e.g., separating an anode compartment from a cathode compartment), where ions can flow through the membrane from one liquid to the other, while electrons flow around the membrane, e.g., through an external circuit, and can be harnessed for power. In some cases, the membrane may be an ion-selective membrane, such as an anion-selective membrane or a cationselective membrane. In some embodiments, one, or both liquids may flow, e.g., from a reservoir, past the membrane, or through the device. In some cases, one or both liquids may be recirculated, e.g., to and from the reservoir. In some embodiments, the electrolyte may be static without flow inside one or more compartments in the battery. In some embodiments, one or both of the liquids may be aqueous, e.g., using water as a solvent, e.g., as in an aqueous electrolyte.

[0079] In some embodiments, the battery may be a flow battery. A flow battery, or a redox flow battery, is a type of electrochemical device where chemical energy is provided by chemical components dissolved in liquids that are present on separate sides of a membrane, such as an ion selective membrane. As discussed, ions can flow through the membrane while electrons flow around the membrane, e.g., through an external circuit. In some cases, liquids may flow on one or both sides of the membrane, e.g., pumped to and / or from a reservoir. In some cases, the

[0080] #14802252vlliquids may be static without flow inside one or more compartments in the battery. The energy capacity of the battery can be controlled by controlling the volume of liquid within the reservoir. The liquid on the anode side is called the anolyte, while the liquid on the cathode side is called the catholyte, both generally referred to as the electrolyte.

[0081] Redox-active chemical species may be present within the electrolyte solutions in a battery (e.g., in a flow battery or static battery), where they can function as the anode and cathode electrolytes in some embodiments. The electrolyte in the anode compartment may be referred to as the anolyte, while the electrolyte in the cathode compartment may be referred to as the catholyte. During discharge of the electrochemical device, electrons flow from the anolyte to the catholyte (e.g., through a load). Oxidation (loss of electrons) occurs in the anolyte within the anode compartment, while reduction (gain of electrons) occurs in the catholyte within the cathode compartment. The electrons may flow from the anolyte, to an anode current collector, through an electrical circuit, to a cathode current collector, to the catholyte. In addition, to balance charge, cations (positively charged ions) may flow across the ion-exchange membrane from the anode compartment to the cathode compartment, or anions (negatively charged ions) may flow across the ion-exchange membrane from the cathode compartment to the anode compartment. During charging, this process is reversed. Electrons move from the catholyte to the anolyte (typically requiring energy to cause the electrons to flow in that direction).

[0082] Reduction (gain of electrons) occurs in the anolyte within the anode compartment, while oxidation (loss of electrons) occurs in the catholyte within the cathode compartment. The electrons may flow from the catholyte, to a cathode current collector, through an electrical circuit, to an anode current collector, to the anolyte. In addition, to balance charge, cations (positively charged ions) flow across the ion-exchange membrane from the cathode compartment to the anode compartment, or anions (negatively charged anions) flow across the ion-exchange membrane from the anode compartment to the cathode compartment. In some cases, the liquid within the cathode may flow to and / or from a cathodic reservoir, and / or the liquid within the anode may flow to and / or from an anodic reservoir. In some cases, one or more liquid pumps may be used to cause liquid flow to occur. In some cases, the electrochemical or battery device may be a hybrid design, meaning that one of the anolyte or catholyte has liquid flow while the other is a static electrode / electrolyte material (e.g., zinc or iron deposition anode, sulfur cathode,

[0083] #14802252vlor intercalation-based electrodes) or utilizes a gas flow (e.g., hydrogen as an anode or oxygen as a cathode).

[0084] A non-limiting schematic diagram of a battery is shown in Fig. 1, as an illustrative nonlimiting example. Fig. 1A shows a battery 10 in discharging mode. In anode compartment 20, an anolyte having a charge state n (i.e., An) is oxidized to produce an electron (e ) and a more positively charged state (An+1). The electrons may be collected by anode current collector 25, and can flow through load 40 to reach cathode current collector 35 in cathode compartment 30. In cathode compartment 30, the electrons from cathode current collector 35 may reduce the catholyte (having a charge state Cm+1) to produce a catholyte with a more negatively charged state m (i.e., Cm). In addition, counter-cations M+may flow from anode compartment 20 to cathode compartment 30 across ion exchange membrane 50, for example, which may be selectively permeable to the counter-cations. In these examples, n and m may independently be any suitable value, indicating a charge state, depending on the anolyte and the catholyte. For instance, n and m may each independently be -3, -2, -1, 0, 1, 2, 3, etc.

[0085] Fig. IB shows battery 10 in charging mode, where these processes are essentially reversed. Electrons are pumped from the catholyte to the analyte via energy source 45, which inputs energy into the system to be stored in the battery. In anode compartment 20, the electrons combine with anolyte (having a charge state An+1) to produce an anolyte having a more negatively charged state (An), while the catholyte (having a charge state Cm) in cathode compartment 30 releases electrons to produce a more positively charged state (Cm+1). Countercations M+also can flow from cathode compartment 30 to anode compartment 20 across ion exchange membrane 50.

[0086] In some embodiments, for example, when battery 10 is a flow battery, one or both compartments may have fluid flowing therethrough. For example, as is shown in battery 10 in Fig. 2, pump 27 may recirculate a fluid containing the anolyte between anode compartment 20 and anode reservoir 22, and / or pump 37 may recirculate a fluid containing the catholyte between cathode compartment 30 and cathode reservoir 32.

[0087] A variety of redox species can be used as anolytes or catholytes in a battery, such as a flow battery, including inorganic species (e.g., sulfide / polysulfide, Zn / ZnX2 (X=I, Br, Cl), Cr2+ / Cr3+, V2+ / V3+, V4+ / V5+, permanganate), organic species (e.g., viologens, anthraquionones, phenazines, thiolate, TEMPOs), metal-organic species (e.g., ferro / ferricyanide, metal-

[0088] #14802252vlbipyridines, metal-polyaminocarboxylates), and halogen species. TEMPO derivatives, such as any of those described in US Pat. Apl. Ser. No. 63 / 552,006, filed February 9, 2024 (incorporated herein by reference in its entirety), and other nitroxyl radical derivatives, may be used in certain embodiments. Additional non-limiting examples of suitable redox species include any of those described in US Pat. Apl. Pub. Nos. 2022 / 0363663 and 2023 / 0006250.

[0089] In one aspect, certain embodiments relate to redox materials, or metal complex redox materials. A metal complex may include a metal ion coordinated or complexed to one or more organic ligands. The ligands may be moieties that are able to bind to metal to form such complexes. In some cases, the ligands can be organic molecules that include binding substituents that include alkyl alcohol, carboxylic acid, or phosphonate groups. Under certain conditions, such groups can be deprotonated (for example, with a base), which may form anionic binding sites that coordinate to a metal, e.g., to form a metal complex. For example, an alkyl alcohol can be deprotonated to form an alkoxide, a carboxylic acid can be deprotonated to form a carboxylate, or a phosphonate can be deprotonated to form a phosphonate. In some cases, the ligands can include polyamino groups, e.g., with organic linkers connecting the nitrogen atoms to form amines.

[0090] In some embodiments, the metal complex redox materials may be coordinated with amino polydentate functionalized ligands. An amino may refer to a ligand with one or more amine groups, e.g., a tertiary alkyl amine. Other amine groups are contemplated as well, including but not limited to primary amines, secondary amines, quaternary amines, and protonated ammoniums. In addition, a poly dentate ligand may have two or more binding sites that, in some embodiments, can coordinate to a metal ion. In some embodiments, polydentate ligands may enhance the stability of the metal complex, e.g., through a chelating effect.

[0091] Non-limiting examples of amino polydentate ligands include triethanolamine (TEA), which is a monoamine ligand with three additional alkyl alcohol groups (forming alkoxide binding sites), and ethylenediaminetetraacetic acid (EDTA), which is a diamine ligand with four additional carboxylic acid groups (forming carboxylate binding sites). Other examples of amino polydentate ligands are discussed in more detail herein.

[0092] In some embodiments, the metal complex may be used as an anolyte or as a catholyte redox material, e.g., as in a redox flow battery. In some embodiments, the metal complex may comprise a transition metal ion. In some embodiments, the metal may comprise a 3d-block (first

[0093] #14802252vlrow) transition metal. As non-limiting examples, the metal may include titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), etc. For example, in some embodiments, a metal complex comprising iron metal ion in the Fe(II) / Fe(III) oxidation states may be utilized as the anolyte redox material. In another example, a metal complex comprising chromium metal ion in the Cr(II) / Cr(III) oxidation states may be utilized as the anolyte redox material. In yet another example, a metal complex comprising manganese metal ion in the Mn(II) / Mn(III) may be utilized as the catholyte redox material.

[0094] In some embodiments, the metal complex may comprise a transition metal ion from beyond the first row. As non-limiting examples, this metal complex may include metal ions such as molybdenum (Mo) or tungsten (W) of the Group 6 d-block, for example, as anolyte redox materials. In another set of embodiments, the metal complex may comprise a non-transition metal ion. As non-limiting examples, this may include metals such as tin (Sn) or antimony (Sb), for example, as anolyte redox materials. In some embodiments, the redox material electrolyte may comprise a single metal ion within either the catholyte or anolyte. In other embodiments, the redox material electrolyte may comprise two or more metal ions within either the catholyte or anolyte.

[0095] In some embodiments, redox material complexes comprising different metal ions may exhibit different properties, including but not limited to formal potential. In some embodiments, the anolyte redox materials may have negative formal potentials, e.g., 0.0 V to -1.5 V vs. SHE, and that catholyte redox materials may have positive formal potentials, e.g., 0.0 V to +1.5 V vs. SHE. In some embodiments, the redox material complex may exhibit shift in formal potential to a more negative potential, e.g., when compared to the metal ion formal potential without a ligand. In some embodiments, redox material complexes with different metal ions may result in additional different metal complex properties, including but not limited to molecular stability, redox kinetics, water solubility, and solution viscosity.

[0096] In some embodiments, the complex may include an amino polydentate ligand. The amino polydentate ligand may comprise one amine group, e.g., a monoamine. In other embodiments, the amino polydentate ligand may comprise two, three, or four amine groups, as in a diamine, triamine, or tetraamine, respectively. In other embodiments, the amino polydentate ligand may comprise five or more amine groups. As a non-limiting example, the amine may be a tertiary amine, e.g., with alkyl or substituted alkyl functionalization. Having a ligand with two or

[0097] #14802252vlmore amines (polyamino) may provide additional functionalization sites to control metal complex properties in some cases, including but not limited to water solubility, solution viscosity, membrane compatibility, complex stability, formal potential, and redox kinetics. In some embodiments, a polyamino ligand with additional binding substituents (forming anionic binding sites) may exhibit improved metal complex stability, for example, through the chelating effect, and / or may exhibit decreased membrane crossover (e.g., cation-exchange membrane), for example, through size exclusion or coulombic repulsion mechanisms.

[0098] In some embodiments, the amine may act as a binding site to the metal ion, for example, coordinating through a nitrogen lone pair. In some embodiments, the amino polydentate ligand may be utilized in an electrolyte solution in which the amine is deprotonated (i.e., not present as an ammonium cation), for example, at pH greater than 7 in some embodiments. In some embodiments, the amino polydentate ligand may not comprise any aromatic groups, and in some embodiments, the ligand may not comprise any alkene or alkyne groups. In some embodiments, the amino polydentate ligand may only comprise amine, alkane, alcohol, ether, carboxylic acid, and phosphonic acid groups.

[0099] In some embodiments, the total coordination or binding site number of the amino polydentate ligand may be greater than 4. In other embodiments, the total coordination or binding site number of the amino polydentate ligand may be less than 10. The total coordination or binding site number of the amino polydentate ligand is inclusive of the amines in addition to any other binding site, e.g., alkyl alcohols (e.g., forming alkoxides), carboxylic acids (e.g., forming carboxylates), or phosphonic acids (e.g., forming phosphonates). In some cases, the total coordination or binding site number is 4, 5, 6, 7, 8, 9, or 10. The number of binding sites on the amino polydentate ligand may control molecular stability, formal potential, and redox kinetics of the metal complex in some embodiments. Not wishing to be bound by any theory, increasing the number of binding sites may improve the metal complex molecular stability or shift the formal potential to more negative potential (vs. SHE).

[0100] Fig. 3 shows example non-limiting general structures of amino polydentate ligands, in which each L independently is an organic linker and each b independently is a binding substituent (e.g., comprises at least one alkyl alcohol group, carboxylic acid group, or a phosphonic acid group), an alkyl sulfonate substituent, or a hydrogen. In some embodiments, each b may comprise at least one alkyl alcohol group, carboxylic acid group, phosphonic acid

[0101] #14802252vlgroup, or alkyl sulfonate group. In some embodiments, each b may comprise at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group. In some embodiments, each b may comprise between 1 and 10 total carbons, or in other embodiments, may be smaller and comprise between 1 and 6 total carbons. In some embodiments, each b may comprise only nonaromatic groups. In short, L connects two or more amine groups in the general structure and b branches off a single amine group in the general structure.

[0102] In some embodiments, the amino polydentate ligand may be a polyamino ligand with two or more amine groups. The amines may be connected by an organic linker (L), for example, an alkyl chain, a substituted alkyl chain (e.g., alkyl alcohol or carboxylic acid), a cyclic alkyl group, or a polyethylene glycol (ether) chain. In some embodiments, the substituted alkyl chain may be a branched alkyl chain or an alkyl alcohol group. In some embodiments, organic linkers with smaller size (e.g., reduced molecular mass) may be favorable to increase the water solubility and reduce the viscosity of the metal complex. In some embodiments, organic linkers with larger size (e.g., increase molecular mass) may be favorable to reduce membrane crossover, for example, through size exclusion mechanisms. In some embodiments, the size and geometry of the organic linker may control the spatial coordination and binding constant of the ligand with the metal ion. In some embodiments, the amino polydentate ligand may comprise more than one organic linker, for example, 2, 3, or 4 organic linkers. In some embodiments, the structure of each of the organic linkers on the ligand may be identical. In some embodiments, a single ligand may comprise more than one different organic linker structure. In some embodiments, different linkers may control the metal complex redox material properties, including but not limited to water solubility, metal complex stability, and membrane crossover.

[0103] In some cases, the amino polydentate functionalized ligand may comprise an alkyl chain. The alkyl chain may have, for example, 2, 3, 4, 5, or 6 total carbons. In some embodiments, the alkyl chain may comprise more than 6 total carbons, for example, 6, 7, 8, 9, 10, 11, 12, or more in some cases. The alkyl chain may be linear or branched, and the alkyl chain may be substituted or unsubstituted. Specific examples include ethane, propane chain, butane chain, pentane chain, hexane chain, 1 -methylethane chain, 1 -ethylpropane chain, 2,2-dimethylpropane chain, 2-methylpentane chain, 1 -methanolethane, 2,2-dimethylpropane-l,3-diol chain, and 2-methylethanol chain. In another set of embodiments, the ligand may include a cyclic alkyl group. In some cases, the cyclic alkyl group may have 6, 7, 8, or 9 total carbons. In some

[0104] #14802252vlembodiments, the cyclic alkyl group may have more than 9 total carbons, for example, between 10 and 15. The cyclic alkyl group may also be substituted or unsubstituted. Specific examples include hexane group and 1,1,3,3-tetramethylcyclohexane . In another set of embodiments, the ligand may include a polyethylene glycol (ether) chain. The polyethylene glycol chain may include, 4, 6, 8, 10, or up to 12 carbons. In some embodiments, the organic linker (L) may comprise an alkyl alcohol group, a carboxylic acid group, an ether group, a sulfonate group, or a phosphonic acid group, which may tune the water solubility and membrane compatibility properties of the redox material.

[0105] Fig. 4 shows non-limiting examples of organic linkers (L) for polyamino polydentate ligands, where the wavy line (^) generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3).

[0106] In some embodiments, the amino groups comprising an organic linker may be commercially available. Non-limiting examples of such linkers, formatted as IUPAC name (CAS number), include ethane- 1,2-diamine (107-15-3), propane- 1,3-diamine (109-76-2), butane-1,4-diamine (110-60-1), pentane- 1,5-diamine (462-94-2), hexane- 1,6-diamine (124-09-4), propane- 1,2-diamine (78-90-0), pentane- 1,3 -diamine (589-37-7), 2,2-dimethylpropane-l,3-diamine (7328-91-8), 2-methylpentane-l,5-diamine (15520-10-2), cyclohexane- 1,2-diamine (694-83-7), 3-(aminomethyl)-3,5,5-trimethylcyclohexan-l-amine (2855-13-2), 2,3-diaminopropan-l-ol (2811-20-3), 2,2-bis(aminomethyl)propane-l,3-diol (63375-50-8), 2-[2-(2-aminoethoxy)ethoxy]ethanamine (929-59-9), 2-[2-[2-(2-aminoethoxy)ethoxy]ethoxy]ethanamine (929-75-9), and 2,6-diaminohexanoic acid (70-54-2). In some cases, an organic linker may be produced through amine (e.g., ammonia) reaction with di-substituted reagents. Non-limiting examples of di-substituted reagents include di-halogens (e.g., dibromo ethane), di-epoxides (e.g., ethylene glycol diglycidyl ether), di-nitriles (e.g., adiponitrile), di-aldehydes (e.g., glutaraldehyde), or di-ketones (e.g., diacetyl). For di-halogens, the amine may react with the halogenated carbon to form C-N bonds, with the halogen atoms acting as leaving groups. For diepoxides, the amine may open the epoxide rings through nucleophilic attack, forming hydroxylamine linkages, which may be further reduced if desired. For di-nitriles, the nitrile groups may undergo hydrogenation or reaction with amines to form primary amines. For di-aldehydes, the amine may react with aldehyde groups to form Schiff bases, which can subsequently be reduced

[0107] #14802252vlto primary amines. For di-ketones, the amine may react with ketone groups to form imines, which can then be reduced to create stable C-N bonds.

[0108] Certain amino polydentate ligand structures herein may include one or more binding substituents (b) as functionalization connected to an amino group nitrogen (e.g., as shown in Fig.

[0109] 3). The binding substituent may be an organic moiety that comprises one or more binding sites that, in some embodiments, may coordinate to the metal ion. In some embodiments, the binding site or sites of the binding substituent may be deprotonated (e.g., with a base) to form an anionic group. Non-limiting examples of binding substituents include alkyl alcohols (e.g., which may form alkoxide binding sites), carboxylic acids (e.g., which may form carboxylate binding sites), phosphonic acids (e.g., which may form phosphonate binding sites), etc. In some embodiments, each of the binding substituents or the type of binding site (e.g., alkyl alcohol) on the amino polydentate ligand may be identical. In other embodiments, two or more different binding substituents or type of binding site (e.g., alkyl alcohol) may be present. As a non-limiting example, the ligand may comprise two different alkyl alcohol binding substituents. As another non-limiting example, the ligand may comprise both an alkyl alcohol binding substituent and a carboxylic acid binding substituent. In some embodiments, the total number of binding sites, meaning the sum of the alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups, may range from 3 to 12, which may tune the binding and solution properties of the redox material. In some embodiments, the total number of binding sites may be smaller with this sum may ranging from 3 to 10 or ranging from 3 to 6. In some embodiments, the ligand may comprise more binding sites for sufficient metal complex binding, for example comprising at least 3, at least 4, at least 5, or at least 6 total binding sites (i.e., when summing the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups on the ligand).

[0110] In some embodiments, the binding substituent may be deprotonated to form an anionic binding site that may coordinate to the metal ion. For example, alkyl alcohols may form alkoxides, carboxylic acids may form carboxylates, and phosphonic acids may form phosphonates. The pH at which the anionic binding site forms may depend on the specific moiety and the electrolyte conditions. Non-limiting example pKa values for these moieties are shown in Fig. 5, where R generally represents other organic functionalization, and these pKa values are average values for these types of organic functionalizations as is shown in Fig. 5. Not

[0111] #14802252vlwishing to be bound by any theory, in some embodiments, partial coordinate to a cationic metal ion may acidify the binding site proton, decreasing the pKa value of the binding site in solution.

[0112] In some embodiments, the amino polydentate ligand may be functionalized with one or more alkyl alcohol (e.g., forming alkoxides) binding substituents. Akyl alcohols, which can include primary, secondary, and tertiary alcohols, may be deprotonated to form anionic alkoxide groups, typically in an aqueous solution with pH greater than 12. In some embodiments, without wishing to be bound by any theory, primary alcohols may result in stable metal complexes due to the alcohol pKa and steric effects, while secondary alcohols may alter metal complex redox material properties due to coordination geometry effects. In some embodiments, alkoxide binding sites may coordinate with cationic metal ions, e.g., due to their localized negative charge.

[0113] In some embodiments, a single amino binding substituent may have one or more binding sites, e.g., alkyl alcohols (forming alkoxides). For example, an alkyl alcohol binding substituent may have one, two, three, or more alkyl alcohol groups (forming alkoxides binding sites). In some embodiments, the backbone of the alkyl alcohol (forming alkoxides) binding substituent may be an alkyl chain, and in certain embodiments, it may be a branched alkyl chain. In some embodiments, the backbone of the alkyl alcohol (forming alkoxides) binding substituent may comprise additional functional groups, including but not limited to ether, carboxylic acid, or phosphonic acid groups. Different numbers of binding sites on a binding substituent may affect the binding number of the ligand, which, in some embodiments, may affect the properties of the metal complex. For example, in some embodiments, additional alky alcohol (forming alkoxide) binding sites may increase the complex stability and shift the formal potential to more negative potential.

[0114] Fig. 6 shows non- limiting examples of alkyl alcohol (forming alkoxide) binding substituents, where the wavy line (^) generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3), and furthermore where each R is independently a hydrogen, an alkyl group, an alkyl chain comprising a sulfonate group, or an alkyl chain comprising a sulfonate group. The alkyl chain may be substituted or unsubstituted. In some embodiments, alkyl alcohol binding substituents with an amino group connection may be commercially available, including but not limited to 2-aminoethanol (141-43-5), 3 -aminopropan- l-ol (156-87-6), 4-aminobutan-l-ol (13325-10-5), 3-

[0115] #14802252vlaminopropane- 1,2-diol (616-30-8), l-aminobutan-2-ol (13552-21-1), 2-aminopropan-l-ol (6168-72-5), 2-aminobutan-l-ol (96-20-8), 2-amino-2-methylpropane-l,3-diol (115-69-5), 2-amino-2-(hydroxymethyl)propane- 1,3 -diol (77-86-1), 2-amino-2-methylpropan-l-ol (124-68-5), 2-amino-2-ethylbutan-l-ol (19792-52-0). In some cases, such substituents can be produced via amine (e.g., ammonia) reaction with epoxides (e.g., ethylene oxide), formaldehyde, or other oxygen containing reagents.

[0116] In some embodiments, the amino polydentate ligand may be functionalized with one or more carboxylic acid (forming carboxylate) binding substituents. Carboxy licacids may be deprotonated to form anionic carboxylate groups, typically a pH greater than 4, greater than 5, or greater than 6 in some cases. In some embodiments, without wishing to be bound by any theory, it is believed that carboxylates may coordinate strongly with cationic metal ions due to their negative charge, which is delocalized between the -COO group.

[0117] In some embodiments, a single amino binding substituent may have one or more binding sites, e.g., carboxylic acids (forming carboxylates). For example, a carboxylic acid binding substituent may have one, two, three, or more carboxylic acid groups (forming carboxylate binding sites). In some embodiments, the backbone of the carboxylic acid (forming carboxylate) binding substituent may be an alkyl chain, and in some cases, it may be a branched alkyl chain. In certain embodiments, the backbone may be a substituted alkyl chain, e.g., an alkyl alcohol. In some embodiments, the backbone of the carboxylic acid (forming carboxylate) binding substituent may comprise additional functional groups, including but not limited to ether, alcohol, or phosphonic acid groups.

[0118] Fig. 7 shows non- limiting examples of carboxylic acid (forming carboxylate) binding substituents, where the wavy line ( generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3), and furthermore where each R is independently a hydrogen, an alkyl group, an alkyl chain comprising a sulfonate group, or an alkyl chain comprising a sulfonate group. The alkyl chain may be substituted or unsubstituted. In some embodiments, carboxylic acid binding substituents with an amino group connection may be commercially available, including but not limited to 2-aminoacetic acid (56-40-6), 2-aminopentanedioic acid (617-65-2), 2-amino-3-hydroxybutanoic acid (80-68-2), 2-amino-3-hydroxypropanoic acid (302-84-1), and 2-amino-3-methylbutanoic acid (516-06-3). In some cases, the substituents can be produced via amine (e.g., ammonia)

[0119] #14802252vlreaction with chloroacetic acid, formaldehyde (e.g., with hydrogen cyanide), or various amino acid bio-processes.

[0120] In some embodiments, the ligand may be functionalized with one or more phosphonic acid (e.g., forming phosphonate) binding substituents. Phosphonic acids may be deprotonated to form anionic phosphonate groups, which may form mono-anions or di-anions in aqueous solution at pH typically greater than 2 and 8, respectively. In some embodiments, phosphonates may coordinate strongly with cationic metal ions due to their negative charge or charges which, without wishing to be bound by any theory, may be delocalized between the -PO3 or -PO2OH groups. In some embodiments, the phosphonic acid (i.e., -PO3H2) may coordinate to the metal as a mono-anion binding site (i.e., -PO2OH), while in certain embodiments it may coordinate to the metal as a di-anion binding site (i.e., -PO3). In some embodiments, the di-anion phosphonate may form stable metal complexes, e.g., due to the increase in electrostatic charge.

[0121] In some embodiments, a single amino binding substituent may have one or more binding sites, e.g., phosphonic acids (forming phosphonates). For example, a phosphonic acid binding substituent may have one, two, three, or more phosphonic acid groups (forming phosphonate binding sites). In some embodiments, the backbone of the phosphonic acid (forming phosphonate) binding substituent may be an alkyl chain, and in some cases, it may be a branched alkyl chain. In certain cases, the backbone may be a substituted alkyl chain, e.g., alkyl alcohol. In some embodiments, the backbone of the phosphonic acid (forming phosphonate) binding substituent may comprise additional functional groups, including but not limited to ether, alcohol, or phosphonic acid groups.

[0122] Fig. 8 shows non- limiting examples of phosphonic acid (forming phosphonate) binding substituents, where the wavy line ( generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3). In some embodiments, phosphonic acid binding substituents with an amino group connection may be commercially available, including but not limited to aminomethylphosphonic acid (1066-51-9). In some cases, the substituents can be produced via amine (e.g., ammonia) reaction with phosphoric acid (e.g., with hydrogen cyanide) or other phosphorus containing reagents.

[0123] It should be noted that in some embodiments, the organic linker (L) between amino group nitrogens may itself comprise one or more binding sites, e.g., alkyl alcohols (forming alkoxide), carboxylic acids (forming carboxylates), or phosphonic acids (forming phosphonate). Depending

[0124] #14802252vlon the solution pH, these groups may be deprotonated to form additional anionic binding sites that, in some embodiments, coordinate to the metal ion. Not wishing to be bound by any theory, in some embodiments, binding sites on organic linkers may improve metal complex stability, reduce membrane crossover, or improve the water solubility.

[0125] Fig. 9 shows non-limiting examples of organic linkers (L) with potential binding sites, where the wavy line ( ) generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3).

[0126] In some embodiments, the amino polydentate ligand may comprise two or more different binding substituents. In some embodiments, the amino polydentate ligand may comprise two or more different binding substituents with the same class of binding sites, e.g., two different alkyl alcohol (forming alkoxides) binding substituents, while in other embodiments, the ligand may comprise two or more different binding substituents with different classes of binding sites, e.g., an alkyl alcohol (forming alkoxides) binding substituents with carboxylic acid (forming carboxylate) binding substituents.

[0127] In some embodiments, without wishing to be bound by any theory, two or more different binding substituents on the same amino polydentate ligand may improve the water solubility through symmetry breaking effect. Additionally, combining various binding substituents may permit control of metal complex properties, including but not limited to stability, formal potential, redox kinetics, and membrane crossover. Not wishing to be bound by any theory, different combinations of binding substituents may alter the metal complex coordination geometry and orbital configuration, affecting stability and redox properties.

[0128] Ligands that comprise a majority of alkyl alcohol binding substituents may exhibit improved binding constants or more negative redox potentials in certain cases. In some embodiments, the ligand may comprise a least one alkyl alcohol group and carboxylic acid group, at least one alkyl alcohol group and phosphonic acid group, or at least one alkyl alcohol group, carboxylic acid groups, and phosphonic acid group. In some embodiments, the sum of the total number of alkyl alcohol groups may be greater than the sum of the carboxylic acid groups or the sum of the phosphoric acid groups independently or, in some embodiments, may be greater than the sum of the carboxylic acid groups and phosphonic acid groups together. In some embodiments, the ligand may comprise at least 3, at least 4, at least 5, or at least 6 alkyl alcohol groups, which may provide sufficient binding to the metal ion core. In some embodiments, each

[0129] #14802252vlb (Fig. 3) may comprise an alkyl alcohol while in other embodiments, at least one b may not comprise an alkyl alcohol. In some embodiments, the ligand may comprise at least one primary alkyl alcohol or at least one secondary alkyl alcohol. Not wishing to be bound by theory, in some embodiments, the alkyl alcohol groups may strongly bind to the metal ion while the carboxylic acid and / or phosphonic acid groups interact with the solvation shell to tune solubility and membrane compatibility properties.

[0130] Fig. 10 shows non-limiting examples of various binding substituents (b) and organic linkers (L) with binding sites that may be combined in any combination to form an amino polydentate ligand with a mixture of binding substituents, where the wavy line (b generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3), and furthermore where each R is independently a hydrogen, an alkyl group, an alkyl chain comprising a sulfonate group, or a alkyl chain comprising a sulfonate group. The alkyl chain may be substituted or unsubstituted.

[0131] In some embodiments, the amino polydentate ligand may be functionalized with substituents comprising additional anionic groups, such as sulfonic acid (e.g., forming sulfonate) groups. Not wishing to be bound by any theory, these additional anionic groups may possess weak binding affinity to the metal ion, meaning they do not act as strong binding sites with metal coordination. The additional anionic groups, (e.g., sulfonate) may increase the water solubility through water solvation effects and reduce the membrane crossover (e.g., through cationexchange membrane) through size exclusion and coulombic repulsion effects. In some embodiments, the additional anionic group may be a sulfonic acid (forming sulfonate) group. In aqueous solution, sulfonic acids may have very low pKa values near -5, meaning that they typically exist as anionic sulfonate groups in weakly acidic (e.g., pH 0 to 5), near-neutral (e.g., pH 5 to 9), or alkaline (e.g., pH 9 to 14 or more) solution.

[0132] In some embodiments, a ligand binding substituent may comprise one or more sulfonate groups. For example, an alkyl alcohol (forming alkoxide), a carboxylic acid (forming carboxylate), or a phosphonic acid (forming phosphonate) binding substituent may comprise one or more sulfonate groups.

[0133] #14802252vlFig. 11 shows a non-limiting example of a binding substituent comprising a sulfonate group, where the wavy line ( ) generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3).

[0134] In some cases, binding substituents with sulfonate groups with an amino group connection may be commercially available. In some cases, amino binding substituents with sulfonate groups may be synthesized. For example, amine reagents (e.g., ammonia, primary amine, or secondary amine), may be reacted with halogenated reagents comprising the sulfonated binding substituent, e.g., 3-chloro-2-hydroxy-l -propanesulfonic acid or 3 -bromo-2 -hydroxy- 1-propanesulfonic acid.

[0135] In some embodiments, one or more binding substituent (b), for example, as shown in Fig.

[0136] 3, may be r a functionalization substituent comprising a sulfonate group (e.g., an alkyl sulfonate) without a binding site, e.g., without an alkyl alcohol (forming alkoxide), a carboxylic acid (forming carboxylate), or a phosphonic acid (forming phosphonate). Fig. 12 shows non-limiting examples of functionalization substituents comprising sulfonate groups, where the wavy line (b generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3).

[0137] In some cases, functionalization substituents comprising a sulfonate group and an amino group without a binding site may be commercially available. In some cases, functionalization substituents comprising a sulfonate group and an amino group without a binding site may be synthesized. For example, amine reagents (e.g., ammonia, primary amine, or secondary amine), may be reacted with halogenated reagents comprising the sulfonated binding substituent, e.g., 2-chloroethanesulfonate, or with a sultone ring, e.g., 1,3-propanesultone or 1,4-butane sultone.

[0138] In some embodiments, the backbone of the sulfonate functionalization may be an alkyl chain, a branched alkyl chain, or a substituted alkyl chain, including but not limited to substituted alkyl chains with alcohol or ether groups.

[0139] The ratio of the sulfonate groups to the number of binding substituents or number of binding sites on the ligand may be controlled. In some embodiments, the number of sulfonate groups may alter the metal complex properties. Not wishing to be bound by any theory, increasing the number of sulfonate groups on the metal complex ligand may decrease the membrane crossover but increase the solution viscosity. In some embodiments, at least one b

[0140] #14802252vlmay comprise an alkyl sulfonate group. In some embodiments, only one b comprising an alkyl sulfonate may be sufficient to tune the solubility and membrane compatibility properties of the redox material.

[0141] In some embodiments, the metal complex may possess an overall negative charge.

[0142] Various cations may be used as the counter-ion in various embodiments. As non-limiting examples, potassium (K+), sodium (Na+), or ammonium (NH4+) may be used. In some embodiments, the counter-cation can be controlled by selecting the base used to deprotonate the binding sites, e.g., alkyl alcohols (forming alkoxides), carboxylic acids (forming carboxylates), or phosphonic acids (forming phosphonates). In some embodiments, the electrolyte may comprise supporting salt, which may improve the conductivity of the solution. Non-limiting examples of supporting salt cations include potassium (K+), sodium (Na+), or ammonium (NH4+). Non-limiting examples of support salt anions include chloride (Cl-), bromide (Br“), sulfate (SO42”), phosphate (PO43” or HPO42”), carbonate (HCO3” or CO32”), acetate, borate, sulfonates (e.g., methane sulfonate), oxalate, citrate, tartrate, malonate, succinate, or other organic anions. In some embodiments, changing the supporting salt or counter-ions may affect membrane conductivity, metal complex water solubility, and redox properties.

[0143] In some embodiments, a metal complex with an amino polydentate ligand may be synthesized through reaction of the desired metal ion (e.g., Fe(III)), the desired ligand (e.g., TEA), and a base (e.g., NaOH). Examples of such metal complex synthesis may be found in published sources. In these works, redox material complexes are synthesized between various metal ions and amino polydentate ligand structures through the mixing of the reagents with based (e.g., NaOH). Those familiar with the art can translate such methods to different redox material complexes with different metal ions and amino poly dentate ligands.

[0144] In some embodiments, the amino polydentate ligand may comprise a structure such as:

[0145] R2

[0146] " oH

[0147] where the wavy line ( ) generally represents a point of connection to an amine group nitrogen (e.g., the wavy line indicates a C-N bond) of the ligand (e.g., as shown in Fig. 3), and furthermore where R2 may comprise amine, alkyl, alkyl alcohol, ether, carboxylic acid, phosphonic acid, or sulfonic acid groups. In some embodiments, such groups may be

[0148] #14802252vlcommercially available, including 2-aminopentanedioic acid (617-65-2), 2-amino-3-hydroxybutanoic acid (80-68-2), 2-amino-3-hydroxypropanoic acid (302-84-1), and 2-amino-3-methylbutanoic acid (516-06-3) as non- limiting examples.

[0149] U.S. Provisional Patent Application Serial No. 63 / 759,919, filed February 18, 205, entitled “Metal Complex Redox Materials and Methods,” by Sullivan, et al., is incorporated herein by reference in its entirety.

[0150] The following examples are intended to illustrate certain embodiments of the present disclosure, but do not exemplify the full scope of the disclosure.

[0151] EXAMPLE 1

[0152] Various redox material complexes were synthesied for characterization in this example. Specifically, iron metal compelxes with six different ligands were produced. Fig. 13 shows the structures of the ligands used in this study. Ligands comprising various binding substituents and functionalization were used to provide a representative test set. Each of these ligands have three or more potential binding sites (e.g., alkyl alcohols forming alkoxides or carboxylic acids forming carboxylates) that can coordinate to the metal ion in solution.

[0153] The iron complexes were generally syntehsized by mixing the ligands with a Fe(III) salt (i.e., FeCE). The Fe(III) salt was used instead of the Fe(II) salt for metal complex synthesis, as its higher oxidation state and increased cationic charge results in improved reaction kinetics with the ligand binding sites. Accordingly, the follow reaction steps were used to synthesize the redox materal complexes with amino poly dentate ligands:

[0154] (1) 8 mM of ligand was weighed into a 50 mL glass bottle

[0155] (2) 4 mL of IM aqueous FeCh was added and stirred for 30 minutes

[0156] (3) 2.7 mL of de-ionized water was added and stirred for an additional 30 minnutes

[0157] (4) 2.5 M of 10 M NaOH was added a stirred for 12 hours, monitioring solution pH

[0158] (5) An additional 4 mL of 10 M NaOH and 6 mL of de-ionized water was added

[0159] (6) The resultant solution was collected for characerization

[0160] To confirm the succesfull synthesis of the metal complex, UV-Vis measurements were taken of each product solution. Figs. 14A-14F show the spectrum for each resultant metal complex aquoues solution in this example. Each show a feature between 450 nm to 500 nm,

[0161] #14802252vlwhich suggests ligand-to-metal charge transfer (LMCT) between the binding substituents of the ligand and the Fe(III) ion. Some metal complex solutions show an additional broad feature from 550 nm to 600 nm, which suggestions additional coordination speciation between the ligand and the Fe(III) ion. These results support the successful synthesis of redox materal complexes with various amino poly dentate ligands.

[0162] EXAMPLE 2

[0163] The redox material compelxes shown in Example 1 were electroehmically characterized to explore their redox properties in this example. Namely, Cyclic Voltametry (CV) measurements were performed on the Fe(III) metal compelxes with the various amino poly dentate ligands. Through CV experimentation, the redox kinetics and formal potential can be observed. For CV experiments, 0.2 M aquoues solutions of the metal complexes in approximately 1 M NaOH were studied. A scan rate of 80 mV / s was used on glassy carbon electrode (GCE). Figs. 15A-15F shows a representative CV scan of the metal complex solutions. Each metal complex solution in these figures showed a reverisble redox feature between -0.3 V and -1.0 V vs. SHE. Metal complexes comprising amino groups fully substituted with bidning susbtituents (i.e., no N-H bond) showed ideally reversible redox peaks with a E1 / 2 near -0.7 V vs. SHE, which is estaimted by the half potential between the anodic and cathodic peaks. The E1 / 2 shifts depending on the exact structure of the binding substituent. For example, the anodic peak is observed to shift towards more negative potential as the primiary alcohol binding substituents are replaced with secondary alcohol substituents. Additionally, the ligand comprising the trialkyl alcohol binnding sustituents (Fig. 15F) exhbits a negative potential shift in both the anodic and cathodic peaks. Thus, the redox material complexes showed electrochemical activity.

[0164] EXAMPLE 3

[0165] The metal complex solutions that showed ideally reversible electrocehmical behavior were characerized in redox flow battery cycling experimentation in this non-limiting example. A customized redox flow cell was used for experimentation. In short, the redox flow cell comprised carbon bipolar plates and 2 mm thickness carbon felt, each with 4 cm2active area. The anode and cathode compartments were seperated by a Selemion CMVN cation-exchange membrane with 40 micrometer thickness. The anolyte comprised 10 mL of 0.1 M metal complex in 2 M NaOH, and the catholyte comprised 10 mL of 0.1 M NaFe(CN)e in 2 M NaOH. The redox flow cell cycling was performed in a nitrogen glovebox (below 10 ppm O2). Galvanic cycling with

[0166] #14802252vlpotential limits (GCPL) experimentation was performed on the cells with a 20 mA / cm2chargedischarge current density, a charge potential cutoff of 1.4 V, and a discharge potential cutoff of 0.8 V. Redox material complexes studied in redox flow cell exhibited reversible charge-dicharge behavior over tens of cycles. Figs. 16A-16J show the charge-discharge curves of a representative cycle and the electrocehmical cell capacity and efficiency peroformance over tens of cycles.

[0167] EXAMPLE 4

[0168] Four iron-complexes comprising ligands that comprise both an alkyl alcohol and a carboxylic acid were synthesized as non-limiting examples. These were produced through the reaction of alcohol-bearing amino acids — i.e., 2-amino-3-hydroxybutanoic acid (80-68-2) and 2-amino-3-hydroxypropanoic acid (302-84-1) — with an epoxide reaction (ethylene oxide (75-21-8) and 1,2-propylene oxide (75-56-9)). Yields were over 95% for each reaction (Figs. 17A-17D) Two representative iron-complex ligands were selected for further carhacterization, namely bis(hydroxylethyl)serine (BHES) and bis(hydroxypropyle)serine (BHPS). CV experiments were conducted using 0.2M solutions of the metal-complex in 2.0M NaOH with GCE working electrode and a scan rate of 10 mV / s. Each showed quasi-reversible redox behavior with E1 / 2 near -0.85 V vs. SHE (Figs. 18A and 18B). Interestingly, the BHPS ligand showed more reversible redox behavior (e.g., redued peak splitting) in these conditions, suggesting that the specific ligand structure may alter electrochemical properties.

[0169] The BHES and BHPS iron-complexes were characterized in redox flow battery cycling experimentation. Briefly, the redox flow cell comprised carbon bipolar plates and 2 mm thickness carbon felt, each with 4 cm2active area. The anode and cathode compartments were seperated by a Selemion CMVN cation-exchange membrane with 40 micrometer thickness. The anolyte comprised 6 mL of 0.1 M metal complex in 0.5 M NaOH, and the catholyte comprised 10 mL of 0.1 M NaFe(CN)e in 0.5 M NaOH. The redox flow cell cycling was performed in a nitrogen glovebox (below 10 ppm O2). Galvanic cycling with potential limits (GCPL) experimentation was performed on the cells with a 10 mA / cm2charge-discharge current density, a charge potential cutoff of 1.45 V, and a discharge potential cutoff of 0.8 V. The BHES and BHPS iron-compelx electrochemical cells exhibited reversible charge-dicharge behavior over tens of cycles (Figs. 19A-19D).

[0170] #14802252vlWhile several embodiments of the present disclosure have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the present disclosure. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and / or configurations will depend upon the specific application or applications for which the teachings of the present disclosure is / are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the disclosure described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the disclosure may be practiced otherwise than as specifically described and claimed. The present disclosure is directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent, is included within the scope of the present disclosure.

[0171] In cases where the present specification and a document incorporated by reference include conflicting and / or inconsistent disclosure, the present specification shall control. If two or more documents incorporated by reference include conflicting and / or inconsistent disclosure with respect to each other, then the document having the later effective date shall control.

[0172] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0173] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

[0174] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements

[0175] #14802252vlso conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0176] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.”

[0177] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0178] #14802252vlWhen the word “about” is used herein in reference to a number, it should be understood that still another embodiment of the disclosure includes that number not modified by the presence of the word “about.”

[0179] It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

[0180] In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of’ and “consisting essentially of’ shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

[0181] #14802252vl

Claims

CLAIMSWhat is claimed is:

1. An electrochemical device, comprising :an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:">>>wherein each L independently is an organic linker, and each b is independently selected with at least one b selected from the group consisting of:#14802252vlwherein the < is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

2. The electrochemical device of claim 1, wherein the device is a battery.

3. The electrochemical device of claims 1-2, wherein the device is a redox flow battery.

4. The electrochemical device of claims 1-3, wherein the device is an aqueous redox flow battery.

5. The electrochemical device of claim 4, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

6. The electrochemical device of claim 4, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.

7. The electrochemical device of claims 1-6, wherein the complex is an anolyte redox material.

8. The electrochemical device of claims 1-6, wherein the complex is a catholyte redox material.

9. The electrochemical device of claims 1-8, wherein the metal is a transition metal.

10. The electrochemical device of claims 1-9, wherein the metal is a 3d-block (first row) transition metal.

11. The electrochemical device of claims 1-10, wherein the metal is iron.

12. The electrochemical device of claims 1-10, wherein the metal is chromium.#14802252vl13. The electrochemical device of claims 1-10, wherein the metal is manganese.

14. The electrochemical device of claims 1-9, wherein the metal is molybdenum.

15. The electrochemical device of claims 1-9, wherein the metal is tungsten.

16. The electrochemical device of claims 1-8, wherein the metal is tin.

17. The electrochemical device of claims 1-8, wherein the metal is antimony.

18. The electrochemical device of claims 1-17, wherein the ligand comprises the core structure:

19. The electrochemical device of claims 1-17, wherein the ligand comprises the core structure:b^ A. 'bN Ni ib b20. The electrochemical device of claims 1-17, wherein the ligand comprises the core structure:b’'N'L"N'iL"N'i ibb b b21. The electrochemical device of claims 1-17, wherein the ligand comprises the core structure:#14802252vl22. The electrochemical device of claims 19-21, wherein at least one L comprises a substituted or unsubstituted alkyl chain.

23. The electrochemical device of claim 22, wherein the alkyl chain is branched.

24. The electrochemical device of claims 22-23, wherein the alkyl chain has 2 to 6 carbons.

25. The electrochemical device of claims 19-21, wherein at least one L comprises a substituted or unsubstituted cyclic alkyl group.

26. The electrochemical device of claim 25, wherein the cyclic alkyl group has 6 to 12 carbons.

27. The electrochemical device of claims 19-26, wherein at least one L comprises an alcohol group.

28. The electrochemical device of claims 19-27, wherein at least one L comprises an ether group.

29. The electrochemical device of claims 19-28, wherein at least one L comprises a carboxylic acid group.

30. The electrochemical device of claims 19-21, wherein at least one L comprises a structure selected from the group consisting of:#14802252vlwherein the ’ is a point of connection to the N in the core structure.

31. The electrochemical device of claim 30, wherein at least one L is ethyl.

32. The electrochemical device of claims 20-21, wherein each L is identical.

33. The electrochemical device of claims 20-21, wherein at least two L’s are not identical.

34. The electrochemical device of claims 1-33, wherein each b comprises between 1 and 10 carbons inclusively.

35. The electrochemical device of claims 1-34, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen.

36. The electrochemical device of claims 1-34, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group.

37. The electrochemical device of claims 1-34, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group.

38. The electrochemical device of claims 1-37, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.#14802252vl39. The electrochemical device of claims 1-37, wherein the ligand structure is non-aromatic.

40. The electrochemical device of claims 1-39, wherein at least one b comprises an alkyl sulfonate group.

41. The electrochemical device of claims 40, wherein only one b comprises an alkyl sulfonate.

42. The electrochemical device of claims 40-41, wherein the alkyl sulfonate comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure or to a N in the b structure.

43. The electrochemical device of claims 1-42, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

44. The electrochemical device of claims 1-43, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

45. The electrochemical device of claims 1-44, wherein at least one b comprises the structure:#14802252vlwherein the is a point of connection to the N in the core structure.

46. The electrochemical device of claims 1-45, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

47. The electrochemical device of claims 1-46, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

48. The electrochemical device of claims 1-47, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

49. The electrochemical device of claims 1-48, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.#14802252vl50. The electrochemical device of claims 1-49, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure.

51. The electrochemical device of claims 1-50, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

52. The electrochemical device of claims 1-51 , wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

53. The electrochemical device of claims 1-52, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.#14802252vl54. The electrochemical device of claims 1-53, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

55. The electrochemical device of claims 1-54, wherein at least one b comprises the structure:wherein the < is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

56. The electrochemical device of claims 1-55, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

57. The electrochemical device of claims 1-56, wherein at least one b comprises the structure:JDH#14802252vlwherein the < is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

58. The electrochemical device of claims 1-57, wherein each b is identical.

59. The electrochemical device of claims 1-57, wherein at least two b’s are not identical.

60. An electrochemical device, comprising:an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:>wherein each L independently is an organic linker, and each b is independently selected with at least one b selected from the group consisting of:#14802252vlwherein the is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

61. The electrochemical device of claim 60, wherein the device is a battery.

62. The electrochemical device of claims 60-61, wherein the device is a redox flow battery.

63. The electrochemical device of claims 60-62, wherein the device is an aqueous redox flow battery.#14802252vl64. The electrochemical device of claim 63, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

65. The electrochemical device of claim 63, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.

66. The electrochemical device of claims 60-65, wherein the complex is an anolyte redox material.

67. The electrochemical device of claims 60-65, wherein the complex is a catholyte redox material.

68. The electrochemical device of claims 60-67, wherein the metal is a transition metal.

69. The electrochemical device of claims 60-68, wherein the metal is a 3d-block (first row) transition metal.

70. The electrochemical device of claims 60-69, wherein the metal is iron.

71. The electrochemical device of claims 60-69, wherein the metal is chromium.

72. The electrochemical device of claims 60-69, wherein the metal is manganese.

73. The electrochemical device of claims 60-68, wherein the metal is molybdenum.

74. The electrochemical device of claims 60-68, wherein the metal is tungsten.

75. The electrochemical device of claims 60-67, wherein the metal is tin.

76. The electrochemical device of claims 60-67, wherein the metal is antimony.#14802252vl77. The electrochemical device of claims 60-76, wherein the ligand comprises the core structure:

78. The electrochemical device of claims 60-76, wherein the ligand comprises the core structure:bN i 'L'N i 'L'N i 'bb b b .

79. The electrochemical device of claims 60-76, wherein the ligand comprises the core structure:>80. The electrochemical device of claims 60-79, wherein at least one L comprises a substituted or unsubstituted alkyl chain.

81. The electrochemical device of claim 80, wherein the alkyl chain is branched.

82. The electrochemical device of claims 80-81, wherein the alkyl chain has 2 to 6 carbons.

83. The electrochemical device of claims 60-82, wherein at least one L comprises a substituted or unsubstituted cyclic alkyl group.

84. The electrochemical device of claim 83, wherein the cyclic alkyl group has 6 to 12 carbons.

85. The electrochemical device of claims 60-84, wherein at least one L comprises an alcohol group.#14802252vl86. The electrochemical device of claims 60-84, wherein at least one L comprises an ether group.

87. The electrochemical device of claims 60-84, wherein at least one L comprises a carboxylic acid group.

88. The electrochemical device of claims 60-79, wherein at least one L comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure.

89. The electrochemical device of claim 88, wherein at least one L is ethyl.

90. The electrochemical device of claims 78-79, wherein each L is identical.

91. The electrochemical device of claims 78-79, wherein at least two L’s are not identical.

92. The electrochemical device of claims 60-91, wherein each b comprises between 1 and 10 carbons inclusively.

93. The electrochemical device of claims 60-92, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen.#14802252vl94. The electrochemical device of claims 60-92, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group.

95. The electrochemical device of claims 60-92, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group.

96. The electrochemical device of claims 60-95, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.

97. The electrochemical device of claims 60-96, wherein the ligand structure is non-aromatic.

98. The electrochemical device of claims 60-97, wherein at least one b comprises an alkyl sulfonate group.

99. The electrochemical device of claim 98, wherein only one b comprises an alkyl sulfonate.

100. The electrochemical device of claims 98-99, wherein the alkyl sulfonate comprises a structure selected from the group consisting of: / / so3wherein the is a point of connection to the N in the core structure or to a N in the b structure.

101. The electrochemical device of claims 60-100, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.#14802252vl102. The electrochemical device of claims 60-101, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

103. The electrochemical device of claims 60-102, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

104. The electrochemical device of claims 60-103, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

105. The electrochemical device of claims 60-104, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

106. The electrochemical device of claims 60-105, wherein at least one b comprises the structure:#14802252vlwherein the ’ is a point of connection to the N in the core structure.

107. The electrochemical device of claims 60-106, wherein at least one b comprises the structure:""wherein the is a point of connection to the N in the core structure.

108. The electrochemical device of claims 60-107, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

109. The electrochemical device of claims 60-108, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

110. The electrochemical device of claims 60-109, wherein at least one b comprises the structure:#14802252vlwherein the * is a point of connection to the N in the core structure.

111. The electrochemical device of claims 60-110, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

112. The electrochemical device of claims 60-111, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

113. The electrochemical device of claims 60-112, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.#14802252vl114. The electrochemical device of claims 60-113, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

115. The electrochemical device of claims 60-114, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

116. The electrochemical device of claims 60-115, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

117. The electrochemical device of claims 60-116, wherein at least one b comprises the structure:wherein the < is a point of connection to the N in the core structure.#14802252vl118. The electrochemical device of claims 60-117, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

119. The electrochemical device of claims 60-118, wherein each b is identical.

120. The electrochemical device of claims 60-118, wherein at least two b’s are not identical.

121. An electrochemical device, comprising:an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:wherein each L independently is an organic linker, and each b is independently selected with at least one b selected from the group consisting of:#14802252vlwherein the ? is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

122. The electrochemical device of claim 121 , wherein the device is a battery.

123. The electrochemical device of claims 121-122, wherein the device is a redox flow battery.#14802252vl124. The electrochemical device of claims 121-123, wherein the device is an aqueous redox flow battery.

125. The electrochemical device of claim 124, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

126. The electrochemical device of claim 124, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.

127. The electrochemical device of claims 121-126, wherein the complex is an anolyte redox material.

128. The electrochemical device of claims 121-126, wherein the complex is a catholyte redox material.

129. The electrochemical device of claims 121-128, wherein the metal is a transition metal.

130. The electrochemical device of claims 121-129, wherein the metal is a 3d-block (first row) transition metal.

131. The electrochemical device of claims 121-130, wherein the metal is iron.

132. The electrochemical device of claims 121-130, wherein the metal is chromium.

133. The electrochemical device of claims 121-130, wherein the metal is manganese.

134. The electrochemical device of claims 121-129, wherein the metal is molybdenum.

135. The electrochemical device of claims 121-129, wherein the metal is tungsten.

136. The electrochemical device of claims 121-128, wherein the metal is tin.#14802252vl137. The electrochemical device of claims 121-128, wherein the metal is antimony.

138. The electrochemical device of claims 121-137, wherein the ligand comprises the core structure:

139. The electrochemical device of claims 121-137, wherein the ligand comprises the core structure:

140. The electrochemical device of claims 121-139, wherein at least one L comprises a substituted or unsubstituted alkyl chain.

141. The electrochemical device of claim 140, wherein the alkyl chain is branched.

142. The electrochemical device of claims 140-141, wherein the alkyl chain has 2 to 6 carbons.

143. The electrochemical device of claims 121-139, wherein at least one L comprises a substituted or unsubstituted cyclic alkyl group.

144. The electrochemical device of claim 143, wherein the cyclic alkyl group has 6 to 12 carbons.

145. The electrochemical device of claims 121-144, wherein at least one L comprises an alcohol group.#14802252vl146. The electrochemical device of claims 121-144, wherein at least one L comprises an ether group.

147. The electrochemical device of claims 121-144, wherein at least one L comprises a carboxylic acid group.

148. The electrochemical device of claims 121-139, wherein at least one L comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure.

149. The electrochemical device of claim 148, wherein at least one L is ethyl.

150. The electrochemical device of claims 121-149, wherein each L is identical.

151. The electrochemical device of claims 121-149, wherein at least two L’s are not identical.

152. The electrochemical device of claims 121-151, wherein each b comprises between 1 and 10 carbons inclusively.

153. The electrochemical device of claims 121-152, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen.#14802252vl154. The electrochemical device of claims 121-152, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group.

155. The electrochemical device of claims 121-152, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group.

156. The electrochemical device of claims 121-155, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.

157. The electrochemical device of claims 121-156, wherein the ligand structure is nonaromatic.

158. The electrochemical device of claims 121-157, wherein at least one b comprises an alkyl sulfonate group.

159. The electrochemical device of claim 158, wherein only one b comprises an alkyl sulfonate.

160. The electrochemical device of claims 158-159, wherein the alkyl sulfonate comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure or to a N in the b structure.

161. The electrochemical device of claims 121-160, wherein at least one b comprises the structure:#14802252vlwherein the < is a point of connection to the N in the core structure.

162. The electrochemical device of claims 121-161, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure.

163. The electrochemical device of claims 121-162, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure.

164. The electrochemical device of claims 121-163, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

165. The electrochemical device of claims 121-164, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure.

166. The electrochemical device of claims 121-165, wherein at least one b comprises the structure:#14802252vlwherein the ? is a point of connection to the N in the core structure.

167. The electrochemical device of claims 121-166, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

168. The electrochemical device of claims 121-167, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

169. The electrochemical device of claims 121-168, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

170. The electrochemical device of claims 121-169, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.#14802252vl171. The electrochemical device of claims 121-170, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

172. The electrochemical device of claims 121-171, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

173. The electrochemical device of claims 121-172, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

174. The electrochemical device of claims 121-173, wherein at least one b comprises the structure:#14802252vlwherein the < is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

175. The electrochemical device of claims 121-174, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

176. The electrochemical device of claims 121-175, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

177. The electrochemical device of claims 121-176, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

178. The electrochemical device of claims 121-177, wherein at least one b comprises the structure:#14802252vlwherein the < is a point of connection to the N in the core structure.

179. The electrochemical device of claims 121-178, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

180. The electrochemical device of claims 121-179, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

181. The electrochemical device of claims 121-180, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

182. The electrochemical device of claims 121-181, wherein each b is identical.

183. The electrochemical device of claims 121-181, wherein at least two b’s are not identical.

184. An electrochemical device, comprising:an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:#14802252vl>wherein each L independently is an organic linker, and each b independently is selected from the group consisting of:#14802252vlwherein the < is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

185. The electrochemical device of claim 184, wherein the device is a battery.

186. The electrochemical device of claims 184-185, wherein the device is a redox flow battery.

187. The electrochemical device of claims 184-186, wherein the device is an aqueous redox flow battery.

188. The electrochemical device of claim 187, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

189. The electrochemical device of claim 187, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.

190. The electrochemical device of claims 184-189, wherein the complex is an anolyte redox material.

191. The electrochemical device of claims 184-189, wherein the complex is a catholyte redox material.

192. The electrochemical device of claims 184-191, wherein the metal is a transition metal.

193. The electrochemical device of claims 184-192, wherein the metal is a 3d-block (first row) transition metal.

194. The electrochemical device of claims 184-193, wherein the metal is iron.

195. The electrochemical device of claims 184-193, wherein the metal is chromium.#14802252vl196. The electrochemical device of claims 184-193, wherein the metal is manganese.

197. The electrochemical device of claims 184-192, wherein the metal is molybdenum.

198. The electrochemical device of claims 184-192, wherein the metal is tungsten.

199. The electrochemical device of claims 184-191, wherein the metal is tin.

200. The electrochemical device of claims 184-191, wherein the metal is antimony.

201. The electrochemical device of claims 184-200, wherein at least one L comprises a substituted or unsubstituted alkyl chain.

202. The electrochemical device of claim 201, wherein the alkyl chain is branched.

203. The electrochemical device of claims 201-202, wherein the alkyl chain has 2 to 6 carbons.

204. The electrochemical device of claims 184-203, wherein at least one L comprises a substituted or unsubstituted cyclic alkyl group.

205. The electrochemical device of claim 204, wherein the cyclic alkyl group has 6 to 12 carbons.

206. The electrochemical device of claims 184-205, wherein at least one L comprises an alcohol group.

207. The electrochemical device of claims 184-205, wherein at least one L comprises an ether group.#14802252vl208. The electrochemical device of claims 184-205, wherein at least one L comprises a carboxylic acid group.

209. The electrochemical device of claims 184-200, wherein at least one L comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure.

210. The electrochemical device of claim 209, wherein at least one L is ethyl.

211. The electrochemical device of claims 184-210, wherein each L is identical.

212. The electrochemical device of claims 184-210, wherein at least two L’s are not identical.

213. The electrochemical device of claims 184-212, wherein each b comprises between 1 and 10 carbons inclusively.

214. The electrochemical device of claims 184-213, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen.

215. The electrochemical device of claims 184-213, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group.#14802252vl216. The electrochemical device of claims 184-213, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group.

217. The electrochemical device of claims 184-216, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.

218. The electrochemical device of claims 184-217, wherein the ligand structure is nonaromatic.

219. The electrochemical device of claims 184-218, wherein at least one b comprises an alkyl sulfonate group.

220. The electrochemical device of claim 219, wherein only one b comprises an alkyl sulfonate.

221. The electrochemical device of claims 219-220, wherein the alkyl sulfonate comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure or to a N in the b structure.

222. The electrochemical device of claims 184-221, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

223. The electrochemical device of claims 184-222, wherein at least one b comprises the structure:#14802252vlwherein the ’ is a point of connection to the N in the core structure.

224. The electrochemical device of claims 184-223, wherein at least one b comprises the structure:wherein the < is a point of connection to the N in the core structure.

225. The electrochemical device of claims 184-224, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure.

226. The electrochemical device of claims 184-225, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

227. The electrochemical device of claims 184-226, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.#14802252vl228. The electrochemical device of claims 184-227, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

229. The electrochemical device of claims 184-228, wherein at least one b comprises the structure:>wherein the is a point of connection to the N in the core structure.

230. The electrochemical device of claims 184-229, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

231. The electrochemical device of claims 184-230, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

232. The electrochemical device of claims 184-231, wherein at least one b comprises the structure:#14802252vlwherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

233. The electrochemical device of claims 184-232, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

234. The electrochemical device of claims 184-233, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

235. The electrochemical device of claims 184-234, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.#14802252vl236. The electrochemical device of claims 184-235, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

237. The electrochemical device of claims 184-236, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

238. The electrochemical device of claims 184-237, wherein at least one b comprises the structure:wherein the * is a point of connection to the N in the core structure.

239. The electrochemical device of claims 184-238, wherein at least one b comprises the structure:>wherein the is a point of connection to the N in the core structure.

240. The electrochemical device of claims 184-239, wherein at least one b comprises the structure:#14802252vlwherein the * is a point of connection to the N in the core structure.

241. The electrochemical device of claims 184-240, wherein at least one b comprises the structure:wherein the ? is a point of connection to the N in the core structure.

242. The electrochemical device of claims 184-241, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

243. The electrochemical device of claims 184-242, wherein at least one b comprises the structure:wherein the is a point of connection to the N in the core structure.

244. The electrochemical device of claims 184-243, wherein at least one b comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

245. The electrochemical device of claims 184-244, wherein each b is identical.#14802252vl246. The electrochemical device of claims 184-244, wherein at least two b’s are different.

247. An electrochemical device, comprising:an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:wherein each L independently is an organic linker, and each b is independently selected and each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen, and wherein at least one L comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure.

248. The electrochemical device of claim 247, wherein the device is a battery.

249. The electrochemical device of claims 247-248, wherein the device is a redox flow battery.#14802252vl250. The electrochemical device of claims 247-149, wherein the device is an aqueous redox flow battery.

251. The electrochemical device of claim 250, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

252. The electrochemical device of claim 250, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.

253. The electrochemical device of claims 247-252, wherein the complex is an anolyte redox material.

254. The electrochemical device of claims 247-252, wherein the complex is a catholyte redox material.

255. The electrochemical device of claims 247-254, wherein the metal is a transition metal.

256. The electrochemical device of claims 247-255, wherein the metal is a 3d-block (first row) transition metal.

257. The electrochemical device of claims 247-256, wherein the metal is iron.

258. The electrochemical device of claims 247-256, wherein the metal is chromium.

259. The electrochemical device of claims 247-256, wherein the metal is manganese.

260. The electrochemical device of claims 247-255, wherein the metal is molybdenum.

261. The electrochemical device of claims 247-255, wherein the metal is tungsten.

262. The electrochemical device of claims 247-254, wherein the metal is tin.#14802252vl263. The electrochemical device of claims 247-254, wherein the metal is antimony.

264. The electrochemical device of claims 247-263, wherein the ligand comprises the core structure:A. bN i N ib b265. The electrochemical device of claims 247-263, wherein the ligand comprises the core structure:bN i 'L'N i 'L'N i 'bb b b .

266. The electrochemical device of claims 247-263, wherein the ligand comprises the structure:"267. The electrochemical device of claims 247-266, wherein each b comprises between 1 and 10 carbons inclusively.

268. The electrochemical device of claims 247-267, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group.

269. The electrochemical device of claims 247-267, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group.

270. The electrochemical device of claims 247-269, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.#14802252vl271. The electrochemical device of claims 247-270, wherein the ligand structure is non- aromatic.

272. The electrochemical device of claims 247-271, wherein at least one b comprises an alkyl alcohol.

273. The electrochemical device of claim 272, wherein at least one b comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

274. The electrochemical device of claims 247-273, wherein at least one b comprises a carboxylic acid.#14802252vl275. The electrochemical device of claim 274, wherein at least one b comprises a structure selected from the group consisting of:wherein the * is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

276. The electrochemical device of claims 247-275, wherein at least one b comprises a phosphonic acid.

277. The electrochemical device of claim 276, wherein at least one b comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure.

278. The electrochemical device of claims 247-277, wherein at least one b comprises an alkyl sulfonate.#14802252vl279. The electrochemical device of claim 278, wherein only one b comprises an alkyl sulfonate.

280. The electrochemical device of claims 278-279, wherein the alkyl sulfonate comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure or to a N in the b structure.

281. The electrochemical device of claims 247-280, wherein each b is identical.

282. The electrochemical device of claims 247-280, wherein at least two b’s are different.

283. The electrochemical device of claims 247-282, wherein at least one L comprises the structure:wherein the is a point of connection to the N in the core structure.

284. The electrochemical device of claims 247-283, wherein at least one L comprises the structure:wherein the * is a point of connection to the N in the core structure.

285. The electrochemical device of claim 247-284, wherein at least one L comprises the structure:wherein the * is a point of connection to the N in the core structure.#14802252vl286. The electrochemical device of claims 247-285, wherein at least one L comprises the structure:wherein the is a point of connection to the N in the core structure.

287. The electrochemical device of claims 247-286, wherein at least one L comprises the structure:wherein the is a point of connection to the N in the core structure.

288. The electrochemical device of claims 247-287, wherein at least one L comprises the structure:wherein the is a point of connection to the N in the core structure.

289. The electrochemical device of claims 247-288, wherein at least one L comprises the structure:wherein the is a point of connection to the N in the core structure.

290. The electrochemical device of claims 247-289, wherein at least one L comprises the structure:#14802252vlwherein the is a point of connection to the N in the core structure.

291. The electrochemical device of claims 247-290, wherein at least one L comprises the structure:wherein the ’ is a point of connection to the N in the core structure.

292. The electrochemical device of claims 247-291, wherein at least one L comprises the structure:wherein the ? is a point of connection to the N in the core structure.

293. The electrochemical device of claims 265-266, wherein each L is identical.

294. The electrochemical device of claims 265-266, wherein at least two L’s are different.

295. An electrochemical device, comprising:an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:#14802252vl">>wherein each L independently is an organic linker, and each b is independently selected and each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen, and wherein at least one L comprises an alkyl alcohol group, a carboxylic acid group, a sulfonate group, or an ether group.

296. The electrochemical device of claim 295, wherein the device is a battery.

297. The electrochemical device of claims 295-296, wherein the device is a redox flow battery.

298. The electrochemical device of claims 295-297, wherein the device is an aqueous redox flow battery.

299. The electrochemical device of claim 298, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

300. The electrochemical device of claim 298, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.

301. The electrochemical device of claims 295-300, wherein the complex is an anolyte redox material.

302. The electrochemical device of claims 295-300, wherein the complex is a catholyte redox material.

303. The electrochemical device of claims 295-302, wherein the metal is a transition metal.#14802252vl304. The electrochemical device of claims 295 -303, wherein the metal is a 3d-block (first row) transition metal.

305. The electrochemical device of claims 295 -304, wherein the metal is iron.

306. The electrochemical device of claims 295 -304, wherein the metal is chromium.

307. The electrochemical device of claims 295 -304, wherein the metal is manganese.

308. The electrochemical device of claims 295 -303, wherein the metal is molybdenum.

309. The electrochemical device of claims 295 -303, wherein the metal is tungsten.

310. The electrochemical device of claims 295 -302, wherein the metal is tin.

311. The electrochemical device of claims 295 -302, wherein the metal is antimony.

312. The electrochemical device of claims 295 -311, wherein the ligand comprises the core structure:b_ . 'bN i N ib b313. The electrochemical device of claims 295 -311, wherein the ligand comprises the core structure:b''N"L"N "N"i i ibb b b314. The electrochemical device of claims 295-311, wherein the ligand comprises the core structure:#14802252vl315. The electrochemical device of claims 295-314, wherein each b comprises between 1 and 10 carbons inclusively.

316. The electrochemical device of claims 295-315, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group.

317. The electrochemical device of claims 295-315, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group.

318. The electrochemical device of claims 295-317, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.

319. The electrochemical device of claims 295-318, wherein the ligand structure is nonaromatic.

320. The electrochemical device of claims 295-319, wherein at least one b comprises an alkyl alcohol.

321. The electrochemical device of claim 320, wherein at least one b comprises a structure selected from the group consisting of:#14802252vlwherein the is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

322. The electrochemical device of claims 295-321, wherein at least one b comprises a carboxylic acid.

323. The electrochemical device of claim 322, wherein at least one b comprises a structure selected from the group consisting of:#14802252vlwherein the ? is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

324. The electrochemical device of claims 295-323, wherein at least one b comprises a phosphonic acid.

325. The electrochemical device of claim 324, wherein at least one b comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure.

326. The electrochemical device of claims 295-325, wherein at least one b comprises an alkyl sulfonate.

327. The electrochemical device of claim 326, wherein only one b comprises an alkyl sulfonate.#14802252vl328. The electrochemical device of claims 326-327, wherein the alkyl sulfonate comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure or to a N in the b structure.

329. The electrochemical device of claims 295-328, wherein each b is identical.

330. The electrochemical device of claims 295 -328, wherein at least two b’s are different.

331. The electrochemical device of claims 295 -330, wherein at least one L comprises an alkyl alcohol.

332. The electrochemical device of claims 295 -331, wherein at least one L comprises a carboxylic acid.

333. The electrochemical device of claims 295 -332, wherein at least one L comprises a phosphonic acid.

334. The electrochemical device of claims 295 -333, wherein at least one L comprises a sulfonate.

335. The electrochemical device of claims 295 -334, wherein at least one L comprises an ether.

336. The electrochemical device of claims 295 -335, wherein each L comprises between 2 and 12 carbons.

337. The electrochemical device of claims 313-314, wherein each L is identical#14802252vl338. The electrochemical device of claims 313-314, wherein at least two L’s are different.

339. An electrochemical device, comprising:an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:wherein each L independently is an organic linker, and each b is independently selected and each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen.

340. The electrochemical device of claim 339, wherein the device is a battery.

341. The electrochemical device of claims 339-340, wherein the device is a redox flow battery.

342. The electrochemical device of claims 339-341, wherein the device is an aqueous redox flow battery.

343. The electrochemical device of claim 342, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

344. The electrochemical device of claim 342, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.#14802252vl345. The electrochemical device of claims 339-344, wherein the complex is an anolyte redox material.

346. The electrochemical device of claims 339-344, wherein the complex is a catholyte redox material.

347. The electrochemical device of claims 339-346, wherein the metal is a transition metal.

348. The electrochemical device of claims 339-347, wherein the metal is a 3d-block (first row) transition metal.

349. The electrochemical device of claims 339-348, wherein the metal is iron.

350. The electrochemical device of claims 339-348, wherein the metal is chromium.

351. The electrochemical device of claims 339-348, wherein the metal is manganese.

352. The electrochemical device of claims 339-347, wherein the metal is molybdenum.

353. The electrochemical device of claims 339-347, wherein the metal is tungsten.

354. The electrochemical device of claims 339-346, wherein the metal is tin.

355. The electrochemical device of claims 339-346, wherein the metal is antimony.

356. The electrochemical device of claims 339-355, wherein the ligand comprises an alkyl alcohol and a carboxylic acid group, an alkyl alcohol and a phosphonic acid group, or an alkyl alcohol, a carboxylic acid, and a phosphonic acid group357. The electrochemical device of claims 339-356, wherein the ligand comprises at least 3 alkyl alcohol groups.#14802252vl358. The electrochemical device of claims 339-357, wherein the ligand comprises the core structure:S irbb359. The electrochemical device of claims 339-357, wherein the ligand comprises the core structure:

360. The electrochemical device of claims 339-357, wherein the ligand comprises the core structure:bN i 'L'N i 'L'N i 'bb b b .

361. The electrochemical device of claims 339-357, wherein the ligand comprises the core structure:

362. The electrochemical device of claims 357-361, wherein at least one L comprises a substituted or unsubstituted alkyl chain.

363. The electrochemical device of claim 362, wherein the alkyl chain is branched.

364. The electrochemical device of claims 362-363, wherein the alkyl chain has 2 to 6 carbons.

365. The electrochemical device of claims 357-364, wherein at least one L comprises a substituted or unsubstituted cyclic alkyl group.#14802252vl366. The electrochemical device of claim 365, wherein the cyclic alkyl group has 6 to 12 carbons.

367. The electrochemical device of claims 357-366, wherein at least one L comprises an alcohol group.

368. The electrochemical device of claims 357-367, wherein at least one L comprises an ether group.

369. The electrochemical device of claims 357-368, wherein at least one L comprises a carboxylic acid group.

370. The electrochemical device of claims 357-369, wherein at least one L comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure.

371. The electrochemical device of claim 370, wherein at least one L is ethyl.

372. The electrochemical device of claims 358-371, wherein each L is identical.

373. The electrochemical device of claims 358-371, wherein at least two L’s are not identical.#14802252vl374. The electrochemical device of claims 339-373, wherein each b comprises between 1 and 10 carbons inclusively.

375. The electrochemical device of claims 339-374, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group.

376. The electrochemical device of claims 339-374, wherein each b comprises at least one alkyl alcohol group, carboxylic acid group, or phosphonic acid group.

377. The electrochemical device of claims 339-376, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.

378. The electrochemical device of claims 339-377, wherein the ligand structure is nonaromatic.

379. The electrochemical device of claims 339-378, wherein at least one b comprises an alkyl sulfonate group.

380. The electrochemical device of claims 379, wherein only one b comprises an alkyl sulfonate.

381. The electrochemical device of claims 337-380, wherein the alkyl sulfonate comprises a structure selected from the group consisting of:wherein the is a point of connection to the N in the core structure or to a N in the b structure.#14802252vl382. The electrochemical device of claims 339-381, wherein the ligand comprises an alkyl alcohol group and a carboxylic acid group.

383. The electrochemical device of claims 339-381, wherein the ligand comprises an alkyl alcohol group and a phosphonic acid group.

384. The electrochemical device of claims 339-381, wherein the ligand comprises an alkyl alcohol group, a carboxylic acid group, and a phosphonic acid group.

385. The electrochemical device of claims 339-384, wherein the ligand comprises at least 4 alkyl alcohol groups.

386. The electrochemical device of claims 339-384, wherein the ligand comprises at least 5 alkyl alcohol groups.

387. The electrochemical device of claims 339-384, wherein the ligand comprises at least 6 alkyl alcohol groups.

388. The electrochemical device of claims 339-387, wherein the ligand comprises more alkyl alcohol groups than the amount of carboxylic acid or the amount of phosphonic acid groups independently.

389. The electrochemical device of claims 339-387, wherein the ligand comprises more alkyl alcohol groups than the amount of carboxylic acid and phosphonic acid groups summed together.

390. The electrochemical device of claims 339-389, wherein the ligand comprises at least one primary alcohol group.

391. The electrochemical device of claims 339-390, wherein the ligand comprises at least one secondary alcohol group.#14802252vl392. The electrochemical device of claims 339-391, wherein each b comprises at least one alkyl alcohol group.

393. The electrochemical device of claims 339-391, wherein at least one b does not comprise an alkyl alcohol group.

394. The electrochemical device of claims 339-393, where at least one b comprises a structure selected from the group consisting of:wherein the * is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

395. The electrochemical device of claims 339-393, where at least one b comprises a structure selected from the group consisting of:#14802252vlwherein the ’ is a point of connection to the N in the core structure, and each R is independently a hydrogen, an alkyl group, or an alkyl sulfonate group.

396. An electrochemical device, comprising:an anode or an anode compartment containing an anolyte;a cathode or a cathode compartment containing a catholyte; anda membrane or separator between the anode compartment and the cathode compartment;wherein the anolyte and / or the catholyte redox material comprises a complex of a metal and a ligand comprising a core structure:wherein each L independently is an organic linker, and each b is independently selected and each b comprises at least one alkyl alcohol group, carboxylic acid group, phosphonic acid group, or alkyl sulfonate group, or is a hydrogen,wherein at least one b comprises the structure:#14802252vlwherein the is a point of connection to the N in the core structure, and R2 comprises an amine, alkyl, alkyl alcohol, ether, carboxylic acid, phosphonic acid, or sulfonic acid group.

397. The electrochemical device of claim 396, wherein the device is a battery.

398. The electrochemical device of claims 396-397, wherein the device is a redox flow battery.

399. The electrochemical device of claims 396-398, wherein the device is an aqueous redox flow battery.

400. The electrochemical device of claim 399, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH between 7 and 12.

401. The electrochemical device of claim 399, wherein the aqueous redox flow battery has an aqueous electrolyte having a pH greater than 12.

402. The electrochemical device of claims 396-401, wherein the complex is an anolyte redox material.

403. The electrochemical device of claims 396-401, wherein the complex is a catholyte redox material.

404. The electrochemical device of claims 396-403, wherein the metal is a transition metal.

405. The electrochemical device of claims 396-404, wherein the metal is a 3d-block (first row) transition metal.#14802252vl406. The electrochemical device of claims 396-405, wherein the metal is iron.

407. The electrochemical device of claims 396-405, wherein the metal is chromium.

408. The electrochemical device of claims 396-405, wherein the metal is manganese.

409. The electrochemical device of claims 396-404, wherein the metal is molybdenum.

410. The electrochemical device of claims 396-404, wherein the metal is tungsten.

411. The electrochemical device of claims 396-403, wherein the metal is tin.

412. The electrochemical device of claims 396-403, wherein the metal is antimony.

413. The electrochemical device of claims 396-412, wherein the ligand comprises the core structure:

414. The electrochemical device of claims 396-412, wherein the ligand comprises the core structure:

415. The electrochemical device of claims 396-412, wherein the ligand comprises the core structure:b’'N'L"N'iL"N'i ibb b b#14802252vl416. The electrochemical device of claims 396-412, wherein the ligand comprises the core structure:

417. The electrochemical device of claims 414-416, wherein at least one L comprises a substituted or unsubstituted alkyl chain.

418. The electrochemical device of claim 417, wherein the alkyl chain is branched.

419. The electrochemical device of claims 417-418, wherein the alkyl chain has 2 to 6 carbons.

420. The electrochemical device of claims 417, wherein at least one L comprises a substituted or unsubstituted cyclic alkyl group.

421. The electrochemical device of claim 420, wherein the cyclic alkyl group has 6 to 12 carbons.

422. The electrochemical device of claims 414-421, wherein at least one L comprises an alcohol group.

423. The electrochemical device of claims 414-422, wherein at least one L comprises an ether group.

424. The electrochemical device of claims 414-423, wherein at least one L comprises a carboxylic acid group.

425. The electrochemical device of claims 414-416, wherein at least one L comprises a structure selected from the group consisting of:#14802252vlwherein the ’ is a point of connection to the N in the core structure.

426. The electrochemical device of claim 425, wherein at least one L is ethyl.

427. The electrochemical device of claims 414-426, wherein each L is identical.

428. The electrochemical device of claims 414-426, wherein at least two L’s are not identical.

429. The electrochemical device of claims 396-428, wherein each b comprises between 1 and 10 carbons inclusively.

430. The electrochemical device of claims 396-429, wherein each b comprises at least one alkyl alcohol group or carboxylic acid group.

431. The electrochemical device of claims 396-429, wherein the ligand comprises a sum ranging from three to twelve when adding the total number of alkyl alcohol groups, carboxylic acid groups, and phosphonic acid groups together.

432. The electrochemical device of claims 396-431, wherein the ligand structure is nonaromatic.

433. The electrochemical device of claims 396-432, wherein the ligand does not comprise an alkyl sulfonate group.#14802252vl434. The electrochemical device of claims 396-432, wherein at least one b comprises an alkyl sulfonate group.

435. The electrochemical device of claims 396-432, wherein only one b comprises an alkyl sulfonate group.

436. The electrochemical device of claims 434-435, wherein the alkyl sulfonate comprises a structure selected from the group consisting of:\^SO3fjJJX^x'SO3wherein the is a point of connection to the N in the core structure or to an N in the b structure.

437. The electrochemical device of claims 396-436, wherein the ligand comprises an alkyl alcohol group and a carboxylic acid group.

438. The electrochemical device of claims 396-437, wherein the ligand comprises an alkyl alcohol group, a carboxylic acid group, and a phosphonic acid group.

439. The electrochemical device of claims 396-438, wherein the ligand comprises at least 4 alkyl alcohol groups.

440. The electrochemical device of claims 396-439, wherein the ligand comprises at least one primary alcohol group.

441. The electrochemical device of claims 396-440, wherein the ligand comprises at least one secondary alcohol group.

442. The electrochemical device of claims 396-441, wherein each b comprises at least one alkyl alcohol group.#14802252vl443. The electrochemical device of claims 396-442, wherein at least one b does not comprise an alkyl alcohol group.

444. The electrochemical device of claims 396-443, where at least one b comprises a structure selected from the group consisting of:wherein the ? is a point of connection to the N in the core structure.

445. The electrochemical device of claims 396-444, where at least one b comprises a structure selected from the group consisting of:wherein the ’ is a point of connection to the N in the core structure.#14802252vl446. The electrochemical device of claims 396-444, where R2 comprises at least one alkyl alcohol group.

447. The electrochemical device of claims 396-443, where R2 comprises at least one carboxylic acid group.#14802252vl

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