Cyclic imide-dioxime vanadium complexes and uses thereof

Abstract

An organo-metallic complex, comprising at least one ligand coordinating an early transition metal, the ligand comprising a cyclic imidedioxime, and the early transition metal comprising vanadium; method of synthesizing cyclic imidedioxime ligands; methods of extracting vanadium; and uses of the same.

Description

ORGANOMETALLIC COMPLEXES, METHODS, AND USES THEREOF FIELD

[0001] The present disclosure relates generally to organometallic complexes comprising cyclic imidedioxime ligands and vanadium, methods, and uses thereof. BACKGROUND

[0002] Vanadium is a rare and refractory metal used in various industries, including manufacturing, construction, aerospace, and renewable energy. Recycling Vanadium from alternative sources is desirable because of its expanding demands, depletion in natural sources, increased prices, and environmental concerns. SUMMARY

[0003] As described herein, the present disclosure generally provides an organo- metallic complex, comprising at least one ligand coordinating an early transition metal,

[0004] the ligand comprising a cyclic imidedioxime, and the early transition metal comprising vanadium.

[0005] In an embodiment of the present disclosure, there is provided a complex wherein the cyclic imidedioxime comprises one or more of the structures, , .

[0006] In another embodiment, there is provided a complex wherein the early transition metal comprises an oxide of the early transition metal.

[0007] In another embodiment, there is provided a complex wherein the early transition metal comprises pentavalent vanadium (V(V)).

[0008] In another embodiment, there is provided a complex wherein the early transition metal oxide has the structure VO2(OH)2, VO3OH2-, or a combination thereof.

[0009] In another embodiment, there is provided a complex wherein the organo- metallic complex has the structure:.

[0010] In another embodiment, there is provided a complex wherein the organo- metallic complex is unsupported. In an embodiment, unsupported refers to the complex not being bound to, adsorbed to, or absorbed on a solid support. A solid support may include polymeric beads or chromatographic solid supports, such as alumina, charcoal, diatomaceous earth, molecular sieves, ion exchange resins, silica gel, etc.

[0011] As described herein, the present disclosure also generally provides a method of synthesizing an cyclic imidedioxime ligand, the method comprising reacting a halo-functionalized cyclic compound in the presence of a cyanation reagent to form a cyano-functionalized cyclic compound; and reacting the cyano-functionalized cyclic compound in the presence of hydroxylamine to form a cyclic imidedioxime ligand.

[0012] In an embodiment of the present disclosure, there is provided a method wherein the halo-functionalized cyclic compound is substituted or unsubstituted.

[0013] In another embodiment, there is provided a method wherein the halo- functionalized cyclic compound comprises a cycloalkyl halide, a polycyclic alkyl halide, an aryl halide, a polycyclic aryl halide, or a combination thereof.

[0014] In another embodiment, there is provided a method wherein the halo- functionalized cyclic compound comprises one or more halo substituents, wherein the halo substituent comprises a chloro substituent, a bromo substituent, an iodo substituent, or a combination thereof.

[0015] In another embodiment, there is provided a method wherein the halo- functionalized cyclic compound comprises 1,8-dibromonaphthalene, 1,9-dibromoanthracenes, or a combination thereof; each of which may be substituted or unsubstituted.

[0016] In another embodiment, there is provided a method wherein the cyanation reagent comprises Cu(I)CN, potassium ferrocyanide, sodium cyanide, nickel cyanide, trimethyl silyl cyanide, potassium ferriccyanide, acetone cyanohydrin, potassium ferrocyanide trihydrate, zinc cyanide, potassium cyanide, hydrocyanic acid, sodium nitroprusside, benzoyl cyanide, 2,2-dimethylpropanenitrile, cyanuric chloride, malonitrile, N-cyano-4-methyl-N-phenylbenzenesulfonamide, 4-methylbenzenesulfonylcyanide, ethyl cyanoacetate, butyronitrile, 2-phenylpropionitrile, tert-butyl isocyanide, ammonium cyanide, ethanedinitrile, or a combination thereof.

[0017] In another embodiment, there is provided a method wherein the cyano- functionalized cyclic compound is substituted or unsubstituted.

[0018] In another embodiment, there is provided a method wherein the cyano- functionalized cyclic compound comprises a cycloalkyl nitrile, a polycyclic alkyl nitrile, an aryl nitrile, a polycyclic aryl nitrile, or a combination thereof.

[0019] In another embodiment, there is provided a method wherein the cyano- functionalized cyclic compound comprises one or more nitrile substituents.

[0020] In another embodiment, there is provided a method wherein the cyano- functionalized cyclic compound comprises substituted or unsubstituted 1,8- naphthalenedicarbonitrile.

[0021] In another embodiment, there is provided a method wherein reacting a halo- functionalized cyclic compound in the presence of a cyanation reagent comprises reacting at a temperature between about 100 to about 140 °C, optionally in the presence of a polar aprotic solvent.

[0022] In another embodiment, there is provided a method wherein reacting the cyano-functionalized cyclic compound in the presence of hydroxylamine comprises reacting at a temperature between about 70 to about 100 °C, optionally in the presence of a polar protic solvent.

[0023] In another embodiment, there is provided a method wherein the cyclic imidedioxime has the structure.

[0024] As described herein, the present disclosure also generally provides a method of extracting vanadium, the method comprising providing a cyclic imidedioxime (CID) ligand into a solution comprising vanadium (V) to form an V-CID complex; and precipitating the V-CID complex.

[0025] In an embodiment of the present disclosure, there is provided a method wherein providing a cyclic imidedioxime (CID) ligand into a solution comprising vanadium comprises providing the cyclic imidedioxime (CID) ligand into a solution having a pH between <7 to about 3; or a pH <3.

[0026] In another embodiment, there is provided a method wherein precipitating the V-CID complex comprises decreasing pH of the solution to precipitate the V-CID complex.

[0027] In another embodiment, there is provided a method wherein decreasing the pH comprises decreasing the pH to <7; or <7 to about 3; or <3.

[0028] In another embodiment, there is provided a method wherein precipitating the V-CID complex comprises contacting the V-CID complex with a cationic polymer comprising aromatic rings.

[0029] In another embodiment, there is provided a method wherein the cationic polymer comprising aromatic rings comprises poly(4-vinylpyridine hydrochloride) / Cross- linked with divinyl benzene; poly(styrene)-b-poly(4-vinyl pyridine, quaternized with methyl iodide); Amberlite IRA-402; or a combination thereof.

[0030] In another embodiment, there is provided a method further comprising isolating the precipitated V-CID complex, and contacting the V-CID complex with a eluant for decomplexing the vanadium from the CID ligand.

[0031] In another embodiment, there is provided a method further comprising isolating the decomplexed vanadium; and incorporating the decomplexed vanadium into a saleable product.

[0032] In another embodiment, there is provided a method wherein the saleable product comprises batteries, or steel. In an embodiment, the decomplexed vanadium is incorporated into a battery, or steel. Vanadium in its V(V) state strengthens steel inconstruction and aerospace, while V(III) powers redox flow batteries for efficient energy storage.

[0033] In another embodiment, there is provided a method further comprising isolating the decomplexed vanadium; preparing a catalyst from the decomplexed vanadium; and using the vanadium catalyst in a chemical process.

[0034] In another embodiment, there is provided a method wherein the chemical process comprises epoxidation; oxidative bromination, alcohol oxidation, catalytic hydrogenation, oxidative dehydrogenation, dioxygen activation, polymerization reactions, halide abstraction; or a combination thereof.

[0035] In another embodiment, there is provided a method wherein the cyclic imidedioxime ligand comprises one or more of the structures.

[0036] In another embodiment, there is provided a method wherein the vanadium in the solution comprising vanadium comprises pentavalent vanadium (V(V)).

[0037] In another embodiment, there is provided a method wherein the vanadium in the solution comprising vanadium comprises the structure VO2(OH)2, VO3OH2-, or a combination thereof.

[0038] In another embodiment, there is provided a method further comprising reducing the decomplexed vanadium from V(V) to V(III); reducing the decomplexed vanadium from V(V) to V(0); or a combination thereof.

[0039] In another embodiment, there is provided a method wherein the V-CID complex has the structure:.

[0040] In another embodiment, there is provided a method wherein the V-CID complex is unsupported. In an embodiment, unsupported refers to the complex not being bound to, adsorbed to, or absorbed on a solid support. A solid support may include polymeric beads or chromatographic solid supports, such as alumina, charcoal, diatomaceous earth, molecular sieves, ion exchange resins, silica gel, etc.

[0041] In another embodiment, there is provided a method wherein the solution comprising vanadium further comprises Fe, Cr, Cu, Ni, Zn, or a combination thereof, and forming the V-CID complex comprises the cyclic imidedioxime ligand selectively complexing the vanadium.

[0042] In another embodiment, there is provided a method wherein the solution comprising vanadium comprises wastewaters, oil sand tailings, mining waste streams, vanadium shale, black shale, spent catalysts, vanadium-contaminated carbon black, stone coal, fuel oil, grades fuels, ores, metal alloys, batteries, or a combination thereof.

[0043] In another embodiment, there is provided a method further comprising forming the solution comprising vanadium.

[0044] In another embodiment, there is provided a method wherein forming the solution comprising vanadium comprises forming the solution from wastewaters, oil sand tailings, mining waste streams, vanadium shale, black shale, spent catalysts, vanadium- contaminated carbon black, stone coal, fuel oil, grades fuels, ores, metal alloys, batteries, or a combination thereof.

[0045] In another embodiment, there is provided a method wherein the eluant comprises an acidic solution.

[0046] In another embodiment, there is provided a method wherein the acidic solution comprises an acidic thiourea solution.

[0047] In another embodiment, there is provided a method wherein the cyclic imidedioxime (CID) ligand provided into the solution comprising vanadium (V) is a cyclic imidedioxime (CID) synthesized by the method as described herein.

[0048] As described herein, the present disclosure also generally provides use of vanadium extracted by a method as described herein for production of saleable products.

[0049] As described herein, the present disclosure also generally provides use of vanadium extracted by a method as described herein in catalysis.

[0050] As described herein, the present disclosure also generally provides use of a cyclic imidedioxime ligand synthesized by a method as described herein for vanadium extraction.

[0051] As described herein, the present disclosure also generally provides use of a cyclic imidedioxime ligand synthesized by a method as described herein for forming a vanadium- cyclic imidedioxime ligand complex.

[0052] As described herein, the present disclosure also generally provides use of an organo-metallic complex as described herein as a catalyst. In an embodiment of the present disclosure, the complex is used as an epoxidation catalyst. BRIEF DESCRIPTION OF THE FIGURES

[0053] Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.

[0054] FIG. 1 depicts cyclic imidedioximes H2CIDI, H2CIDII, and H2CIDIII. (Atom labels in H2CIDIapplies to all structures).

[0055] FIG. 2 depicts complexation-precipitation technique for recovery of Vanadium. a, Structures of V(V) and H2CIDIII. b, 1:1 and 1:2 V-CIDIII complexes. c, neutralized V-CIDIII complexes. d, and π-π stacked V-CIDIII complexes. e, Procedures of selective recovery of Vanadium. Key atoms are identified in Figure 2a and apply to other Figures via structural correlation.

[0056] FIG. 3 depicts studies of recovering V(V) from mixed-metal aqueous solutions. a, Influence of pH on V(V) complexation and precipitation. b, The extraction isotherm of V(V) on H2CIDIII(Inset shows1H NMR of pristine H2CIDIII, 1:2 V-CIDIIIcomplex and 1:1 V-CIDIIIcomplex obtained from samples in isotherm with qe of 80 mg g-1and 200mg g-1, respectively). c, The extraction kinetics of V(V) on H2CIDIIIfrom aqueous solutions with initial concentrations of 20 and 50 mg L-1. d, Extraction performances of H2CIDIIIfor various metals from simulated mixed solutions containing V(V) (large, darkest bar) and excess Fe(III), Cr(III), Cu(II), Ni(II), and Zn(II) (small, lighter bars). e, The efficiencies of various reagents for decomplexing V(V) from its complex. f, Extraction and decomplexation cycles of H2CIDIIIfor V(V).

[0057] FIG. 4 depicts crystal structures of metal-CIDIIIcomplexes and spectroscopic analyses. a, Crystal structures of 1:1 V-CIDIIIcomplex, 1:2 V-CIDIIIcomplex and 1:1 Fe-CIDIIIcomplex. b, Potentiometric titration curves of 1:2 and 1:1 V-CIDIIIcomplexes. c, FT-IR spectra of pristine H2CIDIII(0), Na+-form (1) and H+-form (2) 1:2 V- CIDIIIcomplexes, and Na+-form (3) and H+-form (4) 1:1 V-CIDIIIcomplexes. d,1H NMR spectra of H2CIDIII(0), and V-CIDIIIcomplex (1, 1'), Fe-CIDIIIcomplex (2, 2'), Cr-CIDIIIcomplex (3, 3'), Cu-CIDIIIcomplex (4, 4'), Ni-CIDIIIcomplex (5, 5'), and Zn-CIDIIIcomplex (6, 6') before and after treatment with HNO3(pH 1.5) solution.

[0058] FIG.5 depicts theoretical computations via DFT methods. a-b, Ecomplxationand electrostatic potential maps (EPM) of 1:1 V-CIDIIIcomplex (a) and 1:2 V-CIDIIIcomplex (b). c-d, Eneutralizationand EPM of neutral 1:1 V-CIDIIIcomplex (c) and 1:2 V-CIDIIIcomplex (d). e-f, Ecomplxation and EPM of 1:1 Fe-CIDIIIcomplex (e) and deprotonated 1:1 Fe-CIDIIIcomplex (f).

[0059] FIG. 6 depicts selective recovery of V(V) on H2CIDIIIfrom a real waste source containing a series of metal ions.

[0060] FIG. 7 depicts1H NMR spectra of recovered and simulated V(V)-CIDIIIcomplexes.

[0061] FIG.8 depicts GCMS analysis on geraniol epoxidation. a. Chemical reaction and experimental condition on the synthesis of 2,3-epoxygeraniol. b-c. Gas chromatograph for gerniol epoxidation by V(V) catalyst under mild conditions.

[0062] FIG.9 depicts schematic representation of the suggested mechanism of an alkene moiety epoxidation with TBHP catalyzed by V(V)-CIDIIIcatalyst.

[0063] FIG.10 depicts schematic representation of Cyclic Imide Dioximes (CIDs) and their degradation. a, Structures of glutarimidedioxime (H2CIDI), phthalimidedioxime (H2CIDII) and naphthalimidedioxime (H2CIDIII). b, The degradation pathway of metal- specific binding sites.

[0064] FIG. 11 depicts complexation-precipitation technique for recovery of vanadium. a, V(V) aqueous solution and H2CIDIII. b, V(V)-complexes in solutions. c, complex solutions after adjusted pH from 8 to 2. d, precipitations of V(V)-complex.

[0065] FIG.12 depicts optimized synthetic route for H2CIDIII.

[0066] FIG.13 depicts1H NMR spectra of dinitrile (a), H2CIDIII(b) and D2CIDIII(c).

[0067] FIG.14 depicts13C NMR spectra of dinitrile (a) and H2CIDIII(b).

[0068] FIG. 15 depicts evolution of the1H NMR spectrum and degradation pathways of H2CIDIII. a, The degradation pathway of H2CIDIII. b, Evolution of the1H NMR spectrum of H2CIDIIIwith time in 1 M DCl at 25°C and 80°C (t1 / 2= ∞ and 196 hours, respectively).

[0069] FIG.16 depicts the recovery isotherm of V(V) on H2CIDIIIfrom aqueous solutions with initial concentrations of 1 to 200 mg L-1via a one-step complexation and precipitation process.

[0070] FIG. 17 depicts the recovery kinetics of V(V) on H2CIDIIIfrom aqueous solutions with initial concentrations of 20 and 50 mg L-1via a one-step complexation and precipitation process.

[0071] FIG. 18 depicts recovery of V(V) from mixed metal ion solutions under various pH.

[0072] FIG.19 depicts the recovery kinetics of V(V) on H2CIDIIIfrom a mixed metal ion solution.

[0073] FIG. 20 depicts the recovery efficiencies of V(V) on various amounts of H2CIDIII.

[0074] FIG. 21 depicts1H NMR of pristine H2CIDIII, and V-CIDIIIcomplex after immersion in HCl solutions and HCl acidified thiourea solutions.

[0075] FIG.22 depicts crystal structure of H2CIDIII.

[0076] FIG.23 depicts1H NMR spectra of H2CIDIIIand V-CIDIIIcomplexes. Pristine H2CIDIII(red), 1:1 V-CIDIIIcomplex (green) and 1:2 V-CIDIIIcomplex (blue) obtained from crystal samples.

[0077] FIG.24 depicts equilibrium diagrams for V(V) solutions. a-b, 50 mg L-1V(V) solution (a), 20 mg L-1V(V) solution (b). The diagrams were obtained by the program of MEDUSA (Royal Institute of Technology, Sweden).

[0078] FIG. 25depicts complexation and decomplexation of vanadium(V) with H2CIDI. a, V(V) aqueous solution and H2CIDI. b, V(V)-complexes in solutions. c, complex solutions after adjusted pH from 8 to 2.

[0079] FIG.26 depicts charges of oxygen (red) and nitrogen (blue) in V-complexes and Fe-complex. a-c, 1:1 V-complex (a), 1:2 V-complex (b), and 1:1 Fe-complex before neutralization (c).DETAILED DESCRIPTION

[0080] Unless defined otherwise, all technical and scientific terms used herein have the meaning as commonly understood in the art.

[0081] As used in the specification and claims, the singular forms "a", "an" and "the" include plural references unless the context dictates otherwise.

[0082] "Substituted" refers to a compound having one or more substituents, otherwise referred to as functional groups, whose presence does not prevent, hinder, or otherwise interfere with the desired reaction - but may facilitate, support, or accelerate the desired reaction. Examples of substituents include alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, Si(alkyl)3, Si(alkoxy)3, alkoxyl, amino, alkylamino, alkenylamino, amide, hydroxyl, thioether, alkylcarbonyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carbonate, alkoxycarbonyl, aminocarbonyl, alkylthiocarbonyl, phosphate, phosphate ester, phosphonato, phosphinato, acylamino, imino, sulfhydryl, a!kylthio, arylthio, thiocarboxylate, dithiocarboxylate, sulfate, sulfato, sulfonate, sulfamoyl, sulfonamide, nitro, nitrile, azido, heterocyclyl, ether, ester, silicon-containing moieties, thioester, or a combination thereof.

[0083] Vanadium is a rare and refractory metal with notable physicochemical properties including high melting point, hardness, and strong corrosion resistance.1,2These properties make vanadium a desirable element in producing ferrovanadium and titanium- vanadium alloys employed in various industries like machinery and automotive manufacturing, shipbuilding, railway and bridge constructions, and aerospace manufacturing, among others.3Vanadium’s significance is increasing as a fundamental component of vanadium redox flow batteries, which are highly efficient for storing renewable energy generated from wind and solar sources.4,5However, owing to its expanding demands and depletion in natural sources, prices have increased from 21 US$ / kg in 2016 to 33.5 US$ / kg in 2022.6With growing demand and associated environmental issues with terrestrial mining, recycling vanadium from alternative sources is needed.7In addition to its occurrence in natural terrestrial deposits, vanadium, predominantly as the pentavalent vanadium ion, V(V), is present in significant concentrations in solid and liquid waste streams from petroleum refining including fly ash (1.6%, w / w), coal (0.0001-0.15%, w / w), crude oil (0.004 – 0.013%, w / w), oil shale (0.18- 1.7%, w / w), and oil sands (0.06%, w / w).8,9From the environmental side, V(V) exhibits toxic properties, presenting a substantial hazard to aquatic organisms and the potential to contaminate groundwater, potable water, and soil.10Hence, the recovery of vanadium fromits waste sources holds importance, not only for economic gains but also for ensuring environmental safety and protection.

[0084] The selective and efficient recovery of Vanadium from vanadium-bearing waste sources remains a challenge due to the presence of interfering ions (Fe(III), Cr(III), Cu(II), Ni(II), Zn(II), Cl-, etc.). and organic species (benzene, toluene, ethylbenzene, xylene (BTEX), phenolic compounds, etc.) which can impact the performance of candidate technologies.11Conventional hydrometallurgical approaches such as solvent extraction and ion-exchange resins have been extensively employed to separate V(V) with high efficacy.12However, solvent extraction suffers from several shortcomings, including non- selectivity, the necessity for a high dosage of organic extractant, challenges in extractant reuse, and the generation of toxic effluent.13–16Similarly, ion-exchange resins also face limitations like low affinity and selectivity,17–19and slow rates making the process time- consuming, and ultimately leading to higher costs. As a result, the pursuit of materials and viable methods for the recovery of V(V) from acidic aqueous wastes is desirable.

[0085] The cyclic imidedioximes (CIDs) (Fig. 1 and FIG. 10a) may be useful materials for the efficient recovery of V(V) from wastewaters. CIDs are a class of organic molecules containing nitrogen and oxygen-based donor groups with amphoteric nature, enabling metal-chelation over a wide pH range. Since 1960, glutarimidedioxime (H2CIDI)- based materials have found industrial-scale use in sequestering uranium from seawater.20,21More recently, studies have explored H2CIDI’s potential for extracting and removing radioactive elements such as uranium (UIVand UVI),22–24cerium (CeIV),25,26plutonium (PuIV),27and neptunium (NpV)28from nuclear wastewaters. Notably, H2CIDIhas demonstrated remarkable affinity and selectivity for V(V) even at significantly lower concentrations compared to other competing metal ions, owing to the formation of a unique and highly stable non-oxido vanadium complex.21,29The extraction efficiency of H2CIDItends to decline under acidic aqueous conditions due to the degradation of the CID moiety (FIG. 10b). V(V) extraction and elution usually take place in an acidic aqueous phase, underscoring the need to enhance the acid stability of the CID materials. Furthermore, CID complexes are challenging to isolate from water due to the high solubility of their metal complexes. As a solution, fabrication of supported CIDs as sorbents by grafting them onto polymeric back bones has been reported.30Nevertheless, the resulting sorbents may encounter new issues related to the reduction of functional group(s) density, reaction rate and separation efficiency when compared with the solution properties of the CID molecules.31–33

[0086] Scalability is also a consideration for practical applications,34as a material may exhibit excellent recovery performance but lack feasibility in large-scale production. Various materials, ranging from agricultural wastes,35bacteria,36anion exchange resins,37ionic liquids,38,39algae,40and many others,17,41–45have been used to recover pentavalent vanadium ions, V(V), from several sources. An ideal material should exhibit a high capacity and selectivity for the target species and be readily available / scalable. Ease of synthesis and cost-effectiveness are prerequisites; nevertheless, intricately designed compounds synthesized at elevated costs could prove economically viable, given their extensive reusability.34Therefore, a stable and reusable material makes the V(V) extraction cheap and more sustainable. Unfortunately, despite the tremendous progress in materials development for V(V) recovery, reported findings in the field often fail to address their pragmatic applicability, disregarding pivotal scalability considerations comprehensively.

[0087] Described herein is an organo-metallic complex, comprising at least one ligand complexing an early transition metal, the ligand comprising a cyclic imidedioxime, and the early transition metal comprising vanadium. Also described herein are methods of making and using the complex. For example, described herein is a synthesis of a naphthalene-based CID material (H2CIDIII) with greater acid-resistance and its vanadium extraction properties. A complexation-precipitation technique was also developed, and described herein (Fig.2a-e and FIG.11a-d) to achieve efficient and selective separation of Vanadium from acidic aqueous solutions containing competing metal ions including tailings water.

[0088] In an example, the present disclosure generally provides: 1. An organo-metallic complex, comprising at least one ligand coordinating an early transition metal, the ligand comprising a cyclic imidedioxime, and the early transition metal comprising vanadium. 2. The complex of example 1, wherein the cyclic imidedioxime comprises one or more of the, , or .3. The complex of any one of examples 1-2, wherein the early transition metal comprises an oxide of the early transition metal. 4. The complex of any one of examples 1-3, wherein the early transition metal comprises pentavalent vanadium (V(V)). 5. The complex of any one of examples 1-4, wherein the early transition metal oxide has the structure VO2(OH)2, VO3OH2-, or a combination thereof. 6. The complex of any one of examples 1-5, wherein the organo-metallic complex has the structure:. 7. The complex of any one of examples 1-6, wherein the organo-metallic complex is unsupported.

[0089] In another example, the present disclosure generally provides: 8. A method of synthesizing an cyclic imidedioxime ligand, the method comprising reacting a halo-functionalized cyclic compound in the presence of a cyanation reagent to form a cyano-functionalized cyclic compound; and reacting the cyano-functionalized cyclic compound in the presence of hydroxylamine to form a cyclic imidedioxime ligand. 9. The method of example 8, wherein the halo-functionalized cyclic compound is substituted or unsubstituted.10. The method of any one of examples 8-9, wherein the halo-functionalized cyclic compound comprises a cycloalkyl halide, a polycyclic alkyl halide, an aryl halide, a polycyclic aryl halide, or a combination thereof. 11. The method of any one of examples 8-10, wherein the halo-functionalized cyclic compound comprises one or more halo substituents, wherein the halo substituent comprises a chloro substituent, a bromo substituent, an iodo substituent, or a combination thereof. 12. The method of any one of examples 8-11, wherein the halo-functionalized cyclic compound comprises 1,8-dibromonaphthalene, 1,9-dibromoanthracenes, or a combination thereof; each of which may be substituted or unsubstituted. 13. The method of any one of examples 8-12, wherein the cyanation reagent comprises Cu(I)CN, potassium ferrocyanide, sodium cyanide, nickel cyanide, trimethyl silyl cyanide, potassium ferriccyanide, acetone cyanohydrin, potassium ferrocyanide trihydrate, zinc cyanide, potassium cyanide, hydrocyanic acid, sodium nitroprusside, benzoyl cyanide, 2,2- dimethylpropanenitrile, cyanuric chloride, malonitrile, N-cyano-4-methyl-N- phenylbenzenesulfonamide, 4-methylbenzenesulfonylcyanide, ethyl cyanoacetate, butyronitrile, 2-phenylpropionitrile, tert-butyl isocyanide, ammonium cyanide, ethanedinitrile, or a combination thereof. 14. The method of any one of examples 8-12, wherein the cyano-functionalized cyclic compound is substituted or unsubstituted. 15. The method of any one of examples 8-14, wherein the cyano-functionalized cyclic compound comprises a cycloalkyl nitrile, a polycyclic alkyl nitrile, an aryl nitrile, a polycyclic aryl nitrile, or a combination thereof. 16. The method of any one of examples 8-15, wherein the cyano-functionalized cyclic compound comprises one or more nitrile substituents. 17. The method of any one of examples 8-16, wherein the cyano-functionalized cyclic compound comprises substituted or unsubstituted 1,8-naphthalenedicarbonitrile. 18. The method of any one of examples 8-17, wherein reacting a halo-functionalized cyclic compound in the presence of a cyanation reagent comprises reacting at a temperature between about 100 to about 140 °C, optionally in the presence of a polar aprotic solvent. 19. The method of any one of examples 8-18, wherein reacting the cyano-functionalized cyclic compound in the presence of hydroxylamine comprises reacting at a temperature between about 70 to about 100 °C, optionally in the presence of a polar protic solvent.20. The method of any one of examples 8-20, wherein the cyclic imidedioxime has the structure .

[0090] In another example, the present disclosure generally provides: 21. A method of extracting vanadium, the method comprising providing a cyclic imidedioxime (CID) ligand into a solution comprising vanadium (V) to form an V-CID complex; and precipitating the V-CID complex. 22. The method of example 21, wherein providing a cyclic imidedioxime (CID) ligand into a solution comprising vanadium comprises providing the cyclic imidedioxime (CID) ligand into a solution having a pH between <7 to about 3; or a pH <3. 23. The method of example 21, wherein precipitating the V-CID complex comprises decreasing pH of the solution to precipitate the V-CID complex. 24. The method of example 23, wherein decreasing the pH comprises decreasing the pH to <7; or <7 to about 3; or <3. 25. The method of example 21, wherein precipitating the V-CID complex comprises contacting the V-CID complex with a cationic polymer comprising aromatic rings. 26. The method of example 25, wherein the cationic polymer comprising aromatic rings comprises poly(4-vinylpyridine hydrochloride) / Cross-linked with divinyl benzene; poly(styrene)-b-poly(4-vinyl pyridine, quaternized with methyl iodide); Amberlite IRA-402; or a combination thereof. 27. The method of any one of examples 21-26, further comprising isolating the precipitated V-CID complex, and contacting the V-CID complex with a eluant for decomplexing the vanadium from the CID ligand. 28. The method of any one of examples 21-27, further comprising isolating the decomplexed vanadium; and incorporating the decomplexed vanadium into a saleable product. 29. The method of any one of examples 27-28, wherein the saleable product comprises batteries, or steel.30. The method of any one of examples 21-29, further comprising isolating the decomplexed vanadium; preparing a catalyst from the decomplexed vanadium; and using the vanadium catalyst in a chemical process. 31. The method of any one of examples 21-30, wherein the chemical process comprises epoxidation; oxidative bromination, alcohol oxidation, catalytic hydrogenation, oxidative dehydrogenation, dioxygen activation, polymerization reactions, halide abstraction; or a combination thereof. 32. The method of any one of examples 21-31, wherein the cyclic imidedioxime ligand comprises one or more of the structures. 33. The method of any one of examples 21-32, wherein the vanadium in the solution comprising vanadium comprises pentavalent vanadium (V(V)). 34. The method of any one of examples 21-33, wherein the vanadium in the solution comprising vanadium comprises the structure VO2(OH)2, VO3OH2-, or a combination thereof. 35. The method of any one of examples 21-34, further comprising reducing the decomplexed vanadium from V(V) to V(III); reducing the decomplexed vanadium from V(V) to V(0); or a combination thereof. 36. The method of any one of examples 21-35, wherein the V-CID complex has the structure:. 37. The method of any one of examples 21-36, wherein the V-CID complex is unsupported. 38. The method of any one of examples 21-37, wherein the solution comprising vanadium further comprises Fe, Cr, Cu, Ni, Zn, or a combination thereof, and forming the V-CID complex comprises the cyclic imidedioxime ligand selectively complexing the vanadium. 39. The method of any one of examples 21-38, wherein the solution comprising vanadium comprises wastewaters, oil sand tailings, mining waste streams, vanadium shale, black shale, spent catalysts, vanadium-contaminated carbon black, stone coal, fuel oil, grades fuels, ores, metal alloys, batteries, or a combination thereof. 40. The method of any one of examples 21-39, further comprising forming the solution comprising vanadium. 41. The method of any one of examples 21-40, wherein forming the solution comprising vanadium comprises forming the solution from wastewaters, oil sand tailings, mining waste streams, vanadium shale, black shale, spent catalysts, vanadium-contaminated carbon black, stone coal, fuel oil, grades fuels, ores, metal alloys, batteries, or a combination thereof. 42. The method of any one of examples 21-41, wherein the eluant comprises an acidic solution.43. The method of example 42, wherein the acidic solution comprises an acidic thiourea solution. 44. The method of any one of examples 21 to 43, wherein the cyclic imidedioxime (CID) ligand provided into the solution comprising vanadium (V) is a cyclic imidedioxime (CID) synthesized by the method of any one of examples 8 to 20.

[0091] In another example, the present disclosure generally provides: 45. Use of vanadium extracted by the method of any one of examples 21 to 44 for production of saleable products. 46. Use of vanadium extracted by the method of any one of examples 21 to 44 in catalysis. 47. Use of the cyclic imidedioxime ligand synthesized by the method of any one of examples 8 to 20 for vanadium extraction. 48. Use of the cyclic imidedioxime ligand synthesized by the method of any one of examples 8 to 20 for forming a vanadium- cyclic imidedioxime ligand complex. 49. Use of the organo-metallic complex of any one of examples 1 to 7 as a catalyst. 50. Use of the organo-metallic complex of any one of examples 1 to 7 as an epoxidation catalyst.

[0092] To gain a better understanding of the invention described herein, the following examples are set forth. It should be understood that these examples are for illustrative purposes only. Therefore, they should not limit the scope of this invention in anyway.

[0093] EXAMPLES

[0094] Example 1 - Selective and / or Regenerable Vanadium Extraction via a Complexation and Precipitation Process

[0095] Described herein is a practical and straightforward complexation- precipitation method to selectively recover pentavalent vanadium ions, V(V), from intricate mixtures using an acid-stable cyclic imidedioxime, naphthalimidedioxime (H2CIDIII). H2CIDIIIshowed high extraction capacity and fast binding towards V(V) giving a dimer, [V2(O)3(C12H6N3O2)2]2-and non-oxido, [V(C12H6N3O2)2]- complex. It was considered that the dimer [V2(O)3(C12H6N3O2)2]2-may be in equilibrium with the monomeric oxido form, [V(O)2(C12H6N3O2)]- complex when in solution. The resulting V-CIDIIIcomplexes could be separated by precipitation through pH adjustment. Subsequent spectroscopic analyses, including single crystal X-ray diffraction,1H NMR, and FTIR, alongside potentiometric titration and theoretical computations, were conducted to investigate the mechanisms ofcomplexation and precipitation. Results suggested that the negatively charged nature and acid resistance of V-CIDIIIcomplexes played a prominent role in the facile and selective separation and recovery of V(V). Moreover, this selective complexation-precipitation technique was applied to recovering V(V) from a real waste source – oil sand tailings. Notably, the complexation-precipitation technique achieved a notably high recovery selectivity for V(V) from both simulated mixed metal solution and oil sand tailings containing Fe(III), Cr(III), Cu(II), Ni(II), Zn(II), etc. The selectivity coefficient (βV / competing metal) was found to be notably high, with values above 3×105for V(V) compared to competing metals (for example, it was observed that no metals other than vanadium was precipitated from solution; and that the selectivity coefficient was on the order of 105).

[0096] The performance of H2CIDIIIfor complexation and precipitation was investigated through batch experiments, encompassing pH-dependent effects, isotherm, and kinetic studies. To gain deeper insights into the underlying mechanisms governing complexation, precipitation, and selectivity, various spectroscopic analyses were employed, including nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR), alongside theoretical computations employing density functional theory (DFT) methods. The results of the investigation indicated the anionic nature of the V-CIDIIIcomplexes (Fig. 2a-b), enhanced stability, recyclability and the ability to selectively precipitate through pH adjustment (Fig.2c & d). Moreover, the selective extraction and precipitation procedures were simplified (Fig.2e), and were applied to recover V(V) from an industrial oil sand tailings water sample.

[0097] Characterization of H2CIDIII

[0098] In consideration of practical applications, optimizing H2CIDIIIsynthesis aimed to reduce synthesis duration and energy consumption. In previous reports, the synthesis pathway entailed a three-step process, commencing with acenaphthenequinone sulfamation via acid-catalyzed condensation. Subsequently, a high-energy-demanding cyanation process at 180°C was used to eliminate sulfur dioxide and furnish the dinitrile intermediate. Finally, hydroxylamination of the dinitrile was conducted to yield the desired product, leading to a total synthetic yield of 27.89% within a time span of approximately four days. In contrast, the synthesis procedure described herein used 1,8- dibromonapthalene (dibromide) as starting material, resulting in a two-step approach, that could be accomplished within a span of 24 hours (as depicted in FIG.12). Cyanation of aryl halides via the Rosenmund-von Braun Reaction46was adopted and performed under atmospheric conditions in dimethylformamide (DMF) at 130 °C to afford 1,8- naphthalenedicarbonitrile (dinitrile, yield = 84%).1H NMR (400 MHz, DMSO) δ 8.51 (d, J =1.2 Hz, 1H), 8.39 (dd, J = 7.3, 1.2 Hz, 2H), 7.85 (dd, J = 8.4, 7.3 Hz, 2H).13C NMR (101 MHz, DMSO) δ 139.02, 135.76, 133.46, 128.29, 127.58, 117.16, 107.48 (Fig.13a and 14a). Analytic calculation for C12H6N2: C, 80.88; H, 3.39; N, 15.72. Found: C, 80.10; H, 3.26; N, 15.62. Notably, the excess copper cyanide could be recovered, enabling its reuse for subsequent syntheses and eliminating the potential for environmental pollution and material wastage. Subsequently, the dinitrile was treated with aqueous hydroxylamine to give H2CIDIIIin high yield (94%), and a total synthetic yield of 78.96%.1H NMR (400 MHz, DMSO) δ 11.06 (s, 1H), 8.97 (s, 0H), 8.15 (dd, J = 7.4, 1.1 Hz, 1H), 8.07 (dd, J = 8.5, 1.1 Hz, 1H), 7.64 (dd, J = 8.3, 7.3 Hz, 1H).13C NMR (101 MHz, DMSO) δ 141.53, 132.92, 129.94, 126.92, 126.17, 122.41, 121.10 (Fig. 13b and 14b). Analytic calculation for C12H9N3O2: C, 61.76; H, 5.18; N, 15.43. Found: C, 61.75; H, 5.48; N, 15.63.

[0099] The evaluation of acid stability is considered important in verifying the suitability of materials for repeated adsorption / desorption cycles, given that the leaching of oil sands tailings involves concentrated acids,47leading to the creation of highly acidic environments. As described herein, the acid stability was studied to ensure the viability of materials during complexation, precipitation, and elution processes, which a key aspect of the economic feasibility of extraction procedures. Kang et al. elucidated that the degradation of strong Vanadium-specific binding sites in H2CIDI(t1 / 2 = 0.9h) in acidic solutions arose from water's nucleophilic attack on its structure (Fig.10b).48One approach to slow or inhibit this process is to reduce the charge density of the imino carbons in H2CIDI. This concept led to the synthesis of a related ligand, phthalimidedioxime (H2CIDII), which exhibited enhanced acid stability (t1 / 2 = 147h at 25°C) due to aromatic resonance stabilization.48To evaluate the acid stability of H2CIDIII, the ligand was exposed to a 1M DCl aqueous solution and monitored using1H NMR. The imide and oxime hydrogens of H2CIDIIIappeared at 8.97 and 11.06 ppm in DMSO-d6, respectively (Fig.13b), but disappeared after exposure to D2O / DCl solution due to proton exchange between the ligand and deuterated solvent (Fig. 13c). Consequently, hydrogens on the aromatic moiety corresponding to doublet-doublet and triplet signals at 8.06 – 8.16 ppm and 7.66 – 7.62 ppm, respectively, were utilized to track the ligand's degradation. After several months of exposure at room temperature (t1 / 2 = ∞ at 25°C), the representative peaks were well retained (star marked spectra in Fig.15a-b), and higher temperatures were necessary to accelerate hydrolysis. At 80°C, two new signals corresponding to glutaric acid and glutarimide were observed after 30 minutes and became more pronounced after 2 hours (circle-marked spectra in Fig. 15a-b). The hydrolysis process was complete after 196 hours of exposure (triangle-marked spectra in Fig. 15a-b). Thus, while H2CIDIIIfollowed a similar degradation pathway via amonoxime to a carboxylic acid final product, it was much more resistant than H2CIDIIand H2CIDIto acid-catalyzed hydrolysis at room temperature.

[0100] The performance of H2CIDIIIin the recovery of V(V) was investigated under varying pH, metal concentration, and time conditions. pH-dependent experiments were conducted to explore the complexation and precipitation of 20 mg L-1V(V) using 0.05 g of H2CIDIII. H2CIDIIIexhibited notable performance in V(V) complexation over a broad pH range from 5 to 12, with extraction efficiency exceeding 99% and extraction capacity reaching 80 mg g-1(Fig.3a). These results underscored the robust coordination between V(V) and H2CIDIII, despite the presence of a high degree of protons and hydroxide ions in the solution. In a separate experiment, the effect of pH on precipitation of V-CIDIIIcomplex was assessed while complexation pH was maintained at 8-9. The precipitation increased with a decrease in pH, achieving approximately 20% extraction efficiency at pH 5, approximately 75% at pH 4, and reaching its maximum efficiency of around 99% at pH 3 and beyond (Fig.3a). This finding indicates that the extent of precipitation is dependent on the acidity of the solution necessary to neutralize the negative charge on the V-CIDIIIcomplexes. Overall, this means V(V) can be effectively recovered from the solution via a unique method involving the complexation of V(V) and precipitation under acidic conditions (inset in Fig.3a).

[0101] The extraction capacity of H2CIDIIIfor V(V) was determined in the complexation and precipitation steps, as explained previously, under pH 8 and 3, respectively. To assess the capacity, the concentration of V(V) in the solution was varied while keeping the ligand mass at 0.05 g, the duration at 12 hours, and the temperature at 25°C to ensure isotherm equilibrium. As depicted in Fig. 3b and Table 1, the extraction isotherm data were well-fitted with the Langmuir model, yielding a coefficient of determination (R2) higher than 0.95. Consequently, the maximum extraction capacity (qm) of H2CIDIIIfor V(V) reached 205.4 mg g-1, surpassing that of many common V(V) adsorbents (Table 2). Additionally, the b value of 2.71 L mg-1obtained from Langmuir fitting indicated a high affinity of H2CIDIIIfor V(V) compared to a wide range of adsorbents used for V(V) recovery (Table 2).

[0102] During the isotherm experiments, depending on the metal to ligand stoichiometry ratio, two complexes were obtained with qe values of 80 mg g-1and 200 mg g-1, corresponding to 1:2 and 1:1 V-CIDIIIcomplexes, respectively. The inset of Fig. 3b displays the1H NMR spectra of pristine H2CIDIIIand these two V-CIDIIIcomplexes. All samples exhibited two1H signals at doublet-doublet (8.06 – 8.16 ppm) and triplet (7.65 – 7.62 ppm) regions, which are assigned to protons on the aromatic moieties of the ligand.The constant multiplicity of signals in the free ligand and complexes indicates that the equivalency of the1H atoms remain unchanged in the complexes. This observation suggests a symmetrical tridentate coordination mode between the ligand and the metal ion in the complexes. Moreover, in the 1:1 V-CIDIIIcomplex (top spectrum), the1H signals consistently shifted upfield relative to the corresponding peaks of the free deprotonated ligand. This shift indicates the presence of oxo groups that reduce the charge density of the metal center, causing a reduction in the deshielding impact on the aromatic protons. This influence is coupled with a shielding effect from the electron density from the opposite aromatic ring resulting in an upward chemical shift of peaks. On the other hand, in the case of the 1:2 V-CIDIIIcomplex (middle spectrum), all1H signals experienced a downfield shift compared to those of the free deprotonated ligand. This shift, along with the symmetrical coordination mode, suggests the complete displacement of the bent oxo groups on V(V), leading to the formation of a non-oxido complex. The high charge density of V(V) significantly reduces the electron densities on proton atoms due to their proximity to the coordination sites, resulting in a substantial downfield displacement of their chemical shifts. Overall, these features confirm the successful interactions between H2CIDIIIand V(V) in forming stable complexes.

[0103] Despite achieving a high extraction capacity, H2CIDIIIalso needs to exhibit rapid capture of the target ions. To assess the kinetics of V(V) capture by H2CIDIII, kinetic experiments were conducted for the complexation and precipitation steps at concentrations of 50 mg L-1and 20 mg L-1, respectively. The experimental data were best fitted with the pseudo-second-order kinetics model, yielding coefficient of determinations (R2) greater than 0.95 (Table 1). In the complexation experiment, the removal rate of V(V) by H2CIDIIIrapidly reached equilibrium within minutes at 20 mg L-1and 50 mg L-1(Fig.3c). Notably, at both concentrations, approximately 90%of V(V) binding was achieved within one minute, underscoring remarkably fast kinetics of the complexation process. Additionally, precipitation occurred essentially instantaneously upon the addition of acid at both concentrations, achieving maximum capacity within 5 minutes. This rapid extraction process stands in contrast to the lengthy contact times often required for other adsorbents, which typically range from several hours to several days.49,42In conclusion, the combination of high extraction capacities and rapid kinetics can be attributed to the synergistic effects of strong binding and fast interaction between the monomeric ligand and V(V).

[0104] Due to the acidic nature of many mining waste streams containing V(V) content,50a one-step process involving concurrent complexation and precipitation under acidic conditions was explored. Interestingly, H2CIDIIIstill exhibited a high extractioncapacity of 195.4 mg / g in strongly acidic solutions (~pH 1.5) (Fig.16). However, H2CIDIIIdisplayed slower kinetics, achieving the maximum extraction capacity in approximately 2 hours at concentrations of 50 mg L-1and 20 mg L-1(Fig.17). This was attributed to the poor solubility of H2CIDIIIat such a low pH value.

[0105] The selectivity of H2CIDIIItowards V(V) is important for its practical application in waste sources that typically contain a complex mixture of various metal ions. To assess the selectivity, different experiments were conducted, varying pH, ligand amount, and time in a simulated mixed metal solution containing Fe(III), Cr(III), Cu(II), Ni(II), and Zn(II) under acidic conditions to keep all metal ions in solution and evaluate the effectiveness of a one-step extraction process. With an initial concentration of 1 mg L-1for all metal ions, H2CIDIIIdisplayed impressive selectivity, exhibiting a high V(V) adsorption capacity of 7 mg g-1within 30 minutes at pH 1.5, while other metals were scarcely recovered (Fig. 18 & 19). The selectivity coefficient (βV / competing metal) for V(V) versus Fe(III), Cr(III), Cu(II), Ni(II), and Zn(II) was extraordinarily high, with values of 2.9×105, 6.4×105, 4.3×105, 1.2×106, and 1.3×106, respectively, confirming the notable selectivity of H2CIDIIIfor V(V). Furthermore, complete extraction of V(V) was observed within 30 minutes and beyond (Fig. 19), and the variation of ligand amount did not affect the selectivity performance of H2CIDIII(Fig. 20). Considering the possibility of some competing metal cations being present in higher concentrations than V(V) in certain waste sources, a selectivity assessment was conducted in the presence of 5-, 10-, and 20-times excess of competing metal ions, with the solution pH at 1.5. The binding competitive assay revealed that even with a 20-fold excess, most metal ions, including iron, could not compete effectively with V(V) (Fig.3d).

[0106] Regeneration and reusability

[0107] The regeneration process plays a role in ensuring the reusability of H2CIDIIIfor multiple extractions, as well as enabling the recovery of V(V) for post-extraction studies. The success of this process hinges upon the stability of the ligand and the ease of metal elution. Here, thiourea was employed as a mild eluant due to its well-known ability to conveniently elute strongly bound metal ions from adsorbents, owing to synergistic effects from electrostatic interactions and covalent binding of the lone pairs on the nitrogen atom.51To achieve the regeneration, H2CIDIIIwas initially complexed with 20 mg L-1V(V) at pH 8 and precipitated at pH 3, within a duration of 1 hour at room temperature. Subsequently, the obtained solids were subjected to HCl and HCl acidified thiourea solutions for decomplexation. The decomplexation efficiency (DE) was calculated using the following equation:DE = mass of V in the desorption solution (mg) / mass of V complexed with CIDIII (mg) × 100%(1)

[0108] When decomplexed, the vanadium was recovered in oxide form. Without wishing to be bound by theory, it is considered that the regeneration / decomplexation process may include a reductive regeneration step, wherein the vanadium is decomplexed and then reduced to an oxidation state less than 5+, such as V(III) or V(0); or the regeneration / decomplexation process may include a reductive regeneration step, wherein the vanadium is decomplexed by reduction to an oxidation state less than 5+, such as V(III) or V(0). When vanadium is at a lower oxidation state, it may be more readily released or decomplexed from the CID ligand.

[0109] The results of the decomplexation efficiency demonstrated that thiourea in low acid concentration could completely elute the bound V(V) from CIDIII(the deprotonated ligand) (Fig.3e). In contrast, only H+from concentrated HCl solutions was not sufficiently strong to elute the bound V(V). Additionally, analysis of the1H NMR spectra of the V-CIDIIIcomplex after immersion in the eluents indicated that the samples in HCl solutions retained identical signals of the V-CIDIIIcomplexes, while the V-CIDIIIcomplexes were fully decomplexed in HCl acidified thiourea solutions, leaving pure CIDIIIligands as solid residues (Fig.21). These observations verify the super strong coordination between V(V) and CIDIII. After decomplexation, H2CIDIIIwas washed with deionized water and found to retain its initial V(V) binding capacity after up to six cycles of extraction and decomplexation (Fig.3f). This demonstrates the successful reusability of the ligand for multiple extraction processes.

[0110] Complexation, precipitation, and selectivity mechanisms

[0111] To gain insight into the mechanisms of complexation, precipitation and selectivity, single crystal X-ray diffraction (SC-XRD), potentiometric titration, Fourier transform infrared spectroscopy (FT-IR) and1H NMR spectroscopy were employed.

[0112] Single crystal X-ray diffraction contrasted the structures of vanadium(V), and iron(III) complexes (Fig.4a, Table 3-6). The crystal structure of H2CIDIIIwas determined, as shown in Fig. 22, confirming the successful synthesis of the ligand. Two V-CIDIIIcomplexes and one Fe-CIDIIIcomplex were obtained, as depicted in Fig.4a and Fig.2a-b. The 1:1 V-CIDIIIcomplex consists of a one-dimensional long sheet of V(V) dimers bridged by sodium ions. Each dimer exhibits a distorted square pyramidal structure with two V(V) centers sharing bridging µ-oxo groups, and each V(V) center is coordinated to a triply deprotonated ligand through a κ3binding motif involving the imide nitrogen atom and the two oxime oxygen atoms. The aromatic moieties in CIDIIIπ-stack with an inter-ring distance of 3.7 Å, ultimately forming the dimer structure. On the other hand, the 1:2 V-CIDIIIcomplex reveals a distorted octahedral anionic structure with two fully deprotonated ligandscoordinating to uncoordinated V(V), forming a non-oxido complex. The crystal structures of these complexes are arranged orthogonally to each other, creating an arene-bone type arrangement of the naphthalene moiety. The complexes are bridged by a sodium ion, forming a one-dimensional chain and exhibits inter-ring π-stacking of 4.3 Å observed between chains along the x-axis. Notably, the protons of the imide (–C–NH–C–) and both oxime groups (–C=N–OH) were completely deprotonated upon coordination to V(V) in both V-CIDIIIcomplexes, illustrating strong complexations that resulted in the formation of anionic V-CIDIIIcomplexes. On the other hand, the Fe-CIDIIIcomplex had similar attributes to the 1:1 V-CIDIIIcomplex, such as O-V-N and O-Fe-N bond angles of approximately 73- 75°, and complete deprotonation of the –C–NH–C– group. However, the nitrogen in the oxime groups (–C=N–O) were protonated (–C=NH–O) upon coordination to Fe(III), resulting in the formation of a neutral Fe-CIDIIIcomplex. Furthermore,1H NMR spectra of crystal samples of H2CIDIIIand V-CIDIIIcomplexes were acquired (Fig.23) and found to be consistent with the NMR spectra of these complexes obtained from the isotherm experiments (Fig.3b) are consistent with the NMR spectra of these crystal samples.

[0113] The negative charge properties of the 1:1 V-CIDIIIcomplex and 1:2 V-CIDIIIcomplex in acidic solutions were confirmed by potentiometric titration with starting solution pH above 10. At such high pH values, the major species of V(V) is VO3OH2-(Fig.24a-b), which can accept protons during complexation with H2CIDIII(inset of Fig.4b). The pH of these two solutions was then adjusted from 10 to 2.5 using HNO3 solution. The titration curves of both the 1:2 V-CIDIIIcomplex and 1:1 V-CIDIIIcomplex exhibited two stages of pH decrease, from 10.5 to 9.5 and from 7.0 to 5.8, respectively (Fig.4b). These stages correspond to the acceptance of protons during complexation and the neutralization of the anionic V-CIDIIIcomplexes. An abrupt pH change at around 4.0 indicated the formation of V-CIDIIIprecipitates. The pH ranges for complexation, neutralization, and precipitation extracted from titration curves agreed with the experimental results of the influence of pH on V(V) complexation and precipitation, as shown in Fig.3a.

[0114] FT-IR spectra of pristine H2CIDIII, crystal samples of 1:2 V-CIDIIIcomplex (Na+-form) and 1:1 V-CIDIIIcomplex (Na+-form), and V-CIDIIIcomplexes obtained from complexation and precipitation experiments (H+-form) were acquired to verify the sites for protonation in the neutralization process. As seen in the spectrum (0) in Fig.4c, the bands at 3450 cm−1, 3300 cm−1, 1620 cm−1and 750 cm−1in the spectrum of pristine H2CIDIIIcan be attributed to N–H stretching vibration in imide (–C–NH–C–) and oxime (–C–NH=O) groups, O–H stretching vibration, N–H deformation vibration in imide and oxime groups, and C–H deformation vibration in naphthalene ring, respectively.52The absence of N–Hand O–H in the Na+-form 1:2 V-CIDIIIcomplex and 1:1 V-CIDIIIcomplex, is observed from the disappearance of the bands at 3450 cm−1, 3300 cm−1and 1620 cm−1from their spectra (1, 3). While the band attributed to N–H stretching, and deformation vibration can be observed in both spectra of H+-form V-CIDIIIcomplexes (2, 4); and the band attributed to O–H stretching vibration can only be observed in the spectra of H+-form 1:1 V-CIDIIIcomplex (4). These results demonstrate that the nitrogen atom in the oxime group (–C=N– O) is the only site in the 1:2 V-CIDIIIcomplex that can accept a proton during neutralization, whereas in the 1:1 V-CIDIIIcomplex, both nitrogen atom in the oxime group and the oxygen atom in the V–O group can be protonated.

[0115] Furthermore,1H NMR spectra of V-CIDIIIcomplex, Fe-CIDIIIcomplex, Cr- CIDIIIcomplex, Cu-CIDIIIcomplex, Ni-CIDIIIcomplex, and Zn-CIDIIIcomplex were obtained before and after treatment with HNO3(pH 1.5) solution to examine the acid stability of these metal-CIDIIIcomplexes. As shown in Fig.4d, only the V-CIDIIIcomplex retained the identical signals of the pristine V-CIDIIIcomplex (1, 1'). In contrast, all the other metal-CIDIII complexes decomplexed after acid treatment, leaving pure CIDIIIligands as residues (2-6, 2'-6'). These results indicated the high acid resistance of the V-CIDIIIcomplex compared with the other metal-CIDIIIcomplexes, including Fe-CIDIIIcomplex, Cr-CIDIIIcomplex, Cu- CIDIIIcomplex, Ni-CIDIIIcomplex, and Zn-CIDIIIcomplex.

[0116] Based on all the spectroscopy analyses, the negative charge of V-CIDIIIcomplexes, as well as their high acid resistance, are the main mechanisms of selective complexation and precipitation, as depicted in Fig.2a-e. Additionally, as a comparison and to showcase the importance of the aromatic moiety on H2CIDIII, the performance of H2CIDI(the CID ligand without aromatic ring(s)) for complexation and precipitation of V(V) was investigated. The results showed no precipitation in the V-CIDIcomplex solutions at low pH (Fig. 25a-c), owing to the lack of π-π stacking as the driving force for precipitation upon neutralization.

[0117] To further investigate the complexation of V(V) and Fe(III) with H2CIDIIIand the neutralization behaviors of these metal-CIDIIIcomplexes, the complexation energies (Ecomplexation) and neutralization energies (Eneutralization) of the 1:1 V-CIDIIIcomplex, 1:2 V-CIDIIIcomplex, and 1:1 Fe-CIDIIIcomplex were computed using DFT methods. As depicted in Fig.5a and b, the Ecomplexation of the 1:2 V-CIDIIIcomplex is -1606 kJ mol-1, which is slightly higher than that of the 1:1 V-CIDIIIcomplex (-1558 kJ mol-1), indicating that V(V) ion and H2CIDIIIhave a larger preference for forming the 1:2 V-CIDIIIcomplex. Nevertheless, due to the small energy gap, the 1:2 V-CIDIIIcomplex can readily convert to the 1:1 V-CIDIIIcomplex in the presence of excess V(V) in solution, as observed in the isotherm experimentwith a qevalue around 200 mg g-1(Fig.3b). As demonstrated in Fig.5c and d, the Eneutralizationof the 1:1 V-CIDIIIcomplex and 1:2 V-CIDIIIcomplex are -1427 and -609 kJ mol-1, respectively. This implies that both the 1:1 V-CIDIIIcomplex and 1:2 V-CIDIIIcomplex can be easily neutralized and form more stable complexes at low pH conditions. In contrast, for the 1:1 Fe-CIDIIIcomplex, the Ecomplexationof the deprotonated complex is positive (+751 kJ mol-1in Fig.5f), while the Ecomplexationof the neutralized complex is negative (-603 kJ mol-1in Fig. 5e). This indicates that the 1:1 Fe-CIDIIIcomplex can only stably exist in its protonated state, which is consistent with the observation of the neutral 1:1 Fe-CIDIIIcomplex in the single crystal structure (Fig.4a). Furthermore, the Ecomplexationof the V-CIDIIIcomplexes is significantly higher than that of the neutral 1:1 Fe-CIDIIIcomplex, confirming the super high stabilities of the V-CIDIIIcomplexes.

[0118] Furthermore, electrostatic potential maps of the 1:1 V-CIDIIIcomplex, 1:2 V- CIDIIIcomplex, and 1:1 Fe-CIDIIIcomplex were obtained based on the DFT calculations (Fig.5a, b). The maps illustrate significant negative (blue isosurfaces) electrostatic potential on the N in the oxime group (–C=N–O) and O in the V–O group, indicating their propensity to accept protons during the neutralization process. The charges of oxygen and nitrogen in the V-CIDIIIcomplexes and Fe-complex were also recorded (Fig.26a-c). In the 1:1 V-CIDIIIcomplex, the negative charge on nitrogen atom in the oxime group (0.63) is comparable to that of a terminal oxygen atom in a V–O group (0.67) (Fig.26a). This indicates that both N in oxime groups (–C=N–O) and O in V–O groups in the 1:1 V-CIDIIIcomplex can bind with protons during neutralization. Conversely, in the 1:2 V(V)-complex, the negative charges of N in oxime groups (0.65) are significantly higher than those of O in V–O groups (≤0.30) (Fig. 26b). Consequently, only N in oxime groups in the 1:2 V(V)-complex has a higher priority to bind with protons during neutralization. These findings are consistent with the observations from FT-IR spectra (Fig.4c).

[0119] To validate the practical applicability, H2CIDIIIwas employed for the recovery of V(V) from processed oil sand tailing waste (see Methods). The leachate of oil sand tailing waste contained 1.57 mg L-1of V(V), along with various competing metal ions, such as 763.6 mg L-1of Fe(III), 0.86 mg L-1of Cr(III), 20.87 mg L-1of Cu(II), 76.95 mg L-1of Ni(II), 1.84 mg L-1of Zn(II), among others (Table 8). The leachate was initially adjusted to a pH of 1.5 and treated with 0.05 g of H2CIDIIIunder room temperature and stirring conditions. After a 5-hour exposure period, H2CIDIIIdemonstrated a V(V) recovery of 6.0 mg g-1with a recovery efficiency of 95.5%, while the recovery of competing metal ions by H2CIDIIIwas negligible (Fig.6). These outcomes signify the capability of H2CIDIIIto selectively extractV(V) in the presence of more abundant competing metal ions, indicating that it is a candidate for the practical extraction of V(V) from V-contained waste sources.

[0120] Table 7 compares H2CIDIIIto alternative materials. Noteworthy results from the extraction process, including its extraction capacity and selectivity achieved at ambient conditions, was set a benchmark for other materials. These outcomes and its scalable synthesis method suggest that use of H2CIDIIImay offer cost-effectiveness, enhanced performance, and suitability for practical applications.

[0121] In summary, there is described herein an approach for synthesizing an acid- stable chelating agent, H2CIDIII, dedicated to V(V) recovery, exhibiting potential for practical applications. The ligand's binding and separation mechanisms with V(V) were explored using SC-XRD, potentiometric titration, FT-IR, NMR, and DFT calculations, providing valuable insights into the factors governing the selectivity and efficiency of metal sequestration from complex aqueous media. H2CIDIIIdemonstrated the formation of strong and distinctive complexes with V(V), leading to the generation of anionic 1:1 oxido and 1:2 non-oxido complexes, enabling selective precipitation in the presence of competing metal cations. Further investigations extended the application of this strategy to real-world oil sand waste sources, validating the results obtained from simulated studies. Overall, this complexation-precipitation technique may be useful for efficient V(V) recovery from waste sources. H2CIDIIIexhibits several features as a V(V) scavenger, including excellent acid resistance, rapid adsorption kinetics, and high adsorption capacities over a broad pH range. Moreover, it allows for ligand-based extraction through stepwise complexation and precipitation or one-step processes, where both complexation and precipitation occur concurrently. Additionally, H2CIDIIIoffers easy desorption and reusability, further enhancing its practicality. Implementing the findings as described herein may have implications for addressing challenges in the vanadium extraction field, including V(V) depletion in natural sources, minimizing material wastage during terrestrial mining, and mitigating environmental and health-related concerns associated with extraction processes.

[0122] Methods

[0123] Procedure for the synthesis of H2CIDIII. According to standard procedures outlined in literature,53,54H2CIDIIIwas synthesized by reacting the corresponding nitriles with 35% hydroxylamine in a methanolic solution (Fig. 12). The optimized synthesis of H2CIDIIIinvolved a 2-step process, starting with the reaction of 1,8-dibromonaphthalene (3.49 mmol) and copper cyanide (30 mmol) in 50 mL DMF at 130 °C for 12 hours. After cooling to room temperature, the reaction mixture was poured into water, resulting in a precipitate. The precipitate was filtered, treated with aqueous ammonium hydroxidesolutions (30% NH3) and extracted with ethyl acetate. Recrystallization from toluene yielded the purified product (84% yield). In the second step, H2CIDIIIwas obtained by reacting 1,8- naphthalenedicarbonitrile (2.83 mmol) and 35% hydroxylamine (14.1 mmol) in methanol. The reaction mixture was stirred at 80 °C for 12 hours, and the desired product was obtained after recrystallization from boiling absolute ethanol (94% yield).

[0124] For the synthesis of the 1:1 and 1:2 V-CIDIIIcomplexes, stoichiometric amounts of sodium metavanadate and H2CIDIIIwere reacted in an H2O / MeOH solution for 5 hours at room temperature. The dark brown solutions obtained were freeze-dried, and the solids were redissolved in acetone. Shiny black crystals of 1:1 and 1:2 V-CIDIIIcomplexes were obtained by vapor diffusion of ether into the acetone solution. A similar synthetic route using ferric chloride as the metal source was adopted to obtain the 1:1 Fe- CIDIIIcrystals. Additionally, yellow crystals of H2CIDIIIwere grown through slow evaporation from methanol.

[0125] Characterization of materials. All NMR data were acquired on Bruker Avance III 400 and 600 MHz spectrometers. The concentrations of V(V) and interfering metals were measured by an inductively coupled plasma optical emission spectrometer (ICP-OES, Varian 725-ES). The crystals were selected and mounted on a glass loop using paratone. Diffraction experiments were performed on a Bruker Smart diffractometer equipped with an Incoatec Microfocus (graphite monochromated Cu Kα, λ = 1.54178 Å) and an APEX II CCD detector. The crystal was kept at 173 K during data collection. Diffraction spots were integrated and scaled with SAINT55and the space group was determined with XPREP56Using Olex257the structure was solved with the ShelXT58structure solution program using Intrinsic Phasing and refined with the ShelXL59refinement package using Least Squares minimization. Potentiometric analyses were completed using an Orion 960 Titrator (Thermo Electron Corporation). A 10 mL aliquot of each sample was titrated with 0.01 M nitric acid until a pH of 2.5 was reached. End-point determination was accomplished via double differentiation of titration results. Functional groups detection analysis was performed on a Nicolet 4700 FTIR spectrometer.

[0126] V(V) extraction experiments. In experiments to determine pH effect, extraction capacity, Kinetics and desorption, complexation and precipitation were performed in steps. The effect of pH on complexation and precipitation of V(V) were determined by treating a 200 mL 20 mg L-1V(V) spiked deionized water with 0.05 g H2CIDIIIfor 12 hours at room temperature. The pH range for complexation and precipitation were kept at 4-12 and 1-3, respectively and adjusted with HNO3 and NaOH solutions. The extraction isotherm experiments were conducted in a concentration ranging from 5-200 mgL-1. The extraction kinetics experiments were conducted with initial V(V) concentrations of 20 and 50 mg L-1. The pH of complexation and precipitation was adjusted and kept at 8 and 2, respectively. All solutions from complexation and precipitation were filtered through a 0.2 micrometre syringe filter and were analyzed by ICP-OES to determine residual metal concentrations. The complexation and precipitation amount of V(V) were calculated by using: qe= (Ci− Ct) V / m (2) where qe(mg g-1) refers to the V(V) extraction capacity, Ci(mg g-1) represents the initial V(V) concentration, Ct(mg g-1) indicates the V(V) concentration at a time, V (L) refers to the volume of solution, and m (mg) is the mass of the used H2CIDIIIligand.

[0127] Metal ions competition assay. To test the selectivity of H2CIDIIIto V(V) in the presence of competing metal ions, the concentrations of V(V) to Fe(III), Cr(III), Cu(II), Ni(II) and Zn(II) were kept at ratios 1:1, 1:2, 1:5, 1:10 and 1:20. The mixed metal solution was acidified to keep all metals in solution. Selectivity was assessed in varying pH, time, and ligand amount conditions. In this experiment, complexation and precipitation occurred concurrently under acidic conditions. The acidity of the solutions was adjusted by HNO3solution. Each metal extraction capacity was calculated as described earlier and compared to ascertain selectivity. Hereafter, the distribution coefficient (Kd) was calculated using: Kd = q / Ce (3) And the selectivity coefficientwas calculated as follows: ^^^^ ^^(4) where q (mg g-1) refers to the V(V) extraction capacity, and concentration, Ce (mg g-1) indicates the equilibrium concentration of V(V) and competing metal ion.60

[0128] Theoretical Computation Methods. To investigate the complexation energies (Ecomplexation) of V(V) and Fe(III) with CIDIII, and the neutralization energies (Eneutralization) of these metal-CIDIIIcomplexes, density functional theory (DFT) calculations were performed using DMol3 tools in Material Studio (Accelrys Software Inc.). In the DFT methods, local density approximation (LDA) with the PWC functions, double numeric polarization (DNP) basis set, and DFT semi-core Pseudopots approximation were utilized to compute the energies involved in “Density of states”, “Electron density”, “Electrostatics”, “Fukui function”, “Orbitals” and “Population analysis”. The cleaved structures taken from crystal structures of 1:1 V-CIDIIIcomplex, 1:2 V-CIDIIIcomplex and 1:1 Fe-CIDIIIcomplex (Fig.4a) were used to simulate the local environments of complexation and neutralization. The value of the complexation and neutralization energies (Ecomplexation and Eneutralization) werecalculated as the energy difference before and after complexation or neutralization, respectively, as defined by: Ecomplexation= EMetal-CID– (EMetal+ ECID) (5) whereand 1:1 Fe-CIDIIIcomplexes, while EMetaland ECIDare the energies of V(V) ion, Fe(III) ion and CIDIII. EH-[Metal-CID]is the energy of metal complexes after protonation.61In addition, DMol3 electrostatic potential maps of 1:1 V-CIDIII, 1:2 V-CIDIIIand 1:1 Fe-CIDIIIcomplexes were obtained based on DFT calculations.51

[0129] V(V) extraction from oil sand tailings waste. Oil sand tailings waste, known as Mature Fine Tailings (MFT), generated from oil sands extraction via steam- assisted methods in Alberta, Canada, were obtained from InnoTech Alberta. The viscous oil-laden mixture was dried at 120°C for 24 hours, followed by pulverization. Subsequently, it was subjected to nitric acid leaching at 130°C and used for V(V) extraction studies under the previously established conditions. The detailed metal ion concentrations of the leached solution are shown in Table 8.

[0130] Table 1 | Isotherm and kinetic parameters of the Langmuir and pseudo- second-order model, respectively. Method Initial Concentration Langmuir modela)qm (mg g-1) b (L mg-1) R25 to 200 mg-1Two-stepb)L (Complexation) 205.4 2.71 0.963 5 to 200 mg-1One-stepc)L (Recovery) 195.8 3.70 0.986 Method Initial Concentration Pseudo-second-order modeld)k (g-1qe (mg g-1) 2 mg2min) R Two-step 50 mg L-1(Complexation) 204.8 0.057 0.985 20 mg L-1(Complexation) 90.0 0.066 0.959 50 mg L-1(Precipitation) 203.3 1.491 0.999 20 mg L-1(Precipitation) 83.4 2.516 0.999 One-step 50 mg L-1(Recovery) 216.6 0.007 0.988 20 mg L-1(Recovery) 100.1 0.010 0.962a)Langmuir model: qe = bqmCe / (1 + bCe), while Ce is the equilibrium concentration (mg L-1) of V(V) in the solution; qeis the equilibrium extraction amount (mg g-1); b is the Langmuir constant related to the affinity between the V(V) and H2CIDIII; and the qm is the maximum extraction capacity.b)Complexation at pH 8, and precipitation at pH 3.c)Complexation and precipitation combined as one step at pH 3.d)Pseudo-second-order model: qt = qe2k2t / (1 + qek2t), while qe is the V(V) extraction amount at equilibrium, qtis the extraction amount at any time (mg g-1), and k2is the pseudo-second- order rate constants.

[0131] Table 2 | Comparison of adsorbent / material performance in the recovery of V(V) from several sources. Capacity b value Technology Material ID V(V) source Ref. (mg g-1) (L mg-1) Complexation- Naphthal- Oil sands This H2CIDIII205.4 2.71 precipitation imidedioxime tailings workInorganic- Simulated Adsorption biopolymer zirconium 208 1.68 1 composite (IV)Commercial iron synthesis gas Adsorption sorbent CFH-12 scrubber 7.4 1.41 2 Thio S2O4 Spiked lake, functionalized 112.3 1.264 Ion exchange LDH tap and pond 3 layered double hydroxide water Ion exchange Sawdust TEA-I-SD Mine water 31.6 0.835 4 Chitosan bead Simulated Adsorption modified with TiCB5 solutions titanium ions Sulfonated calixarene Spiked well, modified Poly C-PMN Adsorption lake and tap 322.6 0.477 6 (methyl water methacrylate) nanoparticlesAdsorption Resin 201*7 Waste liquid 48.7 0.246 7 201*7 Red mud Simulated Adsorption modified sawdust RM-BC 16.45 0.202 8 solutions biochar Nanoporous carbon materials NPC@C Simulated Adsorption (carbon NT 285.7 0.18 9 solutions nanotubes / MOF- 199) Cellulose-based anion exchanger (Amine-Modified Cell-AE Simulated Ion Exchange Poly (glycidyl 197.75 0.175 10 solutions methacrylate)- Grafted Cellulose) KOH modified seaweed Simulated Adsorption (Ascophyllum HCKOH solutions 12.33 0.166 11 nodosum) Nanosized hydrous HZrO@D Contaminated zirconium oxide Ion 201 110.9 0.1529 12D201Carbon quantum CQDots dots decorated- @PHQF Adsorption Wastewater 210 0.149 13 polymeric B nanocomposite Binary oxide T7Zn3 Vanadium- Adsorption (TiO2-ZnO type) 195.9 0.014 14 based catalyst Electro- ZnO Simulated Zinc anode 158.76 0.13 15 coagulation solutions Cellulose HDTMA- Simulated Adsorption 37.9 0.13 16 nanocrystal Br / CNC solutions Chitosan bead Simulated Adsorption modified with TiCB 210 0.48 5 solutions titanium ions Simulated Ion exchange Palm fruit husk PFCTAB 17 solutionsZIF-8-derived ZDPC Simulated Adsorption porous carbon 89.85 0.01 18 solutions Phosphoric acid AcM Simulated Adsorption modified rice 21.3 0.008 19 solutions straw (AcM) Adsorption Amidoxime resin LSC700 Bayer liquor 48.08 0.0534 20 Simulated Adsorption Steel slag SS 0.0477 21 solutionsMagnetic Fe3O4- Oil refinery Adsorption chitosan CSN and jewelry 186.6 0.07 22 nanoparticles wastewaters Amberlite Steel slag Ion exchange Resin ®IRA- 27 0.004 23 leachate 400 Simulated Adsorption Exchange resin SIRs-CI 107.5 0.0029 24 solutions

[0132] Table 3 | Crystallographic data and structure refinement of H2CIDIII. Identification code H2CIDIIIEmperical formula C14H17N3O4 Formular weight 291.30 Temperature / K 173.0 Crystal system Monoclinic Space group P21 / n a / Å 17.654(6) b / Å 9.529(3) c / Å 18.411(6) α / ° 90 β / ° 106.840(5) γ / ° 90 Volume / Å32964.4(17) Z 8 ρcalcg / cm31.305 μ / mm-10.097 F(000) 1232.0 Crystal size / mm30.457 × 0.405 × 0.142 Radiation MoKα (λ = 0.71073) 2Θ range for data collection / ° 2.814 to 56.576 Index ranges -23 ≤ h ≤ 22, -12 ≤ k ≤ 12, -24 ≤ l ≤ 24 Reflections collected 56723 Independent reflections 7371 [Rint = 0.0573, Rsigma = 0.0335] Data / restraints / parameters 7371 / 0 / 413 Goodness-of-fit on F21.028 Final R indexes [I>=2σ (I)] R1= 0.0525, wR2= 0.1371 Final R indices [all data] R1= 0.0946, wR2= 0.1601 Largest diff. peak / hole / e Å-30.34 / -0.24

[0133] Table 4 | Crystallographic data and structure refinement of 1:1 V-CIDIIIcomplex. Identification code 1:1 V-CIDIIIEmperical formula C33H30N6Na2O10V2 Formular weight 818.49 Temperature / K 173 Crystal system Monoclinic Space group P21 / n a / Å 7.8419(2) b / Å 28.2476(7) c / Å 15.9108(4) α / ° 90 β / ° 92.898(2) γ / ° 90 Volume / Å33519.97(15) Z 4 ρcalcg / cm31.544 μ / mm-15.266 F(000) 1672.0 Crystal size / mm30.318 × 0.071 × 0.048 Radiation CuKα (λ = 1.54178) 2Θ range for data collection / ° 6.258 to 133.28 Index ranges -7 ≤ h ≤ 9, -32 ≤ k ≤ 33, -17 ≤ l ≤ 18 Reflections collected 32011 Independent reflections 6069 [Rint= 0.0442, Rsigma= 0.0314] Data / restraints / parameters 6069 / 0 / 484 Goodness-of-fit on F21.037 Final R indexes [I>=2σ (I)] R1 = 0.0309, wR2 = 0.0770 Final R indices [all data] R1 = 0.0379, wR2 = 0.0803 Largest diff. peak / hole / e Å-30.33 / -0.25

[0134] Table 5 | Crystallographic data and structure refinement of 1:2 V-CIDIIIcomplex. Identification code 1:2 V-CIDIIIEmperical formula C31H28N6NaO6V Formular weight 654.52 Temperature / K 173.0 Crystal system Triclinic Space group P-1 a / Å 8.4698(3) b / Å 12.0186(6) c / Å 15.1203(6) α / ° 103.702(3) β / ° 103.305(4) γ / ° 94.079(4) Volume / Å31442.32(11) Z 2 ρcalcg / cm31.507 μ / mm-13.509 F(000) 676.0 Crystal size / mm30.212 × 0.06 × 0.046 Radiation CuKα (λ = 1.54178) 2Θ range for data collection / ° 6.222 to 136.584 Index ranges -10 ≤ h ≤ 10, -14 ≤ k ≤ 14, -18 ≤ l ≤ 18 Reflections collected 42023 Independent reflections 5088 [Rint= 0.0311, Rsigma= 0.0160] Data / restraints / parameters 5088 / 0 / 410 Goodness-of-fit on F21.054 Final R indexes [I>=2σ (I)] R1 = 0.0311, wR2 = 0.0875 Final R indices [all data] R1 = 0.0327, wR2 = 0.0891 Largest diff. peak / hole / e Å-30.52 / -0.26

[0135] Table 6 | Crystallographic data and structure refinement of 1:1 Fe-CIDIIIcomplex. Identification code 1:1 Fe-CIDIIIEmperical formula C20H20Cl3FeN4O3 Formular weight 526.60 Temperature / K 173.0 Crystal system Triclinic Space group P-1 a / Å 9.3427(3) b / Å 10.3852(3) c / Å 13.4374(4) α / ° 93.163(2) β / ° 101.365(2) γ / ° 114.877(2) Volume / Å31145.55(6) Z 2 ρcalcg / cm31.527 μ / mm-18.753 F(000) 538.0 Crystal size / mm30.355 × 0.077 × 0.07 Radiation CuKα (λ = 1.54178) 2Θ range for data collection / ° 6.792 to 133.166 Index ranges -10 ≤ h ≤ 11, -12 ≤ k ≤ 12, -15 ≤ l ≤ 15 Reflections collected 13319 Independent reflections 3902[Rint= 0.0518, Rsigma= 0.0512] Data / restraints / parameters 3902 / 181 / 321 Goodness-of-fit on F21.047 Final R indexes [I>=2σ (I)] R1 = 0.0311, wR2 = 0.0875 Final R indices [all data] R1 = 0.0327, wR2 = 0.0891 Largest diff. peak / hole / e Å-30.52 / -0.26

[0136] Table 7 | Comparison of the performance of H2CIDIIIand several materials during the extraction of Vanadium from several sources Material Waste Capacity Eff. time Competing name source (mg / g) (%) (hrs) ions Remarks Ref. Journal Articles H2CIDIIIdisplayed high extraction Na, Co, Fe, capacity and Al, Ca, Ni, selectivity for V(V) H2CIDIIIMg during extraction (Chelating Oil sands , K, Cu, 205.6 95. from oil sands tailings 5 2 Mn, Ba, Sr, Zn, V, Cr, ta * agent) ilings via a 2-step Pb, Th, Mo, technique Be, U performed at room temp. H2CIDIIIis stable, reusable, and scalable. Low adsorption capacity achieved. V, Al, Fe, Also, the selectivity DS418 (Ion Vanadium 112.3 study was not exchange resin) shale 6 94.1 3 Na, comprehensive 25(only competition with Fe was considered). Stability and regeneration studies were not performed. BacterialTherefore, there is a cellulose (Agro- s 5.24 - nr - high possibility of 26 waste) olution the generation of secondary wastes. Also, selectivity of the material for V(V) was not assessed. Sim. spent The technology is hydro- based on Polymer desulphur- electrodialysis and inclusion ization - 92.9 25 Mo, Co, Ni, could be energy ane (HDS) Mn, and Al i 27 membr ntensive. Material catalysts co-extracted Mo(IV) solution and reduced its affinity for V(V). Lewatit Monoplus Lo (Porous Spen ng extraction MP600 t 75.3 100 24 V, W time nion-exchange Cata and limited 28 A lysts selectivity studies. resin) Extraction was Oxalic acid and performed at a high hexamethylenet V, Mo, N temperature etramine (HMT) Carbon i, - 95.4 nr F (100°C) to achieve black e, optimum effici 29 (Complexing and Ca ency. agent) Co-extraction of Mo, which required separationAmino- phosphonic acid 90.1 V, Fe, Al, Adsorption capacity chelating resin Black shale - 7 nr K, Na, Mg, and time not 30 (Ion-exchange P reported. resin) The bacteria were cultivated for seven oalgal S days. The Micr imulated V(V) - 59.9 2 extraction process strains 4 - a 31 solution chieved lowefficiency and longduration. Selectivity was not assessed. Glycine Simulated 95.7 High temp. (90°C) (extractant - V(V) - 5 1 - required for 32 precipitation) solution extraction Low extraction Bacillus Stone coal - 44.4 18 - efficiency and long mucilaginosus duration. Selectivity 33 was not assessed. Spent Co-extraction of Alamine 308 hydro- V, Mo, Ni Mo. Loss o processing - 99.8 0.08 f and Al effectiveness after 34 catalyst the 4th cycle. Patents Crude or Extraction Calgon CPG residual - 81 ~12 nr performed at high 35 fuel oil temperature (80°C) High temperature (200°C) required for BMIM(l-butyl- Organic extraction. Co-3methylimidazoli residues extraction of Mo. um) from hydro- - 58.1 24 nr Subsequent 36 Acetate (Ionic conversion separation liquid) processes required, achieving 36.4% V(V) extraction efficiency. Co-extraction of Sc, Co, Ni, Mn, Cu, V, Mg. Subsequent purification steps required. A range of extraction efficiency was reported depending on D201 resin andmining samples. It P507 extractant Acid n leached - 5(a 1.9- 1V, assume that organophosphor ores Mg efficiency was ic extractant) affected by the extractant's affinity for other competing metal ions present in each sample. Also, the stability and reuse of extractants were not discussed. Magnesium Co-extraction of Ni,oxide, cobalt Low-grade Ni, Fe and Fe and Al. A high oxide, fuel - 99.7 nr Al. temperature (400- 38 molybdenum 1000°F) wasoxide, activated required for the carbon, zeolites extraction. or combinations thereof Chromium Co-extraction of Cr. Electrolysis ore, - 97.2 2 Cr High temperature 39 chromite (90°C) required Quaternary ammonium High temperature polystyrene- Acid leach (65°C) requi vinyl benzene liquor - 94 red for di 0.13 Fe the extraction 40 type (anionprocess. exchange resin) * - This work nr – not reported

[0137] Table 8 | Composition of the real waste source (solution pH 1.5). Cations Concentration (mg L-1) Cations Concentration (mg L-1) Na 12465.0 Ba 3.18 Co 1332.5 Sr 2.16 Fe 763.6 Zn 1.84 Al 416.7 V 1.57 Ca 138.5 Cr 0.86 Ni 76.95 Pb 0.70 Mg 67.82 Th 0.19 K 57.20 Mo 0.17 Cu 20.87 Be 0.04 Mn 15.5 U 0.04

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[0152] 14. Li, M., Zhang, B., Zou, S., Liu, Q. & Yang, M. Highly selective adsorption of vanadium (V) by nano-hydrous zirconium oxide-modified anion exchange resin. J. Hazard. Mater.384, 121386 (2020).

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[0155] 17. Aregay, G. G. et al. Application of layered double hydroxide enriched with electron rich sulfide moieties (S2O42−) for efficient and selective removal of vanadium (V) from diverse aqueous medium. Sci. Total Environ.792, 148543 (2021).

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[0166] 28. Ansari, S. A., Bhattacharyya, A., Zhang, Z. & Rao, L. Complexation of Neptunium(V) with Glutaroimide Dioxime: A Study by Absorption Spectroscopy, Microcalorimetry, and Density Functional Theory Calculations. Inorg. Chem. 54, 8693– 8698 (2015).

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[0173] 35. Thamilarasi, M. J. V., Anilkumar, P., Theivarasu, C. & Sureshkumar, M. V. Removal of vanadium from wastewater using surface-modified lignocellulosic material. Environ. Sci. Pollut. Res.25, 26182–26191 (2018).

[0174] 36. Dong, Y., Chong, S. & Lin, H. Bioleaching and biosorption behavior of vanadium-bearing stone coal by Bacillus mucilaginosus. Int. J. Miner. Metall. Mater.30, 283–292 (2022).

[0175] 37. Tan, L., Liu, T., Zhang, Y., Xue, N. & Hu, P. Enhance selective separation of vanadium and iron from acid-leaching solution with sulfamic acid modified resin. Chem. Eng. J.457, 141286 (2023).

[0176] 38. Guidetti, S. & De Angelis, A. Process for the selective recovery of transition metals from organic residues. (2020).

[0177] 39. Yudaev, P. A. & Chistyakov, E. M. Ionic Liquids as Components of Systems for Metal Extraction. ChemEngineering vol.6 (2022).

[0178] 40. Kim, H. S. et al. Microalgae as an Effective Recovery Agent for Vanadium in Aquatic Environment. Energies 15, 4467 (2022).

[0179] 41. Gogoi, H. et al. Vanadium removal by cationized sawdust produced through iodomethane quaternization of triethanolamine grafted raw material. Chemosphere 278, (2021).

[0180] 42. Liu, X. & Zhang, L. Insight into the adsorption mechanisms of vanadium(V) on a high-efficiency biosorbent (Ti-doped chitosan bead). Int. J. Biol. Macromol.79, 110–117 (2015).

[0181] 43. Mazinai, A., Zare, K., Moradi, O. & Attar, H. Sulfonated calixarene modified Poly(methyl methacrylate) nanoparticles:A promising adsorbent for Removal ofVanadium Ions from aqueous media. Chemosphere 299, 134459 (2022).

[0182] 44. Zhu, X., Li, W. & Zhang, C. Extraction and removal of vanadium by adsorption with resin 201*7 from vanadium waste liquid. Environ. Res.180, 108865 (2020).

[0183] 45. Ghanim, B. et al. Removal of vanadium from aqueous solution using a red mud modified saw dust biochar. J. Water Process Eng.33, 101076 (2020).

[0184] 46. v. Braun, J. & Manz, G. Fluoranthen und seine Derivate. IV. Justus Liebigs Ann. Chem.496, 170–196 (1932).

[0185] 47. Utting, N. Long-term column leaching study of centrifuged oil sands fine tailings. Environ. Earth Sci.80, (2021).

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[0188] 50. Zhang, G. et al. A novel synergistic extraction method for recovering vanadium (V) from high-acidity chloride leaching liquor. Sep. Purif. Technol.165, 166–172 (2016).

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[0190] 52. Simons, W. W. The Sadtler Handbook of Infrared Spectra. in Sadtler Research Laboratories (1978).

[0191] 53. Bernstein, K. J. et al. The synthesis and spectroscopic characterization of an aromatic uranium amidoxime complex. Inorganica Chim. Acta 421, 374–379 (2014).

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[0193] 55. Bruker-AXS. SAINT. Madison, Wisconsin, USA (2017).

[0194] 53. Bernstein, K. J. et al. The synthesis and spectroscopic characterization of an aromatic uranium amidoxime complex. Inorganica Chim. Acta 421, 374–379 (2014)..

[0195] 56. Bruker-AXS. XPREP. Madison, Wisconsin, USA (2017).

[0196] 57. Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. &Puschmann, H. OLEX2: A complete structure solution, refinement and analysis program. J. Appl. Crystallogr.42, 339–341 (2009).

[0197] 58. Sheldrick, G. M. SHELXT - Integrated space-group and crystal- structure determination. Acta Crystallogr. Sect. A Found. Crystallogr.71, 3–8 (2015).

[0198] 59. Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Crystallogr. Sect. C Struct. Chem.71, 3–8 (2015).

[0199] 60. Liu, J. et al. Soy protein-based polyethylenimine hydrogel and its high selectivity for copper ion removal in wastewater treatment. J. Mater. Chem. A 5, 4163– 4171 (2017).

[0200] 61. Liu, Y. et al. Super-Stable, Highly Efficient, and Recyclable Fibrous Metal–Organic Framework Membranes for Precious Metal Recovery from Strong Acidic Solutions. Small 15, 1–9 (2019).

[0201] FIGURE 10-26 AND TABLE 1-8 REFERENCES

[0202] 1. Zhang, L., Liu, X., Xia, W. & Zhang, W. Preparation and characterization of chitosan-zirconium(IV) composite for adsorption of vanadium(V). Int. J. Biol. Macromol.64, 155–161 (2014).

[0203] 2. Leiviskä, T., Khalid, M. K., Sarpola, A. & Tanskanen, J. Removal of vanadium from industrial wastewater using iron sorbents in batch and continuous flow pilot systems. J. Environ. Manage.190, 231–242 (2017).

[0204] 3. Aregay, G. G. et al. Application of layered double hydroxide enriched with electron rich sulfide moieties (S2O42−) for efficient and selective removal of vanadium (V) from diverse aqueous medium. Sci. Total Environ.792, 148543 (2021).

[0205] 4. Gogoi, H. et al. Vanadium removal by cationized sawdust produced through iodomethane quaternization of triethanolamine grafted raw material. Chemosphere 278, (2021).

[0206] 5. Liu, X. & Zhang, L. Insight into the adsorption mechanisms of vanadium(V) on a high-efficiency biosorbent (Ti-doped chitosan bead). Int. J. Biol. Macromol.79, 110–117 (2015).

[0207] 6. Mazinai, A., Zare, K., Moradi, O. & Attar, H. Sulfonated calixarene modified Poly(methyl methacrylate) nanoparticles:A promising adsorbent for Removal of Vanadium Ions from aqueous media. Chemosphere 299, 134459 (2022).

[0208] 7. Zhu, X., Li, W. & Zhang, C. Extraction and removal of vanadium by adsorption with resin 201*7 from vanadium waste liquid. Environ. Res.180, 108865 (2020).

[0209] 8. Ghanim, B. et al. Removal of vanadium from aqueous solution using a red mud modified saw dust biochar. J. Water Process Eng.33, 101076 (2020).

[0210] 9. Salehi, S., Mandegarzad, S. & Anbia, M. Preparation and characterization of metal organic framework-derived nanoporous carbons for highly efficient removal of vanadium from aqueous solution. J. Alloys Compd.812, 152051 (2020).

[0211] 10. Anirudhan, T. S., Jalajamony, S. & Divya, L. Efficiency of amine- modified poly(glycidyl methacrylate)-grafted cellulose in the removal and recovery of vanadium(V) from aqueous solutions. Ind. Eng. Chem. Res.48, 2118–2124 (2009).

[0212] 11. Ghanim, B. et al. Application of KOH modified seaweed hydrochar as a biosorbent of Vanadium from aqueous solution: Characterisations, mechanisms and regeneration capacity. J. Environ. Chem. Eng.8, 104176 (2020).

[0213] 12. Li, M., Zhang, B., Zou, S., Liu, Q. & Yang, M. Highly selective adsorption of vanadium (V) by nano-hydrous zirconium oxide-modified anion exchange resin. J. Hazard. Mater.384, 121386 (2020).

[0214] 13. Mahmoud, M. E., Abdelfattah, A. M. & Fekry, N. A. High performance of carbon quantum dots-decorated-polymeric nanocomposite for enhanced microwave adsorption of vanadium (V) from water. Groundw. Sustain. Dev.14, 100582 (2021).

[0215] 14. Wołowicz, A. et al. Enhanced removal of vanadium(V) from acidic streams using binary oxide systems of TiO2-ZrO2 and TiO2-ZnO type. Sep. Purif. Technol. 280, (2022).

[0216] 15. Solís–Rodríguez, R., Pérez–Garibay, R., Alonso–González, O., Mendieta–George, D. & Alvarado–Gómez, A. Vanadium removal by electrocoagulation with anodes of zinc. J. Environ. Chem. Eng.10, 108082 (2022).

[0217] 16. Zulu, B., Oyewo, O. A., Sithole, B., Leswifi, T. Y. & Onyango, M. S. Functionalized Sawdust-Derived Cellulose Nanocrystalline Adsorbent for Efficient Removal of Vanadium From Aqueous Solution. Front. Environ. Sci.8, 1–11 (2020).

[0218] 17. Thamilarasi, M. J. V., Anilkumar, P., Theivarasu, C. & Sureshkumar, M. V. Removal of vanadium from wastewater using surface-modified lignocellulosic material. Environ. Sci. Pollut. Res.25, 26182–26191 (2018).

[0219] 18. Wan, X., Bao, S. & Zhang, Y. ZIF-8-derived porous carbon: application in capacitive deionization for vanadium (V) adsorption. J. Appl. Electrochem. 52, 639–651 (2022).

[0220] 19. He, W. yan, Liao, W., Yang, J. yan, Jeyakumar, P. & Anderson, C. Removal of vanadium from aquatic environment using phosphoric acid modified rice straw. Bioremediat. J.24, 80–89 (2020).

[0221] 20. Zhao, Z., Li, X. & Zhao, Q. Recovery of V2O5 from Bayer liquor by ion exchange. Rare Met.29, 115–120 (2010).

[0222] 21. Gao, Y. et al. BOF steel slag as a low-cost sorbent for vanadium (V) removal from soil washing effluent. Sci. Rep.7, 1–10 (2017).

[0223] 22. Omidinasab, M. et al. Removal of vanadium and palladium ions by adsorption onto magnetic chitosan nanoparticles. Environ. Sci. Pollut. Res. 25, 34262– 34276 (2018).

[0224] 23. Gomes, H. I., Jones, A., Rogerson, M., Burke, I. T. & Mayes, W. M. Vanadium removal and recovery from bauxite residue leachates by ion exchange. Environ. Sci. Pollut. Res.23, 23034–23042 (2016).

[0225] 24. Chen, B., Bao, S., Zhang, Y. & Zheng, R. Ultrasound-assisted synthesis of N235- impregnated resins for vanadium (V) adsorption. R. Soc. Open Sci.5, (2018).

[0226] 25. Tan, L., Liu, T., Zhang, Y., Xue, N. & Hu, P. Enhance selective separation of vanadium and iron from acid-leaching solution with sulfamic acid modified resin. Chem. Eng. J.457, 141286 (2023).

[0227] 26. Tseng, Y. S. et al. Removal of heavy metal vanadium from aqueous solution by nanocellulose produced from Komagataeibacter europaeus employing pineapple waste as carbon source. Bioresour. Technol.369, 128411 (2023).

[0228] 27. Qin, Z. et al. Vanadium recovery by electrodialysis using polymer inclusion membranes. J. Hazard. Mater.436, 129315 (2022).

[0229] 28. Jeon, J. H., Cueva Sola, A. B., Lee, J.-Y., Koduru, J. R. & Jyothi, R. K. Separation of vanadium and tungsten from synthetic and spent catalyst leach solutions using an ion-exchange resin. RSC Adv.12, 3635–3645 (2022).

[0230] 29. Tan, H., Fan, B., Zheng, S. & Zhang, Y. Recovery and Separation of Vanadium, Nickel, and Molybdenum from the Industrial Waste of a Petroleum Refinery by a Complexation Method. ACS Sustain. Chem. & Eng.11, 4894–4902 (2023).

[0231] 30. Wang, L., Xue, N., Zhang, Y. & Zheng, Q. Selective separation and recovery of vanadium from acid leaching solution of polymetallic black shale as function of aminophosphonic acid. J. Chem. Technol. & Biotechnol.97, 1978–1986 (2022).

[0232] 31. Kim, H. S. et al. Microalgae as an Effective Recovery Agent for Vanadium in Aquatic Environment. Energies 15, 4467 (2022).

[0233] 32. Peng, H. et al. Vanadium recovery by glycine precipitation. Environ. Chem. Lett.20, 1569–1575 (2022).

[0234] 33. Dong, Y., Chong, S. & Lin, H. Bioleaching and biosorption behavior of vanadium-bearing stone coal by Bacillus mucilaginosus. Int. J. Miner. Metall. Mater.30, 283–292 (2022).

[0235] 34. Sahu, K. K., Agrawal, A. & Mishra, D. Hazardous waste to materials: Recovery of molybdenum and vanadium from acidic leach liquor of spent hydroprocessing catalyst using alamine 308. J. Environ. Manage.125, 68–73 (2013).

[0236] 35. Silva J, P. C. and L. G. Adsorption of vanadium compounds from fuel oil and adsorbents thereof. (2008).

[0237] 36. Guidetti, S. & De Angelis, A. Process for the selective recovery of transition metals from organic residues. (2020).

[0238] 37. Gauthier, P. & Di Cesare, E. Recovery of scandium and vanadium values from feedstocks using ultrasound-assisted extraction. (2018).

[0239] 38. Kulkarni, P. Methods and systems for removing vanadium from low- grade fuels. (2009).

[0240] 39. Weber, R., Block, H. & Batz, M. Process for the utilization of vanadium bound in chromium ore as vanadium (V) oxide by electrolysis. (2003).

[0241] 40. McLean, D. Multistage adsorption of pentavalent vanadium values on anion exchange resins. (1960).

[0242] Example 2 - Application of the V-CID complexes

[0243] Catalytic application of MFT-derived vanadium complexes in epoxidation reactions

[0244] Epoxides are regarded as an important intermediate in applied chemistry because they are widely used in preparing natural products and biologically active substances, including polymers, surfactants, paints, medicines, insecticides, cosmetics, textiles, and detergents.1,2Notably, the epoxidation of olefins has become a key chemical reaction because this process can convert relatively cheap and available olefins into expensive epoxide intermediates.3Unfortunately, one of the most known efficient synthetic methods for olefin epoxidation uses non-green conditions involving toxic inorganic oxidants, strong acids and organic solvents.4Alternatively, using metal complexes or metal oxides as catalysts, with a relatively greener oxidant such as tert-butyl hydroperoxide (TBHP), or oxygen (O2) tends to be preferable.5However, most of those metal-catalyzed epoxidation processes still use organic solvents, which can be a challenge in the industrial sector. Therefore, designing solvent-free catalytic systems performed at ambient conditions and using greener oxidants in catalytic epoxidation systems is desirable.

[0245] Transition metal compounds such as metalloporphyrin, titanosilicates, methyltrioxorhenium, tungsten compounds, polyoxometalates, and manganese complexes have been employed as catalysts for epoxidation, either in homogeneous or heterogeneoussystems.6–8While the homogenous systems are considered more efficient due to the easy phase transitions and effective interaction of multiple substituents, they tend to suffer from poor catalyst recoverability, material wastage and high costs.9As such, many reports in the literature lean towards heterogenous systems via immobilization of transition metal complexes onto solid supports, including silica gel, mesoporous silicas and clays.10–12Unfortunately, these systems also tend to experience challenges, such as low efficiency and selectivity to epoxides, a limited number of applicable olefins, and high reaction temperatures. Overall, reusable, homogenous catalysts based on transition metals are more appealing from a technical, economical, and environmental standpoint, particularly for industrial processes.

[0246] Among the efficient metals for epoxidation, vanadium catalysts have garnered interest due to their high efficiency and lower toxicity compared to other metals. Research has focused on designing vanadium catalysts for stereoselective olefin epoxidation.13–15Notably, oxovanadium(IV) compounds were first discovered by Sharpless as effective oxidation catalysts for the regioselective epoxidation of allylic alcohols.16

[0247] Epoxidation of common reagents

[0248] The 1:1 oxido-vanadium(V) complex (V-CIDIII) derived as an intermediate product from the vanadium extraction process was utilized for epoxidation of various olefins. The epoxidation reactions were carried out under ambient conditions, specifically at room temperature, using tert-butyl hydroperoxide (t-BuOOH) as the oxidant. The process was conducted in a solvent-free and homogeneous system. Catalyst recovery was achieved through a simple pH adjustment method, offering a convenient and efficient means of recycling the catalyst. The catalytic performance of V(V)-CIDIIIwas investigated in the epoxidation of geraniol (an allylic alcohol).

[0249] Materials and methods

[0250] The chemicals used were purchased from Aldrich and used without further purification. The vanadium catalyst was prepared by treating Mature Fine Tailings (MFT) leachate (200 mL, pH ~ 1.5) with 0.05 g of H2CIDIIIfor 5 hours at room temperature. After allowing the mixture to sit for 15 minutes, the solid catalyst was obtained by filtration. The catalyst was then washed with water and THF and dried under vacuum for 2 hours.

[0251] The resulting catalyst was characterized using1H NMR, to confirm its structure and composition. A comparison was made between the catalyst prepared from MFT leachate and a ‘simulated’ catalyst synthesized by reacting ammonium metavanadate (2 ppm) and H2CIDIII(0.05g) in 200 mL of water set at pH 1.5 for 5 hours at room temperature.

[0252] In the epoxidation reaction, the reagent (2mmol), TBHP (20 mmol, 0.274mL) and a magnetic stirrer were placed in a 10-mL round bottom flask. Thereafter, the catalyst (0.02mmol, 6.4mg) was added to the flask and the reaction was continued with stirring at room temperature for 7 hours. After completion, the solution was slightly acidified, and the catalyst was separated by simple filtration through a Buckner funnel. The filtrate was analyzed by GCMS. GC–MS analyses were performed using Agilent 7890GC / 5977MS series with an electron ionization (EI) source, and DB-5MS (non-polar) column (25m x 0.25mm x 0.25μm), equipped with an Agilent 7890 gas chromatograph and a 150 sample autosampler. The temperature program used for the epoxidation reaction of geraniol and 1-decene was: Injector Temp. 220°C, 0.9 mL / min He. Hold at 80°C for 1 min, ramp 25°C / min to 155 C, then 5°C / min to 200°C, hold for 2 min at 200°C. The conditions for cyclooctene was: Injector Temp. 250°C, 0.9 mL / min He. Hold at 50°C for 2 min, ramp 10°C / min to 250 C, hold for 8 min at 250°C. The quantification and purification of these reagents have been discussed in detail in the literature,4,17,18and could be followed in future experiments.

[0253] Results and discussion

[0254] The1H NMR spectra of the recovered V(V)-CIDIIIcatalyst in DMSO-d6revealed signals attributed to the protons on the aromatic rings, similar to those observed for the simulated V(V)-CIDIIIcomplex. The observation of similar chemical shifts in both compounds indicates that the recovered catalyst retains the same structural features as the simulated V(V)-CIDIIIcomplex (FIG.7).

[0255] The catalytic performance of V(V)-CIDIIIwas evaluated in the epoxidation reactions of geraniol under mild conditions and room temperature. The reactions were conducted in a solvent-free system using tert-Butyl hydroperoxide, TBPH (t-BuOOH) as the oxidant. The results, presented in FIG.8a-c, demonstrate that V(V)-CIDIIIcan offer a more sustainable approach compared to other catalysts that require higher temperatures and organic solvents.4,18,19V(V)-CIDIIIexhibited excellent activity with ~100% conversion of geraniol and high selectivity towards the formation of 2,3-epoxygeraniol. This suggests V(V)-CIDIIImay be used as a homogeneous catalyst precursor for the epoxidation of geraniol.

[0256] Catalyst durability can support cost-effective and ecologically friendly processes. As a result, the recyclability and reusability of the catalyst was investigated in the epoxidation reaction. It was found that the catalyst could be readily separated by filtration, after acidifying the solution, rinsed with water, dried, and reutilized for subsequentreactions after adding fresh substrate and oxidant (50% TBPH). In these experiments conversion as well as selectivity remained substantially the same.

[0257] An analogy to the existing mechanism for epoxidation by vanadium complexes19,20was considered for understanding the epoxidation mechanism by V(V)-CIDIII; for example, see FIG.9. Epoxidation is considered to begin with activation of the catalyst via coordination of TBPH to the metal center. This is then followed by the interaction of the alkene with the TBHP molecules present in the coordination sphere of the vanadium complex. The Lewis acidity of the V center increases the oxidizing power of the peroxo group, and the alkene is subsequently oxygenated by nucleophilic attack to the electrophilic oxygen atom of the coordinated TBHP peroxide with the generation of the intermediate product, III. Subsequently, the epoxide is formed with the elimination of tert‐butanol and regeneration of the catalyst.

[0258] In summary, V(V)-CIDIIIwas shown to be an effective catalyst in epoxidation of geraniol under mild and green reaction conditions. The catalyst could be easily recovered from the reaction mixture by the acidification of the solution and filtration. V(V)-CIDIIIcatalyst offered higher conversions with improved selectivity for the epoxide products, mild reaction condition, and recyclability of the catalyst.

[0259] EXAMPLE 2 REFERENCES

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[0264] (5) Ghaffari, A.; Behzad, M.; Dutkiewicz, G.; Kubicki, M.; Salehi, M. Crystal Structure, Electrochemistry, and Catalytic Studies of a Series of New Oxidovanadium(IV) Schiff-Base Complexes Derived from 1,2-Diphenyl-1,2-Ethylenediamine. J. Coord. Chem. 2012, 65 (5), 840–855. https: / / doi.org / 10.1080 / 00958972.2012.662275.

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[0280] EXAMPLE 3 - Assessment Of Cationic Materials For Complex Precipitation

[0281] In addition to decreasing pH (for example, by adding acid) to precipitate the herein described V-CID complexes, a range of cationic materials were tested to investigate separation of said complexes from solution. Cationic polymers were selected due to their general ease of material recovery and relatively more environmentally friendly extraction process, as they tend to remain insoluble in aqueous solutions and can generally be reclaimed following extraction.

[0282] Further, the potential effectiveness of aromatic-based materials was investigated based on a hypothesis that the presence of aromatic rings may enhance π interactions between the cationic polymers and the anionic V(V)-CID complexes, promoting precipitation.

[0283] To test this, commercial polymers were protonated and methylated to create Poly(4-vinylpyridine hydrochloride) / cross-linked with divinylbenzene and Poly(styrene)-b- poly(4-vinyl pyridine, quaternized with methyl iodide). Additionally, Amberlite IRA-402 commercial resin (R1) was purchased and used as received. It was found that each material effectively removed the V-CID complexes from solution. Table 9 provides a summary of the characteristics and structures of each cationic material assessed in this study.

[0284] Table 9. Summary of characteristic of cationic materials tested for V(V)-CID complex precipitation Material Structure Remarks While Py-HCl demonstrated Pyridine successful separation of the V(V) Hydrochloride complexes from the solution, it (Py-HCl) raised environmental concerns owing to its solubility in aqueoussolutions and reported toxicity. Poly(4-vinylpyridine hydrochloride) / Cross- PV-HCl / DVB exhibited remarkable linked with divinyl separation efficiency while posing benzene fewer environmental risks, primarily (PV-HCl / DVB) because of its insolubility in aqueous solutions and ease of recovery.

[0285] The embodiments described herein are intended to be examples only. Alterations, modifications, and / or variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.

[0286] The aspects, embodiments, and / or examples of the present disclosure being thus described, it should be recognized that said aspects, embodiments, and / or examples may be varied in ways that do not depart from the spirit and scope of the present disclosure, and that said variations are intended to be included within the scope of the following claims.

[0287] All publications, patents and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication patent, or patent application was specifically and individually indicated to be incorporated by reference.

Claims

WHAT IS CLAIMED IS:

1. An organo-metallic complex, comprising at least one ligand coordinating an early transition metal, the ligand comprising a cyclic imidedioxime, and the early transition metal comprising vanadium.

2. The complex of claim 1, wherein the cyclic imidedioxime comprises one or more of the structures.

3. The complex of any one of claims 1-2, wherein the early transition metal comprises an oxide of the early transition metal.

4. The complex of any one of claims 1-3, wherein the early transition metal comprises pentavalent vanadium (V(V)).

5. The complex of any one of claims 1-4, wherein the early transition metal oxide has the structure VO2(OH)2, VO3OH2-, or a combination thereof.

6. The complex of any one of claims 1-5, wherein the organo-metallic complex has the structure:.

7. The complex of any one of claims 1-6, wherein the organo-metallic complex is unsupported.

8. A method of synthesizing an cyclic imidedioxime ligand, the method comprising reacting a halo-functionalized cyclic compound in the presence of a cyanation reagent to form a cyano-functionalized cyclic compound; and reacting the cyano-functionalized cyclic compound in the presence of hydroxylamine to form a cyclic imidedioxime ligand.

9. The method of claim 8, wherein the halo-functionalized cyclic compound is substituted or unsubstituted.

10. The method of any one of claims 8-9, wherein the halo-functionalized cyclic compound comprises a cycloalkyl halide, a polycyclic alkyl halide, an aryl halide, a polycyclic aryl halide, or a combination thereof.

11. The method of any one of claims 8-10, wherein the halo-functionalized cyclic compound comprises one or more halo substituents, wherein the halo substituentcomprises a chloro substituent, a bromo substituent, an iodo substituent, or a combination thereof.

12. The method of any one of claims 8-11, wherein the halo-functionalized cyclic compound comprises 1,8-dibromonaphthalene, 1,9-dibromoanthracenes, or a combination thereof; each of which may be substituted or unsubstituted.

13. The method of any one of claims 8-12, wherein the cyanation reagent comprises Cu(I)CN, potassium ferrocyanide, sodium cyanide, nickel cyanide, trimethyl silyl cyanide, potassium ferriccyanide, acetone cyanohydrin, potassium ferrocyanide trihydrate, zinc cyanide, potassium cyanide, hydrocyanic acid, sodium nitroprusside, benzoyl cyanide, 2,2- dimethylpropanenitrile, cyanuric chloride, malonitrile, N-cyano-4-methyl-N- phenylbenzenesulfonamide, 4-methylbenzenesulfonylcyanide, ethyl cyanoacetate, butyronitrile, 2-phenylpropionitrile, tert-butyl isocyanide, ammonium cyanide, ethanedinitrile, or a combination thereof.

14. The method of any one of claims 8-12, wherein the cyano-functionalized cyclic compound is substituted or unsubstituted.

15. The method of any one of claims 8-14, wherein the cyano-functionalized cyclic compound comprises a cycloalkyl nitrile, a polycyclic alkyl nitrile, an aryl nitrile, a polycyclic aryl nitrile, or a combination thereof.

16. The method of any one of claims 8-15, wherein the cyano-functionalized cyclic compound comprises one or more nitrile substituents.

17. The method of any one of claims 8-16, wherein the cyano-functionalized cyclic compound comprises substituted or unsubstituted 1,8-naphthalenedicarbonitrile.

18. The method of any one of claims 8-17, wherein reacting a halo-functionalized cyclic compound in the presence of a cyanation reagent comprises reacting at a temperature between about 100 to about 140 °C, optionally in the presence of a polar aprotic solvent.

19. The method of any one of claims 8-18, wherein reacting the cyano-functionalized cyclic compound in the presence of hydroxylamine comprises reacting at a temperature between about 70 to about 100 °C, optionally in the presence of a polar protic solvent.

20. The method of any one of claims 8-20, wherein the cyclic imidedioxime has the structure.

21. A method of extracting vanadium, the method comprising providing a cyclic imidedioxime (CID) ligand into a solution comprising vanadium (V) to form an V-CID complex; and precipitating the V-CID complex.

22. The method of claim 21, wherein providing a cyclic imidedioxime (CID) ligand into a solution comprising vanadium comprises providing the cyclic imidedioxime (CID) ligand into a solution having a pH between <7 to about 3; or a pH <3.

23. The method of claim 21, wherein precipitating the V-CID complex comprises decreasing pH of the solution to precipitate the V-CID complex.

24. The method of claim 23, wherein decreasing the pH comprises decreasing the pH to <7; or <7 to about 3; or <3.

25. The method of claim 21, wherein precipitating the V-CID complex comprises contacting the V-CID complex with a cationic polymer comprising aromatic rings.

26. The method of claim 25, wherein the cationic polymer comprising aromatic rings comprises poly(4-vinylpyridine hydrochloride) / Cross-linked with divinyl benzene; poly(styrene)-b-poly(4-vinyl pyridine, quaternized with methyl iodide); Amberlite IRA-402; or a combination thereof.

27. The method of any one of claims 21-26, further comprising isolating the precipitated V-CID complex, and contacting the V-CID complex with a eluant for decomplexing the vanadium from the CID ligand.

28. The method of any one of claims 21-27, further comprising isolating the decomplexed vanadium; and incorporating the decomplexed vanadium into a saleable product.

29. The method of any one of claims 27-28, wherein the saleable product comprises batteries, or steel.

30. The method of any one of claims 21-29, further comprising isolating the decomplexed vanadium; preparing a catalyst from the decomplexed vanadium; and using the vanadium catalyst in a chemical process.

31. The method of any one of claims 21-30, wherein the chemical process comprises epoxidation; oxidative bromination, alcohol oxidation, catalytic hydrogenation, oxidative dehydrogenation, dioxygen activation, polymerization reactions, halide abstraction; or a combination thereof.

32. The method of any one of claims 21-31, wherein the cyclic imidedioxime ligand comprises one or more of the structures, , or .

33. The method of any one of claims 21-32, wherein the vanadium in the solution comprising vanadium comprises pentavalent vanadium (V(V)).

34. The method of any one of claims 21-33, wherein the vanadium in the solution comprising vanadium comprises the structure VO2(OH)2, VO3OH2-, or a combination thereof.

35. The method of any one of claims 21-34, further comprising reducing the decomplexed vanadium from V(V) to V(III); reducing the decomplexed vanadium from V(V) to V(0); or a combination thereof.

36. The method of any one of claims 21-35, wherein the V-CID complex has the structure:.

37. The method of any one of claims 21-36, wherein the V-CID complex is unsupported.

38. The method of any one of claims 21-37, wherein the solution comprising vanadium further comprises Fe, Cr, Cu, Ni, Zn, or a combination thereof, and forming the V-CID complex comprises the cyclic imidedioxime ligand selectively complexing the vanadium.

39. The method of any one of claims 21-38, wherein the solution comprising vanadium comprises wastewaters, oil sand tailings, mining waste streams, vanadium shale, black shale, spent catalysts, vanadium-contaminated carbon black, stone coal, fuel oil, grades fuels, ores, metal alloys, batteries, or a combination thereof.

40. The method of any one of claims 21-39, further comprising forming the solution comprising vanadium.

41. The method of any one of claims 21-40, wherein forming the solution comprising vanadium comprises forming the solution from wastewaters, oil sand tailings, mining waste streams, vanadium shale, black shale, spent catalysts, vanadium-contaminated carbon black, stone coal, fuel oil, grades fuels, ores, metal alloys, batteries, or a combination thereof.

42. The method of any one of claims 21-41, wherein the eluant comprises an acidic solution.

43. The method of claim 42, wherein the acidic solution comprises an acidic thiourea solution.

44. The method of any one of claims 21 to 43, wherein the cyclic imidedioxime (CID) ligand provided into the solution comprising vanadium (V) is a cyclic imidedioxime (CID) synthesized by the method of any one of claims 8 to 20.

45. Use of vanadium extracted by the method of any one of claims 21 to 44 for production of saleable products.

46. Use of vanadium extracted by the method of any one of claims 21 to 44 in catalysis.

47. Use of the cyclic imidedioxime ligand synthesized by the method of any one of claims 8 to 20 for vanadium extraction.

48. Use of the cyclic imidedioxime ligand synthesized by the method of any one of claims 8 to 20 for forming a vanadium- cyclic imidedioxime ligand complex.

49. Use of the organo-metallic complex of any one of claims 1 to 7 as a catalyst.

50. Use of the organo-metallic complex of any one of claims 1 to 7 as an epoxidation catalyst.

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