Method of synthesizing a 1,6-diazabicyclo[4.4.4]tetradecan-1,6-IUM cationic structure, use of said cationic structure in electrochemical applications, and polymers comprising said cationic structure

Abstract

A method of synthesizing 1,6-diazabicyclo[4.4.4]tetradecan-1,6-ium (in-DBD) cationic structure, a method of integrating in-DBD cationic structure into a polymer, and the use of in-DBD polymers in electrochemical applications such as an anion exchange membrane (AEM) are described. The configuration of in-DBD allows a cationic charge to be carried by a proton stabilized inside an aliphatic cage formed by its three-dimensional structure and anchored between two nitrogen atoms via a symmetrical intra-bridgehead hydrogen bond. With the synthesis method of in-DBD and its application in various scenarios, an organic cation-hydroxide is realized that persists at critically low hydration levels and high temperatures (<10% RH at 80 °C) and shows orders of magnitude higher hydroxide stability than conventional cations.

Description

METHOD OF SYNTHESIZING A 1 ,6-DIAZABICYCLO[4.4.4]TETRADECAN-1 ,6-IUM CATIONIC STRUCTURE, USE OF SAID CATIONIC STRUCTURE IN ELECTROCHEMICAL APPLICATIONS, AND POLYMERS COMPRISING SAID CATIONIC STRUCTURETECHNICAL FIELD

[0001] The present disclosure is directed to a method of synthesizing a 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium (in-DBD) cationic structure, polymers comprising an in-DBD cationic structure, and use of in-DBD cationic structures in electrochemical applications such as anion exchange membranes (AEM), catalyst inks, catalyst-coated membranes, fuel cells, water electrolyzers, and carbon dioxide and / or carbon monoxide electrolyzers.BACKGROUND

[0002] The cost of electrochemical devices such as proton exchange membrane fuel cells and water electrolyzers strongly correlates with the cost of platinum group metal electrocatalysts used therein to avoid degradation in highly acidic media. Electrocatalysis in alkaline environments permits less expensive metals to be used but requires anion exchange membranes (AEMs) containing a polymerwith fixed cationic functional groups to serve as a conductor of hydroxide ions.

[0003] Operating electrochemical devices in alkaline environments is challenging as the nucleophilic nature of hydroxide tends to degrade organic molecules and polymers. This degradation risk amplifies under conditions of decreased relative humidity (RH). Certain AEM technologies, such as high- temperature or dry-cathode operated AEM water electrolyzers, AEM fuel cells, and CO / CO2 electrolyzers have been explored, but are dependent on humidified gas inputs. However, localized dehydration zones can emerge during their operation. Dry conditions and elevated temperatures can heighten alkalinity within the AEM, potentially leading to accelerated degradation of organic cations.

[0004] Efforts have been made to stabilize organic cations. Steric protection strategies have been researched, with specific studies on enhancing the stability ofimidazolium cations. Other research avenues have included the stabilization of ammonium cations using distinct configurations and by managing alkyl-chain lengths.

[0005] Despite some advancements, the lifetimes of known AEMs remain too short for many commercial applications, especially those applications which are prone to low-hydration conditions and elevated temperatures, such as those encountered in AEM fuel cells, which typically operate at 80 °C and where water is consumed at and electro-osm otical ly dragged away from the cathodic catalyst layer. These low- hydration conditions can be minimized by strictly controlling the input humidity, limiting the current density, and designing membrane-electrode assemblies to retain water, but these increase module cost and lower performance.

[0006] Presently, a few cations, namely N,N-dimethylpiperidin-1-ium (DMP), 1 ,3-dimethyl-2-mesityl-4,5-diphenyl-1 H-imidazol-3-ium (MMI), and benzyltrimethylammonium (BTMA), have been implemented in commercial AEMs. The most hydroxide-stable known organic cations are 6-azaspiro[5.5]undecan-6-ium (ASU), 1 ,3-dibutyl-2-mesityl-4,5-diphenyl-1 H-imidazol-3-ium (BMI), and tetrakis(cyclohexyl(methyl)amino)phosphonium (TCAP). Although highly stable under caustic conditions when fully hydrated, no known organic cations are considered sufficiently stable overextended periods in vapor-phase AEM applications. Moreover, no known stable organic cation has a sufficiently low molecular weight to enable the formation of materials with sufficient charge carrier density to create AEMs with high ion exchange capacity (IEC) and high ionic conductivity; BMI and TCAP are both relatively large cations, with a low charge-to-mass ratios having lECs of 2.13 meq / g and 2.01 meq / g, respectively, and thus less relevant to low-hydration applications.

[0007] The work of R. W. Alder, et al. (Inside- and outside-protonated ions from 1,6-diazabicyclo[4.4.4]tetradecane. Journal of the American Chemical Society. 101 , 3652-3653 (1978)) disclosed 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium (in-DBD), a cationic structure bearing an endohedrally trapped proton. While Aider's work was pioneering, it was caught in a web of complexity. The processes described therein were highly complicated, often required the use of hazardous chemicals, and lacked concrete experimental support for the claimed stability of in-DBD. This made themethodology not only potentially dangerous, but also challenging for scalable production.

[0008] It is therefore an objective of the present invention to provide a new and improved approach to produce hydroxide stable organic cation structures that are commercially viable candidates for electrochemical applications, including incorporation into polymers and AEMs used in alkaline environments.SUMMARY

[0009] According to a first aspect of the disclosure, there is provided a method of synthesizing 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium (in-DBD), comprising: i) oxidizing maleic hydrazide with in the presence of, or before mixing with, 1 ,3-butadiene to produce 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione; ii) hydrogenating 1 ,6- diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione; iii) reducing the hydrogenated 1 ,6- diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione with a reducing agent to produce 1 ,6- diazabicyclo[4.4.0]decane; iv) singly-alkylating 1 ,6-diazabicyclo[4.4.0]decane with a 1 ,4-substituted butane derivative having leaving groups at the 1 and 4 positions; v) cyclizing the singly-alkylated 1 ,6-diazabicyclo[4.4.0]decane by addition into a metal salt to produce 1 ,6-diazatricyclo[4.4.4.01’6]tetradec-1 ,6-diylium tetrafluoroborate; vi) reducing an N-N bond of 1 ,6-diazatricyclo[4.4.4.01’6]tetradec-1 ,6-diylium by a reducing metal, excluding sodium, in acidic media to produce an outside-protonated DBD tetrafluoroborate salt; and vii) inside-protonating the outside-protonated DBD tetrafluoroborate salt by oxidation with a one-electron oxidant in acidic media to produce the in-DBD.

[0010] Step i) can be isolated through an extraction and recrystallized in a solvent selected from a group consisting of dichloromethane (DCM), toluene, and diethyl ether.

[0011] The reducing agent in step iii) can be selected from a group consisting of LiAlhU, NaBH4, Diisobutylaluminium hydride (DIBAL-H), and EtsSiH, or comprising a Wolff-Kishner reduction. The 1 ,4-substituted butane derivative in step iv) can be 1 ,4- dibromobutane, 1 ,4-diiodobutane, or 1 ,4-dichlorobutane. The 1 ,4-substituted butane derivative in step iv) can have a substituent at one or more of 2-position or 3-positionof the butane chain. The reducing metal in step vi) can be selected from a group consisting of zinc, magnesium, and aluminum. The one-electron oxidant in step vii) can be a peroxydisulfate salt, wherein a cation of the peroxydisulfate salt is selected from a group consisting of potassium (K+), sodium (Na+), ammonium (NH4+), and lithium (Li+). Alternatively, the one-electron oxidant in step vii) can be selected from a group consisting of hydrogen peroxide (H2O2), benzoyl peroxide, and their salts. The solvent in step iv) can be tetrahydrofuran (THF). The metal salt in step v) can be silver tetrafluoroborate (AgBF4). The acidic media in step vi) or vii) can comprise tetrafluoroboric acid (HBF4). The acidic media utilized in steps vi) and vii) can be the same acidic media.

[0012] The outside-protonated DBD tetrafluoroborate salt produced in step vi) can be air-stable, and the reduction in step vi) and the inside-protonation in step vii) can be performed sequentially without isolating the outside-protonated DBD tetrafluoroborate salt.

[0013] According to another aspect of the disclosure there is provided a method of integrating in-DBD into a polymer. The method comprises: i) polymerizing a bicycloheptene monomer comprising bromomethyl groups using a vinyl-addition polymerization catalyst in a first solvent to produce a brominated polymer; ii) reacting the brominated polymer with 1 ,6-diazabicyclo[4.4.0]decane in a second solvent to produce a polymer with pendant bicyclo[4.4.0]decane groups; iii) reacting the polymer with pendant bicyclo[4.4.0]decane groups with a silver salt in a third solvent, wherein the silver salt forms an insoluble salt with bromomethyl groups of the polymer; iv) reacting the product of step iii) with a reducing metal in an acidic solvent to produce a polymer with pendant reduced groups; and v) reacting the polymer with pendant reduced groups with an oxidizing agent to produce a polymer comprising integrated in-DBD.

[0014] The vinyl-addition polymerization catalyst can be selected from a group consisting of palladium catalysts, nickel catalysts, and combinations thereof, and wherein the first solvent in step i) is selected from a group consisting of toluene, dichloromethane, and ethers. The second solvent in step ii) can be selected from a group consisting of tetrahydrofuran, toluene, dichloromethane, and ethers. The silversalt in step iii) can be selected from a group consisting of silver tetrafluoroborate, silver nitrate, and silver fluoride, and the third solvent in step iii) is selected from a group consisting of tetrafluoroboric acid, water, and nitric acid. The reducing metal in step iv) can be selected from a group consisting of zinc, aluminum, and magnesium, and wherein the acidic solvent in step iv) is selected from a group consisting of tetrafluoroboric acid, sulfuric acid, and hydrochloric acid. The oxidizing agent in step v) can be a one-electron oxidant, and wherein the one-electron oxidant is a peroxydisulfate with a cation selected from a group consisting of potassium (K+), sodium (Na+), ammonium (NH4+), and lithium (Li+). The brominated polymer in step i) can be Poly[(5S,6S)-5,6-bis(bromomethyl)bicyclo[2.2.1]hept-2-ene], and a catalyst to monomer ratio in step i) can range from 1 :50 to 1 :50000.

[0015] According to another aspect of the disclosure there is provided a method of integrating in-DBD into a polymer. The method comprises: i) reacting a bicycloheptene monomer comprising bromomethyl groups with 1 ,6- diazabicyclo[4.4.0]decane in a first solvent to produce a first intermediate product; ii) reacting the first intermediate product with a silver salt in a second solvent to form a second intermediate product; iii) reacting the second intermediate product with a reducing metal in an acid solvent to produce a third intermediate product; iv) reacting the third intermediate product with an oxidizing agent to produce a fourth intermediate product; and v) reacting the fourth intermediate product with a vinyl-addition polymerization catalyst in a third solvent to produce a polymer comprising integrated in-DBD.

[0016] The first solvent in step i) can be selected from the group consisting of tetrahydrofuran, toluene, dichloromethane, and ethers. The silver salt in step ii) can be selected from the group consisting of silver tetrafluoroborate, silver nitrate, and silver fluoride. The acid solvent in step iii) can be selected from the group consisting of tetrafluoroboric acid, sulfuric acid, and hydrochloric acid, and wherein the reducing metal in step iii) is selected from the group consisting of zinc, aluminum, and magnesium. The oxidizing agent in step iv) can be potassium peroxydisulfate. The third solvent in step v) can be selected from the group consisting of toluene, dichloromethane, and ethers, and the vinyl-addition polymerization catalyst in step v)can be selected from the group consisting of palladium and nickel catalysts. The catalyst to monomer ratio in step v) can range from 1 :50 to 1 :50000.

[0017] According to another aspect of the disclosure there is provided in-DBD polymer comprising: a polymer matrix; and 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium (in-DBD) cationic structure integrated into the polymer matrix. A cationic charge of the in-DBD cationic structure is carried by an immobilized proton inside an aliphatic cage formed by a three-dimensional structure of the in-DBD cationic structure and is stabilized between two nitrogen atoms of the in-DBD cationic structure via a symmetrical intra-bridgehead hydrogen bond.

[0018] The polymer matrix can be selected from a group consisting of: polysulfones, polyphenylenes, poly(arylene ether ketones), poly(phenylene oxides), polyethylenes, polypropylenes, polystyrenes, polybenzimidazoliums, and polynorbornenes. The polymeric matrix can connect to the in-DBD cationic structure at multiple locations.

[0019] According to another aspect of the disclosure there is provided an in- DBD polymer ionic exchange membrane comprising the in-DBD polymer.

[0020] According to another aspect of the disclosure there is provided an in- DBD catalyst ink comprising a catalyst material, water, an organic solvent, and the in- DBD polymer.

[0021] According to another aspect of the disclosure there is provided an in- DBD catalyst coated membrane comprising a polymer ion exchange membrane coated with the in-DBD catalyst ink, or the in-DBD polymer ionic exchange membrane coated with a conventional catalyst ink or the in-DBD catalyst ink.

[0022] According to another aspect of the disclosure there is provided a membrane electrode assembly comprising an anode layer, a cathode layer, and the in-DBD polymer ionic exchange membrane.

[0023] According to another aspect of the disclosure there is provided a fuel cell comprising at least one of the in-DBD polymer ionic exchange membrane, the in-DBD catalyst ink, and the in-DBD catalyst coated membrane.

[0024] According to another aspect of the disclosure there is provided an electrolyzer comprising at least one of the in-DBD polymer ionic exchange membrane, the in-DBD catalyst ink, and the in-DBD catalyst coated membrane.

[0025] According to another aspect of the disclosure there is provided a use of in-DBD as a cationic functional group for the preparation of an anion exchange membrane (AEM), wherein a cationic charge of the in-DBD is carried by an immobilized proton inside an aliphatic cage formed by a three-dimensional structure of the in-DBD and is stabilized between two nitrogen atoms of the in-DBD via a symmetrical intra-bridgehead hydrogen bond.

[0026] This summary does not necessarily describe the full scope of all aspects. Other aspects, features and advantages will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the accompanying drawings, which illustrate one or more exemplary embodiments:

[0028] FIG. 1 illustrates1H Nuclear Magnetic Resonance (NMR) of 1 ,6- diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione in CDCh.

[0029] FIG. 2 illustrates1H NMR of 1 ,6-diazabicyclo[4.4.0]decan-2, 5-dione in CDCh. Residual dichloromethane solvent signal marked by CH2CI2.

[0030] FIG. 3 illustrates1H NMR of 1 ,6-diaza-1-(4-bromobutyl)bicyclo[4.4.0] decan-1 -ium bromide in D2O.

[0031] FIG. 4 illustrates1H NMR of 1 ,6-diazatricyclo[4.4.4.01’6]tetradecan-1 ,6- diylium tetrafluoroborate in D2O.

[0032] FIG. 5 illustrates1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1-ium tetrafluoroborate in D2O. Residual diethyl ether solvent signals marked by Et20.

[0033] FIG. 6 illustrates1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate in D2O. Residual diethyl ether and methanol solvent signals marked by Et20 and CH3OH, respectively.

[0034] FIG. 7 illustrates13C NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate in D2O.

[0035] FIG. 8 illustrates19F NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate in D2O.

[0036] FIG. 9 illustrates1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride in CD3OD.

[0037] FIG. 10 illustrates13C NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride in CD3OD.

[0038] FIG. 11 illustrates19F NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride in CD3OD.

[0039] FIG. 12 illustrates thermogravimetric analysis of in-DBD Cl under nitrogen atmosphere at a ramp speed of 10 °C per minute. Grey line indicates 95% of the original mass, which defines the approximated degradation temperature of 388 °C.

[0040] FIG. 13 illustrates NMR spectroscopic degradation study of organic cations. (A) Percent cation remaining vs. time, measured relative to NaDSS internal standard. The lines are a guide to the eye. (B) Half-life of cations, estimated from rate of degradation. Degradation studies were conducted in dry CD3OD with KOH (2M), 0.03 M analyte and 0.03 M NaDSS internal standard.

[0041] FIG. 14 illustrates1H NMR spectra of BTMA on day 0 of the NMR degradation test. Circles show proton signals from BTMA and the squares show proton signals from the NaDSS internal standard.

[0042] FIG. 15 illustrates stacked1H NMR of experiment blank; 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. Peaks around 1.2 ppm are a contaminant found in all tested commercial sources of KOH and NaOH (multiple batches and suppliers), and were found to not change over the course of the experiment and did not appear to interfere with the study.

[0043] FIG. 16 illustrates stacked1H NMR of benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0044] FIG. 17 illustrates expanded, stacked1H NMR spectra of benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0045] FIG. 18 illustrates day 291H NMR spectra of benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the29 days. Overlay shows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0046] FIG. 19 illustrates stacked1H NMR of 1 ,3-dimethyl-2-mesityl-4,5- diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0047] FIG. 20 illustrates expanded, stacked1H NMR spectra of 1 ,3-dimethyl- 2-mesityl-4,5-diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0048] FIG. 21 illustrates day 291H NMR spectra of 1 ,3-dimethyl-2-mesityl-4,5- diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 29 days. Overlay shows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0049] FIG. 22 illustrates stacked1H NMR of 1 ,1-dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0050] FIG. 23 illustrates expanded, stacked1H NMR spectra of 1 ,1- dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. The region in the box was increased in intensity to show the small amount of elimination product that was formed.

[0051] FIG. 24 illustrates day 301H NMR spectra of 1 ,1-dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 30 days. Overlayshows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0052] FIG. 25 illustrates stacked1H NMR of 6-azaspiro[5.5]undecan-6-ium bromide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0053] FIG. 26 illustrates expanded, stacked1H NMR spectra of 6- azaspiro[5.5]undecan-6-ium bromide (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0054] FIG. 27 illustrates day 291H NMR spectra of 6-azaspiro[5.5]undecan-6- ium bromide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 29 days. Overlay shows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0055] FIG. 28 illustrates stacked1H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0056] FIG. 29 illustrates expanded, stacked1H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0057] FIG. 30 illustrates day 291H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 29 days. Overlay shows the remaining analytepeaks (circles), and degradation product peaks are not observed so could not be highlighted.

[0058] FIG. 31 illustrates stacked1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan- 1 , 6-ium [inside proton] tetrafluoroborate (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0059] FIG. 32 illustrates expanded, stacked1H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. The region in the box was increased in intensity to show the region where elimination degradation products should show up.

[0060] FIG. 33 illustrates percent cation remaining of in-DBD is its chloride and BF4- ion-form.

[0061] FIG. 34 illustrates (A) Stacked19F NMR of sodium tetrafluoroborate (molarity) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (molarity) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. (B) Ratio of the integration of the BFs(OH) degradation product signal to the BF4signal.

[0062] FIG. 35 illustrates NMR stability plot of cation remaining over time for benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data, for the first 10 days.

[0063] FIG. 36 illustrates NMR stability plot of cation remaining over time for 1 ,3-dimethyl-2-mesityl-4,5-diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.

[0064] FIG. 37 illustrates NMR stability plot of cation remaining over time for 1 , 1 -dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.

[0065] FIG. 38 illustrates NMR stability plot of cation remaining over time for 6- azaspiro[5.5]undecan-6-ium bromide (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.

[0066] FIG. 39 illustrates NMR stability plot of cation remaining over time for 1 ,6-diazabicyclo[4.4.4]tetradecan-1 , 6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.

[0067] FIG. 40 illustrates Dynamic Vapor Sorption (DVS) degradation studies of cation-hydroxides. DVS mass as a function of time upon lowering RH for (A) in-DBD OH, (B) DMP OH, (C) ASU OH, and (D) MMI OH, all at 80 °C.

[0068] FIG. 41 illustrates DVS stability tests of the fully volatilized cationhydroxides. (A) The normalized mass loss over time (B) The extracted half-life of the cations at 11 % RH and 80 °C.

[0069] FIG. 42 illustrates (A) Raw relative humidity vs time of DVS studies and (B) the last 30 minutes of each new (or reference) RH.

[0070] FIG. 43 illustrates DVS analysis of in-DBD hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0071] FIG. 44 illustrates stacked1H NMR spectra of in-DBD hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide- exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0072] FIG. 45 illustrates DVS analysis of DMP hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment.The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0073] FIG. 46 illustrates stacked1H NMR spectra of DMP hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide-exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0074] FIG. 47 illustrates DVS analysis of ASU hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0075] FIG. 48 illustrates stacked1H NMR spectra of ASU hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide-exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0076] FIG. 49 illustrates DVS analysis of MMI hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0077] FIG. 50 illustrates stacked1H NMR spectra of MMI hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide-exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0078] FIG. 51 illustrates stacked1H NMR spectra of the four cations hydroxides, taken after their respective DVS experiment and allowed to carbonate. Arrows point to common impurity / artifact arising from the experiment, not from degradation products.

[0079] FIG. 52 illustrates extracted onset and substantial degradation of the cation-hydroxides, measured from the DVS tests at 80 °C. The estimated A levels, defined as a ratio of water to hydroxide, are obtained from the in-DBD hydroxideisotherm shown below. The light bars represent the RH that no degradation was observed, the dashed bars represent the region where the mass loss at the specified RH was greater than 0.4 % and less than 2 % over 1 hour. The dark bars represent the RHs that over 2% mass loss was observed per hour. The horizontal box represents the defined critical conditions of 30% to 10% RH.

[0080] FIG. 53 illustrates (A) DVS analysis of in-DBD hydroxide at decreasing relative humidity levels at 60 °C. (B) The last 30 minutes of each RH step plotted. The two grey regions represent the 30-10 and 10-0% RH conditions, respectively. The shading represents the RHs where degradation occurs, and the number beside is the first RH that substantial degradation was observed. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0081] FIG. 54 illustrates (A) Humidity isotherms of in-DBD hydroxide at 60 °C and 80 °C, with estimations of hydration numberfrom the slope to 0% RH. (B) Humidity isotherms of the four cation-hydroxides studied with the raw mass vs relative humidity (due to insufficient stability to estimate mass at 0% RH for all ions except in-DBD).

[0082] FIG. 55 illustrates DVS control analysis of MMI iodide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0083] FIG. 56 illustrates stacked1H NMR spectra of MMI iodide before and after the DVS experiment. *the small amount of residual DMSO was removed by the gas flow of the experiment, and is represented in the small amount of mass loss.

[0084] FIG. 57 illustrates DVS mass traces of ASU hydroxide vs time at 80 °C. (A) experimental mass and RH trace over the course of the experiment, and (B) mass and RH traces of the data after the RH was stabilized for each measurement. The dashed line represents the reference (stable) 55% RH before degradation, and the dashed-dot line represents the initial mass at the test 11 % RH. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0085] FIG. 58 illustrates DVS mass traces of DMP hydroxide vs time at 80 °C. (A) experimental mass and RH trace over the course of the experiment, and (B) mass and RH traces of the data after the RH was stabilized for each measurement. The dashed line represents the reference (stable) 55% RH before degradation, and the dashed-dot line represents the initial mass at the test 11 % RH. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0086] FIG. 59 illustrates DVS mass traces of in-DBD hydroxide vs time at 80 °C. (A) experimental mass and RH trace over the course of the experiment, and (B) mass and RH traces of the data after the RH was stabilized for each measurement. The dashed line represents the reference (stable) 55% RH before degradation, and the dashed-dot line represents the initial mass at the test 11 % RH. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0087] FIG. 60 illustrates1H NMR spectrum of the collected DVS out-gas of in- DBD after complete degradation, captured in 5% v / v acetic acid solution. The only identified product protons are labeled; the poor integration quality is assumed to be a result of tautomerization of the protonated nitrogen(s), and / or inversion of the nitrogen center causing multiple chemical environments. The circle at 17 ppm is shown to highlight the lack of the caged proton in the degradation product, indicating complete degradation.

[0088] FIG. 61 illustrates13C NMR spectrum of the collected DVS out-gas of in- DBD after complete degradation, captured in 5% v / v acetic acid solution. The only identified product carbons are labeled.

[0089] FIG. 62 illustrates positive-ion mass spectrogram of the collected DVS out-gas of in-DBD after complete degradation, captured in 5% v / v acetic acid solution. The only identified product is shown, with its theoretical m / z.

[0090] FIG. 63 illustrates DFT calculations of cations. (A) LUMO isosurfaces and (B) electrostatic potentials (ESP) of in-DBD. ESP is shown on a scale of Hartree atomic units, where more positive numbers represent a stronger positive potential, and higher electrophilicity. (C) Free energy difference between parent cations and degradation products, calculated in a water solvent continuum model. Experimentally-unobserved degradation products are shown as dotted lines. (D) The energy barrier required to deprotonate the caged proton of in-DBD. The structure shows the approach of OH- to the caged proton. DFT calculations were performed at wB97XD / 6- 31g(d.p) level of theory.

[0091] FIG. 64 illustrates calculated orbital isosurfaces of the HOMO and LUMO of in-DBD. Calculations were performed at the wB97XD / 6-31g(d.p) level of theory.

[0092] FIG. 65 illustrates Formation energy calculations of the relative energy of outside vs inside protonation for in-DBD (left two) and a typical proton sponge (right two). Calculations were performed at the wB97XD / 6-31g(d.p) level of theory.DETAILED DESCRIPTION

[0093] Embodiments disclosed herein relate generally to a new method of synthesizing an in-DBD cationic structure, and incorporating the in-DBD cationic structure into polymers for use in electrochemical applications such as anion exchange membranes (AEM), catalyst inks, catalyst-coated membranes, fuel cells, water electrolyzers, and carbon dioxide and / or carbon monoxide electrolyzers. The in-DBD cationic structure allows a cationic charge to be carried by a proton stabilized inside an aliphatic cage formed by its three-dimensional structure and anchored between two nitrogen atoms via a symmetrical intra-bridgehead hydrogen bond. With the synthesis method of in-DBD and its application in various electrochemical applications, an organic cation-hydroxide is realized that persists at critically low hydration levels and high temperatures (<10% RH at 80 °C) and shows orders of magnitude higher hydroxide stability than conventional cations.

[0094] Utilizing innovative chemical pathways and novel synthetic techniques, the new in-DBD synthesis method emphasizes safety, repeatability, and scalability. In particular, the present embodiments introduce a refined workshop procedure which not only bolsters scalability but also augments safety by eliminating the use of hazardous solvents like benzene and carbon tetrachloride. The workshop procedures also avoid time intensive distillation and instead simply filters and concentrates the reaction mixture, thereby reducing associated purification costs and enhancing scalability. The resulting in-DBD cationic structure, characterized by improved yieldsand consistent quality, demonstrated a significant advancement on prior art techniques for synthesizing in-DBD structures, and reveals new opportunities to integrate in-DBD cationic structures into polymers for electrochemical applications not previously apparent or straightforward.Synthesizing in-DBD

[0095] According to some embodiments, a method of synthesizing an in-DBD cationic structure comprises the following steps:Step 1 : oxidizing maleic hydrazide with in the presence of, or before mixing with, 1,3- butadiene to produce 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione

[0096] To initiate the synthesis, maleic hydrazide is combined with 1 ,3- butadiene in a suitable solvent selected from a group that does not react with the oxidant or otherwise influence the reaction, and includes, but is not restricted to, dichloromethane (DCM), toluene, and various ethers (such as diethyl ether), and excludes polar aprotic solvents (DMSO, DMF, acetone), alcoholic solvents and water which react with the lead acetate.

[0097] An oxidizing agent is introduced to assist the reaction, and more particularly to oxidize the maleic hydrazide to make a good dienophile, thereby allowing any diene (butadiene, isoprene, etc.) to react to make the key structure and whatever functionality is on the diene. The oxidizing agent may be chosen from agents such as lead tetraacetate (Pb(OAc)4), other metal-based oxidants, organic peroxides, or any other well-established oxidizing compounds. The proposed mechanism for the oxidizing agent is a concerted 2-electron oxidation; however, in the presence of a base, there are similar oxidations that could proceed via two one-electron oxidants.

[0098] Depending on the specific reactants and oxidants employed, the reaction temperature may range from as low as approximately -78°C to roomtemperature or even higher. Once mixed, the components are allowed to react until the desired conversion is achieved, with the progression of the reaction being monitored through techniques such as colorimetric assays, spectroscopy, or other pertinent analytical methods. Upon completion of the reaction, the mixture can be quenched using suitable agents, for instance, water or dilute aqueous solutions. Subsequently, the targeted product, 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione, is isolated and purified employing standard separation methodologies like extraction, filtration, or chromatography. The isolated compound may be further confirmed and characterized utilizing common analytical techniques, including, but not confined to, nuclear magnetic resonance (NMR), mass spectrometry, and infrared spectroscopy.

[0099] Notably, prior methodologies for Step 1 typically necessitated a workup process using an alumina gel column chromatography in carbon tetrachloride, followed by a recrystallization step in benzene, both of which pose notable safety and environmental concerns. The present disclosure substantially ameliorates these issues by introducing a refined workup procedure that solely requires extraction followed by straightforward recrystallization in a non-toxic solvent such as diethyl ether. This enhancement not only bolsters scalability by eschewing column chromatography but also augments safety standards by eliminating the use of hazardous solvents like benzene and carbon tetrachloride.

[0100] For clarity, the specific components mentioned in the chemical reactions, including Pb(OAc)4 and DCM, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step 2: hydrogenating 1,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione

[0101] 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione is combined with a suitable hydrogenation catalyst, which can be selected from a group including but not limited to palladium, platinum, and nickel. One skilled in the art will appreciate thereaction is a simple olefin hydrogenation and many suitable catalysts are available including palladium on charcoal (carbon) and Raney nickel (nickel nanoparticles).

[0102] This catalyst may be supported on a carbon substrate or remain unsupported. The reaction is facilitated in a solvent chosen from a group comprising, but not restricted to, water, ethyl acetate, alcohols, and ethers. However, it is expected that any solvent that dissolves the reagents and does not get hydrogenated will work.

[0103] Hydrogen gas is introduced into the mixture at atmospheric pressure or at an elevated pressure to facilitate the reaction. The reaction temperature can vary, with conditions ranging from about 0°C to ambient temperatures or even higher, contingent upon the chosen hydrogen pressures and catalyst(s). The reaction progress can be monitored using various techniques, such as colorimetric methods, spectroscopy, or other suitable analytical methods.

[0104] Once the reaction reaches completion, the catalyst can be separated using techniques known in the art, like filtration or decanting. This separation can occur post-quenching with an appropriate agent or without the need for quenching. Subsequently, the target product, 1 ,6-diazabicyclo[4.4.0]decan-2, 5-dione, is isolated and purified using traditional separation techniques like extraction, filtration, or chromatography.

[0105] The obtained product can be further characterized using conventional analytical methods, including but not limited to NMR, mass spectrometry, or infrared spectroscopy. Notably, in this step, the workup procedure was uniquely developed and presented as it had not been previously reported.

[0106] For clarity, the specific components mentioned in the chemical reactions, including Pd / C, H2 and H2O, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step 3: reducing 1 ,6-diazabicyclo[4.4.0]decan-2, 5-dione with a reducing agent to produce 1, 6-diazabicyclo[4.4.0]decane

[0107] Hydrogenated 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione is reduced with a suitable reducing agent such as lithium aluminum hydride (UAIH4), which is a strong hydride reducing agent and chelates to oxygen to allow alcohol group to further be reduced. Other reducing agents suitable for this reaction are commonly known to one skilled in the art, and for example include sodium borohydride or siliconhydrides to partially reduce and another lewis acid to fully reduce this group. Other ways to reduce a ketone could also be used, such as a Wolff-Kishner reduction, provided that the reaction can be done in a solvent that is easy to recover the product and the next reaction can be done directly in the same solvent (no isolation required).

[0108] In this embodiment, 1 ,6-diazabicyclo[4.4.0]decan-2, 5-dione is combined with a solvent suitable for LiAl H4 reductions, which include but are not limited to ethers such as tetrahydrofuran (THF), diethyl ether, dimethoxyethane, dioxane, and dibutyl ether. A suitable metal-hydride reducing agent is introduced to this mixture. The range of reducing agents can include lithium aluminum hydride, other metal hydrides, or any other hydride reducing agents recognized in the field. The employed solvent may be anhydrous, and oxygen exclusion is achieved through the use of an inert gas, such as nitrogen or argon. Reaction temperatures can vary from ambient conditions to the refluxing temperature of the selected solvent.

[0109] The progress of this reaction can be monitored using techniques like colorimetric methods, spectroscopy, or other appropriate analytical methods. Upon completion of the reaction, the mixture can be quenched using suitable agents, including water or dilute acids. Subsequently, the intended product, 1 ,6- diazabicyclo[4.4.0]decane, can either be isolated and purified through traditional methods like extraction, filtration, and chromatography or can be directly used for subsequent reactions without further purification. The final product can then be assessed using standard analytical tools, encompassing but not limited to NMR, mass spectrometry, or infrared spectroscopy.

[0110] It is noteworthy that, in contrast to previous literature which necessitated distillation of the product - a process that is both time and energy-intensive - the present disclosure introduces a workup procedure that circumvents this requirement. Instead, the reaction mixture can be simply filtered and concentrated, rendering it ready for the next step, thereby reducing associated purification costs and enhancing scalability.

[0111] For clarity, the specific components mentioned in the chemical reactions, including LiAIFU and THF, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step 4: singly-alkylating 1 ,6-diazabicyclo[4.4.0]decane with a 1 ,4-substituted butane derivative having leaving groups at the 1 and 4 positions in a solvent

[0112] 1 ,6-diazabicyclo[4.4.0]decane is combined with an appropriate solvent that does not react with either reagent, and include alkylating solvents tetrahydrofuran, dichloromethane, and acetonitrile. It should be appreciated however that the reaction can alternatively proceed without a solvent. Furthermore, other polar-aprotic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) can also be used.

[0113] A butane-derivative, wherein the 1 and 4 positions possess functional groups acting as effective leaving groups, is added to the mixture. This butane derivative may also encompass different functional groups at the 2 and 3 positions. Effective leaving groups can include, but are not confined to, halogens, tosylate, or mesylate groups. Within this embodiment, 1 ,4-dibromobutane is employed. Alternatively, 1 ,4-diiodobutane or 1 ,4-dichlorobutane may be employed. The reaction temperature can span from ambient conditions to the refluxing temperature of the solvent, or even exceed it when executed in a sealed apparatus. Monitoring of theprogression of the reaction is feasible through various techniques, including colorimetric methods, spectroscopy, or other relevant analytical procedures.

[0114] Upon reaction completion, the target compound, referred to in this embodiment as 1 ,6-diaza-1-(4-bromobutyl)bicyclo[4.4.0]decan-1-ium, may be isolated and refined through standard separation methods, such as extraction, filtration, or chromatography. The specific counterion, such as bromide, associated with the product may vary based on the selected leaving group. The final compound can be characterized using conventional analytical methods, such as NMR, mass spectrometry, or infrared spectroscopy.

[0115] Notably, previous literature often details the execution of this reaction using pure 1 ,4-dibromobutane and in substantial excess. The present disclosure illustrates a methodology that may involve a reduced quantity of 1 ,4-dibromobutane and enable the reaction to transpire within the prior reaction mixture. Such modifications potentially lead to decreased reagent-associated expenses and purification processes. Additionally, proceeding directly from the product of step 3 without interim isolation augments the scalability.

[0116] For clarity, the specific components mentioned in the chemical reactions, including 1 ,4-dibromobutane and THF, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step 5: cyclizing the singly-alkylated 1 ,6-diazabicyclo[4.4.0]decane by addition into a metal salt to produce 1 ,6-diazatricyclo[4.4.4.01-6]tetradec-1 ,6-diylium tetrafluoroborate

[0117] 1 ,6-diaza-1-(4-bromobutyl)bicyclo[4.4.0]decan-1-ium bromide is subjected to reaction with an appropriate silver salt in a selected solvent. A suitable silver salt is water soluble and can react with a halogen (bromine in this case) to forman insoluble silver-halide salt. The chosen silver salt exhibits solubility in the solvent and creates an insoluble compound when paired with the leaving group of the reactant. Concurrently, the solvent may be capable of dissolving both the silver salt and the reactant. Potential candidates for the silver salt encompass silver tetrafluoroborate, silver nitrate, and silver fluoride, among others. The salt can be generated in-situ or introduced separately. Possible solvents for this reaction range from tetrafluoroboric acid, water, and nitric acid, to various ethers. The reaction temperature is flexible, ranging from ambient conditions up to the solvent's refluxing temperature. Continual monitoring of the reaction's progression can be achieved through methods such as colorimetric analysis, spectroscopy, or other established analytical techniques.

[0118] Upon culmination of the reaction, the target compound, identified in this embodiment as 1 ,6-diazatricyclo[4.4.4.01’6]tetradecan-1 ,6-diylium tetrafluoroborate, can be isolated and refined using traditional separation methodologies, including extraction, filtration, or chromatography. It should be noted that the specific counterion, such as tetrafluoroborate, is not a critical determinant for the reaction's success. Subsequent characterization of the finalized compound can be undertaken using prevalent analytical tools, encompassing NMR, mass spectrometry, and infrared spectroscopy.

[0119] For clarity, the specific components mentioned in the chemical reactions, including Ag2O and HBF4, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step 6: reducing an N-N bond of 1 ,6-diazatricyclo[4.4.4.01-6]tetradec-1 ,6-diylium by a reducing metal, excluding sodium, in acidic media to produce an outside-protonated DBD tetrafluoroborate salt

[0120] In the described process, 1 ,6-diazatricyclo[4.4.4.01’6]tetradecan-1 ,6- diylium tetrafluoroborate is subjected to reaction with an appropriate reducing metal ina strong acid solvent. In one embodiment, the acid solvent may have a pH value equal to or less than 1. In another embodiment, the acid solvent may be a strong acid as known in the art that ionizes completely or almost completely, such as HCI, H2SO4, HNO3, HBr, and HBF4. Potential solvents encompass tetrafluoroboric acid, sulfuric acid, and hydrochloric acid, among others. Suitable reducing metals, excluding sodium due to its reactivity with water, include but are not limited to aluminum, magnesium, and zinc which all provide one-electron reduction products to form a salt. The reaction temperature is flexible, ranging from ambient conditions up to the solvent's refluxing temperature. The progression of the reaction can be tracked through established methods such as colorimetric analysis, spectroscopy, or other analytical techniques. Upon reaction completion, the target compound, identified in this embodiment as 1 ,6- diazabicyclo[4.4.4]tetradecan-1-ium [outside proton] tetrafluoroborate, can be isolated and refined using conventional separation methodologies, including extraction, filtration, or chromatography, or proceeded to the subsequent reaction without interim purification. Subsequent characterization of the finalized compound can be performed using common analytical tools, including NMR, mass spectrometry, and infrared spectroscopy.

[0121] This step presents an advantageous deviation from previous methodologies. Whereas previous techniques involved birch reduction conditions that made use of liquid ammonia and sodium metal - a combination posing potential safety challenges - the current method offers an advantageous approach. The reduction is achieved using metals such as zinc in an acidic medium, with tetrafluoroboric acid being one suitable option. However, it should be noted that other metals like magnesium and aluminum might also be effective, and other acids could be suitable. The conventional workup, which necessitated isolation of the uncharged product by sublimation in an air-free environment owing to its lack of air stability, has been improved in this method. The current strategy isolates the intermediate as the outside protonated salt, which demonstrates air stability. These modifications present a safer and more scalable approach, with the added benefit of potentially reduced associated costs. Moreover, the potential for conducting the subsequent reaction without prior product isolation further contributes to scalability and cost efficiencies.

[0122] For clarity, the specific components mentioned in the chemical reactions, including Zn and HBF4, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step 7: inside-protonating the outside-protonated DBD tetrafluoroborate salt by oxidation with a one-electron oxidant in acidic media to produce the in-DBDin-DBD

[0123] In this embodiment, 1 ,6-diazabicyclo[4.4.4]tetradecan-1-ium [outside proton] tetrafluoroborate undergoes a reaction with an appropriate oxidizing agent in a strong acid solvent. In one embodiment, the acid solvent may have a pH value equal to or less than 1. In another embodiment, the acid solvent may be a strong acid as known in the art that ionizes completely or almost completely, such as HCI, H2SO4, HNO3, HBr, and HBF4. Solvents encompass tetrafluoroboric acid, sulfuric acid, and hydrochloric acid, among others. A suitable oxidizing agent includes potassium peroxydisulfate, and one skilled in the art would understand that the mechanism for any peroxide is essentially the same, and different peroxides that are a one-electron oxidant and are stable enough to not explode on contact with the acid would also be suitable, such as benzoyl peroxide, and other organic peroxides.

[0124] Reaction temperatures are variable, ranging from ambient conditions to the refluxing temperature of the solvent. Reaction completion can be tracked using established techniques such as colorimetric methods, spectroscopy, or other pertinent analytical procedures. Post-reaction, the compound of interest, delineated in this instance as 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate, can be separated and refined through conventional methodologies, like extraction, filtration, or chromatography. Comprehensive characterization of the resulting product can be executed using common analytical tools, including NMR, mass spectrometry, and infrared spectroscopy.

[0125] This step presents an advantageous variation from conventional methodologies. Prior art literature lacked sufficient detail for reproducibility of the target molecule and lacked complete characterization data for this compound. The present method establishes novel reaction conditions to achieve synthesis of the target molecule, and provides a full suite of characterization to ensure the formation of the specified in-DBD compound. An additional advantage introduced by the present method is the capability to progress to this step directly from the previous reaction mixture, negating the need for intermediary purification. Such a direct progression is conducive to enhanced scalability and potential cost reductions in purification processes.

[0126] For clarity, the specific components mentioned in the chemical reactions, including K2S2O8 and HBF4, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Polymeric Structures Comprising in-DBD

[0127] The structure of the in-DBD molecule, as shown below, is defined such that R6 serves as a versatile functional group, which can range from a simple hydrogen atom to complex polymeric structures.

[0128] The uniqueness of R6 lies in its adaptability. Specifically, R6 has the potential to be a hydrogen atom, any functional group known in the realm of organic chemistry, or a segment of a polymer. When R6 embodies a polymeric structure, it introduces many possibilities for the integration of the in-DBD molecule into a wide range of polymeric matrices (herein referred to as “in-DBD polymers”). This adaptability paves the way for the development of materials with tailored properties suitable for specific applications.

[0129] Illustratively, common polymers compatible with electrochemical applications such as AEMs may include but are not limited to: polysulfones, polyphenylenes, poly(arylene ether ketones), poly(phenylene oxides), polyethylenes, polypropylenes, polystyrenes, polybenzimidazoliums, and polynorbornenes. The incorporation of the in-DBD cationic structure into these polymers can be executed in various configurations. For instance, R6 may connect to the polymer matrix at a singular point or it may establish multiple connections throughout the polymeric structure, thereby achieving an enhanced distribution of the in-DBD molecule within the matrix.

[0130] Furthermore, the mode of connection between the in-DBD molecule and the polymer matrix can be manifold. The in-DBD structure can be directly integrated into the polymer backbone, ensuring seamless compatibility. Alternatively, it can also be connected through various tethering mechanisms, known to those skilled in the art, offering flexibility in design and property optimization.Example 1 : Integration of in-DBD into a polymer

[0131] A first example for integrating in-DBD into a polymer is explained below:Step P1 : polymerizing a bicycloheptene monomer comprising bromomethyl groups using a vinyl-addition polymerization catalyst in a first solvent to produce a brominated polymer

[0132] (5S,6S)-5,6-bis(bromomethyl)bicyclo[2.2.1]hept-2-ene, which may be utilized in conjunction with a co-monomer, undergoes reaction with a suitable vinyladdition polymerization catalyst in a solvent. Possible solvents encompass toluene, dichloromethane, or ethers. Other suitable solvents for similar vinyl-addition norbornene polymerizations that are generally inert to the active catalyst may also be used. Appropriate vinyl-addition polymerization catalysts may comprise palladium or nickel catalysts, either standalone or in synergy with a known co-catalyst. The ratio ofcatalyst to monomer can be modulated to target specific molecular weights, with advantageous ratios ranging from 1 :50 to 1 :50000. The reaction temperature is variable, extending from ambient conditions to the solvent's reflux temperature or potentially higher. The reaction is conducted until deemed complete.

[0133] The evolution of the reaction can be periodically assessed using methods such as colorimetric techniques, spectroscopy, or other pertinent analytical approaches. Subsequent to the reaction's completion, the target product, Poly[(5S,6S)-5,6-bis(bromomethyl)bicyclo[2.2.1]hept-2-ene] in this particular embodiment, is isolated and refined utilizing standard polymer separation methodologies, including extraction, filtration, or precipitation. Characterization of the resultant product is achievable through conventional analytical tools. These encompass, but are not confined to, NMR, gel-permeation chromatography (GPC), and infrared spectroscopy.Step P2: reacting the brominated polymer with 1 ,6-diazabicycio[4.4.0]decane in a second solvent to produce a polymer with pendant bicyclo[4.4.0]decane groups

[0134] The product from P1 undergoes a reaction with 1 ,6- diazabicyclo[4.4.0]decane in a solvent that is polar and aprotic and will dissolve the polymer. Possible solvents include but are not restricted to tetrahydrofuran, toluene, dichloromethane, or ethers. The reaction temperature is variable, ranging from ambient conditions to the solvent's reflux temperature or potentially higher. The reaction is allowed to proceed until deemed complete.

[0135] The reaction's evolution can be periodically assessed using methods such as colorimetric techniques, spectroscopy, or other pertinent analytical approaches. Upon the conclusion of the reaction, the target product, denoted as P2 in this embodiment, is isolated and refined utilizing standard separation methodologies, including extraction, filtration, or chromatography. The resultant product is amenableto characterization via conventional analytical tools, encompassing, but not confined to, NMR, mass spectrometry, and infrared spectroscopy.Step P3: reacting the polymer with pendant bicyclo[4.4.0]decane groups with a silver salt in a third solvent, wherein the silver salt forms an insoluble salt with bromomethyl groups of the polymer

[0136] The product from P2 undergoes a reaction with an appropriate silver salt in a selected solvent. The appropriate silver salt is soluble in the solvent and capable of forming an insoluble salt with the leaving group of the reactant. Concurrently, the chosen solvent may possess the capability to dissolve both the silver salt and the reactant. Suitable silver salts for this process may comprise silver tetrafluoroborate, silver nitrate, and silver fluoride. These salts can either be generated in-situ or introduced separately. Solvents deemed suitable for this reaction may include tetrafluoroboric acid, water, nitric acid, and ethers, although this list is not exhaustive.

[0137] The reaction temperature exhibits flexibility, with a range that spans from ambient conditions to the refluxing temperature of the designated solvent. It is allowed for the reaction mixture to proceed until its conclusion. Monitoring of the progress of the reaction can be achieved via methodologies such as colorimetric techniques, spectroscopy, or other pertinent analytical methods.

[0138] Subsequent to the reaction's completion, the target product is isolated and refined employing standard separation methodologies, which may encompass extraction, filtration, or chromatography. Characterization of the final product can be performed using conventional analytical tools, such as but not limited to NMR, mass spectrometry, and infrared spectroscopy.

[0139] For clarity, the specific components mentioned in the chemical reactions, including AgBF4, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step P4: reacting the product of step Hi) with a reducing metal in an acidic solvent to produce a polymer with pendant reduced groups and reacting the polymer with pendant reduced groups with an oxidizing agent to produce a polymer comprising integrated in-DBD

[0140] The product from P3 is then subjected to a reaction with an appropriate reducing metal in a strong acid solvent. In one embodiment, the acid solvent may have a pH value equal to or less than 1 . In another embodiment, the acid solvent may be a strong acid as known in the art that ionizes completely or almost completely, such as HCI, H2SO4, HNO3, HBr, and HBF4.This solvent may encompass tetrafluoroboric acid, sulfuric acid, or hydrochloric acid among others. Possible reducing metals for this process may comprise zinc, aluminum, and magnesium, among others which provide one-electron reduction products to form a salt. The temperature at which this reaction is conducted is flexible, ranging from ambient conditions to the refluxing temperature of the chosen solvent. The mixture proceeds until perceived completion. Monitoring of this reaction phase can be achieved using various methodologies such as colorimetric techniques, spectroscopy, or other relevant analytical methods.

[0141] Subsequently, any excess reducing metal is separated using techniques which may include filtration or other appropriate methods. Thereafter, the reaction mixture is introduced to a selected oxidizing agent. A suitable oxidizing agent includes potassium peroxydisulfate, and one skilled in the art would understand that the mechanism for any peroxide is essentially the same, and different peroxides that are a one-electron oxidant and are stable enough to not explode on contact with the acidwould also be suitable, such as benzoyl peroxide, and various organic peroxides. The reaction temperature again exhibits flexibility, spanning from ambient conditions to the refluxing temperature of the solvent. The mixture is allowed to reach completion, with its progress being traceable through methods such as colorimetric techniques, spectroscopy, or other fitting analytical tools.

[0142] Following these steps, the target product undergoes isolation and purification. Standard methodologies, potentially including extraction, filtration, or chromatography, serve this purpose. Once obtained, the final product's characterization can be undertaken using common analytical instruments, which might encompass NMR, mass spectrometry, and infrared spectroscopy, among others.

[0143] For clarity, the specific components mentioned in the chemical reactions, including Zn and K2S2O8, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Example 2: Integration of in-DBD into a polymer

[0144] Another example of integrating in-DBD into a polymer is described below:Step M1 : reacting a bicycloheptene monomer comprising bromomethyl groups with 1 ,6-diazabicyclo[4.4.0]decane in a first solvent to produce a first intermediate product

[0145] (5S,6S)-5,6-bis(bromomethyl)bicyclo[2.2.1]hept-2-ene is subjected to a reaction with 1 , 6-diazabicyclo[4.4.0]decane. A suitable solvent for this reaction is polar and aprotic and will dissolve the polymer, and includes but is not restricted to tetrahydrofuran, toluene, dichloromethane, or ethers. Reaction temperature possesses flexibility, ranging from ambient conditions to the refluxing temperature of the chosen solvent or potentially higher. The mixture is allowed to progress until its perceived completion. Reaction monitoring can be achieved using a variety ofmethods, possibly including colorimetric techniques, spectroscopy, or other pertinent analytical tools.

[0146] Upon concluding the reaction, the targeted product undergoes a separation and purification phase. This can be achieved through established methodologies, potentially embracing extraction, filtration, or chromatography. Once isolated, the final product's characterization is possible using recognized analytical instruments. Such instruments might include NMR, mass spectrometry, and infrared spectroscopy, to name a few.Step M2: reacting the first intermediate product with a silver salt in a second solvent to form a second intermediate product

[0147] The product from M1 undergoes a reaction with a selected silver salt in an appropriate solvent. Advantageously, the silver salt exhibits solubility in the solvent and generates an insoluble salt with the leaving group of the reactant. Concurrently, the chosen solvent may accommodate both the silver salt and the reactant. A suitable silver salt is water soluble and can react with a halogen (bromine in this case) to form an insoluble silver-halide salt, and include but are not restricted to silver tetrafluoroborate, silver nitrate, and silver fluoride, with the option to be generated in- situ or introduced separately. Potential solvents may encompass tetrafluoroboric acid, water, nitric acid, or ethers, among others. Suitable solvents include tetrafluoroboric acid, water, nitric acid, and ethers, although this list is not exhaustive. The reaction temperature offers versatility, potentially spanning from ambient conditions to the refluxing point of the solvent.

[0148] As the reaction ensues, it is allowed to proceed until its perceived completion. Monitoring of the reaction's progression can be achieved through a rangeof methods, potentially encompassing colorimetric techniques, spectroscopy, or other relevant analytical approaches.

[0149] Upon reaction culmination, the target product undergoes a separation and purification phase through recognized methodologies, which might involve extraction, filtration, or chromatography. Once isolated, characterization of the final product is attainable using established analytical tools, potentially including NMR, mass spectrometry, and infrared spectroscopy, among others.

[0150] For clarity, the specific components mentioned in the chemical reactions, including AgBF4, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step M3: reacting the second intermediate product with a reducing metal in an acid solvent to produce a third intermediate product and reacting the third intermediate product with an oxidizing agent to produce a fourth intermediate product

[0151] The product from M2 is exposed to a reaction with an appropriate reducing metal in the presence of a strong acid solvent. In one embodiment, the acid solvent may have a pH value equal to or less than 1 . In another embodiment, the acid solvent may be a strong acid as known in the art that ionizes completely or almost completely, such as HCI, H2SO4, HNO3, HBr, and HBF4. A suitable solvent needs to be suitable for both the reduction and oxidation, and include but are not restricted to tetrafluoroboric acid, sulfuric acid, or hydrochloric acid. The reducing metal may be selected from candidates such as zinc, aluminum, or magnesium, among others. Reaction temperatures can span from ambient conditions to the reflux point of the chosen solvent.

[0152] During the reaction, it may be advantageous to allow the mixture to proceed until perceived completion. The course of the reaction can be observed and tracked through a variety of methods, including but not limited to colorimetric techniques, spectroscopy, or other applicable analytical methods. Any excess reducing metal present post-reaction can be conveniently removed through recognized methods, potentially involving filtration.

[0153] Subsequently, the reaction mixture is introduced to a chosen oxidizing agent. A suitable oxidizing agent includes potassium peroxydisulfate, and one skilled in the art would understand that the mechanism for any peroxide is essentially the same, and different peroxides that are a one-electron oxidant and are stable enough to not explode on contact with the acid would also be suitable. Suitable oxidizing agents for consideration may comprise benzoyl peroxide or other recognized organic peroxides or oxidizing agents. The reaction temperature remains versatile, potentially ranging from ambient conditions to the solvent's refluxing point.

[0154] As with the previous step, the reaction is advantageously allowed to continue until its completion, with its progression being monitored by means such as colorimetric methods, spectroscopy, or other fitting analytical techniques.

[0155] Upon finalizing the reaction, it is possible to separate and purify the intended product using well-established separation methodologies, which might include extraction, filtration, or chromatography. Once isolated, the final product's characterization is achievable through conventional analytical tools, potentially including NMR, mass spectrometry, and infrared spectroscopy, among others.

[0156] For clarity, the specific components mentioned in the chemical reactions, including Zn and K2S2O8, serve merely as illustrative examples. They are not intended to restrict or confine the scope of the present disclosure in any way.Step M4: reacting the fourth intermediate product with a vinyl-addition polymerization catalyst in a third solvent to produce a polymer comprising integrated in-DBDvinyl-addition polymerization

[0157] The product from M3 is subjected to a reaction with an appropriate vinyladdition polymerization catalyst in the presence of a solvent. While it is conceivable to include a co-monomer in the process, this representation illustrates a simpler potential polymerization approach. The solvent for this purpose may include options such as toluene, dichloromethane, or ethers, among others. Possible catalysts for vinyladdition polymerization may encompass palladium or nickel catalysts, either independently or in conjunction with known co-catalysts.

[0158] The ratio between the catalyst and monomer is adjustable, allowing for control over the final product's molecular weight. Ratios may vary, with a range that may span from 1 :50 to 1 :50,000 being considered suitable for different applications. The temperature for this reaction can be flexible, potentially ranging from ambient conditions to a temperature exceeding the reflux point of the selected solvent.

[0159] It is advantageous to permit the reaction mixture to proceed to completion. The progress of the reaction can be effectively monitored using various methodologies, including but not limited to colorimetric techniques, spectroscopy, or other appropriate analytical procedures.

[0160] Subsequent to the completion of the reaction, the final product may be isolated and purified utilizing conventional polymer separation methods. These may involve techniques such as extraction, filtration, or precipitation. Characterization of the isolated polymer product is feasible using standard analytical techniques, which could include NMR, GPC, or infrared spectroscopy, among others.Use of in-DBD Polymers in Electrochemical Applications

[0161] The above methods present novel opportunities to use the resulting in- DBD polymers in many different electrochemical applications and devices including but not limited to: fuel cells, water electrolyzers, CO2 electrolyzers, and CO electrolyzers. Some examples are described below:1 . Polymer Ion Exchange Membranes

[0162] Ion exchange in-DBD polymers of the present disclosure, or similar ion exchange polymers containing in-DBD as primary functional group, can be used to form polymer ion exchange materials (herein referred to as “in-DBD polymer ion exchange membranes”) such as polymer electrolyte membranes (PEMs) and ionomeric binders for electrodes in electrochemical energy conversion devices.

[0163] In-DBD polymer ion exchange membranes can be fabricated using a variety of techniques known in the art, such as solution casting, spraying, and extrusion. To facilitate such processing, an appropriate organic solvent is selected to dissolve the in-DBD polymers to facilitate processing.

[0164] Depending on the intended application, a suitable in-DBD polymer is chosen or copolymerized to yield a membrane forming polymer having an ion exchange capacity (IEC, measured as millimoles of ionic groups per unit mass of membrane) in the range of 1-4 mmol / g to ensure high performance.

[0165] The in-DBD polymers can be fabricated into membranes as a homogeneous material. Alternatively, the in-DBD polymer can be fabricated into membranes as a composite material, wherein additional components can be incorporated before, during, or after the membrane formation process, and may be polymeric, metallic, or non-metallic. The incorporation of these components is strategically designed to enhance the stability and performance of the resulting composite membrane.

[0166] After the formation of the monolithic or composite membrane, a posttreatment process can be applied, such as cross-linking or post-functionalization. The primary objective of these additional treatments is to enhance both the stability and performance metrics of the fabricated membrane.

[0167] In some embodiments, the in-DBD polymer ion exchange membrane can be an AEM comprising a polymer matrix as the primary structural backbone and having incorporated in-DBD functional groups. The in-DBD cationic structure, when incorporated into the polymer matrix, serves to securely immobilize a proton within its three-dimensional structure. More specifically, this immobilization is facilitated by the aliphatic cage formed by the in-DBD. Such a structure ensures that the cationic charge is firmly held and provides resistance to aggressive anionic interactions. An additional feature of the in-DBD integration is the symmetrical intra-bridgehead hydrogen bond formed between its nitrogen atoms. This structural advantage provides increased stability, allowing the membrane to maintain its functionality even under challenging conditions such as elevated temperatures and low relative humidity environments.2. Reinforced Polymeric Ion Exchange Membrane

[0168] In some embodiments, the in-DBD polymer is embedded into a reinforcing material to provide mechanical robustness. The reinforcement process employs a porous substrate, which may be woven or non-woven and derived from an array of materials including, but not limited to, fluoropolymers like expanded polytetrafluoroethylene, porous polyethylene or polypropylene, electrospun nanofibers, fiberglass, polymer fibers, fiber mats, perforated films, and porous ceramics. The method involves saturating or coating this porous support with a liquid composition, which may be the in-DBD polymer in its pure form or dissolved in an appropriate solvent. Post saturation, any solvent present is eliminated, thereby embedding the in-DBD polymer within the porous structure of the reinforcement material. Notably, the porous substrate utilized is electrically non-conductive.3. Catalyst Ink

[0169] In some embodiments, a catalyst ink includes the in-DBD polymer (herein referred to “in-DBD catalyst ink”) and serves as ion-conducting “glue” (often called “ionomer”) and is expected to provide improved resistance to ionomer degradation when exposed to dry conditions compared to conventional catalyst inks.

[0170] The in-DBD catalyst ink composition comprises a catalyst material, the ion-conducting in-DBD polymer, water, and an organic solvent. The in-DBD catalystink can be applied directly to a polymer electrolyte membrane or may be applied to a porous transport layer (e.g. carbon paper, woven or nonwoven material made of a suitable material, or a porous metal-based transport layer). Various known coating processes such as spraying, screen printing, stencil printing or off-set printing can be used to deposit the in-DBD catalyst ink, to form a catalyst layer. Known fabrication and processing techniques can be used to either yield a coated membrane (CCM) or a gas diffusion electrode (GDE), coated on a porous transport layer.4. Catalyst Coated Membrane (CCM)

[0171] In some embodiments, a CCM comprises the in-DBD polymer (herein referred to as “in-DBD CCM”) and can serve to provide good ionic contact between polymer membrane and catalyst layer ionomer. The in-DBD CCM can be formed by coating a polymer ion exchange membrane with an in-DBD catalyst ink or by using an in-DBD polymer membrane coated with a conventional catalyst ink or with the in-DBM catalyst ink. Typically, the catalyst coating on the polymer ion exchange membrane consists of 5% to 35% by weight of the described polymer and 65% to 95% by weight of a metallic or non-metallic catalyst.

[0172] The cathode, the anode, and / or in-DBD polymer ion exchange membranes of the present disclosure can be assembled in a device each as separate components or can be fabricated wherein the in-DBD polymer ion exchange membrane (or a portion thereof) is coated or laminated with one or both electrodes or a portion thereof. For example, to maximize cost savings and in some instances performance, the individual components, or layers thereof, may be sufficiently thin, such that some of the components could act as a support during the fabrication of a thin layer. The various components or portions thereof can be laminated together, formed in situ on a surface of a component, and I or coated onto a component.5. Membrane Electrode Assembly

[0173] The in-DBD polymer ion exchange membrane of the present disclosure can be placed between two electrodes, the anode and cathode, of an electrochemical device to form a membrane electrode assembly (MEA). In some embodiments, the electrode is a gas diffusion electrode (GDE) comprising a gas diffusion layer coatedwith a catalyst. Gas diffusion layers are known in the art and include for example carbon paper or cloth, or a metal mesh. Electrode materials can include, for example, graphitic carbon, glassy carbon, titanium, or any of the following “catalytically active elements”: V, Cr, Mn, Fe, Co, Ni, Cu, Sn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt , Au. Hg, Al, Si, In, Tl, Pb, Bi, Sb, Te, U, Sm, Tb, La, Ce, Nd, and alloys or combinations thereof.

[0174] In some embodiments, the in-DBD polymer is used in an electrochemical device comprising catalytically active nanoparticles. The nanoparticles may be supported on carbon particles or nanostructured supports. The electrochemical device can comprise an extended surface area catalyst-based electrode such as a nanostructured thin film electrode, nanotube electrode, porous sponge electrode, or two-dimensional polycrystalline film electrode.6. AEM Fuel Cells (AEMFC)

[0175] In some embodiments, a fuel cell includes one or more of the in-DBD polymer ion exchange membrane, the in-DBD catalyst-coated membrane, and / or a catalyst layer containing the in-DBD polymer. The catalyst-coated membrane has two sides, wherein one side is a cathode, and the other side is an anode. The in-DBD polymer ion exchange membrane can be an AEM in which case the fuel cell is referred to as an “in-DBD AEM fuel cell” or “in-DBD AEMFC”.

[0176] A method of operating the in-DBD AEMFC includes: (a) conditioning the in-DBD AEMFC by supplying hydrogen to the anode, and oxygen and water to the cathode, and operating the in-DBD AEMFC to generate electrical power and water at a potential of 1.1 V to 0.1 V, until the fuel cell reaches at least 90 % of peak performance; and (b) continuing supplying hydrogen to the anode and oxygen and water to the cathode, and operating the in-DBD AEMFC at a potential of 1.1 V to 0.1 V. It is understood that unless otherwise stated, operation of a device (e.g., a fuel cell, a water electrolyzer, etc.) including the catalyst-coated membrane is at 1 atm.

[0177] One method of making an in-DBD AEMFC includes (a) pre-conditioning an in-DBD catalyst-coated membrane by contacting the catalyst-coated membrane with an aqueous hydroxide solution for at least 1 hour to provide a pre-conditionedcatalyst-coated membrane; and (b) incorporating the pre-conditioned catalyst-coated membrane into a fuel cell.

[0178] Another method of making an in-DBD AEMFC includes (a) incorporating an in-DBD catalyst-coated membrane into a fuel cell; and (b) pre-conditioning the fuel cell by contacting the catalyst-coated membrane with an aqueous hydroxide solution for at least 1 hour to provide a pre-conditioned catalyst-coated membrane.

[0179] A key revelation underlying this disclosure is the pronounced stability of in-DBD as an organic cation when exposed to hydroxide. This remarkable property is not only unexpected, but also crucial to breakthrough advances in AEM technology. The ability of in-DBD to maintain stability under hydroxide conditions (demonstrated and discussed in detail in the "Experimental Results and Discussion" section below) enhances the longevity and performance of AEMs. This resistance to hydroxide degradation distinguishes in-DBD AEMs from other current technologies and underscores their transformative potential in electrochemical applications. This feature not only strengthens the commercial viability of in-DBD AEMFCs, but also provides a fundamental framework for future innovations in the field.7. AEM Water Electrolysis (AEM WE)

[0180] In some embodiments, a water electrolyzer includes one or more of the in-DBD polymer ion exchange membrane, the in-DBD catalyst-coated membrane, and / or a catalyst layer containing the in-DBD polymer (herein referred to as “in-DBD water electrolyzer”). The catalyst-coated membrane has two sides, wherein one side is a cathode, and the other side is an anode. The anode, cathode and polymeric ion exchange membranes of the in-DBD water electrolyzer can be separate components that are laminated together.

[0181] A method of operating the in-DBD water electrolyzer includes (a) providing water or an aqueous hydroxide electrolyte to the anode, the cathode, or both the anode and the cathode of the water electrolyzer; and (b) operating the water electrolyzer to generate hydrogen, oxygen, and water.

[0182] One method of making the in-DBD water electrolyzer includes (a) incorporating a catalyst-coated or non-catalyst-coated membrane above into the water electrolyzer; and (b) pre-conditioning the water electrolyzer by contacting the catalyst- coated membrane with an aqueous hydroxide solution for at least 1 hour to provide a pre-conditioned catalyst-coated membrane.

[0183] Another method of making the in-DBD water electrolyzer includes (a) pre-conditioning a catalyst-coated membrane above by contacting the catalyst-coated membrane with an aqueous hydroxide solution for at least 1 hour to provide a preconditioned catalyst-coated membrane; and (b) incorporating the pre-conditioned catalyst-coated membrane into the water electrolyzer.8. Application in AEM-CO2 / COE (Carbon Monoxide / Dioxide Electrolysis)

[0184] In some embodiments, a carbon dioxide and / or carbon monoxide electrolyzer includes one or more of the in-DBD polymer ion exchange membrane, the in-DBD catalyst-coated membrane, and / or a catalyst layer containing the in-DBD polymer (herein referred to as “in-DBD CO / CO2 electrolyzer”). The catalyst-coated membrane has two sides, wherein one side is a cathode, and the other side is an anode.

[0185] A method of operating the in-DBD CO / CO2 electrolyzer includes (a) providing water or an aqueous electrolyte to the anode, the cathode, or both the anode and the cathode of the in-DBD CO / CO2 electrolyzer; and (b) operating the carbon dioxide and / or carbon monoxide electrolyzer to generate CO, hydrogen, water, and value-added products such as but not limited to HCO-, H2CO , (HCO2)-, H2CO2, CH3OH, CH4, C2H4, CH3CH2OH, CH3COO-, CH3COOH , C2H6, (COOH)2 or (COO-)2.

[0186] Another method of making the in-DBD CO / CO2 electrolyzer includes (a) pre-conditioning a catalyst-coated membrane above by contacting the catalyst-coated membrane with an aqueous electrolyte solution for at least 1 hour to provide a preconditioned catalyst-coated membrane; and (b) incorporating the pre-conditioned catalyst-coated membrane into the in-DBD CO / CO2 electrolyzer.Experimental Results and Discussion1 . Synthesis and Structural Characterization of in-DBD

[0187] Maleic hydrazide is oxidized by lead tetraacetate, which undergoes a Diels-Alder reaction with 1 ,3-butadiene to produce 1 ,6-diazabicyclo[4.4.0]dec-3,8- diene-2, 5-dione. This is then subsequently hydrogenated, and then reduced by LiAIH4 to produce 1 ,6-diazabicyclo[4.4.0]decane. This is singly-alkylated with 1 ,4- dibromobutane in THF, and then further cyclized by addition into AgBF4 to produce 1 ,6-diazatricyclo[4.4.4.01’6]tetradec-1 ,6-diylium tetrafluoroborate. The N-N bond is readily reduced by zinc in acidic media to produce the outside-protonated DBD tetrafluoroborate salt, which is then inside-protonated by oxidation with K2S2O8 in acidic media. This inside-protonation proceeds via a single-electron-transfer-mediated intramolecular H-atom abstraction of a p-proton of DBD, rather than direct protonation of the diamine, which implies that a proton (and thus any atom) cannot penetrate the void-space between the bridgehead nitrogen atoms. Further ion-exchanges were performed using ion-exchange resin to the chloride or hydroxide form.

[0188] The caged proton of in-DBD appears in 1 H NMR spectra at (5) 17 ppm, evident of its extensive deshielding by the two nitrogen atoms. The crystal structure of in-DBD chloride shows an extremely short N... N distance (2.5 A), with a symmetrical electron density distribution between them, implying a symmetrical N-H-N bond; this hydrogen bond is shorter and more symmetrical than observed by proton sponge structures. DFT calculations (wB97XD / 6-31g(d.p)) reveal in-DBD to be 36.3 kcal / mol more stable than the outside-protonated form, which is much greater than that gained by moving a proton inside a proton-sponge (18.7 kcal / mol). Collectively, these analyses support the surprising uniqueness of the in-DBD structure.1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione.

[0189] In a round-bottom flask, DCM (250 mL), and acetic acid (5 mL) were cooled to 0 °C, and added maleic hydrazide (5.75 g, 51 .26 mmol) and a solution of 20 wt% 1 ,3-butadiene in toluene (34.4 mL, 102.52 mmol). In roughly 25 portions, lead tetraacetate (25.00 g, 56.38 mmol) was added over the course of roughly 6 hours at 0 °C, allowing each portion to fully react. To test for consumption of Pb(OAc)4, a glass pipette tip was dipped into the solution and the sample was dropped onto a wetted paper towel. If a brown drop was observed, the reaction was allowed to continue, if the drop remained a pale yellow, more Pb(OAc)4 was added to the reaction. The mixture was allowed to warm to room temperature overnight, then quenched with water. The organic layer was extracted, washing with water, and dried with MgSO4. The solvent was removed under reduced pressure, then the product was triturated in diethyl ether (~ 100 mL) and cooled to -20 °C overnight. The product was filtered, collecting product as a yellow powder (5.33 g, 32.47 mmol, 63% yield).1H NMR (400 MHz, CDCh) 5: 6.92 (s, 2H), 6.03 (t, J = 1 .4 Hz, 2H), 4.49 (d, J = 1 .1 Hz, 4H).

[0190] FIG. 1 illustrates1H Nuclear Magnetic Resonance (NMR) of 1 ,6- diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione in CDCh.1 ,6-diazabicyclo[4.4.0]decan-2, 5-dione:

[0191] In a round-bottom flask, 5% Pd / C (1.7 g) was suspended in deionized water (150 mL). 6,9-1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione (4.30 g, 26.19 mmol) was added and the headspace of the flask was evacuated using a water aspirator, re-filling the atmosphere with a balloon of H2(g) three times. The mixture was then stirred at room temperature under a H2 atmosphere for 2 days, re-filling the hydrogen balloon when nearly consumed. When complete, the hydrogen was removed slowly under a stream of argon, then celite (15 g) was added and stirred for ~ 10 minutes. The mix was filtered, washing with 0.5 M K2CO3, then water, then ethyl acetate, then DCM. The rinsings were all collected and combined, and the product was extracted with DCM x3, the organic layer was dried with MgSO4 and solvent wasremoved to obtain the product as an off-white powder (3.68 g, 21.88 mmol, 84% yield).1H NMR (400 MHz, CDCh) 5: 3.74 (m, 4H), 2.60 (s, 4H), 1.71 (p, J = 2.90 Hz, 4H).

[0192] FIG. 2 illustrates1H NMR of 1 , 6-diazabicyclo[4.4.0]decan-2, 5-dione in CDCh. Residual dichloromethane solvent signal marked by CH2CI2.1 ,6-diazabicyclo[4.4.0]decane:

[0193] In a flame-dried 2-neck flask affixed with a reflux condenser, dry THF (60 mL) and 1 ,6-diazabicyclo[4.4.0]decan-2, 5-dione (3.50 g, 20.81 mmol) were mixed under argon atmosphere, sparging with argon for ~ 30 minutes. To the mixture, solid UAIH4 (3.16 g, 83.23 mmol) was added slowly in portions, maintaining a soft reflux. The mixture was then refluxed under an argon atmosphere for 3 days. The mixture was then cooled, quenched dropwise with water (6 mL, 333.15 mmol), then filtered the solid. The solid was collected and triturated 2 times in additional THF (20 mL), recombining all organic fractions and concentrating on rotary evaporator at 330 mbar in 40 °C water to ~ 25 mL volume. This solution was used without further purification for the next reaction.1 ,6-diaza-1 -(4-bromobutyl)bicyclo[4.4.0]decan-1 -ium bromide:

[0194] In a 150 mL thick-walled glass pressure vessel, 1 ,6- diazabicyclo[4.4.0]decane from the previous reaction (nominally 20.81 mmol) in THF (25 mL) was sparged with argon for ~ 10 minutes. 1 ,4-dibromobutane (14.91 mL, 124.85 mmol) was added, and the flask was sealed under argon, heating the vesselto 90 °C overnight. The reaction was cooled, then carefully opened the flask and precipitated with diethyl ether (~50 mL). The mixture was allowed to cool to -20 °C overnight, then filtered, rinsing with cold diethyl ether to obtain the product as a tan powder (5.66 g, 15.89 mmol, 76% yield).1H NMR (400 MHz, D2O) 5: 3.73 (d, J=13.00 Hz, 2H), 3.66 (t, J=8.54 Hz, 2H), 3.55 (t, J=6.32 Hz, 2H), 3.32 (m, J=4.74 Hz, 2H), 3.11 (m, J=4.92 Hz, 2H), 2.90 (d, J=13.47 Hz, 2H), 1.919-2.037 (m, 4H), 1.764-1.895 (m, 8H).

[0195] FIG. 3 illustrates1H NMR of 1 ,6-diaza-1-(4-bromobutyl)bicyclo[4.4.0] decan-1 -ium bromide in D2O.1 ,6-diazatricyclo[4.4.4.01’6]tetradecan-1 ,6-diylium tetrafluoroborate:

[0196] In a round-bottom flask, Ag2O (3.72 g, 16.06 mmol) was dissolved in 48% HBF4 (aq) (25 mL). 5-(4-bromobutyl)octahydro-1 H-pyridazino[1 ,2-a]tetradecan-5- ium bromide (5.20 g, 14.60 mmol) was added to the mixture in portions. The mixture was then heated in a pre-heated 100 °C oil bath for 15 minutes, then filtered through a glass fritted filter, rinsing with 48% HBF4 (10 mL). Ethanol (200 mL) was slowly added to the filtrate, and the mixture was cooled to -20 °C overnight to precipitate. The product was filtered, washing with cold ethanol, to obtain the product as a pale brown powder (4.56 g, 12.32 mmol, 84% yield).1H NMR (400 MHz, D2O) 5: 5.03 (t, J=13.32 Hz, 6H), 3.82 (d, J=14.23 Hz, 6H), 2.49 (t, J=11 .41 Hz, 6H), 2.20 (d, J=10.51 Hz, 6H). HRMS (ESI) (m / z, M2+) expected: 98.0964, found: 98.0965.

[0197] FIG. 4 illustrates1H NMR of 1 , 6-diazatricyclo[4.4.4.01 6]tetradecan-1 ,6- diylium tetrafluoroborate in D2O.1 ,6-diazabicyclo[4.4.4]tetradecan-1-ium [outside proton] tetrafluoroborate:

[0198] In a Schlenk flask, 48% HBF4 (10 mL) was sparged with argon for ~ 10 minutes, then added 1 ,6-diazoniatricyclo[4.4.4.01’6]tetradecane tetrafluoroborate (2.000 g, 5.406 mmol), stirring until dissolved. Zinc shavings (1 .7673 g, 27.030 mmol) were added, and the mixture was stirred vigorously for 1 hour, under argon. The mixture was filtered, rinsing with minimal 48% HBF4 (5 mL) and used for the next reaction.

[0199] Alternatively to isolate the product, to the mixture was slowly added degassed 5 M KOH under argon (the un-protonated form is not air stable, and forms an insoluble polymer upon exposure to air, so it must be handled under argon - once protonated it becomes more stable, but gradually gains a pink colour) until basic, then extracted with degassed diethyl ether x3, adding the extracted organic layer quickly and directly into a solution of 1 :8 48% HBF4 to diethyl ether. The precipitate was filtered, washing with diethyl ether to obtain the product as a pale pink powder (81 % isolated yield).1H NMR (400 MHz, D2O) 5: 3.40 (t, J=4.97 Hz, 6H), 2.57 (t, J=5.32 Hz, 6H), 1 .97 (p, J=5.54 Hz, 6H), 1 .72 (p, J=5.95 Hz, 6H). HRMS (ESI) (m / z, M+) expected: 197.2012, found: 197.2017.

[0200] FIG. 5 illustrates1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1-ium tetrafluoroborate in D2O. Residual diethyl ether solvent signals marked by Et20.1 ,6-diazabicyclo[4.4.4]tetradecan-1 , 6-ium [inside proton] tetrafluoroborate:

[0201] In a Schlenk flask, the filtered crude mixture from the previous reaction, nominally the outside protonated BF4 salt (1.536 g, 5.406 mmol) and 48% HBF4 (15 mL), was sparged with argon for ~ 10 minutes. Potassium peroxydisulfate (1.461 g, 5.406 mmol) was then added and stirred vigorously for 2 hours under argon. The mixture was diluted with diethyl ether (96 mL), filtering the precipitated salts, and removing the solvent under reduced pressure. The mixture was then cooled, adding KHCO3 (12.000 g, 119.86 mmol) to precipitate KBF4, then diluted the mixture in anhydrous ethanol (50 mL) and filtered. The solvent was removed, extracting the product in anhydrous ethanol and removing the solvent under reduced pressure. The bicarbonate salt was too hygroscopic to conveniently handle, so it was converted back into the BF4 form by dissolving the product in anhydrous ethanol (1 mL) and adding 48% HBF4 (0.7 mL), stirring for 1 h. The product was diluted with diethyl ether (50 mL) and decanted the liquid. The product was finally recrystallized from minimal boiling anhydrous ethanol (~ 8 mL), cooling to -20 °C overnight. The precipitate was filtered, washing with minimal cold ethanol, then diethyl ether to obtain the product as a white powder (1.104 g, 3.889 mmol, 72% yield).1H NMR (400 MHz, D2O) 5: 16.98 (s, 1 H), 2.67 (broad s, 12H), 1.87 (broad s, 12H).13C NMR (101 MHz, D2O) 5: 51.71 , 25.95.19F NMR (376 MHz, D2O) 5: -150.43 (s, 0.2F;10B abundance), -150.48 (s, 0.8F;11B abundance). HRMS (ESI) (m / z, M+) expected: 197.2012, found: 197.2011.

[0202] FIG. 6 illustrates1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate in D2O. Residual diethyl ether and methanol solvent signals marked by Et20 and CH3OH, respectively.

[0203] FIG. 7 illustrates13C NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate in D2O.

[0204] FIG. 8 illustrates19F NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate in D2O.1 ,6-diazabicyclo[4.4.4]tetradecan-1 , 6-ium [inside proton] chloride:

[0205] 1 ,6-diazabicyclo[4.4.4]tetradecan-1 , 6-ium [inside proton] tetrafluoroborate (0.50 g, 1.76 mmol) was dissolved in Milli-Q water (10 mL) and passed through a column of amberlite IRA 900-CI form ion exchange resin (3.5 g), recycling the solution 3 times through the column, until no more BF4 signals were observed by19F NMR. The solvent was removed under reduced pressure, extracted in ethanol, and filtered, removing the solvent under reduced pressure. The solid was triturated in diethyl ether, and filtered, collecting the product as a white powder (0.35 g, 1.50 mmol, 85% yield).1H NMR (400 MHz, CD3OD) 5: 16.95 (s, 1 H), 2.70 (broad s, 12H), 1.91 (broad s, 12H).13C NMR (101 MHz, D2O) 5: 53.08, 27.32.

[0206] FIG. 9 illustrates1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride in CD3OD.

[0207] FIG. 10 illustrates13C NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium[inside proton] chloride in CD3OD.

[0208] FIG. 11 illustrates19F NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride in CD3OD.

[0209] FIG. 12 illustrates thermogravimetric analysis of in-DBD Cl under nitrogen atmosphere at a ramp speed of 10 °C per minute. Grey line indicates 95% of the original mass, which defines the approximated degradation temperature of 388 °C.2. Assessing the unique stability of in-DBD to AEM-relevant caustic conditions

[0210] The stability of in-DBD to strongly basic conditions was studied, alongside the previous state-of-the-art cations, using two accelerated degradation methods; solution NMR spectroscopy to determine degradation products, and dynamic vapor sorption (DVS) to probe extreme dehydration conditions found in AEM fuel cells. Both tests are limited by practical factors, namely NMR studies must be carried out in solution and are not equivalent to vapor-phase electrochemical device conditions; DVS studies give little mechanistic insight and can only report on degradation products by ex-situ means. Together these characterization methodscomplement the other and present a more holistic look at the lifetime of cations in device-relevant caustic conditions.2.1 NMR degradation studies

[0211] The inventors adapted a NMR spectroscopic degradation method that used 2M KOH in CD3OH and an internal standard (sodium trimethylsilylpropanesulfonate, NaDSS) in a sealed NMR tube at 80 °C, acquiring NMR spectra every five days. The reported procedure was modified to maintain consistency in hydration levels and observe exchangeable protons: solutions were prepared under argon atmosphere to limit exposure to atmospheric water and CO2, and CD3OD was used instead of CD3OH. The percentage of cation remaining versus time are shown in FIG. 13 (A). Under these conditions, no measurable degradation of in-DBD was found over 30 days (FIG. 28). Of significant note, no deuterium exchange of any proton was observed, implying no electrophilic a or p protons are present and, critically, that the inside-proton is not able to be deprotonated or exchanged for another proton. All other cations undergo degradation, characterized as a relative lowering of the cation NMR signal intensity. BTMA degrades rapidly under these conditions, with less than 15% BTMA remaining after 10 days and no cation detectable after 29 days. MMI and DMP show similar rates of degradation to each other, with DMP having slightly higher stability (65% and 77% cation remaining after 29 and 30 days, respectively). ASU reveals a high stability relative to the other common cations, retaining 95% of the cation after 29 days.

[0212] 1H NMR spectra reveal identified degradation products for all cations, except in-DBD for which no degradation products were found (FIG. 30), even after 60 days (FIG. 32). BTMA degrades via de-methylation and de-benzylation (FIG. 18), while MMI degrades primarily by de-methylation and secondly by C2 attack to give the ring-opened product (FIG. 21). DMP degrades primarily by de-methylation, with a small amount by Hoffmann-type elimination (FIG. 24), while ASU shows exclusively Hoffmann elimination (FIG. 27). The half-lives of these salts in 2 M KOH in CD3OD were estimated from the slope of each degradation plot (FIG. 35-39). As in-DBD exhibited no degradation over 30 days, its half-life estimation was limited to > 100000 hours (>11 years). As shown in FIG. 13 (B), In-DBD (ti / 2 > 100000 h) exhibits an orderof magnitude longer half-life than ASU (ti / 2 ~ 6950 h), > two orders of magnitude longer than MMI or DMP (ti / 2 ~ 990 h and 1440 h, respectively), and > three orders of magnitude longer than BTMA (ti / 2 ~ 130 h).

[0213] In a nitrogen-atmosphere glovebox, potassium hydroxide 85% (56 mg), sodium 3-(trimethylsilyl)-1 -propanesulfonate (3 mg), and the studied organic cation salt (0.015 mmol) were combined, and then taken out of the glovebox in a sealed airtight vial. Under a flow of argon, degassed CD3OD (0.5 mL) was added to the vial and the vial was sealed under argon and sonicated until all solid dissolved.

[0214] NMR samples were prepared under argon to limit the water present in the sample to that of the native water present in the KOH pellets (85% m / m, A ~ 0.55) and commercial CD3OD (99%), as well as to exclude CO2 to limit carbonation of the hydroxide. Under these strictly controlled conditions, the inventors observe much higher rates of decomposition than the previously published studies, likely due to a much lower hydration number in this study. Rough estimates for the hydration number in these conditions range from A ~ 0.88 (if no excess hydration or carbonation was present) to A ~ 1.75 (if KOH was twice as hydrated as expected); this is a similar hydration number to the critical conditions in the DVS around 10% RH.

[0215] The resulting solution was transferred under argon to an argon-filled NMR tube, and flame-sealed under a flow of argon. The1H NMR was then collected for the sample, and then placed in an 80 °C oil bath, removing once every five days to record the next1H NMR. Samples were allowed to cool for one hour before recording1H NMR data.

[0216] NMR were referenced to the trimethylsilane signal of the internal standard, NaDSS, at 0 ppm. All signals of the NaDSS were integrated, setting the signal at 0.595 ppm to 100. All signal intensities were divided by the number of protons represented, for example the signal at 0.595 ppm is a methylene substituent and was therefore divided by 2, resulting in a defined per-proton integration intensity of 50. The integrations of the analyte were also performed, only on signals that were present in the initial NMR (Day 0); these were also divided by the number of protons represented, resulting in a per proton intensity of the analyte. Each signals per-proton intensity was averaged amongst the molecule, and outliers were tested by measuring if theintegrated intensity was more than 20% less intense than the average (without the suspected outlier). Outliers were assumed to have considerable deuterium exchange, and were rejected.

[0217] FIG. 14 illustrates1H NMR spectra of BTMA on day 0 of the NMR degradation test. Circles show proton signals from BTMA and the squares show proton signals from the NaDSS internal standard.Table 1. NMR hydroxide degradation study example integration and averaging to obtain per-proton and molecular unit integration averages.BTMA NaDSSInteAv

[0218] The total averaged per-proton intensity for the analyte molecule was then divided by the total averaged per-proton intensity of the NaDSS internal standard; this number is the relative equivalents of the analyte to NaDSS.

[0219] Relative equivalents = 32.34 / 50.08 = 0.6457

[0220] This number was then divided by the day 0 relative equivalents to get a percent of analyte remaining over time.Table 2. NMR hydroxide stability test example cation remaining calculation.Day _ Relative equivalents _ Percent cation remaining0 0.6457 1005 0.2577 39.910 0.1006 15.615 0.0561 8.720 0.026295 4.125 0.02429 3.829 0.007407 1.1

[0221] FIG. 15 illustrates stacked1H NMR of experiment blank; 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. Peaks around 1.2 ppm are a contaminant found in all tested commercial sources of KOH and NaOH (multiple batches and suppliers), and were found to not change over the course of the experiment and did not appear to interfere with the study.

[0222] FIG. 16 illustrates stacked1H NMR of benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0223] FIG. 17 illustrates expanded, stacked1H NMR spectra of benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0224] FIG. 18 illustrates day 291H NMR spectra of benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 29 days. Overlay shows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0225] FIG. 19 illustrates stacked1H NMR of 1 ,3-dimethyl-2-mesityl-4,5- diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0226] FIG. 20 illustrates expanded, stacked1H NMR spectra of 1 ,3-dimethyl- 2-mesityl-4,5-diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tubewas heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0227] FIG. 21 illustrates day 291H NMR spectra of 1 ,3-dimethyl-2-mesityl-4,5- diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 29 days. Overlay shows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0228] FIG. 22 illustrates stacked1H NMR of 1 ,1-dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0229] FIG. 23 illustrates expanded, stacked1H NMR spectra of 1 ,1- dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. The region in the box was increased in intensity to show the small amount of elimination product that was formed.

[0230] FIG. 24 illustrates day 301H NMR spectra of 1 ,1-dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 30 days. Overlay shows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0231] FIG. 25 illustrates stacked1H NMR of 6-azaspiro[5.5]undecan-6-ium bromide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0232] FIG. 26 illustrates expanded, stacked1H NMR spectra of 6- azaspiro[5.5]undecan-6-ium bromide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0233] FIG. 27 illustrates day 291H NMR spectra of 6-azaspiro[5.5]undecan-6- ium bromide (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 - propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 29 days. Overlay shows the remaining analyte peaks (circles) and the degradation product peaks (squares).

[0234] FIG. 28 illustrates stacked1H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0235] FIG. 29 illustrates expanded, stacked1H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0236] FIG. 30 illustrates day 291H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C for the 29 days. Overlay shows the remaining analyte peaks (circles), and degradation product peaks are not observed so could not be highlighted.

[0237] FIG. 31 illustrates stacked1H NMR of 1 ,6-diazabicyclo[4.4.4]tetradecan- 1 ,6-ium [inside proton] tetrafluoroborate (0.03 M) in 2M KOH (CD3OD) with sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken.

[0238] FIG. 32 illustrates expanded, stacked1H NMR spectra of 1 ,6- diazabicyclo[4.4.4]tetradecan-1 ,6-ium [inside proton] tetrafluoroborate (0.03 M) in 2MKOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. The region in the box was increased in intensity to show the region where elimination degradation products should show up.

[0239] FIG. 33 illustrates percent cation remaining of in-DBD is its chloride and BF4- ion-form.

[0240] A blank test was performed with NaBF4, to test the stability of the BF4anion to the NMR test conditions (2M KOH in CD3OD at 80 °C). The inventors observe a degradation of the BF4counterion similar to that reported for long hydrolysis (Fig. 34). The fluctuations in the intensity of the in-DBD BF4form, with no observed degradation products, are likely due to changes in the chemical environment from the loss of BF4over time.

[0241] FIG. 34 illustrates (A) Stacked19F NMR of sodium tetrafluoroborate (molarity) in 2M KOH (CD3OD) with sodium 3-(trimethylsilyl)-1 -propanesulfonate (molarity) internal standard. NMR tube was heated to 80 °C between samples, allowing to cool before the next spectrum was taken. (B) Ratio of the integration of the BFs(OH) degradation product signal to the BF4signal.

[0242] To estimate a half-life of the cations in the NMR test conditions, the cation remaining vs time was plotted, and the data was fit to a linear curve with formula:Y = 1 + b»X, where b is the slope. The half-life of the cation was calculated to be whereY = 0.5 (50% cation remaining) and X was calculated, in hours. The value was rounded to the nearest 10 hours. Over 30 days, a loss of -0.5% cation would have a half-life of roughly 100000 hours, which is the maximum lifetime this experiment can resolve.

[0243] FIG. 35 illustrates NMR stability plot of cation remaining over time for benzyltrimethylammonium chloride (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data, for the first 10 days.

[0244] FIG. 36 illustrates NMR stability plot of cation remaining over time for 1 ,3-dimethyl-2-mesityl-4,5-diphenyl-1 H-imidazol-3-ium iodide (0.03 M) in 2M KOH(CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.

[0245] FIG. 37 illustrates NMR stability plot of cation remaining over time for1 .1 -dimethylpiperidinium iodide (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3- (trimethylsilyl)-l -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.

[0246] FIG. 38 illustrates NMR stability plot of cation remaining over time for 6- azaspiro[5.5]undecan-6-ium bromide (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.

[0247] FIG. 39 illustrates NMR stability plot of cation remaining over time for 1 ,6-diazabicyclo[4.4.4]tetradecan-1 , 6-ium [inside proton] chloride (0.03 M) in 2M KOH (CD3OD) relative to a sodium 3-(trimethylsilyl)-1 -propanesulfonate (0.03 M) internal standard. The black line is a linear fit of the collected data.2.2 Dynamic vapor sorption (DVS) degradation studies

[0248] Low hydration conditions, in the absence of a solvent, simulate extreme AEM fuel cell cathode conditions. The inventors adapted a method to study these conditions through DVS of the hydroxide salts. Since the hydroxide anion becomes significantly more nucleophilic when waters of hydration are removed, these studies typically reveal substantial degradation of organic cations even at modest relative humidities (60-30%), and to date, no organic cation hydroxide salt has been reported to persist below 10% RH at 80 °C. DVS gravimetric analysis of the cations in their hydroxide form at 80 °C is shown in FIG. 41. To account for the increased nucleophilicity of hydroxide at low A, the inventors define critical conditions of 30% RH and 10% RH, the lower RH range where normal cycling of an AEM fuel cell at high current densities is reported to be expected. Only cations with stability below 10% RH are expected to remain stable over extended periods in an AEM fuel cell, which also facilitates wider operational windows for fuel cells. Sweeping RH scans, from high to low RH conditions, reveal the RH range at which each cation begins to degrade, observed as a mass-loss caused by volatilization of (volatilizable) degradationproducts and reduced hygroscopicity. Intermittent re-humidification of cations to a point with no degradation (stable reference RH) shows the effect of degradation, visualized as lower water uptake under the same conditions due to loss of hygroscopic ionic species. In-DBD (FIG. 40 (A)) remains stable at 10% RH, showing only minor mass loss at 8% RH at 80 °C (1 .2% h-1) and an increased rate of mass loss occurs at 5% RH (6.4% h-1). DMP shows a higher susceptibility to degradation under reduced RH (FIG. 40 (B)), where degradation begins as high as 23% RH (0.6% h-1) and substantial degradation at 11 % RH (2.2% h-1). ASU (FIG. 40 (C)) begins to degrade as high as 23% RH (0.8% IT1), with substantial degradation occurring at 17% RH (3.4% IT1). MMI (FIG. 40 (D)) degrades relatively quickly at a modest 49% RH (4.2% IT1). The relative humidities at which cations begin to degrade is shown in FIG. 52, clearly demonstrating in-DBD is the only cation-hydroxide capable of persisting under the low- humidity conditions of vapor-phase AEM technologies.

[0249] FIG. 40 illustrates Dynamic Vapor Sorption (DVS) degradation studies of cation-hydroxides. DVS mass as a function of time upon lowering RH for (A) in-DBD OH, (B) DMP OH, (C) ASU OH, and (D) MMI OH, all at 80 °C. Samples were exchanged to their OH- form under argon flow in degassed Milli-Q water (or 1 :1 MeOH:H2O for MMI) using freshly regenerated ion-exchange resin and stored under argon until use. Solid, grey lines are the normalized mass (left axis) and dotted black lines are the RH (right axis). 30% RH to 10% RH are considered critical conditions, so the RH was returned to the stable reference (55%) RH before and after these conditions to observe degradation-related decreases in hygroscopicity. The grey, dotted arrow represents the mass at the reference RH prior to degradation; middle and right regions represent 30-10 and 10-0% RH conditions, respectively. Shading represents the RH region where degradation occurs for each cation and the number beside is the RH where substantial degradation (>2% mass loss / h) is first observed upon lowering the RH.

[0250] To assess the long-term stability under the high stress condition of low RH, the cations in their hydroxide form were exposed to 11 % RH at 80 °C. Since in- DBD, DMP, and ASU showed virtually 100% volatilization of the degradation products, the observed mass loss can be taken as a quantitative measure of degradation, where the rate of mass loss is essentially the rate of decomposition. It should be noted thata rate of decomposition cannot be collected for MMI since it had a significant amount of non-volatile decomposition products. As seen in FIG. 41 (A), in-DBD hydroxide is highly stable, observing relatively little mass loss (1.3%) over 12.2 hours. DMP loses more mass over the experiment (4.4%), with ASU losing the most mass (20.2%). The half-life of these cations is shown in FIG. 41 (B), where in-DBD possesses a half-life (450 h) almost 3.5 times higher than DMP (130 h), and over an order of magnitude longer than ASU (30 h). By applying these complementary degradation methods (solution NMR and vapor-phase DVS), the inventors were able to reflect the observed differences in stability translating ASU from ex-situ solution degradation studies (highly stable) to operando polymer studies (poorly stable) and show that in-DBD does not suffer in translating solution stability to vapor-phase stability. When compared to the other cations, in-DBD is substantially more stable in both degradation testing methods and shows unprecedented stability around 10% RH at 80 °C, i.e. , conditions relevant to AEM fuel cells.

[0251] FIG. 41 illustrates DVS stability tests of the fully volatilized cationhydroxides. (A) The normalized mass loss over time (B) The extracted half-life of the cations at 11 % RH and 80 °C.

[0252] To determine the degradation products of in-DBD, the DVS outflow was captured in 5% v / v acetic acid solution. The only observed degradation product was the Hoffmann-type elimination product (FIG. 60-62). The lack of any other degradation products, particularly no deprotonation of the caged proton, shows the incredible stability afforded by the endohedral protection and enforced hydrogen bonding. Calculations (shown below) give insight into why only one degradation product is seen, where the endohedral protection blocks hydroxide access to the central proton, and the low electrophilicity of the a and p positions require very harsh conditions before elimination is favorable.

[0253] DVS degradation tests were performed on the hydroxide-form of the studied ions. To ensure minimal carbonation of the ions, all manipulations were performed under a flow of argon.

[0254] Amberlyst A26-OH form ion-exchange resin was refreshed by adding new resin (as received) to a Schlenk flask, and degassed Milli-Q water was added.The mixture was sparged with argon for 1 hour, then KOH (85%) pellets were added under argon to the mixture to make ~ 1 M KOH solution. The mixture was left under argon for ~ 2 hours, and regenerated 2 more times (each for 2 hours) with fresh degassed 1 M KOH solution under argon, removing the old solution via syringe under argon. The resin was then washed with degassed Milli-Q water x3 under argon, and then stored in a sealed Schlenk flask with excess degassed Milli-Q water under argon until use.

[0255] Under a flow of argon, a pasture-pipette with a small cotton pad (to hold the resin) was loaded with freshly refreshed Amberlyst A26-OH resin (1 g), and washed 3 times with degassed Milli-Q water. Under a flow of argon, 50 mg of cation in its respective halide salt form was dissolved in 1 mL of degassed Milli-Q water (or 1 .5 mL of degassed 1 :1 MeOH:H2O mixture for MMI iodide). The solution was added to the resin under argon, allowing it to gravity drain into a clean glass vial purged with argon. The solution was then added back to the column 2 more times, each time collecting in a new argon-purged vial. The column was then rinsed with 0.5 mL of degassed Milli-Q water (or degassed 1 :1 MeOH:H2O), collecting in the last vial. The final solution was topped with argon and vial closed, sealing with electrical tape (3M) until used (not stored for more than 1 hour).

[0256] The solution of organic cation-hydroxide salt in water (or 1 :1 MeOH:H2O for MMI hydroxide) was added to the DVS crucible (Pt crucible, 0.5 mL) and quickly loaded into the DVS under an argon flow (200 SCCM). The remaining solution was then tested for pH of direct sample (all samples recorded pH of 12-13) and ionic conductivity (Omega CDH-7021) of sample diluted 8 times to ensure the majority of the anions were hydroxide anions.

[0257] A conductivity of 2.4 mS / cm is for pure hydroxide conductivity at ~ 0.012 M solution, so conductivities above this were taken to be a majority OH- form organic salts; 0.53 mS / cm is the pure HCOs- conductivity so a majority carbonated sample could not show these conductivities seen. For example, after hydroxide exchange of in-DBD, a measured conductivity of 3.0 mS / cm at ~ 0.012M was recorded, showing the relative contributions of the cations and anions require mostly hydroxide as the mobile anion.

[0258] The DVS sample was dried at 80 °C under an argon flow (200 SCCM total) at 55% RH (nominally 60% RH), until a stable mass was achieved for at least 1 hour. A step-program was used to alter the RH, maintaining the flow rate (200 SCCM) and oven temperature (80 °C), as shown below.

[0259] 1H NMR were collected on the remaining solution after exchange, to ensure no degradation on the column was observed, and the1H NMR was collected on the mass remaining after the DVS run was finished. The remaining mass is a combination of non-volatile degradation products, carbonated form salt, and unexchanged halide form salt.

[0260] To determine degradation of the samples, the data was normalized to the average mass at the reference RH (55%) before degradation. The last 30 minutes of each RH value were taken and the data was fit to a linear slope (y = mx+b). The onset of degradation was determined as the RH where more than 0.2% mass loss was observed (from the fitted data) over the 30 minutes. Substantial degradation was defined by an RH where more than 1 % mass loss was observed (from the fitted data) over the 30 minutes.

[0261] FIG. 42 illustrates (A) Raw relative humidity vs time of DVS studies and (B) the last 30 minutes of each new (or reference) RH.

[0262] FIG. 43 illustrates DVS analysis of in-DBD hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0263] FIG. 44 illustrates stacked1H NMR spectra of in-DBD hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide- exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0264] FIG. 45 illustrates DVS analysis of DMP hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment.The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0265] FIG. 46 illustrates stacked1H NMR spectra of DMP hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide-exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0266] FIG. 47 illustrates DVS analysis of ASU hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0267] FIG. 48 illustrates stacked1H NMR spectra of ASU hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide-exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0268] FIG. 49 illustrates DVS analysis of MMI hydroxide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0269] FIG. 50 illustrates stacked1H NMR spectra of MMI hydroxide before and after the DVS experiment. The "before DVS” sample is of the hydroxide-exchanged cation, and allowed to carbonate in open air for several days before removing solvent to obtain the NMR spectra.

[0270] FIG. 51 illustrates stacked1H NMR spectra of the four cations hydroxides, taken after their respective DVS experiment and allowed to carbonate. Arrows point to common impurity / artifact arising from the experiment, not from degradation products.

[0271] FIG. 52 illustrates extracted onset and substantial degradation of the cation-hydroxides, measured from the DVS tests at 80 °C. The estimated A levels are obtained from the in-DBD hydroxide isotherm shown below. The light bars representthe RH that no degradation was observed, the dashed bars represent the region where the mass loss at the specified RH was greater than 0.4 % and less than 2 % over 1 hour. The dark bars represent the RHs that over 2% mass loss was observed per hour. The horizontal box represents the defined critical conditions of 30% to 10% RH.

[0272] FIG. 53 illustrates (A) DVS analysis of in-DBD hydroxide at decreasing relative humidity levels at 60 °C. (B) The last 30 minutes of each RH step plotted. The two grey regions represent the 30-10 and 10-0% RH conditions, respectively. The shading represents the RHs where degradation occurs, and the number beside is the first RH that substantial degradation was observed. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0273] FIG. 54 illustrates (A) Humidity isotherms of in-DBD hydroxide at 60 °C and 80 °C, with estimations of hydration numberfrom the slope to 0% RH. (B) Humidity isotherms of the four cation-hydroxides studied with the raw mass vs relative humidity (due to insufficient stability to estimate mass at 0% RH for all ions except in-DBD).

[0274] A control experiment was conducted showing that the hydroxide is the main form of degradation, where MMI iodide shows no degradation over the test conditions (FIG. 55, FIG. 56), whereas MMI hydroxide shows almost complete degradation (FIG. 49, FIG. 50).

[0275] FIG. 55 illustrates DVS control analysis of MMI iodide at decreasing relative humidity levels. The temperature was maintained at 80 °C throughout the experiment. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0276] FIG. 56 illustrates stacked1H NMR spectra of MMI iodide before and after the DVS experiment. *the small amount of residual DMSO was removed by the gas flow of the experiment, and is represented in the small amount of mass loss.

[0277] FIG. 57 illustrates DVS mass traces of ASU hydroxide vs time at 80 °C. (A) experimental mass and RH trace over the course of the experiment, and (B) mass and RH traces of the data after the RH was stabilized for each measurement. The dashed line represents the reference (stable) 55% RH before degradation, and thedashed-dot line represents the initial mass at the test 11 % RH. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0278] FIG. 58 illustrates DVS mass traces of DMP hydroxide vs time at 80 °C. (A) experimental mass and RH trace over the course of the experiment, and (B) mass and RH traces of the data after the RH was stabilized for each measurement. The dashed line represents the reference (stable) 55% RH before degradation, and the dashed-dot line represents the initial mass at the test 11 % RH. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0279] FIG. 59 illustrates DVS mass traces of in-DBD hydroxide vs time at 80 °C. (A) experimental mass and RH trace over the course of the experiment, and (B) mass and RH traces of the data after the RH was stabilized for each measurement. The dashed line represents the reference (stable) 55% RH before degradation, and the dashed-dot line represents the initial mass at the test 11 % RH. The grey line is for the left, grey axis and the black dotted line is for the right, black axis.

[0280] To calculate the DVS half-life of the cations at 11 % RH, the time after RH stabilization (time = 800 min) was set to time = 0. The mass after decomposition at RH = 0 and re-hydration to RH = 11 % was considered the non-degradable mass and subtracted from the mass at each point in the degradation curve (at RH = 11 between t = 800 min and t = 1520 min). The mass at t = 0 minus the non-degradable mass, is considered the degradable mass. Since the three cations studied (ASU, DMP, in-DBD) all had 100% volatile degradation products, this assumption can be made and the inventors caution others from making this assumption if the cations studied leave non-volatile degradation products. This is the reason MMI was not included in the calculation of a DVS half-life.

[0281] The degradation curves were fit to a linear curve with formula: Y = m + b»X, where b is the slope and ma is the degradable mass. The half-life of the cation was calculated to be where Y = 0.5 (50% cation remaining) and X was calculated, in hours. The value was rounded to the nearest 10 hours.

[0282] To capture the degradation product of in-DBD, the out-gas of the DVS degradation experiment was bubbled through a solution of 5% v / v acetic acid in water.The resulting solution was dried under reduced pressure and the residue was collected and characterized by NMR and MS.

[0283] FIG. 60 illustrates1H NMR spectrum of the collected DVS out-gas of in- DBD after complete degradation, captured in 5% v / v acetic acid solution. The only identified product protons are labeled; the poor integration quality is assumed to be a result of tautomerization of the protonated nitrogen(s), and / or inversion of the nitrogen center causing multiple chemical environments. The circle at 17 ppm is shown to highlight the lack of the caged proton in the degradation product, indicating complete degradation.

[0284] FIG. 61 illustrates13C NMR spectrum of the collected DVS out-gas of in- DBD after complete degradation, captured in 5% v / v acetic acid solution. The only identified product carbons are labeled.

[0285] FIG. 62 illustrates positive-ion mass spectrogram of the collected DVS out-gas of in-DBD after complete degradation, captured in 5% v / v acetic acid solution. The only identified product is shown, with its theoretical m / z.2.3 Density Functional Theory (DFT) calculations

[0286] DFT calculations were performed at wB97XD / 6-31 g(d.p) level of theory. The optimized structure for in-DBD shows the HOMO isosurface is located mainly along the N-H-N axis, with substantial electron density also located on the a-carbons next to the N-atoms (FIG. 64). The LUMO isosurface shows the orbital primarily sits between the carbon rings (FIG. 63 (A)), and there is a node at both the carbon rings and along the N-H-N axis; the two nodes present imply that hydroxide attack in these positions is highly unfavorable. The electrostatic potential (ESP) of in-DBD is shown in FIG. 63 (B). It shows that the void-space between the alkyl-rings is the region with the highest positive electrostatic potential, and is thus the point where the hydroxide ion would be expected to attack; this would encourage the hydroxide to remain in the impenetrable (see below) void-space where it is likely geometrically unfavorable to undergo Hoffmann-type elimination reactions and can be one of the reasons there is such high stability to hydroxide.

[0287] FIG. 63 illustrates DFT calculations of cations. (A) LUMO isosurfaces and (B) electrostatic potentials (ESP) of in-DBD. ESP is shown on a scale of Hartree atomic units, where more positive numbers represent a stronger positive potential, and higher electrophilicity. (C) Free energy difference between parent cations and degradation products, calculated in a water solvent continuum model. Experimentally- unobserved degradation products are shown as dotted lines. (D) The energy barrier required to deprotonate the caged proton of in-DBD. The structure shows the approach of OH- to the caged proton. DFT calculations were performed at wB97XD / 6- 31g(d.p) level of theory.

[0288] The inventors performed DFT calculations to obtain additional insight into the reason for the high hydroxide stability of in-DBD. The free energy of the degradation products of cations were calculated, and the relative energies shown in FIG. 63 (C). From this, it is observed that generally the degradation products are much more stable than the parent cation-hydroxide. DMP and MMI both show a stabilization energy of 30-45 kcal / mol for degradation products, whereas ASU shows a fairly low energy difference of -31 kcal / mol for degradation by Hoffman-type elimination, and ~35 kcal / mol for the experimentally unobserved OH-addition product. In-DBD shows elimination to be barely favorable, only stabilized by -17 kcal / mol. Deprotonated DBD is theoretically more stable by ~30 kcal / mol relative to the parent cation, and the hypothetical hydroxide addition product is similarly stable by ~32 kcal / mol. The barrier for hydroxide penetration into in-DBD leading to deprotonation was calculated (FIG. 63 (D)) to be prohibitively large (-400 kcal / mol), confirming why this mode was not observed. Notably, although OH addition products were calculated for in-DBD, the inventors did not observe any of these compounds. The combination of the lack of electrophilic sites, high barrier to internal-deprotonation, and low energy difference between elimination products and parent cation serve to explain the extraordinarily high stability of in-DBD.

[0289] FIG. 64 illustrates calculated orbital isosurfaces of the HOMO and LUMO of in-DBD. Calculations were performed at the wB97XD / 6-31g(d.p) level of theory.

[0290] FIG. 65 illustrates Formation energy calculations of the relative energy of outside vs inside protonation for in-DBD (left two) and a typical proton sponge (right two). Calculations were performed at the wB97XD / 6-31g(d.p) level of theory.

[0291] In conclusion, the inventors showed that in-DBD is immensely more resistant to hydroxide anion promoted degradation than state-of-the-art “stable” organic cations. A combination of endohedral protection (cage structure) and enforced, single-welled, hydrogen bonding enable in-DBD hydroxide to persist at 5% RH at 80 °C. The inventors stress that in-DBD is substantially more stable than the other studied cations in both solution and vapor-state, where all “state-of-the-art” cations had variable stability depending on the testing method; this shows how in-DBD may indeed be a broadly applicable cationic group for alkaline AEM technologies, especially vapor phase AEM technologies. The unprecedented ultra-high stability of in-DBD to hydroxide at elevated temperatures in both solution and low-humidity has the potential to overcome current limitations in AEM fuel cells and a variety of AEM- based devices such as CO / CO2 electrolyzers, and dry-cathode water electrolyzers.

[0292] While certain embodiments have been described in the foregoing, it is to be understood that other embodiments are possible and are intended to be included herein. It will be apparent to those skilled in the art that modifications and adaptations of the foregoing embodiments not shown are possible.

[0293] It is imperative to note that the foregoing description is merely an illustrative embodiment and the actual implementation may vary in myriad ways. While the example encapsulates a particular set of chemical reactions, compounds, or formulations, various elements within this configuration may be substituted, modified, or omitted altogether without detracting from the essence of the disclosure. For instance, the methods of synthesis or analysis could differ, alternative reactants or solvents might be used, or different experimental parameters might be adopted. The underlying chemical processes or synthesis routes can undergo numerous modifications to accommodate different reaction conditions, material properties, or technological advances. The inherent flexibility of the system allows for extensive customization, ensuring that while the basic principle remains consistent, the resulting compounds or reactions can be as diverse as the chemistry they represent.

[0294] Throughout the present disclosure, the term "module" may refer to either laboratory apparatus, software components, or a combination of both. The laboratory apparatus may include, but is not limited to, specific chemical reactors, analytical devices, spectroscopic instruments, or chromatography systems. Software components may involve computer code stored in a memory and executable by a processor, firmware, or scripts. The provided modules may be implemented in various forms, either standalone or in combination, and the functionality described herein may be split among multiple modules or integrated into a single module, depending on design choices and specific implementations.

[0295] The embodiments have been described with reference to sequence and block diagrams of methods, apparatuses, systems, and chemical processes. In this regard, the depicted sequences and diagrams illustrate the architecture, functionality, and operation of implementations of various embodiments. For instance, each block of the diagrams may represent a specific step, reaction, or part of a synthesis, which encompasses one or more specific actions for implementing the described processes. In some alternative embodiments, the actions denoted in those blocks may occur out of the order noted. For example, two blocks shown in succession may be executed substantially concurrently, or in reverse order, depending on the functionality involved.

[0296] The terminology used herein is only for the purpose of describing particular embodiments and is not intended to be limiting. Accordingly, terms such as “molecule”, “compound”, “reactant”, and “product” are intended to include both singular and plural forms unless the context clearly indicates otherwise. It will be further understood that the terms like “includes” and “including” specify the presence of the stated features or components but do not preclude the presence or addition of others. Phrases like "in solution", "in a mixture", or "under reaction conditions" are used for relative reference only and are not intended to suggest any restrictions on the described processes.

[0297] Phrases such as “at least one of A, B, and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, and “A, B, and / or C” are intended to encompass both a single item from the enumerated list of items and multiple items from the list. The phrases “at least one of”, “one or more of’, and similar phrases when used inconjunction with a list are not necessarily indicating that each item of the list must be present.

[0298] It is contemplated that any part of any aspect or embodiment discussed in this specification can be implemented or combined with any other, unless those parts are mutually exclusive. While every effort has been made to provide a detailed and accurate description, it should be noted that the scope of the disclosure is not limited to the exact configurations and embodiments described. The description is intended to illustrate the principles of the disclosure and not to limit its scope, which is defined by the appended claims and their potential applications in other fields.

Claims

CLAIMS1. A method of synthesizing 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium (in-DBD), comprising: i) oxidizing maleic hydrazide with in the presence of, or before mixing with, 1 ,3- butadiene to produce 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione; ii) hydrogenating 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione; iii) reducing the hydrogenated 1 ,6-diazabicyclo[4.4.0]dec-3,8-diene-2, 5-dione with a reducing agent to produce 1 ,6-diazabicyclo[4.4.0]decane; iv) singly-alkylating 1 ,6-diazabicyclo[4.4.0]decane with a 1 ,4-substituted butane derivative having leaving groups at the 1 and 4 positions; v) cyclizing the singly-alkylated 1 ,6-diazabicyclo[4.4.0]decane by addition into a metal salt to produce 1 ,6-diazatricyclo[4.4.4.01’6]tetradec-1 ,6-diylium tetrafluoroborate; vi) reducing an N-N bond of 1 ,6-diazatricyclo[4.4.4.01’6]tetradec-1 ,6-diylium by a reducing metal, excluding sodium, in acidic media to produce an outside- protonated DBD tetrafluoroborate salt; and vii) inside-protonating the outside-protonated DBD tetrafluoroborate salt by oxidation with a one-electron oxidant in acidic media to produce the in-DBD.

2. The method of claim 1 , wherein the product of step i) is isolated through an extraction and recrystallized in a solvent selected from a group consisting of dichloromethane (DCM), toluene, and diethyl ether.

3. The method of claim 1 , wherein the reducing agent in step iii) is selected from a group consisting of LiAIH4, NaBH4, Diisobutylaluminium hydride (DIBAL-H), and EtsSiH , or comprises a Wolff-Kishner reduction.

4. The method of claim 1 , wherein the 1 ,4-substituted butane derivative in step iv) is 1 ,4-dibromobutane, 1 ,4-diiodobutane, or 1 ,4-dichlorobutane.

5. The method of claim 1 , wherein the 1 ,4-substituted butane derivative in step iv) has a substituent at one or more of 2-position or 3-position of the butane chain.

6. The method of claim 1 , wherein the reducing metal in step vi) is selected from a group consisting of zinc, magnesium, and aluminum.

7. The method of claim 1 , wherein the one-electron oxidant in step vii) is a peroxydisulfate salt, wherein a cation of the peroxydisulfate salt is selected from a group consisting of potassium (K+), sodium (Na+), ammonium (NH4+), and lithium (Li+).

8. The method of claim 1 , wherein the one-electron oxidant in step vii) is selected from a group consisting of hydrogen peroxide (H2O2), benzoyl peroxide, and their salts.

9. The method of claim 1 , wherein the solvent in step iv) is tetrahydrofuran (THF).

10. The method of claim 1 , wherein the metal salt in step v) is silver tetrafluoroborate (AgBF4).

11. The method of claim 1 , wherein the acidic media in step vi) or vii) comprises tetrafluoroboric acid (HBF4).

12. The method of claim 1 , wherein the acidic media utilized in steps vi) and vii) is a same acidic media.

13. The method of claim 1 , wherein the outside-protonated DBD tetrafluoroborate salt produced in step vi) is air-stable, and wherein the reduction in step vi) and the inside-protonation in step vii) are performed sequentially without isolating the outside-protonated DBD tetrafluoroborate salt.

14. A method of integrating in-DBD into a polymer, the method comprising:i) polymerizing a bicycloheptene monomer comprising bromomethyl groups using a vinyl-addition polymerization catalyst in a first solvent to produce a brominated polymer; ii) reacting the brominated polymer with 1 ,6-diazabicyclo[4.4.0]decane in a second solvent to produce a polymer with pendant bicyclo[4.4.0]decane groups; iii) reacting the polymer with pendant bicyclo[4.4.0]decane groups with a silver salt in a third solvent, wherein the silver salt forms an insoluble salt with bromomethyl groups of the polymer; iv) reacting the product of step iii) with a reducing metal in an acidic solvent to produce a polymer with pendant reduced groups; and v) reacting the polymer with pendant reduced groups with an oxidizing agent to produce a polymer comprising integrated in-DBD.

15. The method of claim 14, wherein the vinyl-addition polymerization catalyst is selected from a group consisting of palladium catalysts, nickel catalysts, and combinations thereof, and wherein the first solvent in step i) is selected from a group consisting of toluene, dichloromethane, and ethers.

16. The method of claim 14, wherein the second solvent in step ii) is selected from a group consisting of tetrahydrofuran, toluene, dichloromethane, and ethers.

17. The method of claim 14, wherein the silver salt in step iii) is selected from a group consisting of silver tetrafluoroborate, silver nitrate, and silver fluoride, and the third solvent in step iii) is selected from a group consisting of tetrafluoroboric acid, water, and nitric acid.

18. The method of claim 14, wherein the reducing metal in step iv) is selected from a group consisting of zinc, aluminum, and magnesium, and wherein the acidic solvent in step iv) is selected from a group consisting of tetrafluoroboric acid, sulfuric acid, and hydrochloric acid.

19. The method of claim 14, wherein the oxidizing agent in step v) is a one-electron oxidant, and wherein the one-electron oxidant is a peroxydi sulfate with a cation selected from a group consisting of potassium (K+), sodium (Na+), ammonium (NH4+), and lithium (Li+).

20. The method of claim 14, wherein the brominated polymer in step i) is Poly[(5S,6S)-5,6-bis(bromomethyl)bicyclo[2.2.1]hept-2-ene], and wherein a catalyst to monomer ratio in step i) ranges from 1 :50 to 1 :50000.21 . A method of integrating in-DBD into a polymer, the method comprising: i) reacting a bicycloheptene monomer comprising bromomethyl groups with 1 ,6-diazabicyclo[4.4.0]decane in a first solvent to produce a first intermediate product; ii) reacting the first intermediate product with a silver salt in a second solvent to form a second intermediate product; iii) reacting the second intermediate product with a reducing metal in an acid solvent to produce a third intermediate product; iv) reacting the third intermediate product with an oxidizing agent to produce a fourth intermediate product; v) reacting the fourth intermediate product with a vinyl-addition polymerization catalyst in a third solvent to produce a polymer comprising integrated in-DBD.

22. The method of claim 21 , wherein the first solvent in step i) is selected from the group consisting of tetra hydrofuran, toluene, dichloromethane, and ethers.

23. The method of claim 21 , wherein the silver salt in step ii) is selected from the group consisting of silver tetrafluoroborate, silver nitrate, and silver fluoride.

24. The method of claim 21 , wherein the acid solvent in step iii) is selected from the group consisting of tetrafluoroboric acid, sulfuric acid, and hydrochloric acid, and wherein the reducing metal in step iii) is selected from the group consisting of zinc, aluminum, and magnesium.

25. The method of claim 21 , wherein the oxidizing agent in step iv) is potassium peroxydisulfate.

26. The method of claim 21 , wherein the third solvent in step v) is selected from the group consisting of toluene, dichloromethane, and ethers, and wherein the vinyl-addition polymerization catalyst in step v) is selected from the group consisting of palladium and nickel catalysts.

27. The method of claim 21 , wherein a catalyst to monomer ratio in step v) ranges from 1 :50 to 1 :50000.

28. An in-DBD polymer comprising: a polymer matrix; and1 ,6-diazabicyclo[4.4.4]tetradecan-1 , 6-ium (in-DBD) cationic structure integrated into the polymer matrix, wherein a cationic charge of the in-DBD cationic structure is carried by an immobilized proton inside an aliphatic cage formed by a three-dimensional structure of the in-DBD cationic structure and is stabilized between two nitrogen atoms of the in-DBD cationic structure via a symmetrical intra-bridgehead hydrogen bond.

29. The in-DBD polymer of claim 28, wherein the polymer matrix is selected from a group consisting of: polysulfones, polyphenylenes, poly(arylene ether ketones), poly(phenylene oxides), polyethylenes, polypropylenes, polystyrenes, polybenzimidazoliums, and polynorbornenes.

30. The in-DBD polymer of claim 29 wherein the polymeric matrix connects to the in-DBD cationic structure at multiple locations.31 . A polymer ionic exchange membrane comprising the in-DBD polymer claimed in any of claims 28-30.

32. A catalyst ink comprising a catalyst material, water, an organic solvent, and the in-DBD polymer claimed in any of claims 28-30.

33. A catalyst coated membrane comprising a polymer ion exchange membrane coated with the catalyst ink as claimed in claim 32.

34. A catalyst coated membrane comprising the polymer ionic exchange membrane as claimed in claim 31 and coated with a catalyst.

35. A membrane electrode assembly comprising an anode layer, a cathode layer, and the polymer ionic exchange membrane as claimed in any of claims 28-30 in between the anode and cathode layers.

36. A fuel cell comprising at least one of the polymer ionic exchange membrane claimed in claim 31 , the catalyst ink claimed in claim 32, and the catalyst coated membrane as claimed in claim 33 or claim 34.

37. An electrolyzer comprising at least one of the polymer ionic exchange membrane claimed in claim 31 , the catalyst ink claimed in claim 32, and the catalyst coated membrane as claimed in claim 33 or claim 34.

38. Use of 1 ,6-diazabicyclo[4.4.4]tetradecan-1 ,6-ium (in-DBD) as a cationic functional group for the preparation of an anion exchange membrane (AEM), wherein a cationic charge of the in-DBD is carried by an immobilized proton inside an aliphatic cage formed by a three-dimensional structure of the in-DBD and is stabilized between two nitrogen atoms of the in-DBD via a symmetrical intra-bridgehead hydrogen bond.

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