Methods for carbon dioxide separation and materials and systems for same

Abstract

Methods of separating one or more compound(s) of interest, which may include alkene(s), arene(s), CO2, or any combination thereof. A method may comprise irradiating, with electromagnetic radiation, a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and one or more compound(s) of interest, where at least a portion of the compound(s) of interest react with at least a portion of the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom to form one or more cycloaddition product(s). A method may further comprise releasing at least a portion of one or more compound(s) of interest from one or more cycloaddition product(s). Capture sorbent materials for separating one or more compound(s) of interest, which may comprise a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and a substrate. Systems for capture and optionally, isolation, of one or more compound(s) of interest, which may comprise one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom.

Description

METHODS FOR CARBON DIOXIDE SEPARATION AND MATERIALS AND SYSTEMS FOR SAME CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No.63 / 519,734, filed on August 15, 2023, the entire disclosure of which is hereby incorporated by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] This invention was made with government support under contract no. SC0021000 awarded by the U.S. Department of Energy, and contract no. CBET-2047627 awarded by the U.S. National Science Foundation. The government has certain rights in the invention. BACKGROUND OF THE DISCLOSURE

[0003] The rising atmospheric levels of CO2represent a significant climate threat to humanity. Meeting the goals of the Paris accord is ambitious, and, even in the best case scenario, will require the post-combustion removal of CO2from industrial point sources such as natural- gas fired power plants. However, current temperature-swing carbon capture technologies are highly energy- and cost-intensive, prohibiting their global deployment. Carbon capture is fundamentally energy-intensive to compensate for entropy penalties arising from concentrating CO2from a dilute stream into a pure gas for subsequent sequestration or valorization. Currently, the bulk of the required energy is counterproductively provided by combusting fossil fuels; in this case, energy transition efforts may be more productive in reducing atmospheric CO2 concentration than carbon capture. The utilization of renewable energy to capture CO2would overcome the drawback of employing fossil fuel combustion to drive carbon capture. In particular, sunlight is an attractive energy source as it is the most abundant energy resource on Earth, leading to its rapidly growing use for electricity generation and other scalable environmental applications, including a more efficient carbon capture. However, the inefficiency of carbon capture is exacerbated by the many energy exchange and conversion steps between the energy production and the eventual CO2 removal, leading to ample energy loss pathways. For example, state-of-the-art commercial-sized solar panels can currently harness up to 30% of solar energy, while one analysis of a direct air capture of CO2 system shows that only ~8% of the energy supply is consumed to remove CO2, yielding at most a 2.4% efficiency once combined.

[0004] Instead, the direct use of (sun)light as a stimulus for CO2capture and release could be a means to improve its efficiency that remains underexplored. In some examples, light-controlled CO2 capture systems utilize light stimulus to switch on or off the separation of CO2, but additional stimulus remains necessary induce CO2desorption. There are scattered examples using light to drive carbon capture and / or release, but many rely on UV light irradiation, which is scarce within the solar spectrum (FIG.1A). Using light to provide the driving force for CO2 release does circumvent the need for a large amount of energy to desorb CO2, the thermodynamic burden of this separation is allotted solely on the release step. Such systems with a low thermodynamic driving force would perform poorly with dilute sources such the flue gas of natural gas-fired power plants (5–10% CO2), while those with strong reactivity would require high-energy light to drive the release of CO2(FIG.1A).

[0005] Carbon capture from industrial point sources is an important component of the global effort to mitigate climate risks. However, traditional approaches require significant energy input—often provided by fossil fuel combustion. SUMMARY OF THE DISCLOSURE

[0006] The present disclosure provides, inter alia, methods of separating compounds of interest. The present disclosure also provides capture sorbents and systems for separating compounds of interest.

[0007] In an aspect, the present disclosure provides methods of separating one or more compound(s) of interest. In various examples, a method comprises capture of one or more compound(s) of interest. In various examples, a method comprises release of at least a portion, substantially all, or all of the captured compound(s) of interest. In various examples, a method is carried out using a capture sorbent (e.g., a capture sorbent material or the like) of the present disclosure. In various examples, a method is carried out using a system of the present disclosure. Non-limiting examples of methods of separating one or more compound(s) of interest are provided herein.

[0008] In an aspect, the present disclosure provides compositions (e.g., capture sorbent materials or the like). In various examples, a capture sorbent (e.g., capture sorbent materials or the like) comprises one or more ketone(s) (e.g., 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like) or the like. In various examples, a capture sorbent or capture sorbentsis / are used in a method and / or a system of the present disclosure. Non-limiting examples of capture sorbents are provided herein.

[0009] In an aspect, the present disclosure provides systems for separating one or more compound(s) of interest. In various examples, a system is configured to capture one or more compound(s) of interest. In various examples, a system is configured to release at least a portion or all of the captured compound(s) of interest. In various examples, a system is configured to use (or uses) a capture sorbent (e.g., a capture sorbent material or the like) of the present disclosure. In various examples, a system is configured to carry out a method of the present disclosure. Non- limiting examples of systems are provided herein. BRIEF DESCRIPTION OF THE FIGURES

[0010] For a fuller understanding of the nature and objects of the disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying figures.

[0011] FIG.1 shows an example of a design of a fully light-driven capture-and-release system for CO2. A - Terrestrial solar spectrum. B - Illustrative energy diagram of previous carbon capture technologies. C - Illustrative energy diagrams of proposed carbon capture technology. D - CO2fixation by a reactive enol in the RuBisCo enzyme as an inspiration for the CO2 capture mechanism. E - Radical decarboxylation in 4-hydroxyphenylacetate decarboxylase (4HPAD) as an inspiration for the CO2 release mechanism. F - Proposed mechanistic pathways for light-triggered CO2capture and release using inexpensive 2-methylbenzophenones. PT = proton transfer, SET = single electron transfer.

[0012] FIG.2 shows optimization of photoenolization / Diels-Alder capture of CO2. A - CO2 capture using 2 M of 1 in DMSO-d6 from various CO2-containing streams. For the with base experiment, 15 mol% of K3PO4was added. B - CO2capture using 2 M of 1 in DMSO-d6from pure CO2 with light switching on-and-off every 10 min. Concentration of the CO2-adduct 2 was determined by1H NMR spectroscopy against 1,3,5-trimethoxybenzene as internal standard.

[0013] FIG.3 shows optimization of photoredox decarboxylation of CO2-adduct 2 or 3. A - CO2 release of 0.1 M of 3 in DMSO-d6.0.1 M of 2 in DMSO-d6 was used for no base experiment. No light experiment was conducted in the dark with heating in an oil bath at 60^C. B - CO2release using 0.1 M of 3 in DMSO-d6from with periodic light on-and-off switching every10 minutes. Concentration of the CO2-adduct 2 or 3 was determined by1H NMR spectroscopy against 1,3,5-trimethoxybenzene as internal standard.

[0014] FIG.4 shows a proposed mechanism for a fully light- CO2 separation system with energy difference (kJ / mol) for each step calculated at M06-2X / 6-311+G(2d,p)- SMD(DMSO) level at 298.15 K.

[0015] FIG.5 shows a realistic application of the fully light-driven CO2 separation system. A - CO2capture and release of 0.1 M of 1 and 3.0 equiv. of BzOK in DMSO from a simulated and actual flue gas. Concentration of the CO2-adduct 3 was determined by1H NMR spectroscopy against tetra-n-butylammonium hexafluorophosphate as internal standard. B - CO2 capture using 2.0 M of 1 and 15 mol% of K3PO4in DMSO-d6from pure CO2using windowsill sunlight as light source. Concentration of the CO2-adduct 2 was determined by1H NMR spectroscopy against 1,3,5-trimethoxybenzene as internal standard.

[0016] FIG.6 shows synthesis of 2-(2-benzoylphenyl)acetic acid (2).

[0017] FIG.7 shows synthesis of potassium 2-(2-benzoylphenyl)acetate (3).

[0018] FIG.8 shows a scheme of light-driven CO2 capture using 1 with General Procedure A.

[0019] FIG.9 shows a scheme of light-driven CO2capture using 1 with General Procedure B.

[0020] FIG.10 shows a visual example for transferring flue gas sample using a syringe. Each sample load was withdrawn after purging with 3 × 10 mL of the flue gas samples.

[0021] FIG.11 shows an experimental setup for a fully light-driven CO2capture and release from flue gas samples. The syringe pump was programmed to deliver 3 mL min−1of flue gas.

[0022] FIG.12 shows an experimental setup for a fully light-driven CO2 capture and release using sunlight. Sunlight was concentrated using one magnifying glass. Sample positioning was adjusted every 5 minutes to maximize the absorption of the concentrated sunlight.

[0023] FIG.13 shows an experimental setup for a fully light-driven CO2 capture and release using a solar simulator. Sample distance to the solar simulator was adjusted by a pyranometer to match the irradiance of one sun (1000 W m−2) or two suns (2000 W m−2).

[0024] FIG.14 shows CO2 capture from a pure CO2 stream using various concentrations of 1 in DMSO-d6. Two Kessil PR-160L-390nm lamps were used to irradiate the samples. Theconcentration of the CO2-adduct 2 was determined by1H NMR spectroscopy against 1,3,5- trimethoxybenzene as an internal standard.

[0025] FIG.15 shows CO2 capture from a pure CO2 stream using various concentration of 1 in DMSO-d6. Two or four Kessil PR-160L-390nm lamps were used to irradiate the samples. The concentration of the CO2-adduct 2 was determined by1H NMR spectroscopy against 1,3,5- trimethoxybenzene as an internal standard. Slightly improved performance is observed using 4 lamps.

[0026] FIG.16 shows CO2 capture from a 10% CO2 in N2 stream using 2 M of 1 in DMSO- d6 with or without cooling with a fan. Concentration of the CO2-adduct 2 was determined by1H NMR spectroscopy against 1,3,5-trimethoxybenzene as an internal standard. For thewith base, 15 mol% of K3PO4was added. Cooling with a fan is not required to achieve CO2capture in this system. The addition of base leads to improved CO2 uptake.

[0027] FIG.17 shows CO2 release under N2 flow using various concentrations of 3 in DMSO-d6. Concentration of the CO2-adduct 3 was determined by1H NMR spectroscopy against 1,3,5-trimethoxybenzene as an internal standard.

[0028] FIG.18 shows the difference in cycling performance for mixtures of 2.0 M and 0.1 M of 1 in DMSO-d6with 0.15 mmol of K3PO4. The presence of too much 1 in solution inhibits the CO2 release process.

[0029] FIG.19 shows CO2 release of 0.1 M of 3 and 3.0 equiv. of BzOK in DMSO using N2 flow using windowsill sunlight as light source. Concentration of the CO2-adduct 3 was determined by1H NMR spectroscopy against tetra-n-butylammonium hexafluorophosphate as internal

[0030] FIG.20 shows reductive cyclic voltammogram of 1, 2, or 3 (5 mM) dissolved in an electrolyte solution of TBAPF6(0.1 M) in MeCN in a N2-filled glovebox, with Fc as an internal reference and corrected against SCE. Scan rate: 100 mV / s; E1 / 2 (1 / 1∙−) = −1.89 V vs. SCE. E1 / 2 (2 / 2∙−) = −1.78 V vs. SCE. E1 / 2 (3 / 3∙−) = −1.78 V vs. SCE.

[0031] FIG.21 shows oxidative cyclic voltammogram of 3 (5 mM) dissolved in an electrolyte solution of TBAPF6 (0.1 M) in MeCN in a N2-filled glovebox, with Fc as an internal reference and corrected against SCE. Scan rate: 100 mV / s; Ep / 2 = +1.15 V vs. SCE.

[0032] FIG.22 shows UV-vis absorption spectra of 1, 2, and 3 (20 mM) in DMSO.

[0033] FIG.23 shows UV-vis absorption spectra of 1, 2, and 3 (20 mM) in DMSO in the purple light region. By varying their concentration, the molar extinction coefficients at 390 nm (ε390 nm) of 1, 2, and 3 were determined to be 2.08 M cm-1, 2.11 M cm-1, and 2.36 M cm-1, respectively, suggesting little to no difference in their molar absorptivity.

[0034] FIG.24 shows phosphorescence spectra of 1 and 2 (20 mM) in DMSO with 330 nm excitation and 1 ms (ms = millisecond(s)) delay.

[0035] FIG.25 shows relative Gibbs free energy diagram of a fully light-driven CO2separation system with energy difference for each step calculated at M06-2X / 6-311+G(2d,p)- SMD(DMSO) level at 298.15 K. Deprotonation steps are balanced by the protonation of monoanionic K2PO4−into K2HPO4(F to G, L to M), while protonation steps are balanced by the deprotonation of K2HPO4into monoanionic K2PO4−(T to A).

[0036] FIG.26 shows proposed light-driven CO2 separation cycle with a photoenolate pathway for the capture step and 3-mediated photoredox decarboxylation pathway for the release step.

[0037] FIG.27 shows an alternative light-driven CO2 separation cycle with a photoenol pathway for the capture step and 3-mediated photoredox decarboxylation pathway for the release step.

[0038] FIG.28 shows an alternative light-driven CO2 separation cycle with a photoenolate pathway for the capture step and 1-mediated photoredox decarboxylation pathway for the release step.

[0039] FIG.29 shows optimized DFT transition state structures of the Diels-Alder reaction of photoenolized 1 and CO2 in the absence (enol pathway, left) and presence of a base (enolate pathway, right).

[0040] FIG.30 shows a proposed mechanism for a fully light-driven CO2separation system with energy differences (kJ / mol) for each step calculated at the M06-2X / 6-311+G(2d,p)- SMD(DMSO) level at 298.15 K. The values are referenced to the previous step with the starting value of 1 as 0 kJ / mol. The grey colored intermediates refer to the alternative enol pathway as the carbon capture mechanism.

[0041] FIG.31 shows CO2 capture of 0.1 M of 1 and 3.0 equiv. of BzOK in DMSO from a simulated flue gas and release using N2flow with a solar simulator irradiation (2000 W / m2).Concentration of the CO2-adduct 3 was determined by1H NMR spectroscopy against tetra-n- butylammonium hexafluorophosphate as internal standard.

[0042] FIG.32 shows CO2 capture of 0.1 M of 1 and 3.0 equiv. of BzOK in DMSO from a simulated flue gas using windowsill sunlight as light source. Concentration of the CO2-adduct 3 was determined by1H NMR spectroscopy against tetra-n-butylammonium hexafluorophosphate as internal standard. DETAILED DESCRIPTION OF THE DISCLOSURE

[0043] Although claimed subject matter will be described in terms of certain embodiments and examples, other embodiments and examples, including embodiments and examples that do not provide all of the benefits and features set forth herein, are also within the scope of this disclosure. For example, various structural, logical, process step, and electronic changes may be made without departing from the scope of the disclosure.

[0044] As used herein, unless otherwise stated, "about," "approximately," “substantially,” or the like, when used in connection with a measurable variable such as, for example, a parameter, an amount, a temporal duration, or the like, are meant to encompass variations of, for example, a specified value including, for example, those within experimental error (which can be determined by for example, a given data set, an art accepted standard, and / or with a given confidence interval (e.g.90%, 95%, or more confidence interval from the mean), such as, for example, variations of + / -10% or less, + / -5% or less, + / -1% or less, and + / -0.1% or less of and from the specified value) or to encompass alternatives to the members of the list that would be recognized by one of ordinary skill in the art as alternatives, where the members and the alternatives may define a genus or sub-genus, insofar as such variations are appropriate to perform in the context of the disclosure. As used herein, unless otherwise stated, the terms “about,” “approximate,” “at or about,” “substantially,” and “~” can mean that the amount or value in question can be the exact value or a valueequivalent results or effects as recited in the sample claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error, and the like, and other factors known to those of skill in the art such that, for example, equivalent results, effects, or the like are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonablydetermined. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” “at or about,” or “~” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unlessspecifically stated otherwise.

[0045] Ranges of values are disclosed herein. The ranges set out a lower limit value and an upper limit value. Unless otherwise stated, the ranges include the lower limit value, the upper limit value, and all values between the lower limit value and the upper limit value, including, but not limited to, all values to the magnitude of the smallest value (either the lower limit value or the upper limit value) of a range. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 0.1% to 5%” should be interpreted to include not only the explicitly recited values of about 0.1% to about 5%, but also, unless otherwise stated, include individual values (e.g., about 1%, about 2%, about 3%, and about 4%) and the sub-ranges (e.g., about 0.5% to about 1.1%; about 0.5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible sub-ranges) within the indicated range. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further disclosure. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0046] As used herein, unless otherwise stated, the term “group” or “moiety” refers to a chemical entity that is monovalent (i.e., has one terminus that can be covalently bonded to other chemical species), divalent, or polyvalent (i.e., has two or more termini that can be covalently bonded to other chemical species). The term “group” also includes radicals (e.g., monovalent and multivalent, such as, for example, divalent radicals, trivalent radicals, and the like). Illustrativeexamples of groups or moieties include: the like. term “alkyl group” refers to branchedor groups bonds between carbon atoms (not including substituent(s), if any). In various examples, an alkyl group is a C1to C12alkyl group (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, or C12), including all integer numbers of carbons and ranges of numbers of carbons therebetween. In various examples, an alkyl group is a saturated group. In various examples, an alkyl group is a cyclic alkyl group, which may be a heterocyclic alkyl group, e.g., a monocyclic alkyl group or a polycyclic alkyl group or the like. Examples of alkyl groups include, but are not limited to, methyl groups, ethyl groups, propyl groups, butyl groups, isopropyl groups, tert-butyl groups, cyclohexyl groups, adamantyl groups, benzyl groups and the like. In various examples, an alkyl group is unsubstituted or substituted with one or more substituent(s). Examples of substituents include, but are not limited to, various substituents such as, for example, halogen groups (-F, -Cl, -Br, and -I), aliphatic groups (e.g., alkyl groups, alkenyl groups, alkynyl groups, and the like), halogenated aliphatic groups (e.g., trifluoromethyl group and the like), aryl groups, halogenated aryl groups, hydroxyl group, amine groups, nitro group, cyano groups, isocyano groups, azide group, silane groups (e.g., alkyl silane groups, aryl silane groups, alkyl / aryl silane groups, or the like), alkoxide groups, alcohol groups, ether groups, ketone groups, carboxylate groups, carboxylic acid groups, ester groups, amide groups, thioether groups, thioester groups, and the like, and any combination thereof.

[0048] As used herein, unless otherwise indicated, the term “aryl group” refers to C5to C30fully aromatic or partially aromatic carbocyclic groups. In various examples, an aryl group is a C5 to C30 aromatic or partially aromatic carbocyclic group (e.g., C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, and C30), including all integer numbers of carbons and ranges of numbers of carbons therebetween. In various examples, an aryl group comprises (or is) one or more polyaryl group(s) (such as, for example, fused ring group(s), biaryl group(s), or the like, or any combination thereof) or the like, or any combination thereof. In various examples, an aryl group is unsubstituted or substituted with one or more substituent(s). Examples of substituents include, but are not limited to, substituents such as, for example, halogen groups (-F, -Cl, -Br, and -I), aliphatic groups (e.g., alkyl groups, alkenylgroups, alkynyl groups, and the like), halogenated aliphatic groups (e.g., trifluoromethyl group and the like), aryl groups, halogenated aryl groups, hydroxyl group, amine groups, nitro group, cyano groups, isocyano groups, azide group, silane groups (e.g., alkyl silane groups, aryl silane groups, alkyl / aryl silane groups, or the like), alkoxide groups, alcohol groups, ether groups, ketone groups, carboxylate groups, carboxylic acid groups, ester groups, amide groups, thioether groups, thioester groups, and the like, and any combination thereof. In various examples, a substituent is a charged substituent (such as, for example, a static charged substituent or a condition (e.g., pH) specific charged substituent). In various examples, an aryl groups comprises one or more heteroatom(s) (such as, for example, oxygen(s), nitrogen(s) (e.g., pyridinyl groups and the like), sulfur(s), and the like, and any combination thereof), which may be referred to as heteroaryl groups. Examples of aryl groups include, but are not limited to, phenyl groups, biaryl groups (e.g., biphenyl groups and the like), fused ring groups (e.g., naphthyl groups and the like), hydroxybenzyl groups, tolyl groups, xylyl groups, furanyl groups, pyrrolyl groups, thiophenyl groups, benzofuranyl groups, indolyl groups, imidazolyl groups, benzimidazolyl groups, pyridinyl groups, and the like.

[0049] As used herein, unless otherwise indicated, the term “arene” refers to C5 to C30 fully aromatic or partially aromatic carbocyclic compounds. In various examples, an arene is a C5to C30 aromatic or partially aromatic carbocyclic compound (e.g., C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, and C30), including all integer numbers of carbons and ranges of numbers of carbons therebetween. In various examples, an arene comprises (or is) one or more polyaryl group(s) (such as, for example, fused ring group(s), biaryl group(s), or the like, or any combination thereof) or the like, or any combination thereof. In various examples, an arene is unsubstituted or substituted with one or more substituent(s). Examples of substituents include, but are not limited to, substituents such as, for example, halogen groups (-F, -Cl, -Br, and -I), aliphatic groups (e.g., alkyl groups, alkenyl groups, alkynyl groups, and the like), halogenated aliphatic groups (e.g., trifluoromethyl group and the like), aryl groups, halogenated aryl groups, hydroxyl group, amine groups, nitro group, cyano groups, isocyano groups, azide group, silane groups (e.g., alkyl silane groups, aryl silane groups, alkyl / aryl silane groups, or the like), alkoxide groups, alcohol groups, ether groups, ketone groups, carboxylate groups, carboxylic acid groups, ester groups, amide groups, thioether groups, thioester groups, and the like, and any combination thereof. In various examples, an arylgroups comprises one or more heteroatom(s) (such as, for example, oxygen(s), nitrogen(s) (e.g., pyridinyl groups and the like), sulfur(s), and the like, and any combination thereof), which may be referred to as heteroaryl groups. In various examples, a substituent is a charged substituent (such as, for example, a static charged substituent or a condition (e.g., pH) specific charged substituent). Examples of arenes include, but are not limited to, compounds comprising phenyl groups, biaryl groups (e.g., biphenyl groups and the like), fused ring groups (e.g., naphthyl groups and the like), hydroxybenzyl groups, tolyl groups, xylyl groups, furanyl groups, pyrrolyl groups, thiophenyl groups, benzofuranyl groups, indolyl groups, imidazolyl groups, benzimidazolyl groups, pyridinyl groups, or the like, or any combination thereof.

[0050] As used herein, unless otherwise stated, the term “structural analog” refers to any compound (such as, for example, a compound of interest, a capture sorbent (e.g., a 2-alkyl phenyl ketone or the like)), or any portion thereof (such as, for example, one or more group(s) thereof or the like) or group if one atom or group of atoms, functional group or functional groups, or substructure or substructures is / are replaced with another atom or group of atoms, functional group or functional groups, substructure or substructures, or the like. In various examples, the term “structural analog” refers to any group that is derived from an original compound (such as, for example, a compound of interest, a capture sorbent (e.g., a 2-alkyl phenyl ketone or the like)), or any portion thereof (such as, for example, one or more group(s) thereof or the like) by a chemical reaction, where the compound (such as, for example, a compound of interest, a capture sorbent (e.g., a 2-alkyl phenyl ketone or the like)), or any portion thereof (such as, for example, one or more group(s) thereof or the like) is modified or partially substituted such that at least one structural feature of the compound (such as, for example, a compound of interest, a capture sorbent (e.g., a 2-alkyl phenyl ketone or the like)), or any portion thereof (such as, for example, one or more group(s) thereof or the like) is retained.

[0051] The present disclosure describes, inter alia, methods of separating compounds of interest. In various examples, the present disclosure also provides capture sorbents and systems for separating compounds of interest.

[0052] In an aspect, the present disclosure provides methods of separating one or more compound(s) of interest. In various examples, a method comprises capture of one or more compound(s) of interest. In various examples, a method comprises release of at least a portion, substantially all, or all of the captured compound(s) of interest. In various examples, a method iscarried out using a capture sorbent (e.g., a capture sorbent material or the like) of the present disclosure. In various examples, a method is carried out using a system of the present disclosure. Non-limiting examples of methods of separating one or more compound(s) of interest are provided herein.

[0053] In various examples, a method of separating one or more compound(s) of interest comprises irradiating (e.g., a first irradiating), with electromagnetic radiation (e.g., having one or more first wavelength(s)), one or more compound(s) of interest and one or more ketone(s) (e.g., 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom). In various examples, the one or more compound(s) of interest and one or more ketone(s) are in a mixture (e.g., a method comprises irradiating a mixture comprising one or more compound(s) of interest and one or more ketone(s) (e.g., 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom)).

[0054] Various wavelengths of electromagnetic radiation can be used. In various examples, electromagnetic radiation (e.g., in a first and / or a second irradiating) has one or more visible light wavelength(s). In various examples, electromagnetic radiation (e.g., in a first and / or a second irradiating) has one or more wavelength(s) absorbed by one or more or all of the 2-alkyl-phenyl ketone(s) (such as, for example, about 320 nm to about 410 nm for 2-methyl benzophenone). In various examples, electromagnetic radiation has one or more wavelength(s) absorbed by one or more photocatalyst(s), if present, (such as, for example, about 456 nm for Rhodamine G). In various examples, one or more wavelength(s) (e.g., visible wavelength(s)) is / are chosen from wavelengths of sunlight and any combination thereof. In various examples, electromagnetic radiation (e.g., in a first and / or a second irradiating) has one or more wavelength(s) of about 310 nm to about 1,100 nm, including all 0.1 nm wavelengths and ranges therebetween (e.g., about 320 nm to about 410 nm, about 380 nm to about 700 nm, about 380 nm to about 400 nm, or about 390 nm, or the like). In various examples, electromagnetic radiation does not have a UV wavelength. In various examples, electromagnetic radiation is about 3% or less UV radiation (e.g., having a UV wavelength of 380 nm or less, including all 0.1 nm values and ranges therebetween).

[0055] In various examples, electromagnetic radiation is provided by a lamp, a light emitting diode, or a laser, or the like, or any combination thereof. In various examples, electromagnetic radiation is provided by solar irradiation (e.g., ambient sunlight), a solar concentrator, or the like.

[0056] In various examples, irradiation is maintained for a desired duration. In various examples, irradiation is maintained from about X to about X min, including all 0.1 second values and ranges therebetween (e.g., about 15 min, about 60 min, or the like). In various examples, irradiation is maintained for a desired length of time and / or until a desired amount of compound(s) of interest is / are captured (e.g., reacted with 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like). In various examples, a desired length of time for irradiating corresponds to an intensity of electromagnetic radiation.

[0057] Various ketone(s) (e.g., 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom) can be used. In various examples, a 2-alkyl phenyl ketone comprises a 2-alkyl group comprising a C–H bond suitable for light-driven formation of CO2-reactive photoenols. In various examples, a 2-alkyl phenyl ketone is a 2-alkyl phenyl ketone disclosed herein or a structural analog thereof. In various examples, a 2-alkyl phenyl ketone comprises a charged functional group. In various examples, a 2-alkyl phenyl ketone comprises or is a 2-alkylbenzophenone (e.g., 2- methylbenzophenone or the like). In various examples, a 2-alkyl phenyl ketone is o-tolyl(2,4,6- trimethoxyphenyl)methanone or the like. Non-limiting examples of 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom include the following: O Me O Me OMe O Me MeO O Me OH O Me Me Me Me ,

[0058] Various concentrations of ketone(s) can be used. In various examples, one or more 2- alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are present (e.g., in a mixture) at a concentration of about 0.1 to about 2 mmol / liter, including all 0.05 mmol / liter values and ranges therebetween.

[0059] Various compounds of interest can be used. In various examples, a compound of interest comprises any compound that is able to react with a 2-alkyl phenyl ketone (e.g., to react with a C-H bond of the 2-alkyl group) to form a cycloaddition product (e.g., a cycloaddition adduct or the like) or the like. In various examples, a compound of interest comprises an alkene (e.g., a compound comprising an alkene group or the like), arene (e.g., a compound comprising an arene group or the like), or the like, or any combination thereof. In various examples, a compound of interest is CO2(e.g., CO2gas or the like).

[0060] In various examples, a method comprises irradiating (e.g., a first irradiating) one or more compound(s) of interest and one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom whereby at least a portion of the compound(s) of interest and at least a portion of the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom react to form one or more cycloaddition product(s). In various examples, a cycloaddition product comprises or is an adduct (e.g., a carbon dioxide adduct, an alkene adduct, an arene adduct, or the like). Without intending to be bound by any particular theory, it is considered that a compound of interest and a 2-alkyl phenyl ketone react by photoenolization or the like and subsequent Diels-Alder reaction to form a cycloaddition product; it is also considered that a compound of interest and a 2-alkyl phenyl ketone react by nucleophilic addition or the like to form a cycloaddition product.

[0061] In various examples, one or more alkene(s) and / or arene(s) is / are separated from one or more alkane(s) by a method. In various examples, one or more first arene(s) is / are separated from one or more second arene(s) (such as, for example, isomer(s) of the first arene(s)). Without intending to be bound by any particular theory, it is considered that alkene or arene separation (e.g., separation of ethene from ethane, separation of 1-butene from 2-butenes, separation of xylene isomers, or the like) results from different reactivity (e.g., reactivity with one or more 2- alkyl phenyl ketone(s) and / or group(s) formed therefrom) between the separated alkenes and / or arenes.

[0062] In various examples, one or more compound(s) of interest and one or more ketone(s) are in contact with one or more photocatalyst(s) and / or photothermal catalyst(s) (e.g., in contactduring a method or during a portion of a method). Various photocatalysts and / or photothermal catalysts can be used. In various examples, a photocatalyst or photothermal catalyst absorbs one or more visible light wavelength(s) (such as, for example, about 456 nm for Rhodamine 6G). Non-limiting examples of photocatalysts include Rhodamine 6G, 1,2,3,5-Tetrakis(carbazol-9- yl)-4,6-dicyanobenzene (4CzIPN), tetra-n-butylammonium decatungstate (TBADT), xanthone, structural analogs thereof, and the like, and any combination thereof. Non-limiting examples of photothermal catalysts include carbon quantum dots, structural analogs thereof, and the like, and any combination thereof. In various examples, one or more compound(s) of interest and one or more ketone(s) are not in contact with photocatalyst(s) and / or photothermal catalyst(s) (e.g., in contact during a method or during a portion of a method).

[0063] In various examples, one or more compound(s) of interest and one or more ketone(s) are in contact with one or more base(s) (e.g., in contact during a method or during a portion of a method). In various examples, one or more base(s) is / are present during formation of one or more cycloaddition product(s). In various examples, one or more base(s) is / are not present during formation of one or more cycloaddition product(s). In various examples, one or more base(s) is / are added (e.g., to one or more cycloaddition product(s)) after irradiation (e.g., a first irradiation), and prior to or simultaneous to releasing one or more compound(s) of interest (e.g., releasing one or more compound(s) of interest from one or more cycloaddition product(s)). Various bases can be used. In various examples, a base exhibits sufficient basicity to deprotonate and / or exchange protons with a carboxylic acid (e.g., of a cycloaddition product(s) or the like, such as, for example, carbon dioxide adduct or the like). Non-limiting examples of bases include potassium phosphate tribasic, sodium carbonate, and N,N-dimethylbenzylamine, potassium benzoate, structural analogs thereof, and the like, and any combination thereof.

[0064] In various examples, one or more base(s) is / are present (e.g., in a mixture) (e.g., independently prior to irradiation, during irradiation, or both) at a concentration of about 0.1 equivalent (based on the amount of 2-alkyl-phenyl ketone(s) present in the mixture or the amount of cycloaddition product(s) (such as, for example, alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like) to an excess of base(s) (e.g., about 3 equivalents (based on the amount of 2-alkyl-phenyl ketone(s) present in the mixture or the amount of cycloaddition product(s) (such as, for example, alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like), including all 0.05 equivalent values and ranges therebetween).

[0065] Compound(s) of interest may be present in a solution, a mixture, or the like. In various examples, a mixture (e.g., a mixture comprising one or more compound(s) of interest and one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom) is a solution and / or a suspension. In various examples, a mixture comprises one or more solvent(s). In various examples, one or more solvent(s) comprise(s) polar solvent(s) (e.g., polar aprotic solvent(s) or the like) or the like. Non-limiting examples of solvents include dimethyl sulfoxide, dimethyl acetamide, and N-methyl-2-pyrrolidone, structural analogs thereof, and the like, and any combinations thereof.

[0066] In various examples, one or more compound(s) of interest is / are present in a gas or liquid (which may be a stream, such as, for example, a waste gas / liquid stream, an industrial gas / liquid stream (such as, for example, an industrial product gas / liquid stream or an industrial waste gas / liquid stream, or the like), or the like). In various examples, the one or more compound(s) of interest is / are present in a gas or liquid stream (e.g., prior to irradiation) at about 0.005% to about 100%, including all 0.001% values and ranges therebetween (e.g., about 0.04% to about 100%), of the gas or liquid stream (based on the total volume or weight of the gas or liquid stream, or a selected portion thereof).

[0067] In various examples, one or more compound(s) of interest is / are bubbled, sparged, or the like (e.g., continuously bubbled / sparged or bubbled / sparged for a desired time), in a mixture (e.g., a mixture comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed formed therefrom). In various examples, an atmosphere (e.g., gas atmosphere, ambient air, or the like) comprising one or more compound(s) of interest is / are in contact with one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom.

[0068] In various examples, a method comprises separating, isolating, purifying, diluting, concentrating, washing, transferring, or the like, or any combination thereof, at least a portion, substantially all, or all of one or more compound(s) (e.g., one or more compound(s) reacted or formed by a method, such as, for example, one or more cycloaddition product(s), intermediate product(s), final product(s), or the like, or any combination thereof). In various other examples, a method does not comprise separating, isolating, purifying, diluting, concentrating, washing, or transferring one or more compound(s) (e.g., one or more compound(s) formed by a method, such as, for example, one or more cycloaddition product(s)).

[0069] In various examples, one or more cycloaddition product(s) is / are in equilibrium with one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom. In various examples, one or more cycloaddition product(s) is / are in equilibrium with one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and one or more base(s). In various examples, one or more cycloaddition product(s) is / are not reaction intermediates or the like. In various example, a method does not comprise isolation of one or more cycloaddition product(s).

[0070] In various examples, a method further comprises releasing one or more compound(s) of interest (e.g., from one or more cycloaddition product(s) or the like). In various examples, formation of one or more cycloaddition product(s) is reversible (e.g., one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and one or more compound(s) of interest form one or more cycloaddition product(s), and the one or more cycloaddition product(s) is / are able to reverse to form (e.g., re-form or the like) the one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and / or the one or more compound(s) of interest). In various examples, at least a portion, substantially all, or all of one or more compound(s) of interest, one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom, and, optionally, one or more base(s), if present, is / are able to be released, recycled, regenerated, or the like. In various examples, one or more compound(s) of interest is / are captured (e.g., the one or more cycloaddition product(s) is formed) at a first condition and the one or more compound(s) of interest is released (e.g., the one or more cycloaddition product(s) is degraded) at a second condition. In various examples, the first condition and the second condition are different in at least one condition parameter (such as, for example, atmosphere compositions, pressure, partial pressure of one or more compound(s) (e.g., compound(s) of interest) or the like, or any combination thereof. In various examples, a first condition and a second condition are substantially the same (or optionally different) in one or more condition parameters (such as, for example, solvent(s), temperature, catalyst(s), additive(s), electromagnetic radiation wavelength or intensity, or any combination thereof).

[0071] In various examples, releasing comprises irradiating (e.g., a second irradiating) one or more cycloaddition product(s) (e.g., one or more alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like). In various examples, releasing one or more compound(s) of interest comprises irradiating (e.g., a second irradiating) one or more cycloaddition product(s) and one or more base(s) (e.g., where one or more cycloaddition product(s) is / are in contact withone or more base(s)). In various examples, releasing one or more compound(s) of interest comprises irradiating (e.g., a second irradiating) one or more cycloaddition product(s) under a vacuum or a partial vacuum or the like. In various examples, releasing is carried out under an inert atmosphere (e.g., comprising one or more inert gas(es)). In various examples, an inert atmosphere comprises nitrogen, argon, or the like, or any combination thereof. In various examples, releasing is carried out at a reduced pressure (e.g., about 50 mbar to about 1000 mbar, including all 0.1 mbar values and ranges therebetween (e.g., about 100 mbar, about 100 to about 250 mbar, about 200 mbar, and the like)). In various examples, releasing is carried out at the same or substantially the same pressure as irradiating (e.g., a first irradiating). In various examples, releasing is carried out at atmospheric pressure (e.g., about 1000 mbar or the like). In various examples, releasing one or more compound(s) of interest comprises irradiating (e.g., a second irradiating) one or more cycloaddition product(s) under a lower partial pressure of a compound of interest (e.g., lower than a partial pressure of the compound of interest in the formation of the cycloaddition product(s)). In various examples, releasing one or more compound(s) of interest (e.g., from one or more cycloaddition product(s), such as, for example, alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like) comprises separation, capture, or the like of the released compound(s) of interest. In various examples, releasing comprises irradiating (e.g., a second irradiating) one or more cycloaddition product(s) with electromagnetic radiation (e.g., electromagnetic radiation having one or more second wavelength(s)). In various examples, one or more first wavelength(s) is / are the same as one or more second wavelength(s). In various examples, one or more first wavelength(s) is / are different from one or more second wavelength(s). In various examples, releasing is carried out with or without compound(s) of interest (e.g., free compound(s) of interest) present. In various examples, during releasing, one or more base(s) is / are in contact with one or more cycloaddition product(s). In various examples, no catalyst (e.g., photoredox catalyst or the like) is required for releasing (e.g., for decarboxylating the one or more cycloaddition product(s)).

[0072] In various examples, irradiating (e.g., a second irradiating) is maintained for a desired length of time and / or until a desired amount of compound(s) of interest is / are released from one or more cycloaddition product(s). In various examples, irradiation is maintained for a duration of about X to about X min, including all 0.1 s values and ranges therebetween (e.g., about 15 min,about 60 min, or the like). In various examples, a desired length of time for irradiating corresponds to an intensity of electromagnetic radiation.

[0073] In various examples, releasing comprises exposure of one or more cycloaddition product(s) (e.g., cycloaddition product(s) from carbon dioxide) and one or more base(s) (or a mixture comprising the one or more cycloaddition product(s) and one or more base(s)) to an atmosphere (e.g., a static or dynamic atmosphere) of inert gas and / or reduced pressure (such as, for example, a pressure below that of the irradiating that formed the one or more cycloaddition product(s). In various examples, a dynamic inert gas atmosphere is a stream of one or more inert gas(es) (such as, for example, nitrogen, argon, or the like, or any combination thereof). In various examples, a reduced pressure is provided by a pump (e.g., a vacuum pump or the like) or the like. In various examples, a method (e.g., formation of one or more cycloaddition product(s) and / or release of one or more compound(s) of interest and one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom from one or more cycloaddition product(s)) is not carried out in the absence of light.

[0074] In various examples, a method (e.g., separation and / or release of one or more compound(s) of interest) is isothermal. In various examples, a method (e.g., separation and / or release of one or more compound(s) of interest) is carried out at room temperature (e.g. about 20 to about 25 ºC, including all values and ranges therebetween). In various examples, during irradiating, one or more compound(s) of interest, one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom, one or more cycloaddition products, or the like, or any combination thereof, exhibit an increase of temperature (e.g. increase caused by irradiating or the like). In various examples, one or more compound(s) of interest, one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom, one or more cycloaddition products, or the like, or any combination thereof, have a temperature of about 150 ºC or less, including all 0.1 ºC values and ranges therebetween (e.g., about 50 ºC or less, about 40 ºC or less, or the like).

[0075] In various examples, method is a continuous method, a semi-continuous method, or a batch method, or the like.

[0076] In an aspect, the present disclosure provides compositions (e.g., capture sorbent materials or the like). In various examples, a capture sorbent (e.g., capture sorbent materials or the like) comprises one or more ketone(s) (e.g., 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like) or the like. In various examples, a capture sorbent or capture sorbentsis / are used in a method and / or a system of the present disclosure. Non-limiting examples of capture sorbents are provided herein.

[0077] In various examples, a capture sorbent material comprises one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and a substrate. In various examples, one or more 2- alkyl phenyl ketone(s) and / or group(s) formed therefrom are disposed on at least a portion, substantially all, or all of a substrate (e.g., an exterior surface of a substrate). In various examples, one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom are conjugated to a substrate. Suitable conjugation methods are known in the art. In various examples, one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom are bonded to a substrate (e.g., by covalent bond, ionic bond, van der Waals interaction, or the like, or any combination thereof).

[0078] Various substrates can be used. In various examples, a substrate comprises or is a porous solid. In various examples, a substrate comprises or is a polymer substrate (such as, for example, a pre-formed polymer substrate or the like, where the pre-formed polymer undergoes polymerization before functionalization (e.g., conjugation or the like) with one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like) and one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are conjugated to the polymer substrate (e.g., the pre-formed polymer substrate or the like). In various examples, a substrate comprises or is a porous polymer substrate (e.g., a pre-formed porous polymer substrate), such as, for example, a microporous conjugated polymer substrate or the like, or the like.

[0079] In various examples, a composition exhibits resistance to degradation. In various examples, degradation (e.g., structural degradation, oxidative degradation, or the like, or any combination thereof) of a composition (e.g., a composition comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like) is not observed after about 100 cycles (e.g., cycles of capture and release) or more, including all 0.1 values and ranges therebetween (e.g., about 50 cycles or more, about 20 cycles or more, or the like). Degradation (e.g., structural degradation, oxidative degradation, or the like, or any combination thereof) can be observed by methods known in the art. For example, degradation (e.g., structural degradation, oxidative degradation, or the like, or any combination thereof) is observed by1H NMR or the like. In various examples, a composition resists oxidative degradation in contact with, for example, 3% O2or the like. In various examples, a composition resists degradation in contactwith O2, H2O, NOx, SOx, or the like, or any combination thereof. In various examples, a composition does not exhibit a functional decrease (e.g., decrease in capacity of compound(s) of interest able to be captured and / or reacted) of about 15% or less, including all 0.1% values and ranges therebetween (e.g., about 10% or less, about 5% or less, about 1% or less, or the like), after about 100 cycles or more, including all 0.1 values and ranges therebetween (e.g., about 250 cycles or more, about 500 cycles or more, about 1000 cycles or more, or the like).

[0080] In an aspect, the present disclosure provides systems for separating one or more compound(s) of interest. In various examples, a system is configured to capture one or more compound(s) of interest. In various examples, a system is configured to release at least a portion or all of the captured compound(s) of interest. In various examples, a system is configured to use (or uses) a capture sorbent (e.g., a capture sorbent material or the like) of the present disclosure. In various examples, a system is configured to carry out a method of the present disclosure. Non- limiting examples of systems are provided herein.

[0081] In various examples, a system comprises one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom (e.g., one or more capture sorbents comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like) or the like. In various examples, a system is configured to carry out a method of the present disclosure (e.g. a method of separating one or more compound(s) of interest or the like).

[0082] In various examples, a system is configured to carry out a method of separating one or more compound(s) of interest in a “dry” reaction (e.g., where the compound(s) of interest are not in solution). In various examples, a system comprises a capture sorbent (e.g., a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like) in contact with ambient air (e.g., where ambient air comprises one or more compound(s) of interest, such as, for example, CO2or the like). In various examples, a system is configured to contact a capture sorbent (e.g., a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or the like) with ambient air (e.g., where ambient air comprises one or more compound(s) of interest, such as, for example, CO2or the like) or other gaseous sample comprising one or more compound(s) of interest. In various examples, a system comprises a means of irradiation (e.g., of the capture sorbent and one or more compound(s) of interest). In various examples, a system (e.g., a means of irradiation of a system) comprisesexposure to sunlight and / or ambient light or a means for exposure to sunlight and / or ambient light.

[0083] In various examples, a system comprises one or more vessel(s). In various examples, at least one vessel comprises one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom (or a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom) and is configured to irradiate at least a portion of the contents of the vessel with electromagnetic radiation (such as, for example, one or more visible wavelength(s)). In various examples, at least one vessel is configured to irradiate at least a portion of the contents of the vessel (e.g., irradiate with sunlight or a selected wavelength or a portion of sunlight wavelengths). In various examples, a system comprises a solar concentrator, a lamp, a light emitting diode, or a laser, or the like, or any combination thereof.

[0084] In various examples, a system (e.g., at least one vessel of a system) comprises an inlet (e.g., a first inlet) configured to introduce a stream (e.g., a liquid and / or gas stream) comprising the one or more compound(s) of interest into the vessel. In various examples, a system (e.g., at least one vessel of a system) comprises one or more outlet(s) configured to remove at least a portion, substantially all, or all of the contents of the vessel (e.g., one or more compound(s) of interest, one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom, one or more base(s), one or more photocatalyst(s), one or more photothermal catalyst(s), one or more cycloaddition product(s), one or more solvent(s), or the like, or any combination thereof). In various examples, one or more outlet(s) is / are configured to remove a remainder of the stream (e.g., liquid and / or gas stream) after at least a portion of one or more compound(s) of interest (e.g., compound(s) of interest in the stream) react with one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom (e.g., in a capture sorbent or the like).

[0085] In various examples, a system (e.g., at least one vessel of a system) comprises an inlet (e.g., a second inlet) configured to introduce one or more compound(s) to a vessel. In various examples, an inlet (e.g., a second inlet) is configured to introduce one or more base(s) to a vessel.

[0086] In various examples, a system is a part of a CO2scrubbing unit. In various examples, a system is in fluid and / or gas connection with a stream (e.g., an emission stream, such as, for example, an industrial emission stream, a waste emission stream, ambient air and / or an ambient air stream, or the like, or any combination thereof). In various examples, an emission stream comprises one or more compound(s) of interest.

[0087] In various examples, a system is configured to operate in a continuous flow mode, a semi-continuous flow mode, a batch mode, or the like, or any combination thereof.

[0088] The following Statements describe various examples of methods, compositions, and systems of the present disclosure and are not intended to be limiting in any manner. Statement 1. A method of separation of one or more compound(s) of interest comprising irradiating with electromagnetic radiation one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom (or a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom) (which may be referred to in the alternative as a capture sorbent) (or one or more capture sorbents, such as, for example, capture sorbent(s) according to any of Statements 16–18 or the like) and the one or more compound(s) of interest (and optionally, one or more photocatalyst(s), one or more photothermal catalyst(s), one or more base(s), or any combination thereof), wherein at least a portion of, substantially all, or all of the compound(s) of interest react(s) with at least a portion of, substantially, or all of the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom to form one or more cycloaddition product(s) (such as, for example, alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like); and optionally, releasing at least a portion of the one or more compound(s) of interest from the cycloaddition product(s) (such as, for example, alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like). Statement 2. A method according to Statement 1, wherein the compound(s) of interest is / are chosen from carbon dioxide, alkenes, and arenes (such as, for example, xylene (e.g., xylene isomers) and the like) and the like, and any combination thereof. Statement 3. A method according to Statement 1 or 2, wherein the one or more compound(s) of interest is / are present in a gas or liquid (which may be a stream, such as, for example, a waste gas / liquid stream, an industrial gas / liquid stream (such as, for example, an industrial product gas / liquid stream or an industrial waste gas / liquid stream, or the like), or the like).Statement 4. A method according to any one of Statements 1–3, wherein the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are chosen from O Me O Me OMe O Me MeO O Me OH O Me ,Statement 5. A method according to any one of the preceding Statements, wherein at least a portion or all of the one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and the one or more compound(s) of interest are present in a mixture (such as, for example, a solution, a suspension, or the like). Statement 6. A method according to Statement 5, wherein the one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are present in the mixture at a concentration of about 0.1 to about 2 mmol / liter, including all 0.05 mmol / liter values and ranges therebetween. Statement 7. A method according to Statement 5 or 6, wherein the mixture further comprises one or more polar solvent(s) (e.g., polar aprotic solvent(s) or the like) or the like. Statement 8. A method according to any one Statements 5–7, wherein the one or more compound(s) of interest is / are bubbled, sparged, or the like, in the mixture (e.g., continuously bubbled / sparged or bubbled / sparged for a desired time) or an atmosphere comprising the one or more compound(s) of interest is / are in contact with the mixture. Statement 9. A method according to any of the preceding Statements, wherein the mixture further comprises one or more base(s) or the like.Statement 10. A method according to Statement 9, wherein the one or more base(s) is / are present in the mixture (e.g., independently prior to irradiation, during irradiation, or both) at a concentration of about a catalytic amount (such as, for example, about 0.1 equivalent (based on the amount of 2-alkyl-phenyl ketone(s) present in the mixture or the amount of cycloaddition product(s) (such as, for example, alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like)) to an excess of base(s) (such as, for example, about 3 equivalents (based on the amount of 2-alkyl-phenyl ketone(s) present in the mixture or the amount of cycloaddition product(s) (such as, for example, alkene adduct(s), arene adduct(s), carbon dioxide adduct(s), or the like)). Statement 11. A method according to any one of the preceding Statements, wherein the electromagnetic radiation comprises one or more visible light wavelength(s) (which may be first visible light wavelength(s)) (such as, for example, about 380 nanometers (nm) to about 700 nm, including all 0.1 nm values and ranges therebetween (e.g., about 320 nm to about 410 nm)). Statement 12. A method according to any one of the preceding Statements, wherein the releasing comprises irradiating (which may be carried out with no free compound(s) of interest or with free compound(s) of interest present) with electromagnetic radiation (such as, for example, electromagnetic radiation comprising one or more visible light wavelength(s) (which may be second visible light wavelength(s)) (such as, for example, about 310 nanometers (nm) to about 1,100 nm, including all 0.1 nm values and ranges therebetween (e.g., about 320 nm to about 410 nm, about 380 nm to about 700 nm, or the like)) the one or more cycloaddition product(s) and optionally, one or more base(s). Statement 13. A method according to any one of the preceding Statements, wherein the releasing comprises exposure of the one or more cycloaddition product(s) and optionally, the one or more base(s) (or a mixture comprising the one or more cycloaddition product(s) and, optionally, the one or more base(s)) to an atmosphere (e.g., a static or dynamic atmosphere) of inert gas and / or reduced pressure (such as, for example, a pressure below that of the irradiating that formed the one or more cycloaddition product(s). Statement 14. A method according to any one of the preceding Statements, further comprising isolating (e.g., from the mixture or any one or more of the components thereof) the released compound(s) of interest. Statement 15. A method according to any one of the preceding Statements, wherein the method is a continuous method, a semi-continuous method, or a batch method, or the like.Statement 16. A capture sorbent material comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom (such as, for example, 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom of the present disclosure (e.g., 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom according to Statement 4); and a substrate, wherein the one or more 2-alkyl phenyl ketones are disposed on at least a portion of an exterior surface of the substrate or substantially all or all of one or more exterior surface(s) of the substrate. Statement 17. A capture sorbent material according to Statement 16, wherein the substrate is a porous solid. Statement 18. A capture sorbent material according to Statement 16 or 17, wherein the substrate comprises (or is) a conjugated microporous polymer (e.g, a pre-formed microporous polymer) or the like. Statement 19. A system for capture and optionally, isolation or the like, of one or more compound(s) of interest (e.g., a system configured to carry out a method of the present disclosure (such as, for example, a method according to any one of Statements 1–15). Statement 20. A system according to Statement 19, comprising one or more vessel(s), at least one vessel comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom or a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and configured to irradiate at least a portion of the contents of the vessel with electromagnetic radiation (such as, for example, one or more visible wavelength(s)). Statement 21. A system according to Statement 20, wherein the at least one vessel further comprises an inlet (which may be a first inlet) configured to introduce a gas and / or liquid stream comprising the one or more compound(s) of interest into the at least one vessel. Statement 22. A system according to Statement 20 or 21, wherein the at least one vessel further comprises one or more outlet(s) configured remove at least a portion or all of the one or more compound(s) of interest, the remainder of the gas and / or liquid stream after at least a portion of or all the one or more compound(s) of interest react with the one or more 2-alkyl phenylketone(s) or the capture sorbent, one or more cycloaddition product(s) (e.g., formed in the at least one vessel), or any combination thereof.Statement 23. A system according to any one of Statements 20–22, wherein the at least one vessel further comprises an inlet (which may be a second inlet) configured to introduce one or more base(s). Statement 24. A system according to any one of Statements 19–23, wherein the system is part of or is a CO2-scrubbing unit (which may be in fluid or gas connection with an emission stream (such as, for example, an industrial emission stream or the like)). Statement 25. A system according to any one of Statements 19–24, wherein the system is configured to operate in a continuous flow mode, a semi-continuous flow mode, or a batch mode, or the like. Statement 26. A method of separation of one or more compound(s) of interest comprising irradiating with electromagnetic radiation a mixture comprising a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and one or more compound(s) of interest, wherein at least a portion of, substantially all, or all of the compound(s) of interest react(s) with at least a portion of, substantially all, or all of the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom to form one or more cycloaddition product(s); and optionally, releasing at least a portion of, substantially all, or all of the one or more compound(s) of interest from the cycloaddition product(s). Statement 27. A method according to Statement 26, wherein the compound(s) of interest is / are chosen from carbon dioxide, alkenes, arenes, and any combination thereof. Statement 28. A method according to Statement 26 or 27, wherein the one or more compound(s) of interest is / are present in a gas or liquid.Statement 29. A method according to any one of the preceding Statements, wherein the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are chosen from O Me O Me OMe O Me MeO O Me OH O Me ,Statement 30. A method according to any one of the preceding Statements, wherein the mixture comprises a solution or a suspension. Statement 31. A method according to Statement 30, wherein the one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are present in the mixture at a concentration of about 0.1 to about 2 mmol / liter. Statement 32. A method according to Statement 30 or 31, wherein the mixture further comprises one or more polar solvent(s). Statement 33. A method according to any one of Statements 30–32, wherein the one or more compound(s) of interest is / are bubbled or sparged in the mixture or the mixture is in contact with an atmosphere comprising at least a portion of the one or more compound(s) of interest. Statement 34. A method according to any one of the preceding Statements, wherein the mixture is in contact with one or more base(s), one or more photocatalyst(s), one or more photothermal catalyst(s), or any combination thereof.Statement 35. A method according to Statement 34, wherein the one or more base(s) is / are present at a concentration of about 0.1 equivalent to about 3 equivalents (based on the amount of 2-alkyl-phenyl ketone(s) present in the mixture or the amount of cycloaddition product(s)). Statement 36. A method according to any one of the preceding Statements, wherein the electromagnetic radiation comprises one or more visible light wavelength(s) of about 380 nm to about 700 nm. Statement 37. A method according to any one of the preceding Statements, wherein the releasing comprises irradiating at least a portion of the cycloaddition product(s) and, optionally, one or more base(s), with electromagnetic radiation comprising one or more visible light wavelength(s) of about 310 nm to about 1,100 nm. Statement 38. A method according to any one of the preceding Statements, wherein the irradiating is performed at a first pressure, and wherein the releasing is performed in an atmosphere of inert gas and / or at a second pressure lower than the first pressure. Statement 39. A method according to any one of the preceding Statements, further comprising isolating at least a portion of the compound(s) of interest released from the cycloaddition product(s). Statement 40. A method according to any one of the preceding Statements, wherein the method is a continuous method, a semi-continuous method, or a batch method. Statement 41. A capture sorbent material comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom; and a substrate, wherein at least a portion of the one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is disposed on at least a portion of an exterior surface of the substrate. Statement 42. A capture sorbent material according to Statement 41, wherein the substrate comprises a porous solid. Statement 43. A capture sorbent material according to Statement 41 or 42, wherein the substrate comprises a conjugated polymer. Statement 44. A system for capture and optionally, isolation, of one or more compound(s) of interest comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom, wherein the system is configured to carry out a method according to Statement 1.Statement 45. A system for capture and optionally, isolation, of one or more compound(s) of interest comprising one or more vessel(s), at least one vessel comprising a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and configured to irradiate at least a portion of the contents of the vessel with electromagnetic radiation. Statement 46. A system according to Statement 45, wherein the at least one vessel further comprises a first inlet configured to introduce a gas and / or liquid stream comprising the one or more compound(s) of interest into the at least one vessel. Statement 47. A system according to Statement 45 or 46, wherein the at least one vessel further comprises one or more outlet(s) configured to remove at least a portion or all of the one or more compound(s) of interest, the gas and / or liquid stream, one or more cycloaddition product(s) formed in the at least one vessel, or any combination thereof. Statement 48. A system according to any one of Statements 45–47, wherein the at least one vessel further comprises a second inlet configured to introduce one or more base(s). Statement 24. A system according to any one of Statements 45–48, wherein the system is part of or is a CO2-scrubbing unit. Statement 49. A system according to any one of Statements 45–49, wherein the system is in fluid and / or gas connection with an emission stream. Statement 50. A system according to any one of Statements 45–50, wherein the system is configured to operate in a continuous flow mode, a semi-continuous flow mode, or a batch mode.

[0089] The steps of the methods described in the various examples disclosed herein are sufficient to carry out the methods of the present disclosure. Thus, in various examples, a method consists essentially of a combination of the steps of the methods disclosed herein. In various other examples, a method consists of such steps.

[0090] The following Examples are presented to illustrate the present disclosure. They are not intended to be limiting in any manner. EXAMPLE 1

[0091] This example provides methods and compositions for separation and release of compound(s) of interest.

[0092] Herein is provided the first example of a fully visible light-driven CO2separation system, in which selective carbon capture is achieved via the photoenolization / Diels-Alder reaction of inexpensive 2-methylbenzophenone with CO2, and CO2 release is achieved via oxidative photodecarboxylation. This system can operate isothermally, works with sunlight, and can remove CO2 from a flue gas stream. This approach represents the first use of cycloaddition reaction for carbon capture, providing a blueprint for other unique and energy-efficient chemical separations.

[0093] Thus, a carbon capture strategy that utilizes visible light (380–780 nm), which is abundant within the solar light spectrum, for both the capture and release steps, could be an energy-saving strategy with sufficient thermodynamics drive for challenging separations (FIG. 1B).

[0094] Nature provides some inspiration for the design of visible light-driven pathways for CO2 capture and release. Photosynthetic organisms fix CO2 on massive scale using enols generated in the active site of RuBisCo, yet enols (and carbon-based nucleophiles in general) are largely unstudied for chemisorptive carbon capture. Relatedly, 2-alkylphenyl ketones can undergo photoenolization and subsequent Diels-Alder reactions (PEDA) with CO2, although this process reportedly requires UV light irradiation and a relatively long time (2 h) to capture CO2from an atmospheric CO2 condition, which are not realistic for large-scale carbon capture. Nonetheless, it was considered that PEDA may offer a new pathway for light-driven carbon removal from dilute streams. While PEDA can potentially enable CO2capture, it has never been paired with a CO2-releasing mechanism to produce a formal CO2separation system. However, the oxidative decarboxylation of phenylacetic acids is a common pathway in both biology (FIG. 1D) and photoredox catalysis, potentially offering a pathway for CO2 release if an optimal photoredox catalyst can be identified. Through the combination of these two reactions, provided herein the first fully light-driven approach for CO2 capture-and-release, providing a new platform for sustainable carbon capture that does not require thermal management (FIG.1E).

[0095] Results and Discussion.

[0096] It was evaluated whether PEDA can be conducted with shorter reaction times and with light irradiation in the visible region using the appropriate substrate. Among 2-alkylphenyl ketones, 2-methylbenzophenone (1) was chosen as a model sorbent because of its absorbance in the high-energy portion of the visible light region (FIG.21) due to its unusual S0→ Tntransitionand low cost. CO2capture was first explored using varying concentrations of 2- methylbenzophenone (1) dissolved in the green solvent DMSO using a purple light (390 nm) irradiation (FIG.2A). At lower concentrations (0.1 M), a high conversion to 2 (59%) could be achieved in only 30 min upon irradiation with purple light. This amount represents more than half its theoretical uptake capacity (5.5 mmol g-1of 1), comparable to other carbon capture technologies. Higher overall concentration of 2 (reflecting more CO2 capture) could be achieved using higher concentrations of 1 (up to 2 M), and thus a concentration of 2 M was utilized for subsequent experiments. Excitingly, similar performance was observed for CO2 capture with or without cooling with a fan (FIG.16), suggesting a potentially lower downstream operational energy demand.

[0097] The performance of 1 was next interrogated for CO2capture from dilute streams (FIG.2A). Although the capture capacity expectedly decreased for streams with lower partial pressures of CO2, the capture rate was still satisfactory even for a 10% CO2 in N2 stream (26% of the pure CO2capacity at 30 min). The presence of O2in flue gas often presents a challenge for traditional sorbents, which are prone to oxidative degradation. In contrast, the addition of 3% O2 to a 10% CO2 in N2 stream (simulating the composition of a natural gas flue emission stream) only results in a slight decrease in the yield of 2 over time (FIG.2A). This drop is likely due to triplet quenching of photoexcited 1 by O2, as degradation of 1 or 2 was not observed. The need for constant light irradiation—supporting that this is a photo-driven and not photo-initiated process—was also confirmed by turning the light source on and off during the capture process (FIG.2B). Minimal formation of 2 was observed in the dark. Overall, these studies support that the PEDA pathway possesses the requisite fast kinetics, tolerance of contaminants like O2 and H2O, and compatibility with visible light irradiation required for operation under realistic conditions.

[0098] The light-driven self-decarboxylation of 2 is known to require UV light irradiation to attain sufficient kinetics, rendering it impractical. Instead, while carboxylic acids such as 2 are normally resistant to oxidative decarboxylation due to their large-magnitude redox potentials, usually higher than + 2.0 V vs. SCE, the corresponding carboxylates such as 3 (FIG.2) are much easier to oxidize (~+ 0.9–1.4 V vs. SCE). The resulting carboxy radicals undergo rapid decarboxylation via β-scission to produce alkyl radicals, which can undergo single-electron transfer (SET) followed by proton transfer (PT) to return the corresponding alkane (FIG.1E).Unlocking this mechanistic pathway would require the addition of catalytic base to deprotonate 2 to form 3 and a photoredox catalyst to facilitate the photooxidation of 3. However, it is unclear how the presence of base would influence the capture step, as the presence of acids and bases has been shown to accelerate the decay of photoenols. Remarkably, the addition of catalytic amounts (15% relative to 1) of K3PO4 under PEDA conditions with a simulated natural gas power plant emission stream (10% CO2 / 3% O2 / remainder N2) doubled the amount of 2 / 3 that formed after 30 min relative to the base-free conditions (FIG.2A). This is likely due to the additional thermodynamic driving force offered by deprotonation of the carboxylic acid. As such, this finding eliminates the need to separate the base between the capture and release steps, keeping the process setup simple.

[0099] Typically, oxidative photodecarboxylation is triggered with expensive Ir-based photoredox catalysts, which would not be practical on scale. While not common, benzophenones have previously been shown to be reasonable photooxidants as well, suggesting that 1 (or 2 / 3) could be capable of mediating the decarboxylation of 3 without the need for added photocatalysts. Indeed, cyclic voltammetry (CV) and photoluminescence (PL) measurements support that 2 is an almost perfectly suited photooxidant (E1 / 2red* = + 1.22 V vs SCE) to oxidize 3 (E1 / 2ox= + 1.15 V). Although 1 could function as a photocatalyst, it is insufficient as an oxidant (E1 / 2red* = + 1.11 V vs SCE). As such, it was considered that simply irradiating 3 with visible light would trigger decarboxylation without the need for added photocatalysts. Indeed, when 3 is irradiated with purple light under N2flow at different concentrations, near complete decarboxylation and formation of 1 (after protonation) occurs after only 30 min (FIG.3A, FIG. 17). Indeed, attempts to collect PL spectra of 3 were unsuccessful, as irradiation with the light source was sufficient to induce decarboxylation. Similarly, rapid decarboxylation could be achieved by pulling slight vacuum (0.2 atm) on the solution as well, which is feasible because neither 3 nor DMSO are particularly volatile. As control experiments, light irradiation of 2 (without any base) and heating 3 at 60 °C did not result in detectable decarboxylation, supporting the need for both base and light to trigger CO2release (FIG.3A). Consistently, on / off experiments support that the decarboxylation of 3 largely occurs only upon photoirradiation (FIG.3C). Together, these results support that the addition of a catalytic amount of base (to facilitate PT steps) should enable CO2capture from CO2-containing streams and CO2release under vacuum.

[0100] A mechanism for the fully light-driven CO2separation, supported by density functional theory calculated energy differences (FIG.4) was considered. First, the photoexcitation of 1 yields a (Z)-enol that can get deprotonated by an added base and form an enolate species. While the enol pathway is known to undergo a cycloaddition reaction with CO2, the significant improvement with added base begs the question whether the same mechanism is still at play for the enolate pathway. The calculated transition state energy for the enolate pathway was revealed to be significantly lower relative to that of the enol pathway (∆∆G = −51.1 kJ / mol), matching the apparent improved kinetics. As such, it was considered that the mechanism has switched from PEDA into a traditional nucleophilic attack upon base addition. Gas phase intrinsic reaction coordination calculation for the enol pathway agrees with the literature Diels-Alder mechanism with CO2; however, the calculation for the enol pathway resulted in a bond formation mode that more closely resembles a nucleophilic pathway. This finding is consistent with the unsuccessful attempts to optimize the anionic cycloadduct structure. Overall, these results hint at nucleophilic attack being the dominant mechanism for the enolate with CO2 that directly forms 3, similar to other photoenol functionalization examples. However, this finding does not conclusively exclude Diels-Alder reactivity for the enolate pathway, and further experimental evidence are currently under investigation.

[0101] The release cycle then starts with the photoexcitation of 3 that is capable of oxidizing another molecule of 3, affording a carboxylate radical. Benzophenone 1 is deemed unable to catalyze this process due to its lower photoexcited reduction potential (vide supra), matching the calculated energy difference for the SET facilitated by 1 relative to that by 3 (∆∆G = 29.9 kJ / mmol). These results infer that, while the capture step is a function of the concentration of 1, the release step is conversely dependent on the concentration of 3. As such, a complete adsorption / desorption cycle would not lead to the highest productivity (amount of CO2separated per given time). Upon β-scission and CO2 release, the benzylic radical can be reduced back by the catalyzing 3 and reprotonated back into 1, returning into the starting point.

[0102] With a unified fully light-driven CO2separation system along with a mechanistic understanding in place, its cycling performance for capturing CO2 from a natural gas flue emission stream under realistic conditions was evaluated (FIG.5). A careful balance of the concentrations of 1, 2, and 3 in solution is necessary in order to maximize light absorption by the appropriate species during the capture (flue gas) and release (N2, simulating vacuum) steps. Aninitial concentration of 1 of 0.1 M was found to be optimal to achieve this balance (FIG.18). In addition, a weaker base (potassium benzoate) was employed during cycling; while K3PO4 (used above) does work, it leads to some deuterium incorporation into 1 from the solvent DMSO-d6 after several cycles, which complicated quantification of the relevant species over time using1H NMR. Under these optimized conditions, a working capacity of 26 mM of CO2 per h could beachieved for CO2 removal from a simulated natural gas flue gas emission stream (10% CO2 / 3% O2 / remainder N2), as short 15 min capture and release steps could be used. No sorbent degradation was observed by1H NMR over 5 capture-and-release cycles. Actual flue gas contains trace contaminants such as NOx and SOx that significantly impede the performance of traditional sorbents. To test the tolerance of this system to these contaminants, flue gas from Cornell University’s natural gas-fired power plant was procured (9.7% CO2, 3.7% O2,43 ppm of NOx, remainder H2O and N2). Using this inlet stream, an average of 24 mM of CO2 per h could be removed over 3 cycles, similar to that observed with simulated flue gas, demonstrating the utility of this light-driven capture system for post-combustion carbon capture under realistic conditions (FIG.5A).

[0103] Similarly, the compatibility of this system for a solar-driven application was demonstrated. The capture of CO2using 1 with a base was conducted at the windowsill on a summer day in North America, and within an hour, an adequate amount of CO2 was captured using entirely solar light (FIG.5B). Similarly, the solar-driven release of CO2 from 2 was achieved with reasonable kinetics (FIG.19). To standardize its performance, further experiments were conducted using a solar simulator. While the rate of capture is slower based on the lower photon flux, decent cycling performance of 3 mM of CO2 per h was achieved from simulated flue gas stream over 3 cycles using 2 sun equivalence (2000 W / m2) that is achievable using a solar concentrator. Overall, these experiments these results suggest the compatibility of this system for realistic solar-driven applications.

[0104] Provided herein is strategy to separate CO2 by harnessing light energy on both the capture and release steps as a means to distribute the large energy demand of such a separation. A realistic application of this system was showcased by capturing CO2 from an actual flue gas stream as well as directly utilizing sunlight to drive the capture of CO2, highlighting its potential beyond the laboratory scale. Moreover, this strategy captures CO2through a cycloaddition reaction–an unprecedent mode for the separation of CO2or any chemical in general. Triggeringthe CO2release by cycloreversion would have been challenging because of the large energy barrier; instead, its unique pairing with a photoredox decarboxylation pathway enables a more energy-efficient fully light-driven CO2 separation. Accordingly, such a combination could provide a blueprint for a new class of chemisorptive chemical separations.

[0105] Materials and Methods.

[0106] Unless otherwise noted, all chemicals were purchased from commercial vendors (Sigma Aldrich, Alfa Aesar, Apollo Scientific Ltd, Cambridge Isotope Laboratories) and used without additional purification. Gas cylinders were purchased from Airgas as pure cylinders of CO2 (bone dry grade, 99.8%) or N2 (high purity, 99.998%) or mixtures of CO2 with or without O2in N2. Flue gas samples were obtained from the Cornell Combined Heat and Power (CHP) natural-gas fired power plant on May 11th, 2024 in 25 Liter Tedlar Bag with Roberts Style Valve with a concentration of 9.7% CO2, 3.8% O2, and 43 ppm of NOx. A Harvard Apparatus Syringe Infusion Pump 22 was utilized to deliver flue gas samples into reaction mixtures.

[0107] 1H NMR and13C NMR spectra were recorded at 500 MHz (1H) and 126 MHz (13C) on a Bruker AMX500 (500 MHz) spectrometer. Chemical shifts were calibrated using residual solvent as an internal reference (DMSO-d6: 2.50 ppm1H NMR, 39.52 ppm13C NMR).1H NMR spectra in non-deuterated DMSO were acquired using the WET pulse sequence with a relaxation delay of 10 s.1Polynomial fit at seventh order was used to correct the baseline of spectra, and integration was obtained upon linear correction.

[0108] Cyclic voltammograms (CVs) were measured at 25 °C on a Gamry Interface 1010E potentiostat using a glassy carbon working electrode, a platinum wire counter electrode, and a Ag / AgNO3 reference electrode in a N2-filled glovebox. In general, two scans were collected: one with ferrocene (Fc) as an internal reference, and one without Fc. All potentials are reported to V vs. SCE upon conversion of E1 / 2(Fc / Fc+) = +0.400 vs. SCE.2UV / Vis absorption spectra were collected using a Shimadzu UV-2600 spectrophotometer. Fluorescence spectra were collected on a Perkin Elmer Fluorescence Spectrometer FL 6500.

[0109] Samples were illuminated by four Kessil PR160L-390nm lamps at full power distributed evenly in all directions with 5 cm distance. Alternatively, samples were illuminated by Solar Simulator Model 16S-300-2.2-UV with the distance to the sample being adjusted with a pyranometer to achieve irradiance equivalent to one (1000 W / m2) or two suns (2000 W / m2).

[0110] Synthetic Procedures.

[0111] A screw-cap reaction tube was charged with 1 (20 mmol, 3.62 mL, 1.0 equiv.), potassium phosphate tribasic (3 mmol, 637 mg, 0.15 equiv.), and DMSO (6.38 mL). Once tightly capped, a vent needle was attached to the cap, and the reaction mixture was sparged with pure CO2by a long needle for 5 minutes. The mixture was stirred and irradiated by four Kessil PR- 160L-390nm lamps at full power for 12 hours under continuous pure CO2 bubbling (~1 atm). The crude reaction mixture was then diluted with EtOAc (50 mL) and acidified with 1 M aqueous HCl solution (50 mL) to ensure the product is in the organic layer. Subsequently, the organic layer was washed with water (3 × 50 mL) to remove DMSO. The desired product 2 was then extracted from the organic layer using saturated aqueous NaHCO3 solution (50 mL or until the pH of the solution remains basic). The aqueous extract was then acidified to pH 1 to precipitate 2, which was then extracted into EtOAc (50 mL). The organic layer was then washed with saturated aqueous NaCl solution, dried over Na2SO4, and evaporated under reduced pressure to afford 2 as a white solid (2.35 g, 49%).1H NMR (500 MHz, DMSO-d6): δ 12.24 (d, J = 4.6 Hz, 1H), 7.71 (dq, J = 9.0, 1.7 Hz, 2H), 7.68 – 7.62 (m, 1H), 7.53 (td, J = 7.7, 2.3 Hz, 3H), 7.44 (d, J = 7.6 Hz, 1H), 7.39 (t, J = 7.5 Hz, 1H), 7.33 (dd, J = 7.6, 1.5 Hz, 1H), 3.78 (dd, J = 4.5, 2.3 Hz, 2H);13C NMR (126 MHz, DMSO-d6): δ 197.41, 172.17, 138.03, 137.28, 134.45, 133.13, 132.01, 130.75, 129.95, 129.31, 128.49, 126.40, 38.24 ppm. The NMR spectra are consistent with those reported in the literature.

[0112] Synthesis of Potassium 2-(2-Benzoylphenyl)Acetate (3)

[0113] A 20-mL vial was charged with 2 (1 mmol, 240 mg, 1 equiv.), potassium tert- butoxide (1 mmol, 112 mg, 1 equiv.), and MeOH (10 mL). Upon dissolution of all solids by sonication, the solvent was evaporated under reduced pressure. The vial was subsequently charged with acetonitrile (10 mL) and sonicated for 10 minutes. The solvent was then evaporated under reduced pressure to afford 3 as an off-white solid (278 mg, quant.).1H NMR (500 MHz, DMSO-d6): δ 7.72 (d, 2H), 7.60 (t, 1H), 7.48 (t, J = 7.7 Hz, 2H), 7.36 (t, J = 1.6 Hz, 1H), 7.31 (d, 1H), 7.20 (t, J = 1.4 Hz, 1H), 7.13 (d, J = 1.6 Hz, 1H), 3.36 (d, J = 4.7 Hz, 2H);13C NMR (126 MHz, DMSO-d6): δ 196.17, 170.30, 137.42, 136.27, 130.87, 129.36, 128.35, 127.75, 126.49, 126.14, 122.71, 41.25 ppm. IR (neat, cm−1): 3278, 2967, 1665, 1588, 1400, 1311, 1252, 1013, 947, 920, 880, 835, 756, 695, 643, 621, 556.

[0114] General Procedure for CO2Capture and Release.

[0115] General Procedure A.

[0116] This procedure was generally used for CO2capture or release optimization experiments.

[0117] A 4-mL screw-cap vial was charged with 1 (1 equiv.), 1,3,5-trimethoxybenzene (0.1 mmol, 16.8 mg) or tetrabutylammonium hexafluorophosphate (0.1 mmol, 38.7 mg), and DMSO- d6 (totaling the mixture volume to 1 mL). For CO2 release experiments, 2 or 3 was added instead of 1. For relevant reactions, the base was added at this point. Once tightly capped, a vent needle was attached to the cap, and the reaction mixture was sparged with CO2-containing flow (CO2capture experiments) or N2 flow (CO2 release experiments) by a long needle for 5 minutes. The mixture was stirred and irradiated by four Kessil PR-160L-390nm lamps at full power for the listed time period under the continuous bubbling of the CO2-containing flow or N2flow (~1 atm). Unless stated otherwise, a fan and a water bath were used to stabilize the temperature of the reaction mixtures. Precise timing of light irradiation was achieved using a programmable timer switch. Aliquots of the reaction mixture (20 µL) were drawn using a glass syringe while the reaction mixture remained under continuous bubbling and transferred to an NMR tube. Each aliquot was diluted in 500 µL of DMSO-d6, and when applicable, neutralized by 10 µL of acetic acid.

[0118] General Procedure B.

[0119] This procedure was generally used for CO2 capture and release cycling experiments.

[0120] An oven-dried air-free NMR tube was charged with 1 (1 equiv.), 1,3,5- trimethoxybenzene (0.1 mmol, 16.8 mg) or tetrabutylammonium hexafluorophosphate (0.1 mmol, 38.7 mg), and DMSO (totaling the mixture volume to 1 mL). For relevant reactions, base was added at this point. Once tightly capped, a vent needle was attached to the cap, and the reaction mixture was sparged with CO2-containing flow by a long needle for 5 minutes. The mixture was stirred and irradiated by four Kessil PR-160L-390nm lamps at full power for the listed time period under the continuous bubbling of the CO2-containing flow (~1 atm). Precise timing of light irradiation was achieved by using a programmable timer switch. The sparging and vent needles were removed, and1H NMR spectra were directly acquired from the NMR tube without any adjustment using the WET pulse sequence at 10 s relaxation delay. A fresh, oven- dried sparging needle was used for each capture or release step to minimize exposure to water that reduces the signal-to-noise ratio. Subsequent capture or release steps were performed byreattaching the sparging and vent needles, sparging with the desired gas stream for 5 minutes, and then continuing light irradiation under continuous bubbling for the desired time period.

[0121] Experimental Setup for CO2 Separation from Flue Gas Samples (FIG.10, FIG.11).

[0122] Experimental Setup for CO2Separation using Sunlight (FIG.12).

[0123] Experimental Setup for CO2 Capture using Solar Simulator (FIG.13).

[0124] Excited State Reduction Potential Estimation.

[0125] The excited state reduction potentials or Ered*(cat* / cat‧−) of 1 and 3 were calculated to determine the feasibility of each species facilitating the oxidation of 3 (Ep / 2 = +1.15 V vs. SCE), which is crucial for the release of CO2. The Ered*(cat* / cat‧−) value can be calculated using the following formula: ^^^∗^^^ ^^( ^^ ^^ ^^∗ / ^^ ^^ ^^‧−) = ^^^^ ^^ ^^( ^^ ^^ ^^ / ^^ ^^ ^^‧−) + ^^0,0where Ered(cat / cat‧−) is obtained from the reductive cyclic voltammogram of the photocatalyst (FIG.20), and E0,0 is obtained from the phosphorescence spectra of the photocatalyst. Since the phosphorescence spectra of 1 and 3 match that of benzophenone at room temperature (FIG.24), suggesting minimal structure-influenced differences, the E0,0of benzophenone (3.0 eV)5was used for both Ered*(cat* / cat‧−) calculations of 1 and 3, which are then obtained as, ^^^∗^^^ ^^( ^^∗ / ^^‧−) = ^^^^ ^^ ^^( ^^ / ^^‧−) + ^^0,0 ^^ ^^ ^^ ^^ ^^ ^^ℎ ^^ ^^ ^^ ^^ ^^and ^^^∗^^^ ^^( ^^∗ / ^^‧−) = ^^^^ ^^ ^^( ^^ / ^^‧−) + ^^0,0 ^^ ^^ ^^ ^^ ^^ ^^ℎ ^^ ^^ ^^ ^^ ^^^^^∗^^^ ^^( ^^∗ / ^^‧−) = +1.22 V vs. SCE.

[0126] Density Functional Theory Calculations.

[0127] Density functional theory (DFT) calculations were carried out at the M06-2X level of theory with Gaussian 16 to elucidate the mechanistic pathways and investigate the thermodynamic feasibility of the photochemical CO2 capture and release system. Geometry optimization of each structure was first carried out in the gas phase using the 6-31+G(d,p) basis set. Subsequently, the geometry optimization and energy calculation was carried out using the 6- 31+G(d,p) basis set with the SMD continuum solvent model. Transition state structures were calculated at the same level of theory, and intrinsic reaction coordinates were calculated to verify the nature of the computed structures. The resulting relative Gibbs free energy diagram is provided in FIG.25 supported by the schemes in FIGS.26–28.

[0128] Given the nature of the solvent, charged species (G, I, K, M, Q) are calculated without the explicit inclusion of their countercations. On the other hand, the structures N and P as well as M*as their reference point were calculated with the explicit inclusion of a potassium counteraction to avoid unnecessary penalty for the highly unstable dianion N and to match the cyclic voltammetry results. The direct geometry optimization of K was also unsuccessful and instead optimized by freezing or locking the lactone C−O bond.

[0129] Proposed and Alternative Mechanisms.

[0130] For clarity, 2-methyl benzophenone (1), 2-(2-benzoylphenyl)acetic acid (2), and potassium 2-(2-benzoylphenyl)acetate (3) are referred to here as A, L, and M, respectively, and the labels described here follow Figs. S24 to S26. Upon light irradiation, A is excited into the triplet B that can undergo 1,5-hydrogen atom transfer to form a cisoid-hydroxy-biradical C. The biradical C can undergo conformational rearrangement into transoid-hydroxy-biradical D as well as a conical intersection into the ground state (E)-photoenol F. The (E)-photoenol F can either react with CO2or isomerize into the (Z)-photoenol F that readily undergoes 1,5-hydride shift back to A.

[0131] For the CO2 capture step, two pathways are viable under the relevant conditions for this study. The photoenol F can either be deprotonated to form photoenolate G (Fig S24, S25 and S27, enolate pathway) or directly engage in a reaction with CO2 to form J (FIG.28, FIG.29, enol pathway). The lifetime of photoenols have been shown to be quite long (~60 µs for F),7allowing for their reaction with CO2and other coupling partners. As such, the deprotonation of F to yield G should be kinetically feasible. The calculated transition state structures for both pathways, H and I, closely resemble each other (FIG.29), suggesting that the photoenolate may also react with CO2 in a Diels-Alder reaction. However, the ∆G for the enolate pathway was calculated to be significantly lower (∆∆G = −51.1 kJ / mol) than for the enol pathway, matching its increased experimental rate. As such, the photoenolate pathway (proceeding through G) is presumed to be predominant pathway.

[0132] While the optimization of cycloadduct J yielded a computationally stable structure, initial attempts to optimize the structure of cycloadduct K repeatedly resulted in the ring-opened product M instead. As such, the lactone C−O bond of K was frozen to calculate its energy. This observation likely reflects the unstable nature of cycloadduct K, rendering a nucleophilic pathway a viable alternative for the reaction of photoenolate G with CO2. The cycloadduct J cansimilarly go through a ring opening into a carboxylic acid L and subsequently be deprotonated to yield carboxylate M, converging both capture pathways.

[0133] For the CO2 release step, the envisioned photoredox decarboxylation mechanism can be catalyzed by either additional molecules A or M, which get excited to B and N, respectively, leading to two possible release pathways (Figs. S23 to S25). As a potent photooxidant, N then gets reduced into the radical anion P, oxidizing M into the carboxylate radical O. While triplet B should also be a decent oxidant for some other molecules, both experimental evidence by cyclic voltammetry and photoluminescence spectroscopy and DFT calculations suggest that the oxidation of M into O by B, which turns into Q, is energetically uphill. The inability of B (or A) to oxidize M also explains the lack of CO2release after a capture step with high concentration of 2-methyl benzophenone A. As such, the release pathway is likely catalyzed by the CO2adduct M. The carboxylic acid L can serve as an alternative photocatalyst, but given the excess of base in the experimental condition, all molecules L are likely converted into M.

[0134] Once oxidized, the carboxylate radical O goes through an almost barrierless transition state R, extrudes CO2, and undergoes a β-scission to form the benzylic radical S. The reduced photocatalysts P and Q then reduce the radical S into the benzylic anion T. Upon proton transfer, the anion T turns into A, and the overall CO2separation cycle is closed.

[0135] Gaussian Optimized Coordinates. 2-Methyl Benzophenone – Singlet (A or 1) C 1.1445868895,-1.2018920769,0.8040243128 C 1.1303481179,0.0900772001,0.263202299 C 3.4260761557,-0.1826639042,-0.3988080704 C 2.2833336049,0.6226578132,-0.3469273631 C 3.4451393869,-1.4612953647,0.1570063747 C 2.3019823756,-1.9747113846,0.7673586088 H 0.2461679714,-1.5963673474,1.2711957234 H 4.3176954345,0.2051502656,-0.8849088733 H 4.3519890844,-2.0569647885,0.1076122675 H 2.3073647651,-2.9689344196,1.2028465776 C 2.3185564802,2.0018077207,-0.955222263 H 2.4178341712,2.769085899,-0.1821249986 H 3.1696442427,2.0881026316,-1.6351660289 H 1.4042103732,2.2224411033,-1.5127847239 C -1.441663696,0.2981969796,0.1163235856 C -2.5825620589,0.8601818283,0.7033384897 C -1.5753538669,-0.7851705972,-0.760273741C -3.8413982632,0.3351931266,0.4297150398 H -2.4690426567,1.7033377829,1.3779575292 C -2.8397472848,-1.2978294579,-1.0473842679 H -0.6983708184,-1.2177790347,-1.2325216144 C -3.9709034839,-0.7437737123,-0.448420807 H -4.72167149,0.7654444515,0.897443659 H -2.94029608,-2.1299964703,-1.7372385314 H -4.9540150104,-1.1508176696,-0.6658256982 C -0.1100401233,0.9191814308,0.407973761 O -0.0402582206,2.0835389947,0.7716657532 2-Methyl Benzophenone – Triplet (B) C -0.7635307398 C -1.154561402,0.0363187089,-0.2685872732 C -3.4662484578,-0.0816660787,0.4036633229 C -2.2824775212,0.6577507292,0.3167471602 C -3.5521146943,-1.3882783866,-0.0732683123 C -2.4354738635,-1.9911703725,-0.6561690047 H -0.3824661578,-1.7305030061,-1.2376122923 H -4.3345243411,0.3795089925,0.8673175805 H -4.4867963651,-1.9344265588,0.01113573 H -2.4920056475,-3.0070238158,-1.0347778287 C -2.2291713684,2.0538714915,0.8805970633 H -2.3113128638,2.8097928915,0.0931767895 H -3.0541338721,2.208228502,1.5798347095 H -1.2873222395,2.2309293174,1.4093351034 C 1.4448376091,0.2481412352,-0.1301311175 C 2.5847565188,0.9741875655,-0.5614248814 C 1.6452051039,-0.946148005,0.6067932457 C 3.8624809033,0.5100225339,-0.2792918749 H 2.4577334885,1.8922874876,-1.1283426508 C 2.9297389455,-1.3968192703,0.872075174 H 0.790647579,-1.502931839,0.9781708505 C 4.0489589756,-0.6782403503,0.4333088435 H 4.7224021378,1.0777053894,-0.6230695328 H 3.0628336063,-2.3151201512,1.4367495218 H 5.0500511322,-1.0383076811,0.6477761352 C 0.1305970475,0.7466806809,-0.3988804334 O 0.003723644,1.9592923635,-0.9201192883 Cisoid-Hydroxy-Biradical – Triplet (C) C 3.8559935724,0.3935751876,-0.1794161727 C 3.9728428154,-0.8343460068,0.4812433512 C 2.8103331165,-1.5319016369,0.8341187601C 1.5564654417,-1.0227305409,0.5327553595 C 1.4211023968,0.2194784982,-0.1449008149 C 2.6094558103,0.9191212854,-0.4896815496 C -1.9698159337,1.8928887149,1.234773457 C -2.1785829338,0.6874442392,0.5218064053 C -1.1507262839,0.0818704688,-0.2722021232 C 0.1451826222,0.7628602576,-0.455414625 O 0.1348323691,2.010609939,-0.9984063121 C -3.4266387612,0.0178788672,0.6104807202 C -3.645028574,-1.1941521247,-0.0266986925 C -2.6265486471,-1.7831420962,-0.7828226033 C -1.3932724471,-1.1361245262,-0.9049118425 H 4.7496969628,0.9458172544,-0.4568501611 H 4.9508617552,-1.2400085031,0.7198478946 H 2.8863276969,-2.4821025166,1.3552385055 H 0.6684974537,-1.5735574694,0.8273755272 H 2.534509451,1.8705622362,-1.0050239407 H -1.0096309209,2.3942929418,1.2476050962 H -2.7758492921,2.3168822658,1.8226159519 H -0.768234839,2.2525114627,-1.2546080076 H -4.2122668714,0.4679650996,1.2118140212 H -4.6078359433,-1.6874231475,0.0672527903 H -2.7913347318,-2.7325728361,-1.2821837335 H -0.6064152847,-1.5820973141,-1.5077702614 (Z)-ortho-Quinone-Dimethide or (Z)-Photoenol – Singlet (D) C C - 0.6252640778,-0.032715553 C -3.1732982576,-1.1049780441,-0.9790012622 C -1.8558923411,-0.6516176441,-0.9795633823 C -1.4328015044,0.2862705411,-0.0290372951 C -2.3531284481,0.7828887947,0.9039650816 C 2.7142023084,1.882641841,-0.7790455978 C 2.4454729776,0.6708059423,-0.2268594272 C 1.0971258281,0.0581398304,-0.107566232 C -0.048422272,0.8127984661,-0.0370101764 O -0.0427620025,2.1560883993,0.0766681281 C 3.5693927299,-0.14715785,0.2375483003 C 3.4305801044,-1.4628647012,0.5049514996 C 2.1364531573,-2.1088541363,0.3985454989 C 1.0319936366,-1.3825846376,0.1122834315 H -4.3693170873,0.7009201595,1.6426336172 H -5.1052917142,-0.9807581781,-0.0327564598 H -3.4934436294,-1.8270985635,-1.723858033 H -1.1567082987,-1.011855091,-1.7289451945H -2.032502564,1.5236735682,1.63015637 H 1.9768300802,2.4963219977,-1.2865313063 H 3.7409400814,2.2351955503,-0.8135122251 H 0.860190109,2.470809468,0.2636564493 H 4.5423425084,0.3343744745,0.2948126116 H 4.2932159664,-2.05306208,0.8009847785 H 2.0534256513,-3.1720937383,0.5995739093 H 0.0621104109,-1.8666667884,0.1180282794 Transoid-Hydroxy-Biradical – Triplet (E) C -3.8024720288,0.3913249388,0.084103695 C -3.8511991083,-0.8564967086,-0.5483054673 C -2.6537003493,-1.4879145153,-0.9053435352 C -1.4292957109,-0.8945758801,-0.6341539823 C -1.3633110776,0.3666014752,0.0169283252 C -2.5869660188,0.9998593548,0.3634514965 C 0.8388421715,-1.5260776798,1.5777688355 C 1.6483818875,-0.8047685399,0.6660137339 C 1.2189189363,0.4142501141,0.0479322293 C -0.1164636609,0.9884532671,0.3017972445 O -0.1721159072,2.2776990121,0.7321428079 C 2.9524354296,-1.2736153027,0.363663159 C 3.8057059097,-0.5681275297,-0.4721222881 C 3.3868813609,0.6366975602,-1.043325141 C 2.0992461119,1.1129198078,-0.7808638899 H -4.7250281358,0.8932498807,0.3625702547 H -4.8053874819,-1.3269474296,-0.7635283001 H -2.6777849077,-2.4509738873,-1.4074517459 H -0.5130762778,-1.3931253588,-0.9361083742 H -2.5638315251,1.9654059217,0.8572441397 H -0.1368534939,-1.1710446326,1.8836625973 H 1.2140912466,-2.4427678391,2.0185147822 H 0.7139059871,2.5744518495,0.9900703583 H 3.2857372311,-2.1996711993,0.8250605953 H 4.8015038003,-0.9508230984,-0.6748100126 H 4.0493817898,1.1980947137,-1.6943485424 H 1.7668188216,2.0374667056,-1.2472719752 (E)-ortho-Quinone-Dimethide or (E)-Photoenol – Singlet (F) C - C -3.820092412,-0.8200559166,-0.2876050455 C -2.7540730353,-1.2771994708,-1.0677894823 C -1.5082993936,-0.6655946077,-0.976201339 C -1.3150393604,0.4107168788,-0.1008736349C -2.3907948665,0.8840139291,0.6572039788 C 0.5530553931,-1.5861915174,1.3474124813 C 1.3997245536,-0.9161918522,0.5366905517 C 1.2235279343,0.5005872061,0.1170384831 C -0.0004443565,1.093472516,-0.0236749082 O -0.1622828631,2.4316310887,-0.1861549479 C 2.6460685186,-1.5624741223,0.109811029 C 3.7057584885,-0.8392724305,-0.3074959355 C 3.6233379946,0.6099080758,-0.3841839377 C 2.4479546223,1.2447388561,-0.174758024 H -4.4637717395,0.6281757385,1.1727272565 H -4.791064021,-1.3010330316,-0.3586052888 H -2.8974503077,-2.1076898247,-1.752517935 H -0.6780880649,-1.0190867297,-1.5815795188 H -2.2465203945,1.7291614097,1.3240268837 H -0.3294124094,-1.1254533418,1.7789012357 H 0.7485995889,-2.6260097578,1.5960223506 H 0.6526143891,2.9119772161,0.023723182 H 2.7122591215,-2.6425951228,0.2162043151 H 4.6386073821,-1.3295483019,-0.5701727643 H 4.5084438628,1.1781438662,-0.6524855616 H 2.4228977964,2.3234698802,-0.308814715 (E)-Photoenolate Anion – Singlet (G) C -3.6628923522,0.2101721819,0.5157615066 C -3.7925496277,-0.8391802222,-0.3944840573 C -2.691953501,-1.2359848318,-1.1589177634 C -1.4631375579,-0.6013471427,-0.9950445663 C -1.3270570116,0.4506407101,-0.0826179867 C -2.4374332429,0.8623671728,0.6582617152 C 0.5430253187,-1.5525185986,1.3958158002 C 1.4275424847,-0.8520588132,0.6080214272 C 1.239433618,0.4962915539,0.0633533053 C -0.0271849095,1.208167849,0.0409690223 O -0.1076040484,2.4485405065,0.0378571111 C 2.7304599213,-1.4413399759,0.3074886338 C 3.7565833196,-0.7344853106,-0.2488386596 C 3.5999751544,0.6390081496,-0.6124842663 C 2.3552242566,1.2047870259,-0.4522617002 H -4.5167158458,0.5250150986,1.1088876462 H -4.7476177708,-1.3426236882,-0.513435621 H -2.7923631065,-2.0443681943,-1.8774785455 H -0.6006020852,-0.9198259629,-1.575518375 H -2.3326891388,1.6906713202,1.3535939821 H -0.4180994355,-1.156111771,1.7018062227H 0.8014638133,-2.5521969696,1.7354464279 H 2.8840007396,-2.4807387884,0.5927567496 H 4.711183335,-1.2287325623,-0.4190766171 H 4.420810222,1.1952805728,-1.053201051 H 2.1775544506,2.2285666904,-0.7742723409 (E)-Photoenol and CO2 Transition State – Singlet (H) C 3.8083650821,-C 3.8869686222,-0.908459673,- C 2.7666163071,-1.6453039979,-1.4414426298 C 1.5648639797,-1.5058169556,-0.7584169889 C 1.4804592114,-0.6281460828,0.3316952017 C 2.6099710631,0.0871905039,0.7457348608 C -0.5186389237,0.8660427286,-1.5162627767 C -1.3688557806,0.0523826579,-0.7730243117 C -1.0684945686,-0.491604879,0.5477229862 C 0.2201113051,-0.5054000294,1.0813161262 O 0.4319999275,-0.5021190037,2.3952939161 C -2.731885374,-0.1030824502,-1.235278705 C -3.7148736102,-0.6018243135,-0.4391411634 C -3.4345032537,-1.0183970357,0.9043160018 C -2.1602889628,-0.9495703596,1.3744213599 H 4.6793635673,0.5229849619,0.357680586 H 4.8226998326,-1.0144358989,-1.5861457009 H 2.8338427604,-2.3297617173,-2.2812063144 H 0.6896781521,-2.0741025359,-1.0606656955 H 2.5390827831,0.7599979839,1.5946115082 H 0.5504774812,0.9004669037,-1.3506804536 H -0.8608225291,1.1756005619,-2.4988895487 H -0.3749175557,-0.2603521765,2.8822068021 H -2.957675004,0.2300338767,-2.24440086 H -4.7278565479,-0.6885192267,-0.8216857715 H -4.227584845,-1.4249176605,1.5225970991 H -1.9536931441,-1.3420705591,2.3672654357 C -0.7986903857,2.6043689364,-0.3538530674 O -0.1793417763,2.3923673069,0.6445883256 O -1.4648999433,3.3313014404,-1.0254703771 (E)-Photoenolate Anion and CO2Transition State – Singlet (I) C -3.7020220149,0.2527200756,0.0991222874 C -3.8084477749,-0.7928058776,-0.8188389301 C -2.6798445893,-1.2157587436,-1.5257705413 C -1.446146604,-0.6106330769,-1.2977696757 C -1.3346856122,0.4379207246,-0.3783578848C -2.471106279,0.8756693095,0.3060111971 C 0.4299581998,-1.6035448264,1.1889246227 C 1.3744125175,-0.9126648094,0.4387863817 C 1.2314630715,0.4235812032,-0.1206984994 C -0.0277802053,1.1647244175,-0.1837605418 O -0.0743127356,2.40161225,-0.1718314659 C 2.6892690569,-1.5044409689,0.2609952846 C 3.7543137086,-0.8169076869,-0.2556910302 C 3.6208522459,0.5342679659,-0.6802395945 C 2.370250864,1.1112376236,-0.6026925254 H -4.5776383366,0.5863061453,0.6485337249 H -4.7675839145,-1.2737216136,-0.9877336354 H -2.7620720164,-2.0211672547,-2.2498654238 H -0.5626730489,-0.9494934881,-1.8333991906 H -2.3816410803,1.6994172993,1.0088214824 H -0.5882848806,-1.2597982666,1.3175804641 H 0.650546116,-2.6219658202,1.4970546244 H 2.8230177156,-2.531554635,0.5954697707 H 4.7172643776,-1.3160853315,-0.343414486 H 4.4661855364,1.0755650609,-1.0924435674 H 2.2174465698,2.1276475045,-0.9582364196 C 1.0777923676,-0.3635336737,3.2549802601 O 1.8225610817,-1.1347074061,3.7368385419 O 0.4123429736,0.5871914294,3.07232283 (E)-Photoenol and CO2Cycloadduct – Singlet (J) C 3.7922796221,0.4709947208,0.787454004 C 4.1725931279,0.4210515431,-0.5517415667 C 3.239659305,0.0532287324,-1.5242603429 C 1.9348660333,-0.2631852439,-1.155817516 C 1.5551298308,-0.218043219,0.1889510539 C 2.4835118527,0.1546796612,1.1594128254 C 0.1137098892,-0.5098880022,0.5669529412 C -0.848740564,0.6076854215,0.1915756493 C -2.1925597315,0.2606261237,0.0280836823 C -2.5833324543,-1.1854828017,0.1784068928 C -1.4996147019,-2.1281667992,-0.2820750847 O -0.2211879349,-1.7163085789,-0.166274596 C -0.4440177821,1.9380515073,0.0759268218 C -1.3868952147,2.925253439,-0.2049221376 C -2.7282218987,2.5812494676,-0.3775115862 C -3.1296789361,1.2513044067,-0.2659179951 O 0.0472140688,-0.7896977554,1.93358922 O -1.717280478,-3.2197651438,-0.7519927892 H 4.5118425335,0.7572462063,1.5486217756H 5.1902892225,0.6676049441,-0.8393435559 H 3.5287496409,0.0132177933,-2.5700991314 H 1.2096653625,-0.5465802275,-1.9133962111 H 2.1854785127,0.197345665,2.2011813517 H -2.7887671279,-1.425393502,1.231730383 H -3.4915078073,-1.4199893043,-0.3792926953 H 0.6014899409,2.2042850878,0.2011124844 H -1.0727910701,3.9603081355,-0.2956477265 H -3.4613315359,3.3488867864,-0.605703061 H -4.1713518624,0.9768109043,-0.408837471 H -0.803524843,-0.4967819681,2.2925943811 (E)-Photoenolate Anion and CO2 Cycloadduct – Singlet (K) C 3.8182070319,0.3565678005,0.8390643248 C 4.1834277923,0.4632763467,-0.502598969 C 3.2309753042,0.2254713601,-1.4977909728 C 1.9248296131,-0.1143386795,-1.1474654323 C 1.5531742053,-0.2258308799,0.1969686223 C 2.5074134812,0.0136510936,1.1829029963 C 0.1046812541,-0.5637279737,0.6242729106 C -0.8524277044,0.5817657319,0.2085556844 C -2.2009875102,0.2285726468,0.0795166744 C -2.5487203312,-1.2252565125,0.2595887921 C -1.4606183457,-2.1316922882,-0.2707804061 O -0.2120276732,-1.677735423,-0.2226102363 C -0.4814616525,1.9196295024,0.075392479 C -1.4460157495,2.898655731,-0.1813333612 C -2.7865831077,2.5404152573,-0.3198574663 C -3.1619755825,1.200315165,-0.1938763054 O -0.0409434919,-0.8547991666,1.8995522519 O -1.6949352763,-3.2249829604,-0.7526416878 H 4.553667038,0.5395990372,1.6180097768 H 5.201230516,0.7290797452,-0.7738768198 H 3.5083811285,0.3051526789,-2.545457795 H 1.1865852867,-0.2958291792,-1.9254352899 H 2.1960699879,-0.0806355926,2.2191436626 H -2.6390576637,-1.4510621663,1.3293895487 H -3.4876249796,-1.4929328833,-0.2289006633 H 0.5629448334,2.20661306,0.17215419 H -1.1476379899,3.9385922469,-0.2811450755 H -3.5366224711,3.2973098699,-0.5301547211 H -4.2042179431,0.9103854319,-0.3076997121 2-(2-Benzoylphenyl)Acetic Acid – Singlet (L or 2)C 4.0716240336,-0.2948653172,0.5495851249 C 4.2659791946,0.1841214732,-0.7481023187 C 3.1724687928,0.573790948,-1.5218419522 C 1.8835993025,0.5008309873,-0.9960751723 C 1.6851075549,0.0186010055,0.3031471147 C 2.7843631051,-0.3876761319,1.0695468786 C 0.3150129674,-0.1401042203,0.8829594713 C -0.788347454,0.7620626716,0.420652443 C -2.093432004,0.26404004,0.2350431856 C -2.4684732458,-1.182741133,0.4591292902 C -1.6009588275,-2.2357724543,-0.1888208158 O -0.8582188588,-1.7767250193,-1.2091762672 C -0.5209858174,2.1212010704,0.2236887794 C -1.536674906,3.0017325697,-0.1418145023 C -2.824696718,2.5130052695,-0.3432939349 C -3.0916123143,1.1555805439,-0.1631438735 O 0.1002907095,-0.9959817469,1.7298783643 O -1.6033220295,-3.4018403107,0.1347273199 H 4.9228239726,-0.5970517892,1.1519403109 H 5.2700817085,0.251044386,-1.1563840011 H 3.3223770218,0.9359745829,-2.5342214789 H 1.0342945812,0.7993932865,-1.6035589812 H 2.6187341491,-0.7674677505,2.0732417212 H -2.4950127785,-1.4241465248,1.5243168123 H -3.4787522551,-1.3527123437,0.0690805748 H 0.4875533686,2.4955218048,0.3747783413 H -1.3190104655,4.056572561,-0.2757528218 H -3.624238234,3.1835254539,-0.6435855427 H -4.097329887,0.7790811795,-0.3302414622 H -0.352771667,-2.5248560922,-1.5744066078-(2-Benzoylphenyl)Acetate Anion – Singlet (M) C -4.0678456417,0.0753346851,0.5564883269 C -4.2017942386,-0.1529172123,-0.8140716748 C -3.0662077935,-0.3248848232,-1.6086149189 C -1.7982377733,-0.2801112393,-1.0332772688 C -1.6603751539,-0.0509981626,0.3398256822 C -2.7993328866,0.1326372083,1.1302752086 C -0.3118040809,0.0246250981,0.9907570982 C 0.8217646764,-0.7607940682,0.3981860072 C 2.1021756006,-0.189092791,0.2599578316 C 2.3696345663,1.2566187559,0.5673206454 C 1.5232101505,2.2829509321,-0.2457015752 O 0.5282931702,1.848088204,-0.8743393786 C 0.6011921895,-2.0975748345,0.052966908C 1.6443474209,-2.8946012096,-0.4181527944 C 2.9122932454,-2.3379584178,-0.5673149655 C 3.127992237,-0.9985481169,-0.2384324625 O -0.1630847985,0.6409247479,2.0351628714 O 1.9231410573,3.4699075405,-0.1700092903 H -4.9499755974,0.2082497909,1.1756569284 H -5.1898255734,-0.1945532195,-1.2632744521 H -3.1698821692,-0.49027135,-2.6768391982 H -0.9102870706,-0.3891609998,-1.6478174417 H -2.6811972404,0.3137278419,2.1946116217 H 2.1637473934,1.4690127654,1.6211689536 H 3.4260681731,1.4805385684,0.3944474691 H -0.393475221,-2.5223087573,0.1633407067 H 1.4636747395,-3.9348938438,-0.6710014808 H 3.7339161001,-2.9408241526,-0.9435190343 H 4.1174185189,-0.5670319403,-0.3703573228 Potassium 2-(2-Benzoylphenyl)Acetate – Singlet (M*or 3) C 4.0107526362,- C 4.1707107326,0.0885626976,-C 3.0618584079,0.5358002458,-1.6645942024 C 1.7905848416,0.4817361222,-1.0968946786 C 1.6251367701,-0.0326602878,0.1944015367 C 2.739876997,-0.487978633,0.9121718503 C 0.2662514647,-0.2037880869,0.7999238193 C -0.827195355,0.7406500044,0.4231300343 C -2.1268724837,0.2693238166,0.1440049266 C -2.4944894904,-1.1929086384,0.1776420099 C -1.49993156,-2.1602806957,-0.4883449272 O -0.6668828315,-1.6957295325,-1.3136024842 C -0.5397363522,2.1091370221,0.3740479265 C -1.537264104,3.0351696875,0.0777343376 C -2.822799013,2.5813018503,-0.2077524075 C -3.103090831,1.2145502097,-0.1835294013 O 0.0758834018,-1.1145060006,1.6006178536 O -1.5623676499,-3.3645908061,-0.1272877134 H 4.8735783492,-0.7630875926,0.9089913702 H 5.1601936267,0.1359345348,-1.3890499951 H 3.1867007986,0.9217694891,-2.6714847846 H 0.9235631736,0.8075043781,-1.6630056047 H 2.6042983218,-0.8793475975,1.917239417 H -2.6179582233,-1.5296176271,1.2110694663 H -3.4643346551,-1.3263092773,-0.3154022512 H 0.4703213706,2.4510692389,0.5838293424 H -1.3081348151,4.0959609346,0.058928226H -3.6089471036,3.2879193866,-0.4574078925 H -4.1055150245,0.8695953222,-0.4241084746 K 1.0980166599,-3.2050545097,-0.0152878616 Potassium 2-(2-Benzoylphenyl)Acetate Anion – Triplet (N) C -3.7563581797,-1.0574752869,0.8680464516 C -3.9939222025,-1.4140817291,-0.461196271 C -2.9367075275,-1.4388310287,-1.3724277781 C -1.6444290705,-1.1208751133,-0.9567005662 C -1.394442991,-0.7765057543,0.3810207501 C -2.4677375498,-0.7300773592,1.2843552036 C -0.0547918073,-0.2897881833,0.8333051934 C 1.1498747017,-0.8483328645,0.2873971854 C 2.4367300632,-0.0624484411,0.2949105185 C 2.4114285959,1.4302027943,0.3772829794 C 1.3101273655,2.0677812545,-0.4816333359 O 0.7621833214,1.3423022893,-1.3609105148 C 1.2118495988,-2.2134791127,-0.1930487656 C 2.4107131843,-2.82676599,-0.3439613392 C 3.6657775932,-2.1119152862,-0.128379403 C 3.6326818207,-0.7503499427,0.1547236484 O -0.017446491,0.6900300754,1.6336762497 O 0.98468335,3.2532080136,-0.2213732541 H -4.5765705048,-1.0304511714,1.5792901302 H -4.9996436269,-1.6617558709,-0.7870497581 H -3.1194244445,-1.6931882517,-2.4121639864 H -0.8311510803,-1.1082773691,-1.6775439822 H -2.2792979988,-0.4371886178,2.3132550118 H 2.243366888,1.7617947942,1.4077254992 H 3.3818660075,1.8273288246,0.058244288 H 0.2939202132,-2.778313511,-0.3111766583 H 2.4503076799,-3.8775124348,-0.615043698 H 4.6059333727,-2.633430857,-0.2621561183 H 4.5627324963,-0.1892425043,0.1975243113 K -1.4939337779,2.2589916342,-0.1552609913 2-(2-Benzoylphenyl)Acetate Radical – Doublet (O) C 4.0617321008,-0.208910159,0.617911398 C 4.2748046642,0.3615156527,-0.6392559055 C 3.189979661,0.7586492264,-1.4210890878 C 1.890151446,0.6024717444,-0.9428376 C 1.6730469225,0.0285223024,0.3157135202 C 2.764752995,-0.3856329796,1.0890018071 C 0.2962588331,-0.2261804708,0.8408089067C -0.831101138,0.6722013555,0.4256031674 C -2.1333546437,0.1620164026,0.235543625 C -2.4734015187,-1.3061716378,0.3845412893 C -1.6088573593,-2.2233331876,-0.4292983289 O -0.8928761258,-1.6754461757,-1.3962038649 C -0.5960683998,2.0463875513,0.2938603414 C -1.6338623278,2.9206022014,-0.0163203146 C -2.9155982108,2.4172348045,-0.2268393007 C -3.155045008,1.0489558126,-0.1092284782 O 0.0925034178,-1.1596158246,1.6047721741 O -1.5193495723,-3.4326965023,-0.3378965846 H 4.906152239,-0.5173980243,1.2265106443 H 5.2869792093,0.4935532006,-1.0099295024 H 3.3546726349,1.1915632371,-2.4028703064 H 1.0494147848,0.9092718068,-1.5582541994 H 2.5853042547,-0.837536039,2.059856855 H -2.4080280876,-1.6448292346,1.4211989615 H -3.4988831958,-1.4809531152,0.0396905496 H 0.4044101115,2.4360712539,0.4558464125 H -1.4394364563,3.9850914014,-0.0991417933 H -3.7312932412,3.0862829181,-0.4831400882 H -4.1551569894,0.6598774788,-0.2791132971 Potassium 2-(2-Benzoylphenyl)Acetate Radical Anion – Doublet (P) C -3.8365640988,-0.6938301594,0.5387488282 C -3.9642717866,-1.5370511571,-0.5719569453 C -2.7914108695,-1.9768480281,-1.2127676689 C -1.537777786,-1.599731606,-0.7595589841 C -1.3784818541,-0.7505782853,0.3783149919 C -2.5856848694,-0.3055688986,1.0038072451 C -0.1114674173,-0.2384081077,0.8611191231 C 1.1739058988,-0.8602424618,0.4450645739 C 2.3384088578,-0.0872314857,0.1853436625 C 2.3685552365,1.4186000822,0.2813022317 C 1.3078494049,2.1821939181,-0.5295206906 O 0.7424987783,1.6026971531,-1.4938196215 C 1.2767192729,-2.2624583861,0.3608741282 C 2.4628668635,-2.9019533743,0.0108971667 C 3.5974845854,-2.1404024227,-0.2658139561 C 3.5177337944,-0.7497062844,-0.1723555735 O -0.0959889988,0.777540857,1.6495760313 O 1.0549527478,3.3588713473,-0.1473768943 H -4.7271049008,-0.3406216122,1.0541105931 H -4.9420107263,-1.8383105251,-0.934260338 H -2.8646131723,-2.6147488937,-2.0905570148H -0.6610866397,-1.9345319646,-1.3057570655 H -2.5051377067,0.3300866987,1.8820774573 H 2.244107727,1.7378918511,1.3183359814 H 3.3500644339,1.7759056085,-0.0560370977 H 0.4036324911,-2.8655624234,0.5960880151 H 2.5003648191,-3.986935563,-0.0355946886 H 4.5329106206,-2.6175705459,-0.5436505141 H 4.4021284777,-0.1526386679,-0.3859680841 K -1.4331741834,2.327907337,-0.0810478923 -Methyl Benzophenone Radical Anion – Doublet (Q) C -1.264689321,-C - C -3.4410235307,-0.0990288344,0.4412577903 C -2.2588766143,0.6402882431,0.3316650156 C -3.5436158211,-1.4015088988,-0.051169353 C -2.4356688624,-1.986800142,-0.6647669006 H -0.3954619955,-1.7197175697,-1.274041625 H -4.2984479576,0.3562673557,0.9329221594 H -4.4759616914,-1.9502754407,0.0463582962 H -2.4959732388,-2.9967595598,-1.0611546364 C -2.196829387,2.0304585347,0.9108374444 H -2.1841726424,2.7887138647,0.1235798123 H -3.054501265,2.2102781011,1.5653768231 H -1.2770661196,2.1710340502,1.4887296802 C 1.4102551233,0.2648300652,-0.1684133774 C 2.59312958,0.9949700979,-0.5046543002 C 1.6082912272,-0.9696653911,0.5250838101 C 3.8577176903,0.5152365131,-0.1966731243 H 2.4731563244,1.9441245246,-1.0174891046 C 2.8784284659,-1.4353864337,0.8268662679 H 0.7489901155,-1.552399694,0.8437516161 C 4.0285088438,-0.7088613868,0.4683597981 H 4.7308939262,1.1008696266,-0.4775493543 H 2.9816570706,-2.3779854735,1.3600639708 H 5.019644505,-1.0815176801,0.7072108689 C 0.1232278716,0.8348008702,-0.495642693 O 0.0238490981,2.0137764181,-0.9808590778 -(2-Benzoylphenyl)Acetate Radical Transition State – Doublet (R)- C -4.1639061124,-0.5839880862,-0.4806313509 C -3.0906414197,-1.0036958764,-1.2665502009 C -1.7830203445,-0.7966415596,-0.8306018728C -1.5471813857,-0.1477460112,0.3874608939 C -2.6278459538,0.2892642571,1.1637065488 C -0.1629448691,0.16080137,0.8613476322 C 0.9666766905,-0.7488724725,0.4824233325 C 2.2518852065,-0.2313161489,0.219198146 C 2.5889554527,1.2300799499,0.3053778641 C 1.6992736016,2.3192242076,-0.4657020914 O 1.0965404449,1.6942999123,-1.3959676812 C 0.7516474449,-2.129536042,0.4370675467 C 1.7956609849,-3.0060005007,0.144104052 C 3.0591930033,-2.496904595,-0.1375852887 C 3.2782002194,-1.11866882,-0.1076449702 O 0.0434586682,1.1472715239,1.5549115375 O 1.7423818724,3.4828853316,-0.14732896 H -4.7675336612,0.3861965751,1.3487624178 H -5.1819271073,-0.7564342158,-0.8171375518 H -3.2704416819,-1.49414632,-2.2181637132 H -0.9505142487,-1.1210006737,-1.4482252293 H -2.4340375385,0.7986655794,2.1028265556 H 2.5018825538,1.6132778585,1.3249564227 H 3.5889727588,1.4227686064,-0.0930119708 H -0.2371051282,-2.5246619639,0.6503090225 H 1.6158666789,-4.076116901,0.1274160782 H 3.877784689,-3.1659542783,-0.3842264858 H 4.2651347238,-0.7249961349,-0.3342406762-Benzoylbenzyl Radical – Doublet (S) C -1.1436683871,-1.1525578463,-0.7516832013 C -1.1407149455,0.1366089146,-0.2161967925 C -3.4946681986,-0.1530538642,0.3530862505 C -2.3365277105,0.6758728313,0.3617586211 C -3.4792626305,-1.4205620366,-0.1995557687 C -2.3009507684,-1.9305961504,-0.761430485 H -0.2327729443,-1.5473586481,-1.1929654243 H -4.4064294676,0.2366898823,0.7978391339 H -4.3834944991,-2.0219147519,-0.1952466304 H -2.2848450715,-2.9224818897,-1.2009231765 C -2.4119309247,1.9450854387,0.9704565861 H -3.3506918257,2.2669013481,1.407579424 H -1.5611779791,2.6087633195,1.0323337745 C 1.4301433106,0.3143687495,-0.0885464166 C 2.5607411371,0.863256043,-0.7066683758 C 1.5756686702,-0.7718359153,0.7826409229 C 3.8202316658,0.3210133624,-0.4711952917 H 2.4390791496,1.709953993,-1.3754703173C 2.8411108636,-1.3011343684,1.0321377604 H 0.7073534463,-1.1931331229,1.2804948833 C 3.9615361382,-0.7610170057,0.4010414009 H 4.6918903422,0.7409657468,-0.9637610646 H 2.9508932868,-2.1350267086,1.7185150818 H 4.9452170571,-1.1810210039,0.5892516844 C 0.0999418676,0.9600371481,-0.335572667 O 0.0453944174,2.1424425348,-0.6459769122 2-Benzoylbenzyl Anion – Singlet (T) C -1.0009023439,-1.2155207017,-0.4204432373 C -1.1281486389,0.1540372249,-0.0361207599 C -3.5658295565,-0.2461257626,0.0324771004 C -2.472112949,0.7154066288,0.1706751398 C -3.3814121579,-1.5484521462,-0.3169907866 C -2.0694124159,-2.0629462291,-0.5705982439 H -0.0053944617,-1.600472384,-0.6222241881 H -4.5734941714,0.1262737242,0.2094179867 H -4.2440243035,-2.2049102028,-0.4112235448 H -1.927072007,-3.0946482491,-0.8751272494 C -2.790471548,2.0168884054,0.4844637197 H -3.8371759972,2.2718046457,0.6384842957 H -2.0459754335,2.7907761574,0.5871967777 C 1.4230899039,0.3236761513,0.0716988376 C 2.3873638057,0.8388897447,-0.8017944514 C 1.7877056673,-0.6969071679,0.9572529549 C 3.6836742334,0.3259498155,-0.8118717252 H 2.1126919093,1.6444314431,-1.4775841348 C 3.0903950916,-1.1969326623,0.9644148449 H 1.0513572635,-1.0960225132,1.6504362312 C 4.0393549774,-0.692716294,0.0744139263 H 4.4178891541,0.7240386251,-1.5065147249 H 3.3634220059,-1.9810680186,1.6648044577 H 5.0510609499,-1.08770842,0.07416217 C 0.0511875049,0.9664957494,0.1028924968 O 0.0375865178,2.2042274361,0.2626071068 Carbon Dioxide - Singlet O 0.,0.,1.162802 C 0.,0.,0. O 0.,0.,-1.162802 Potassium Phosphate Dibasic – SingletP 0.0286220502,0.6507750866,0.2130061638 O -1.3136802349,1.3730163364,0.3252868192 O 1.0445069305,0.8005586625,1.340208709 O 0.8804696343,1.3309374347,-1.0757897249 H 0.3595054315,1.2654530578,-1.8876371111 O -0.156346807,-0.8278502462,-0.2255777841 K -2.7358342321,-0.7228747977,-0.239418399 K 2.5187172274,-0.9119235341,-0.089442673 Potassium Phosphate Dibasic Anion – Singlet O 1.3180459025,1.6030872982,-0.0002870882 O -1.318595314,1.6019996195,0.0003833173 O 0.0006709702,-0.2043788652,1.2519748952 O 0.0001651736,-0.2042708933,-1.2520879884 K -2.2491910129,-0.9622949791,0.0000287145 K 2.2487549889,-0.9631733231,0.0000275803 P 0.0000932917,0.7740301429,-0.0000304308 EXAMPLE 2

[0136] This example provides methods and compositions for separation and release of compound(s) of interest.

[0137] Provided is a light-driven carbon dioxide separation using photoenolization / Diels- Alder reaction of inexpensive 2-methylbenzophenone as the capture mechanism and photoredox decarboxylation of the formed CO2 adduct as the release mechanism. Struggles in direct air capture of CO2may stem from the utility of the same sorbent to trigger both the capture and release steps, resulting in the reversible sorption of CO2for an atmospheric CO2concentration (400 ppm). As such, the decoupling of these triggers could enable direct air capture of CO2 and manifest in various ways.

[0138] One such strategy is through the separation of states of the capture-triggering functionality and the release-triggering functionality. Specifically, the immobilization of the 2- methyl benzophenone as the capture-triggering functionality was conducted by functionalization of cross-linked polystyrene resins through a Friedel-Crafts reaction (PS-Func). Successful incorporation of the 2-methyl benzophenone moiety was confirmed by infrared spectroscopy, specifically, by the appearance of a new carbonyl peak, as well as gravimetric analysis (see figure below). Subsequently, this material was evaluated for its performance to photochemicallycapture CO2from pure CO2stream as well as directly from air. By infrared spectroscopy, both experiments afforded a resin that displayed a second carbonyl peak that aligns closely to the molecular analog 2-benzoyl phenylacetic acid. Similarly, thermogravimetric analysis of the resin product exhibits a small weight loss near 180 °C that may correspond to the extrusion of CO2. Further investigation by residual gas analysis to confirm that direct air capture of CO2 was achieved is currently in progress. By using this approach to enable the direct air capture of CO2, the synthesis of an energy-saving sorbent can be achieved by upcycling polystyrene waste, which amplifies the impact of such an application.

[0139] An alternative strategy to enable direct air capture of CO2 is by simply tuning the redox potential of the sorbent. At present, the photoexcited reduction potential of the CO2adduction matches well with its ground state oxidation potential, resulting in the undesired release of CO2 at low CO2 partial pressure. At the same time, tuning the structure of the 2-methyl benzophenone has been reported to disrupt its photoenolization / Diels-Alder performance. Hence, careful functionalization of the benzophenone must be pursued. Upon establishing a structure- activity relationship, while o-tolyl(2,4,6-trimethoxyphenyl)methanone (see structure below) showed a similar CO2 capture performance as 2-methyl benzophenone, the release of CO2 was not observed under the appropriate condition. This finding is considered to be attributable to the lower photoexcited reduction potential of this benzophenone, as suggested by its more negative ground state reduction potential using cyclic voltammetry. As such, its performance to capture CO2from a stream containing 400 ppm CO2in N2was investigated. By1H nuclear magnetic resonance spectroscopy, a new peak matching the reference CO2adduct was observed. To further confirm the capture of CO2, direct analysis in real time mass spectrometry (DART-MS) analysis was conducted, showing an exact m / z match in the crude mixture compared to the reference CO2adduct. Not only do these results suggest that the modified sorbent can capture CO2 from air, but also this strategy can thus enable a wavelength-dependent photoswitching CO2 separation by using an oxidizing photocatalyst triggered by a distinct, longer wavelength, whichcould improve its translatability.could indeed unlock other novel chemisorptive chemical separation. For example, while photoenolization / Diels-Alder for CO2 capture was successfully applied as described above, such a reaction pathway is traditionally utilized with alkenes as a coupling partner. With this insight, it is expected that the utility of photoenols can be expanded for a more energy-efficient alkene separation. The reactivity of the enolized 2-methylbenzophenone to react with–and thus effectively capture–alkenes such as 1-hexene was successfully reproduced. While the capture step here is already well-known, the alkene-releasing step has not been reported. It is expected that ring-opening and subsequent alkene extrusion can be induced through radical pathways. Upon consideration and evaluation of several possible pathways, it was considered that the ring opening of an ethylene adduct, 1-phenyl-1,2,3,4-tetrahydronaphthalen-1-ol, as a model substrate can be achieved by engaging the adduct in a photochemical ligand-to-metal charge transfer with CeCl3 to form an alkoxy radical that is followed by β-scission. The resulting radical was then detected by reacting it with dimethyl fumarate, as observed in high conversion by gas chromatography / mass spectrometry. These density functional theory calculations suggest that this second β-scission is thermodynamically uphill for ethylene adduct derived from 2-methyl benzophenone (∆Gcalc = +21.7 kJ / mol). In contrast, this step was calculated to be thermodynamically downhill for ethylene adduct from 2-benzyl benzophenone (∆Gcalc= −6.2 kJ / mol) that yields a more stabilized radical product. Accordingly, the tuning of the sorbent could thus enable this approach to separate alkenes from alkanes.

[0141] Although the present disclosure has been described with respect to one or more particular embodiments and / or examples, it will be understood that other embodiments and / or examples of the present disclosure may be made without departing from the scope of the present disclosure.

Claims

CLAIMS:

1. A method of separation of one or more compound(s) of interest comprising irradiating with electromagnetic radiation a mixture comprising a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and one or more compound(s) of interest, wherein at least a portion of, substantially all, or all of the compound(s) of interest react(s) with at least a portion of, substantially all, or all of the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom to form one or more cycloaddition product(s); and optionally, releasing at least a portion of, substantially all, or all of the one or more compound(s) of interest from the cycloaddition product(s).

2. The method of claim 1, wherein the compound(s) of interest is / are chosen from carbon dioxide, alkenes, arenes, and any combination thereof.

3. The method of claim 1, wherein the one or more compound(s) of interest is / are present in a gas or liquid.

4. The method of claim 1, wherein the 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are chosen from ,structural analogs thereof, and any combination thereof.

5. The method of claim 1, wherein the mixture comprises a solution or a suspension.

6. The method of claim 5, wherein the one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is / are present in the mixture at a concentration of about 0.1 to about 2 mmol / liter.

7. The method of claim 5, wherein the mixture further comprises one or more polar solvent(s).

8. The method of claim 5, wherein the one or more compound(s) of interest is / are bubbled or sparged in the mixture or the mixture is in contact with an atmosphere comprising at least a portion of the one or more compound(s) of interest.

9. The method of claim 1, wherein the mixture is in contact with one or more base(s), one or more photocatalyst(s), one or more photothermal catalyst(s), or any combination thereof.

10. A method according to claim 9, wherein the one or more base(s) is / are present at a concentration of about 0.1 equivalent to about 3 equivalents (based on the amount of 2-alkyl- phenyl ketone(s) present in the mixture or the amount of cycloaddition product(s)).

11. The method of claim 1, wherein the electromagnetic radiation comprises one or more visible light wavelength(s) of about 380 nm to about 700 nm.

12. The method of claim 1, wherein the releasing comprises irradiating at least a portion of the cycloaddition product(s) and, optionally, one or more base(s), with electromagnetic radiation comprising one or more visible light wavelength(s) of about 310 nm to about 1,100 nm.

13. The method of claim 1, wherein the irradiating is performed at a first pressure, and wherein the releasing is performed in an atmosphere of inert gas and / or at a second pressure lower than the first pressure.

14. The method of claim 1, further comprising isolating at least a portion of the compound(s) of interest released from the cycloaddition product(s).

15. The method of claim 1, wherein the method is a continuous method, a semi-continuous method, or a batch method.

16. A capture sorbent material comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom; and a substrate, wherein at least a portion of the one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom is disposed on at least a portion of an exterior surface of the substrate.

17. The capture sorbent material of claim 16, wherein the substrate comprises a porous solid.

18. The capture sorbent material of claim 16, wherein the substrate comprises a conjugated polymer.

19. A system for capture of one or more compound(s) of interest comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom, wherein the system is configured to carry out the method of claim 1.

20. A system for capture and optionally, isolation, of one or more compound(s) of interest comprising one or more vessel(s), at least one vessel comprising a capture sorbent comprising one or more 2-alkyl phenyl ketone(s) and / or group(s) formed therefrom and configured to irradiate at least a portion of the contents of the vessel with electromagnetic radiation.

21. The system of claim 20, wherein the at least one vessel further comprises a first inlet configured to introduce a gas and / or liquid stream comprising the one or more compound(s) of interest into the at least one vessel.

22. The system according to claim 21, wherein the at least one vessel further comprises one or more outlet(s) configured to remove at least a portion or all of the one or more compound(s) of interest, the gas and / or liquid stream, one or more cycloaddition product(s) formed in the at least one vessel, or any combination thereof.

23. The system of claim 21, wherein the at least one vessel further comprises a second inlet configured to introduce one or more base(s).

24. The system of claim 20, wherein the system is part of or is a CO2-scrubbing unit.

25. The system of claim 20, wherein the system is in fluid and / or gas connection with an emission stream.

26. The system of claim 20, wherein the system is configured to operate in a continuous flow mode, a semi-continuous flow mode, or a batch mode.