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Title:
METAL-CONTAINING IONIC LIQUIDS AND METHODS OF PREPARING AND USING SAME
Document Type and Number:
WIPO Patent Application WO/2017/075242
Kind Code:
A1
Abstract:
The invention includes room-temperature ionic liquids that are capable of reversibly binding oxygen gas (O2). The invention further includes methods of preparing and using the compounds of the invention. The room-temperature ionic liquids of the invention have facile processibility and affinity to be impregnated into other supporting materials, and may be used in membrane fabrication and gas separation.

Inventors:
GIN, Douglas L. (708 Teal Circle, Longmont, Colorado, 80502, US)
KONO, Yuki (3-1-15-203, Nakakura Wakabayashi-k, Sendai Miyagi, 984-0821, JP)
COWAN, Matthew G. (1805 Marine Street, Apt. DBoulder, Colorado, 80302, US)
NOBLE, Richard (1262 Bear Mountain Court, Boulder, Colorado, 80305, US)
Application Number:
US2016/059160
Publication Date:
May 04, 2017
Filing Date:
October 27, 2016
Export Citation:
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Assignee:
THE REGENTS OF THE UNIVERSITY OF COLORADO, A BODY CORPORATE (1800 Grant Street, 8th FloorDenver, Colorado, 80203, US)
International Classes:
B01D53/22; B01D53/46; B01D53/54; B01D67/00; B01D71/28; B01J31/16; C07F15/00
Foreign References:
US20150209776A12015-07-30
Other References:
LIN, IJB ET AL.: "Metal-containing ionic liquids and ionic liquid crystals based on imidazolium moiety.", JOURNAL OF ORGANOMETALLIC CHEMISTRY, vol. 690, no. 15;, 1 August 2005 (2005-08-01), pages 3498 - 3512, XP027709113
OKUHATA, M ET AL.: "Ionic liquids from the cationic cobalt (III) Schiff base complex,[Co (acacen) L2][Tf2N](acacen= N, N'-bis (acetylacetone) ethylenediamine, Tf2N= bis (trifluoromethanesulfonyl) amide).", JOURNAL OF COORDINATION CHEMISTRY., vol. 67, no. 8, 18 April 2014 (2014-04-18), pages 1363, 1365, XP055378997
KOHNO, Y ET AL.: "A cobalt (II) bis (salicylate)-based ionic liquid that shows thermoresponsive and selective water coordination.", CHEMICAL COMMUNICATIONS, vol. 50, no. 50, 2014, pages 6633 - 6636, XP055379000
OSSOWICZ, P ET AL.: "Spectroscopic studies of amino acid ionic liquid-supported Schiff bases.", MOLECULES., vol. 18, no. 5;, 29 April 2013 (2013-04-29), pages 4988, XP055379005
MURRAY, LJ ET AL.: "Highly-selective and reversible 02 binding in Cr3 (1, 3, 5-benzenetricarboxylate) 2.", JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 132, no. 23, 19 May 2010 (2010-05-19), pages 7856 - 7857, XP002758703
KOHNO, Y ET AL.: "Reversible and Selective 02 Binding Using a New Thermoresponsive Cobalt (II)-Based Ionic Liquid.", INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, vol. 54, no. 48, 25 November 2015 (2015-11-25), pages 12214 - 12216, XP055379009
Attorney, Agent or Firm:
SILVA, Domingos J. et al. (Saul Ewing LLP, 1500 Market Street 38th Floo, Philadelphia Pennsylvania, 19102, US)
Download PDF:
Claims:
CLAIMS

What is claimed is:

1. A compound of formula (I):

{M(L)3}XT" (I), wherein

M is Co2+ or Fe2+;

X" and Y" are each independently a monovalent anion, and are independently selected from a group consisting of bistrifluoromethylsulphonylamide (Tf2N"), Br", Γ,

trifluoromethylsulphonate (CF3SO3"), CI", hexafluorophosphate (PF6"), tetrafluoroborate (BF4"), benzenesulfonate (C6H5SO3 ), alkanesulfonate (CnH2n+iS03 ) wherein n is an integer ranging from 1 to 24, and amino acid anions; and

each L is a ligand and is independently selected from the group consisting of optionally substituted L-histidine methyl ester dihydrochloride (HisCH3), optionally substituted imidazole, optionally substituted L-histidine, and optionally substituted L- histidine hydrochloride monohydrate.

2. The compound of claim 1 , wherein X" and Y" are Tf2N".

3. The compound of claim 1, wherein M is Co2+.

4. The compound of claim 1, wherein at least one L is imidazole.

5. The compound of claim 1, wherein at least two Ls are HisCH3.

6. The compound of claim 1, wherein (I) can exist in an 02-bound form and an 02-unbound form, wherein the 02-unbound form is prepared by applying vacuum to the 02-bound form, and wherein the 02-bound form is prepared by exposing the 02-unbound

7. The compound of claim 6, wherein conversion of the 02-bound form to the 02-unbound occurs without significant degradation of (I).

8. The compound of claim 1, which is [Co (His2CH3)2Im] [Tf2N]2.

9. A composition comprising the compound of any of claims 1-8.

10. The composition of claim 9, further comprising a porous polymer, wherein the compound is present on the surface of and/or within the porous polymer.

11. The composition of claim 10, which is prepared by contacting the porous polymer with a solution comprising at least one solvent and the compound, and allowing the at least one solvent to evaporate from the porous polymer.

12. The composition of claim 10, wherein the porous polymer is selected from the group consisting of polyethylene (including high-molecular-weight and ultra-high- molecular-weight polyethylene), polyacrylonitrile (PAN), polyacrylonitrile-co-polyacrylate, polyacrylonitrile-co-polymethylacrylate, polysulfone (PSf), Nylon-6,6, poly(vinylidene difluoride), polycarbonate, polyacrylonitrile (PAN), poly ether ether ketone (PEEK), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polypropylene, polysulfone (PSF), poly ether sulfone (PES), and mixtures thereof.

13. The composition of claim 10, wherein the porous polymer is in the form of a membrane.

14. The composition of claim 10, wherein the porous polymer is in the form of microparticles, nanoparticles or mixtures thereof.

15. The composition of claim 10, wherein the porous polymer comprises polytetrafluoroethylene (PTFE).

16. The composition of claim 9, wherein the weight percentage of the compound in the composition is in the range of about 1-90%.

17. The composition of claim 9, wherein the weight percentage of the compound in the composition is about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%.

18. A method of preparing an (Venriched gas, the method comprising: a. contacting a 02-comprising gas mixture with the composition of any of claims 10-17, wherein the porous polymer is in the form of a membrane comprising a feed side and a permeate side, wherein the gas mixture is in contact with the feed side of the membrane; b. applying a pressure difference across the membrane, wherein at least part of the 02 in the 02-comprising gas mixture reversibly binds to the compound on the surface of and/or within the membrane;

c. removing the 02-depleted gas from the permeate side of the membrane; and d. releasing the O2 dissolved to the permeate side of the membrane,

thus generating the 02-enriched gas.

19. A method of making a N2-enriched gas, the method comprising:

a. contacting a 02- and N2-comprising gas mixture with the composition of any of claims 10-17, wherein the porous polymer is in the form of a membrane comprising a feed side and a permeate side, wherein the gas mixture is in contact with the feed side of the membrane;

b. applying a pressure difference across the membrane, wherein at least part of the O2 in the 02-comprising gas mixture is reversibly bound to the compound on the surface of and/or within the membrane; and

c. collecting the 02-depleted (N2-enriched) gas from the permeate side of the membrane.

Description:
TITLE OF THE INVENTION

Metal-Containing Ionic Liquids and Methods of Preparing and Using Same

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 62/247,639, filed October 28, 2015, which application is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Separation of oxygen gas (O2) from air (typically from N2) to produce N 2 - or 02-enriched air (NEA or OEA, respectively) is of importance for numerous industrial and medical applications (e.g. , explosion hazard reduction, oxidation and combustion reactions, and respirator operation). Because the size and physical properties of O2 and N 2 are so similar, OEA is industrially produced via energy -intensive processes such as cryogenic distillation and pressure-swing absorption. Membrane separations can offer an economically effective alternative for O2/N2 separation when >99.5% NEA or OEA is required in moderate quantities (about 1 to 5000 scf/d), if materials with sufficient O2 permeability and O2/N2 selectivity are available.

There have been several reports of attempts to produce selective O2 sorbents and O2/N2 membranes with industrially relevant gas permeability and selectivity properties. In many cases, these research efforts have focused on materials designed to selectively bind or transport O2. Example materials include metal-organic frameworks, facilitated-transport ceramic and polymeric membranes. Coordination complexes of cobalt(II) have been studied for the reversible binding of O2 via the formation of superoxide or μ-peroxide moieties. The complexes reported so far lose suffer from loss of performance due to loss of bound solvent molecules and/or irreversible oxidation of cobalt(II) to cobalt(III). In particular, this irreversible oxidation gradually and irreversibly degrades their performance over repeated cycles and exposure to O2, severely curtailing their potential industrial applications.

There is thus a need in the art for compounds that can selectively and reversibly bind to O2. In certain embodiments, such compounds could be used to prepare OEA. The present invention meets this need. BRIEF SUMMARY OF THE INVENTION

The invention provides a compound of formula (I). The invention further provides a composition comprising at least one compound of the invention. The invention further provides a method of preparing OEA. The invention further provides a method of preparing NEA. The invention further provides a method of preparing an 0 2 -depleted gas. The invention further provides a method of preparing an N 2 -depleted gas.

In certain embodiments, the compound is {M(L) 3 }X " Y " (I), wherein M is Co 2+ or Fe 2+ ; X " and Y " are each independently a monovalent anion, and are independently selected from a group consisting of bistrifluoromethylsulphonylamide (Tf 2 N " ), Br " , Γ,

trifluoromethylsulphonate (CF 3 SO 3 ), CI " , hexafluorophosphate (PF 6 " ), tetrafluoroborate

(BF 4 " ), benzenesulfonate (C 6 H 5 SO 3 ), alkanesulfonate (C n H 2n+ iS03 ) wherein n is an integer ranging from 1 to 24, and amino acid anions; and each L is a ligand and is independently selected from the group consisting of optionally substituted L-histidine methyl ester dihydrochloride (HisCH 3 ), optionally substituted imidazole, optionally substituted L- histidine, and optionally substituted L-histidine hydrochloride monohydrate.

In certain embodiments, X " and Y " are Tf 2 N " . In other embodiments, M is Co 2+ . In yet other embodiments, at least one L is imidazole. In yet other embodiments, at least two Ls are HisCH 3 . In yet other embodiments, (I) exists in at least one form selected from the group consisting of 0 2 -bound form and an 0 2 -unbound form, wherein the 0 2 - unbound form is prepared by applying vacuum to the 0 2 -bound form, and wherein the 0 2 - bound form is prepared by exposing the 0 2 -unbound form to 0 2 . In yet other embodiments, conversion of the 0 2 -bound form to the 0 2 -unbound occurs without significant degradation of (I). In yet other embodiments, the compound comprises [Co n (His 2 CH3) 2 Im][Tf 2 N] 2 .

In certain embodiments, the composition further comprises a porous polymer. In other embodiments, the compound is present on the surface of and/or within the porous polymer. In yet other embodiments, the composition is prepared by contacting the porous polymer with a solution comprising at least one solvent and the compound, and allowing the at least one solvent to evaporate from the porous polymer. In yet other embodiments, the porous polymer is selected from the group consisting of polyethylene (including high- molecular-weight and ultra-high-molecular-weight polyethylene), polyacrylonitrile (PAN), polyacrylonitrile-co-polyacrylate, polyacrylonitrile-co-polymethylacrylate, polysulfone (PSf), Nylon-6,6, poly(vinylidene difluoride), polycarbonate, polyacrylonitrile (PAN), polyether ether ketone (PEEK), poly vinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polypropylene, polysulfone (PSF), polyether sulfone (PES), and mixtures thereof. In certain embodiments, the porous polymer is in the form of a membrane. In other embodiments, the porous polymer is in the form of microparticles, nanoparticles or mixtures thereof. In yet other embodiments, the porous polymer comprises

polytetrafluoroethylene (PTFE). In yet other embodiments, the weight percentage of the compound in the composition is in the range of about 1-90%. In yet other embodiments, the weight percentage of the compound in the composition is about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%.

In certain embodiments, the method comprises contacting a C^-comprising gas mixture with a composition of the invention, wherein the porous polymer is in the form of a membrane comprising a feed side and a permeate side, wherein the gas mixture is in contact with the feed side of the membrane. In other embodiments, the method further provides applying a pressure difference across the membrane, wherein at least part of the O 2 in the 0 2 - comprising gas mixture reversibly binds to the compound on the surface of and/or within the membrane. In yet other embodiments, the method comprises removing the (^-depleted gas from the permeate side of the membrane. In yet other embodiments, the method comprises releasing the O 2 dissolved to the permeate side of the membrane, generating the (Venriched gas.

In certain embodiments, the method comprises contacting a 0 2 - and N 2 - comprising gas mixture with a composition of the invention, wherein the porous polymer is in the form of a membrane comprising a feed side and a permeate side, wherein the gas mixture is in contact with the feed side of the membrane. In other embodiments, the method comprises applying a pressure difference across the membrane, wherein at least part of the 0 2 in the (^-comprising gas mixture is reversibly bound to the compound on the surface of and/or within the membrane. In yet other embodiments, the method comprises collecting the 0 2 -depleted (N 2 -enriched) gas from the permeate side of the membrane.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of specific embodiments of the invention is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are specific embodiments shown in the drawings. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings.

FIG. 1 illustrates thermoresponsive absorption/desorption of O 2 with associated color change for neat metal-containing ionic liquid (MCIL) 1. FIG. 2 is a plot illustrating the O2 sorption/desorption reversibility and consistency of performance for a MCIL 1-impregnated supported ionic liquid membranes (SILM) [MCIL loading: 1.1 (compound MCIL 1/ support)] after five successive O2 uptake and release cycles.

FIG. 3 comprises Χ Η NMR spectra of a sample of MCIL 1 under air dissolved in DMSO-c 6 (red) and a reference sample of blank OMSO-d 6 (black). The right spectra shows an enlarged figure around the solvent peaks. No distinct peaks for MCIL 1 was observed. In the MCIL l/OMSO-d 6 sample, one peak at 3.3 ppm (residual water in DMSO d 6 ) was shifted to lower magnetic field compared to the blank sample of pristine OMSO-d 6 , indicating a paramagnetic susceptibility shift.

FIG. 4 is a graph illustrating differential scanning calorimetry (DSC) profile of neat MCIL 1 under N2 using a temperature ramp rate of 5 °C/min. The glass transition temperature was determined as the onset temperature at which the endothermic peak appeared.

FIG. 5 is a graph illustrating thermogravimetric analysis (TGA) profile of

MCIL 1 under N 2 using a temperature ramp rate of 10 °C/min. The thermal decomposition temperature was determined as the temperature at which 10% mass loss of the sample occurred.

FIG. 6 schematically illustrates the process of preparing MCIL 1-impregnated SILMs with different loading levels.

FIG. 7 is a graph illustrating plots of the amount of O2 sorbed as a function of pure O2 exposure time for SILMs with different loading levels of MCIL 1 (compound MCIL 1 / support): black (0); blue (0.57); green (0.94); and red (1.40).

FIG. 8 is a graph illustrating plots of the amount of N 2 sorbed as a function of pure N 2 exposure time for SILMs with different loading levels of MCIL 1 (compound MCIL 1 / support): black (0); blue (0.57); green (0.94); and red (1.40).

FIG. 9 is a scanning electron microscope (SEM) image of a blank PTFE support without added MCIL 1.

FIG. 10 is a SEM image for a MCIL 1-impregnated SILM with an MCIL loading of 1.1 (compound MCIL 1 / support).

FIG. 11 is an ultraviolet (UV)-visible spectra of neat MCIL 1 before (black) and after (red) exposure to air. A demountable quartz cell with a path length of 0.1 mm was used for the measurement. FIG. 12 is an attenuated total reflectance Fourier-transform infrared (IR) spectroscopy (ATR-FTIR) spectra of neat MCIL 1 before (black) and after (red) air exposure.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the unexpected discovery of metal-containing ionic liquids (MCILs) that selectively and reversibly bind oxygen gas (0 2 ), and composition comprising the MCILs of the invention. The invention further relates to the use of these compounds in preparing oxygen gas (0 2 )-enriched air (OEA) or nitrogen (N 2 ) gas-enriched air (NEA) via either a membrane or pressure-swing adsorption process.

As described herein, the invention includes a thermoresponsive cobalt(II)- based MCIL (1) that reversibly binds O 2 over N 2 with high selectivity and an associated color change. This new MCIL is a neat, liquid-state material that not only has the desired materials properties of an IL but also facile processibility/affinity to be impregnated into other materials, which is valuable for some membrane fabrication and O 2 /N 2 separation

applications. This new MCIL 1 has an extremely high concentration of 0 2 -binding sites, and is synthesized using a simple, scalable method from a non-precious metal and inexpensive and readily available organic compounds

Definitions

As used herein, each of the following terms has the meaning associated with it in this section.

As used herein, unless defined otherwise, all technical and scientific terms generally have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the nomenclature used herein and the laboratory procedures in organic chemistry, inorganic chemistry, polymer science, and chemical engineering are those well known and commonly employed in the art.

As used herein, the articles "a" and "an" refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

As used herein, the term "about" will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which it is used. As used herein, "about" when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20% or ±10%, more preferably ±5%, even more preferably ±1%, and still more preferably ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods.

As used herein, the terms "comprising," "including," "containing," and "characterized by" are exchangeable, inclusive, open-ended and does not exclude additional, non-recited elements or method steps. Any recitation herein of the term "comprising," particularly in a description of components of a composition or in a description of elements of a device, is understood to encompass those compositions and methods consisting essentially of and consisting of the recited components or elements.

As used herein, "consisting of excludes any element, step, or ingredient not specified in the claim element.

As used herein, "consisting essentially of does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim.

As used herein, a "fluid" may be a liquid or a gas. In certain embodiments, the fluid is an aqueous liquid. In other embodiments, the fluid is a non-aqueous liquid.

As used herein, a "membrane" refers to a membrane comprising a compound of the invention, wherein the compound is part of a layer or film. When the membrane is deposited on, or on the surface of a porous support, the combination is referred as "supported membrane".

As used herein, "mole ratio" as relating to two or more compounds refers to ratio between the amounts in moles of the two or more compounds.

As used herein, "nanoporous" and "nanostructured" refer to a structure having a pore size between about 0.5 nanometers and about 5 nanometers in diameter and a "nanofiltration membrane" has an effective pore size between about 0.5 nanometers and about 5 nanometers. "Ultraporous" signifies a pore size between about 2.5 nanometers and about 120 nanometers and an "ultrafiltration membrane" has an effective pore size between about 2.5 nanometers and about 120 nanometers. "Microporous" signifies a pore size between about 45 nanometers and about 2,500 nanometers and a "microfiltration membrane" has an effective pore size between about 45 nanometers and about 2,500 nanometers. As used herein, "nanometer scale dimension" refers to pore dimensions between about 0.5 and about 5 nanometers.

As used herein, the term "polymer" refers to a molecule composed of repeating structural units typically connected by covalent chemical bonds. The term

"polymer" is also meant to include the terms copolymer and oligomers. In certain embodiments, a polymer comprises a backbone (i.e. , the chemical connectivity that defines the central chain of the polymer, including chemical linkages among the various polymerized monomeric units) and a side chain (i. e. , the chemical connectivity that extends away from the backbone).

As used herein, the term "polymerization" or "cross-linking" refers to at least one reaction that consumes at least one functional group in a monomeric molecule (or monomer), oligomeric molecule (or oligomer) or polymeric molecule (or polymer), to create at least one covalent linkage between at least two distinct molecules (e.g. , intermolecular bond), at least one covalent linkage within the same molecule (e.g. , intramolecular bond), or any combinations thereof. A polymerization or cross-linking reaction may consume between about 0% and about 100% of the at least one functional group available in the system. In certain embodiments, polymerization or cross-linking of at least one functional group results in about 100% consumption of the at least one functional group. In other embodiments, polymerization or cross-linking of at least one functional group results in less than about 100% consumption of the at least one functional group.

As used herein, a "porous support" refers to a solid body comprising pores of defined range of diameter at least on its surface. In certain embodiments, the porous support comprises pores of defined range of diameters throughout the entire support. In other embodiments, the diameter of the pores is less than about 10 microns. In yet other embodiments, the support is microporous or ultraporous. In yet other embodiments, the support has a pore size ranging from 0.005 micron to 10 micron, ranging from 0.01 micron to 0.1 micron, ranging from 0.1 micron to 10 microns, ranging from 0.5 micron to 5 microns, ranging from 0.5 micron to 1 micron, or less than about 0.1 micron. A porous support contemplated within the invention is capable of being coated with a thin polymer film on at least a portion of its surface. Materials suitable for the preparation of a porous support include, but are not limited to, ceramics (such as mullite alumina, silica, zirconia, silicon nitride, and silicon carbide), metals (such as aluminum, silver, and stainless steel), or organic polymers (such as polyethylene, polypropylene, poly(tetrafluoroethylene), polysulfone, polyimide, polyethylene, polyacrylonitrile (PAN), polyacrylonitrile-co-polyacrylate, polyacrylonitrile-co-polymethylacrylate, Nylon-6,6, poly(vinylidene difluoride), polycarbonate, and any combinations thereof).

As used herein, the term "alkyl," by itself or as part of another substituent means, unless otherwise stated, a straight or branched chain hydrocarbon having the number of carbon atoms designated (i. e. , Ci-Ce means one to six carbon atoms) and includes straight, branched chain, or cyclic substituent groups. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, fert-butyl, pentyl, neopentyl, hexyl, and cyclopropylmethyl. Most preferred is (Ci-C6)alkyl, particularly ethyl, methyl, isopropyl, isobutyl, «-pentyl, w-hexyl and cyclopropylmethyl.

As used herein, the term "substituted alkyl" means alkyl as defined above, substituted by one, two or three substituents selected from the group consisting of halogen, - OH, alkoxy, -NH 2 , -N(CH 3 ) 2 , -C(=0)OH, trifluoromethyl, -C≡N, -C(=0)0(d-C 4 )alkyl, - C(=0)NH 2 , -SO 2 NH 2 , -C(=NH)NH 2 , and -N0 2 , preferably containing one or two substituents selected from halogen, -OH, alkoxy, -NH 2 , trifluoromethyl, -N(CH 3 ) 2 , and -C(=0)OH, more preferably selected from halogen, alkoxy and -OH. Examples of substituted alkyls include, but are not limited to, 2,2-difluoropropyl, 2-carboxycyclopentyl, and 3-chloropropyl.

As used herein, the term "heteroalkyl" by itself or in combination with another term means, unless otherwise stated, a stable straight or branched chain alkyl group consisting of the stated number of carbon atoms and one or two heteroatoms selected from the group consisting of O, N, and S, and wherein the nitrogen and sulfur atoms may be optionally oxidized and the nitrogen heteroatom may be optionally quaternized. The heteroatom(s) may be placed at any position of the heteroalkyl group, including between the rest of the heteroalkyl group and the fragment to which it is attached, as well as attached to the most distal carbon atom in the heteroalkyl group. Examples include: -0-CH 2 -CH 2 -CH 3 , - CH 2 -CH 2 -CH 2 -OH, -CH 2 -CH 2 -NH-CH 3 , -CH 2 -S-CH 2 -CH 3 , and -CH 2 CH 2 -S(=0)-CH 3 . Up to two heteroatoms may be consecutive, such as, for example, -CH 2 -NH-OCH 3 , or -CH 2 -CH 2 - SS-CH 3 .

As used herein, the term "alkoxy" employed alone or in combination with other terms means, unless otherwise stated, an alkyl group having the designated number of carbon atoms, as defined above, connected to the rest of the molecule via an oxygen atom, such as, for example, methoxy, ethoxy, 1-propoxy, 2-propoxy (isopropoxy) and the higher homologs and isomers. Preferred are (Ci-C 3 ) alkoxy, particularly ethoxy and methoxy.

As used herein, the term "halo" or "halogen" alone or as part of another substituent means, unless otherwise stated, a fluorine, chlorine, bromine, or iodine atom, preferably, fluorine, chlorine, or bromine, more preferably, fluorine or chlorine.

As used herein, the term "cycloalkyl" refers to a mono cyclic or poly cyclic non-aromatic radical, wherein each of the atoms forming the ring (i.e. skeletal atoms) is a carbon atom. In certain embodiments, the cycloalkyl group is saturated or partially unsaturated. In other embodiments, the cycloalkyl group is fused with an aromatic ring. Cycloalkyl groups include groups having from 3 to 10 ring atoms. Illustrative examples of cycloalkyl groups include, but are not limited to, the following moieties:

Monocyclic cycloalkyls include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Dicyclic cycloalkyls include, but are not limited to, tetrahydronaphthyl, indanyl, and tetrahydropentalene.

Poly cyclic cycloalkyls include adamantine and norbornane. The term cycloalkyl includes "unsaturated nonaromatic carbocyclyl" or "nonaromatic unsaturated carbocyclyl" groups, both of which refer to a nonaromatic carbocycle as defined herein, which contains at least one carbon-carbon double bond or one carbon-carbon triple bond.

As used herein, the term "heterocycloalkyl" or "heterocyclyl" refers to a heteroalicyclic group containing one to four ring heteroatoms each selected from O, S, and N. In certain embodiments, each heterocycloalkyl group has from 4 to 10 atoms in its ring system, with the proviso that the ring of said group does not contain two adjacent O or S atoms. In other embodiments, the heterocycloalkyl group is fused with an aromatic ring. In certain embodiments, the nitrogen and sulfur heteroatoms may be optionally oxidized, and the nitrogen atom may be optionally quaternized. The heterocyclic system may be attached, unless otherwise stated, at any heteroatom or carbon atom that affords a stable structure. A heterocycle may be aromatic or non-aromatic in nature. In certain embodiments, the heterocycle is a heteroaryl.

An example of a 3-membered heterocycloalkyl group includes, and is not limited to, aziridine. Examples of 4-membered heterocycloalkyl groups include, and are not limited to, azetidine and a beta lactam. Examples of 5-membered heterocycloalkyl groups include, and are not limited to, pyrrolidine, oxazolidine and thiazolidinedione. Examples of 6-membered heterocycloalkyl groups include, and are not limited to, piperidine, morpholine and piperazine. Other non-limiting examples of heterocycloalkyl groups are:

Examples of non-aromatic heterocycles include monocyclic groups such as aziridine, oxirane, thiirane, azetidine, oxetane, thietane, pyrrolidine, pyrroline, pyrazolidine, imidazoline, dioxolane, sulfolane, 2,3-dihydrofuran, 2,5-dihydrofuran, tetrahydrofuran, thiophane, piperidine, 1 ,2,3,6-tetrahydropyridine, 1 ,4-dihydropyridine, piperazine, morpholine, thiomorpholine, pyran, 2,3-dihydropyran, tetrahydropyran, 1,4-dioxane, 1,3-dioxane, homopiperazine, homopiperidine, 1,3-dioxepane, 4,7-dihydro-l,3-dioxepin, and hexamethyleneoxide.

As used herein, the term "aromatic" refers to a carbocycle or heterocycle with one or more polyunsaturated rings and having aromatic character, i. e. , having (4n + 2) delocalized π (pi) electrons, where n is an integer.

As used herein, the term "aryl," employed alone or in combination with other terms, means, unless otherwise stated, a carbocyclic aromatic system containing one or more rings (typically one, two or three rings), wherein such rings may be attached together in a pendent manner, such as a biphenyl, or may be fused, such as naphthalene. Examples of aryl groups include phenyl, anthracyl, and naphthyl. Preferred examples are phenyl and naphthyl, most preferred is phenyl.

As used herein, the term "aryl-(Ci-C3)alkyl" means a functional group wherein a one- to three-carbon alkylene chain is attached to an aryl group, e.g. , -CH 2 CH 2 - phenyl. Preferred is aryl-CH 2 - and aryl-CH(CH 3 )-. The term "substituted aryl-(Ci-C 3 )alkyl" means an aryl-(Ci-C3)alkyl functional group in which the aryl group is substituted. Preferred is substituted aryl(CH 2 )-. Similarly, the term "heteroaryl-(Ci-C3)alkyl" means a functional group wherein a one to three carbon alkylene chain is attached to a heteroaryl group, e.g., - CH 2 CH 2 -pyridyl. Preferred is heteroaryl-(CH 2 )-. The term "substituted heteroaryl-(Ci- C3)alkyl" means a heteroaryl-(Ci-C3)alkyl functional group in which the heteroaryl group is substituted. Preferred is substituted heteroaryl-(CH 2 )-.

As used herein, the term "heteroaryl" or "heteroaromatic" refers to a heterocycle having aromatic character. A poly cyclic heteroaryl may include one or more rings that are partially saturated. Examples include the following moieties:

Examples of heteroaryl groups also include pyridyl, pyrazinyl, pyrimidinyl (particularly 2- and 4-pyrimidinyl), pyridazinyl, thienyl, furyl, pyrrolyl (particularly 2- pyrrolyl), imidazolyl, thiazolyl, oxazolyl, pyrazolyl (particularly 3- and 5-pyrazolyl), isothiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,3,4-triazolyl, tetrazolyl, 1,2,3-thiadiazolyl, 1,2,3-oxadiazolyl, 1,3,4-thiadiazolyl and 1,3,4-oxadiazolyl.

Examples of poly cyclic heterocycles and heteroaryls include indolyl

(particularly 3-, 4-, 5-, 6- and 7-indolyl), indolinyl, quinolyl, tetrahydroquinolyl, isoquinolyl (particularly 1- and 5-isoquinolyl), 1,2,3,4-tetrahydroisoquinolyl, cinnolinyl, quinoxalinyl (particularly 2- and 5 -quinoxalinyl), quinazolinyl, phthalazinyl, 1,8-naphthyridinyl, 1,4- benzodioxanyl, coumarin, dihydrocoumarin, 1,5-naphthyridinyl, benzofuryl (particularly 3-, 4-, 5-, 6- and 7-benzofuryl), 2,3-dihydrobenzofuryl, 1,2-benzisoxazolyl, benzothienyl (particularly 3-, 4-, 5-, 6-, and 7-benzothienyl), benzoxazolyl, benzothiazolyl (particularly 2- benzothiazolyl and 5-benzothiazolyl), purinyl, benzimidazolyl (particularly 2- benzimidazolyl), benzotriazolyl, thioxanthinyl, carbazolyl, carbolinyl, acridinyl,

pyrrolizidinyl, and quinolizidinyl.

As used herein, the term "substituted" means that an atom or group of atoms has replaced hydrogen as the substituent attached to another group. The term "substituted" further refers to any level of substitution, namely mono-, di-, tri-, tetra-, or penta-substitution, where such substitution is permitted. The substituents are independently selected, and substitution may be at any chemically accessible position. In certain embodiments, the substituents vary in number between one and four. In other embodiments, the substituents vary in number between one and three. In yet other embodiments, the substituents vary in number between one and two.

As used herein, the term "optionally substituted" means that the referenced group may be substituted or unsubstituted. In certain embodiments, the referenced group is optionally substituted with zero substituents, i. e. , the referenced group is unsubstituted. In other embodiments, the referenced group is optionally substituted with one or more additional group(s) individually and independently selected from groups described herein.

In certain embodiments, the substituents are independently selected from the group consisting of oxo, halogen, -CN, -NH 2 , -OH, -NH(CH 3 ), -N(CH 3 ) 2 , alkyl (including straight chain, branched and/or unsaturated alkyl), substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl, fluoro alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted alkoxy, fluoroalkoxy, -S-alkyl, S(=0) 2 alkyl, - C(=0)NH[substituted or unsubstituted alkyl, or substituted or unsubstituted phenyl], - C(=0)N[H or alkyl] 2 , -OC(=0)N[substituted or unsubstituted alkyl] 2 , - NHC(=0)NH[substituted or unsubstituted alkyl, or substituted or unsubstituted phenyl], - NHC(=0)alkyl, -N[substituted or unsubstituted alkyl] C(=0) [substituted or unsubstituted alkyl], -NHC(=0)[substituted or unsubstituted alkyl], -C(OH)[substituted or unsubstituted alkyl] 2 , and -C(NH 2 )[substituted or unsubstituted alkyl] 2 . In other embodiments, by way of example, an optional substituent is selected from oxo, fluorine, chlorine, bromine, iodine, - CN, -NH 2 , -OH, -NH(CH 3 ), -N(CH 3 ) 2 , -CH 3 , -CH 2 CH 3 , -CH(CH 3 ) 2 , -CF 3 , -CH 2 CF 3 , -OCH 3 , - OCH 2 CH 3 , -OCH(CH 3 ) 2 , -OCF 3 , - OCH 2 CF 3 , -S(=0) 2 -CH 3 , -C(=0)NH 2 , -C(=0)-NHCH 3 , - NHC(=0)NHCH 3 , -C(=0)CH 3 , and -C(=0)OH. In yet other embodiments, the substituents are independently selected from the group consisting of \ .e alkyl, -OH, Ci-6 alkoxy, halo, amino, acetamido, oxo and nitro. In yet other embodiments, the substituents are

independently selected from the group consisting of \ .e alkyl, Ci-6 alkoxy, halo, acetamido, and nitro. As used herein, where a substituent is an alkyl or alkoxy group, the carbon chain may be branched, straight or cyclic, with straight being preferred.

Throughout this disclosure, various aspects of the invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range and, when appropriate, partial integers of the numerical values within ranges. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range.

Disclosure

In one aspect, the present invention provides a novel class of metal-containing ionic liquids (MCILs) of formula (I):

[M(L) 3 ]XT (I), wherein

M is Co 2+ or Fe 2+ ; X " and Y " are each independently a monovalent anion, and are independently selected from a group consisting of bistrifluoromethylsulphonylamide (Tf 2 N " ), Br " , Γ, trifluoromethylsulphonate (CF 3 SO 3 ), CI " , hexafluorophosphate (PF 6 " ),

tetrafiuoroborate (BF 4 " ), benzenesulfonate (C 6 H 5 SO 3 ), alkanesulfonate (C n FL n+ iSC ) wherein n is an integer ranging from 1 to 24, and amino acid anions; and each L is a ligand and is independently selected from the group consisting of optionally substituted L-histidine methyl ester dihydrochloride (HisCH 3 ), optionally substituted imidazole, optionally substituted L-histidine, and optionally substituted L-histidine hydrochloride monohydrate.

In certain embodiments, X " and Y " are the same. In one embodiment, X " are Y " areTf 2 N " . In other embodiments, M is Co 2+ . In yet other embodiments, at least one L is imidazole. In yet other embodiments, at least two Ls are HisCF . In yet other embodiments, the MCIL has the formula: [Co n (His 2 CH3)2lm] [Tf 2 N]2.

The MCILs of the invention are liquid at room temperature and have not only the desired materials properties of an ionic liquid but also facile processibility and affinity to be impregnated into other materials, which is valuable for some membrane fabrication and O 2 /N 2 separation applications. As demonstrated herein, the MCILs, in their neat state, reversibly bind to 0 2 . In certain embodiments, the MCILs are used without a solvent for O 2 sorption.

In another aspect, the invention includes a composition comprises at least one MCIL of formula (I). In certain embodiments, the composition further comprises a supporting porous material including at least one selected from the group consisting of polymers, metals, and ceramics. In other embodiments, the supporting material is at least one porous polymer selected from the group consisting of consisting of polyethylene (including high-molecular-weight and ultra-high-molecular-weight polyethylene), polyacrylonitrile (PAN), polyacrylonitrile-co-polyacrylate, polyacrylonitrile-co-polymethylacrylate, polysulfone (PSf), Nylon-6,6, poly(vinylidene difiuoride), polycarbonate, polyacrylonitrile (PAN), poly ether ether ketone (PEEK), polyvinylidene fluoride (PVDF),

polytetrafiuoroethylene (PTFE), polypropylene, polysulfone (PSF), poly ether sulfone (PES), and mixtures thereof.

In certain embodiments, the weight percentage of the MCIL of formula (I) in the composition is in the range of about 1% to about 90%, or in the range of about 1% to about 80%. In other embodiments, the percentage of a MCIL in the composition is in the range of about 2% to 38%, or in the range of about 3% to 35%, or in the range of about 4% to 33%, or in the range of about 5% to 30%, or in the range of about 5% to 25%. In yet other embodiments, the percentage of the MCIL in the composition is about 5%; in yet other embodiments, the percentage of the MCIL in the composition is about 10%; in yet other embodiments, the percentage of a MCIL in the composition is about 15%; in yet other embodiments, the percentage of a MCIL in the composition is about 20%.

In certain embodiments, the weight ratio of the MCIL over the porous polymer in the composition is in the range of about 0.1 to 5. In other embodiments, the weight ratio of the MCIL over the porous polymer in the composition is about 0.1 to 1. In yet other embodiments, the weight ratio of the MCIL over the porous polymer in the composition is about 1 to 2. In yet other embodiments, the weight ratio of the MCIL over the porous polymer in the composition is about 2 to 3. In yet other embodiments, the weight ratio of the MCIL over the porous polymer in the composition is about 3 to 4. In yet other embodiments, the weight ratio of the MCIL over the porous polymer in the composition is about 0.57, about 0.94, about 1.1, or about 1.4.

In certain embodiments, the porous support polymer is selected so that the diameter of the pores is less than about 10 microns. In other embodiments, the support is microporous or ultraporous. In yet other embodiments, the support has a pore size ranging from 0.005 micron to 10 micron, ranging from 0.01 micron to 0.1 micron, ranging from 0.1 micron to 10 microns, ranging from 0.5 micron to 5 microns, ranging from 0.5 micron to 1 micron, or less than about 0.1 micron. The characteristic pore size of the membrane may depend on the method used to measure the pore size. Methods used in the art to determine the pore size of membranes include scanning electron microscopy analysis, capillary flow porometry analysis (which gives a mean flow pore size), measurement of the bubble pressure (which gives the largest flow pore size), and porosimetry. In certain embodiments, the porous support polymer gives physical strength to the composite structure. The support should also be thermally stable over approximately the same temperature range as the MCIL to be used. In certain embodiments, the porous support polymer is in a form of membrane. Once the membrane is impregnated with the MCIL(s), it can be used to separate O 2 from other gases. In other embodiments, the porous support polymer is in a form of microparticles or nanoparticles or a mixture thereof.

Synthesis

The invention includes a method of preparing a MCIL of formula (I). A non- limiting example of the method is illustrated in Scheme 1. A Co(II) salt is reacted with the methyl ester of histidme, imidazole and lithium bistrifluoromethylsulphonylamide to generate a compound of the invention.

2 M , H

Co !! {COO) 2 (H 2 0) 4 [Co 2 iH!sCH 3 )4im]IT½ j4

Methods

The invention also includes a method of preparing a supported ionic liquid membrane (SILM) using the compounds of the invention, as illustrated in FIG. 6. Such membrane can be used to reversibly separate O 2 from other gases.

In certain embodiments, the compounds disclosed in present invention reversibly bind O 2 and have a relatively low solubility for N 2 . Accordingly, the compositions can be used to separate O 2 from other light gases. To that end, a mixture of air comprising O 2 is forced to pass through a membrane comprising a compound of the invention from a feed side to a permeate side. As a result of the membrane's capability of binding O 2 , the air in the permeate side has less O 2 than that in the feed side. After several repeated pass-throughs, the O2 will be substantially separated from the original air mixture. In certain embodiments, the compounds of the invention can reversibly bind O2, as shown in FIG. 2. This reversibility can be used to make OEA, which has a widespread application in industrial and medical fields. In other embodiments, the reversibility of O2 binding by the compounds of the invention does not decrease over repeated sorption and desorption cycles.

In certain embodiments, the method of making OEA comprises providing a membrane comprising a compound of the invention, wherein the membrane has a feed side and a permeate side. In other embodiments, the method further comprises contacting a mixture of air comprising O2 with the feed side of the membrane. In yet other embodiments, the method further comprises applying a pressure difference across the membrane, whereby at least a portion of the O2 is reversibly bound to the compound of the invention within the membrane. In yet other embodiments, the method further comprises releasing the O2 dissolved in the membrane on the permeate side to achieve OEA.

In another aspect, the compounds of the invention bind to O2, allowing for the preparation of NEA.

In certain embodiments, the method of making NEA comprises providing a membrane comprising a compound of the invention, wherein the membrane has a feed side and a permeate side. In other embodiments, the method further comprises contacting a mixture of air with the feed side of the membrane. In yet other embodiments, the method further comprises applying a pressure difference across the membrane, whereby at least a portion of the O2 is bound to the compound of the invention within the membrane. In yet other embodiments, the method further comprises collecting the air at the permeate side. Due to the oxygen-binding ability of the composition, the collected air has a higher weight percentage of N 2 than the air prior to passing the membrane. In yet other embodiments, the method further comprises passing the collected air one or more times though the same membrane or a new membrane to achieve higher weight percentage of N 2 .

Every formulation or combination of components described or exemplified can be used to practice the invention, unless otherwise stated. Specific names of compounds are intended to be exemplary, as it is known that one of ordinary skill in the art can name the same compounds differently. When a compound is described herein such that a particular isomer or enantiomer of the compound is not specified, for example, in a formula or in a chemical name, that description is intended to include each isomers and enantiomer of the compound described individual or in any combination. Although the description herein contains many embodiments, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred

embodiments of the invention.

When a group of materials, compositions, components or compounds is disclosed herein, it is understood that all individual members of those groups and all subgroups thereof are disclosed separately. When a Markush group or other grouping is used herein, all individual members of the group and all combinations and sub-combinations possible of the group are intended to be individually included in the disclosure.

Whenever a range is given in the specification, for example, a temperature range, a time range, or a composition range, all intermediate ranges and sub-ranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. Moreover, all values that fall within these ranges, as well as the upper or lower limits of a range of values, are also contemplated by the present application.

It will be obvious to one of ordinary skill in the art that the invention can be performed by modifying or changing, within a wide and equivalent range, the conditions, formulations and other parameters disclosed herein without affecting the scope of the invention or any specific embodiment thereof, and that such modifications or changes are intended to be encompassed within the scope of the appended claims.

The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations that are not specifically disclosed herein.

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures, embodiments, claims, and examples described herein. Such equivalents were considered to be within the scope of this invention and covered by the claims appended hereto. For example, it should be understood, that modifications in reaction conditions, including but not limited to reaction times, reaction size/volume, and experimental reagents, such as solvents, catalysts, pressures, atmospheric conditions (e.g. , nitrogen gas atmosphere) and reducing/oxidizing agents, with art-recognized alternatives and using no more than routine experimentation, are within the scope of the present application. In general, the terms and phrases used herein have their art- recognized meaning, which can be found by reference to standard texts, journal references and contexts known to those skilled in the art. Any preceding definitions are provided to clarify their specific use in the context of the invention.

The following examples further illustrate aspects of the present invention. However, they are in no way a limitation of the teachings or disclosure of the present invention as set forth herein.

EXAMPLES

The invention is now described with reference to the following Examples. These Examples are provided for the purpose of illustration only, and the invention is not limited to these Examples, but rather encompasses all variations that are evident as a result of the teachings provided herein.

Unless described otherwise, the reagents and equipment used herein was purchased from commercial sources or prepared according to the methods described. Materials and Methods

Cobalt(II) acetate tetrahydrate (≥98.0% purity) and imidazole (Im) (>99% purity) were purchased from the Sigma-Aldrich Chemical Co. L- Histidine methyl ester dihydrochloride (HisCH 3 (HCl) 2 ) (>98.0% purity) was purchased from the Tokyo Chemical Industry Co. Lithium bis(trifluoromethanesulfonyl)imide (Li[Tf 2 N]) (>99% purity) was purchased from the 3M Company. All of the chemicals and other solvents were used as received for synthesis. The hydrophobic PTFE filter support (T020A047A) used to prepare the supported ionic liquid membranes (SILMs) was purchased from the Advantec Co. Elemental analysis of the new metal-containing ionic liquid (MCIL) compound MCIL 1 was performed at Galbraith Laboratories (Knoxville, TN). Differential scanning calorimetry (DSC) was performed with a DSC-6220 instrument (Seiko Instruments, Inc.) at a heating rate of 5 °C/min. Thermogravimetric analysis (TGA) was performed with an EXSTAR TG/DTA 7200 system (Seiko Instruments, Inc.) at a heating rate of 10 °C/min. UV-visible spectroscopy was performed using an Agilent 8453 UV-visible spectroscopy system (Agilent Technologies). Attenuated total reflectance Fourier-transform infrared (ATR- FTIR) spectroscopy was performed with a Nicolet 6700 system (Thermo Scientific).

Scanning electron microscope (SEM) images of the PTFE membranes with and without impregnated MCIL 1 were taken using a JSM-6480LV (JEOL) instrument. Example 1: Synthesis of MCIL 1

Co n (CH 3 COO)2(H 2 0)4, HisCH 3 (HCl) 2 , and Im were mixed in deionized (DI) water at a 1.0/2.1/4.0 molar ratio of Co n (CH 3 COO) 2 (H 2 0)4/HisCH 3 (HCl) 2 /Im in air at room temperature, to form a deep brown color solution. Subsequently, 8 molar equivalents of Li[Tf 2 N] (relative to Co n (CH 3 COO)2(H 2 0)4) were dissolved in DI water, and the resulting aqueous solution was added dropwise to the brown solution. A deep-brown-colored liquid immediately separated out from the aqueous phase. The brown liquid layer was washed with DI water several times, and then dried in vacuo at 80 °C. The product MCIL 1 was obtained as a reddish-purple liquid in 80% yield. The chemical composition of MCIL 1 was

[Co 2 (HisCH 3 ) 4 lm][Tf 2 N]4: Found: C, 23.39.; H, 2.52; N, 12.84%. Calcd. for

C 39 H 48 Co 2 F 24 Ni 8 0 24 S 8 : C, 23.62; H, 2.44; N, 12.71%).

Example 2: Preparation of 1-impregnated SILMs with different MCIL 1 loading levels

FIG. 6 shows the general procedure for fabricating the MCIL 1-impregnated SILMs. The neat MCIL 1 was first dissolved in dry, degassed ethyl acetate to obtain a 30 wt. % solution. When MCIL 1 was dissolved in ethyl acetate, the solution color turned into brown, indicating its 0 2 -bound state. The porous Advantec T020A047A PTFE support was soaked in this solution for several minutes and then removed from the solution. The excess MCIL 1 was wiped off from the support, and the resulting SILM was dried at 80 °C under vacuum. At this drying procedure, the color of MCIL 1-impregnated SILM changed from brown to reddish-purple; this color change indicates desorption of 0 2 to form pristine MCIL 1

Example 3: O2/ 2 sorption behavior of 1-impregnated SILMs

Each SILM with a different loading of MCIL 1 was placed into the sample chamber. Prior to the measurement, the sample was degassed under vacuum at 60 °C for 1 h and then cooled to 25 °C. The sample chamber was then filled with ca. 12.5 psi (0.9 bar) of each pure gas, and the sorption amount of each gas was measured over 2 h. The reversibility of 0 2 sorption in the SILMs (MCIL loading: 1.1 g compound MCIL 1 / 1 g support) was analyzed as follows: The sorption amount of 0 2 was measured at 25 °C for 30 min by using the adsorption method described above. To desorb 0 2 , the sample chamber was placed under dynamic vacuum (<0.1 torr) at 60 °C for 1 h and then cooled down to 25 °C. This sorption/desorption cycle was repeated five times. FIGs. 7 and 8 show the time-dependent O2/N2 sorption amounts for SILMs with different loadings of MCIL 1. In the case of the blank PTFE support, a rapid increase in sorption amount of both O2 and N 2 was observed, typical for the physisorption of gases in porous solid materials. However, the contribution of support physisorption was suppressed by the much higher O2 uptake from the included MCIL. Thus, the chemisorption of O2 due to the added MCIL 1 effectively improves the O2/N2 selectivity. The SEM images revealed that pores in PTFE support were fully filled with the MCIL 1 (FIGs. 9 and 10).

Example 4:

MCIL 1 is a very viscous liquid at room temperature, so it was difficult to directly and accurately measure the amount of O2 and N 2 sorbed by the neat material due to slow adsorption kinetics. Because MCIL 1 has a high affinity to be infused into porous polymer supports, its gas solubility properties were analyzed in SILM form. These SILMs were prepared by impregnating MCIL 1 into a porous PTFE support by solvent casting. The room-temperature sorption (i.e. , gas solubility) values of O2 and N 2 into these membranes were measured as stated above. Table 1 shows the observed room-temperature sorption amounts of O2 and N 2 for several SILMs with different loading levels of MCIL 1. For comparison, the absolute O2 and N 2 sorption amounts of a blank PTFE support (i.e. , no added MCIL 1) were measured using the same method. As can be seen in Table 1, the sorbed amount of O2 and O2/N2 selectivity increases with increasing MCIL 1 loading. The O2/N2 solubility selectivity was found to be as high as (26 ± 8) when the loading of MCIL 1 was 1.4 g MCIL 1/ 1 g support). The time-dependent sorption of O2 and N 2 for these SILMs and the blank PTFE support are presented in FIGs. 7-8).

Table 1. Room-temperature O2 and N 2 sorption amounts and O2/N2 sorption selectivity values for MCIL 1-impregnated SILMs with different MCIL loadings. 3

'The sorption amount was measured by dosing approx. 0.9 bar of each gas at 25 °C for 2 h. The absorbed 0 2 in neat MCIL 1 (and MCIL 1-loaded SILMs) can be removed by moderate heating (60 °C) of the samples in vacuo, producing an associated color change from red-brown (the (Vbound state) to light red (the neat material) (FIG. 1). UV-vis spectroscopy of neat MCIL 1 before and after exposure to air for 2 h (FIG. 11) shows an increase in absorption around 450 nm. This behavior is consistent with the observation that Co 11 complexes that undergo chemisorption of O 2 via μ-peroxo bridge formation (Funasako, et al, Chem. Eur. J. 2012, 18, 119291-1936). ATR-FTIR analysis of neat MCIL 1 before and after air exposure was also undertaken, but no distinct change was observed within the range analyzed (FIG. 12).

The reversibility of 0 2 sorption in the MCIL 1-impregnated SILMs (MCIL loading: 1.1 g MCIL l/(g support)) was analyzed over multiple, successive O 2 uptake (ambient temperature) and release (heating in vacuo at 60 °C) cycles in which the samples were loaded up to approximately 80% of their equilibrium capacity for the sake of reasonable testing times (FIG. 2). The O 2 sorption and desorption behavior remained essentially constant over 5 test cycles, which is comparable to that of a recently reported (^selective Co n -based MOF (Southon, et al, J. Am. Chem. Soc. 2011, 133, 10885-10891). Since our new 0 2 -selective sorbent is a non-volatile, liquid-phase material that can be easily processed and blended into other materials to alter morphology, it has certain obvious advantages over crystalline MOFs and other solid-state sorbents, especially when it comes to forming membrane films.

The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. While the invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope used in the practice of the invention. The appended claims are intended to be construed to include all such embodiments and equivalent variations.