Pillararene and use of said pillararene to remove perfluorinated acid from an aqueous stream

Abstract

The invention relates to a pillararene, a solid support, a composition, a method for removing perfluorinated acid from an aqueous stream, and use of said pillararene. The pillararene comprises n monomers individually selected from formula (I), or a stereoisomer, a tautomer, a racemic, a 5 hydrate, a N-oxide or solvate thereof.

Description

[0001]PILLARARENE AND USE OF SAID PILLARARENE TO REMOVE PERFLUORINATED ACID FROM AN AQUEOUS STREAM The present invention relates to a pillararene, a solid support, a composition, a method for removing perfluorinated acid from an aqueous stream, and use of said pillararene. Per- and polyfluoroalkyl substances (PFAS) are broadly used chemicals for a wide range of consumer and industrial applications, such as in stain-repellent sprays, non-stick pans, firefighting foams and food paper coatings. However, the extremely high stability of these materials also turns out to be one of their drawbacks, e.g. leading to increasing water pollution. Dangerous contamination levels of soils and surface waters with PFAS have already reached many parts of the world, frequently exceeding the US Environmental Protection Agency-advisory limit for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) (70 ng L-1) by several orders of magnitude. Toxicity research has demonstrated that this will cause developmental toxicity, immune function disorder, immunotoxicity, and a range of chronic diseases. This motivates research that can lead to an improved understanding of how to remove PFOS and PFAS from water. In the past decades, many efforts have been made to develop materials for absorbing PFAS, such as activated carbon, cyclodextrin-based polymers, calixarenes, covalent organic frameworks (COFs), metal organic frameworks (MOFs), and porous aromatic frameworks (PAFs). COFs, MOFs and PAFs represent advanced porous materials that use defined channel structures and tailored binding sites to absorb PFAS. However, the binding site can suffer from competitive binding with other organic co-contaminants or natural organic matter, which is detrimental for practical applications. Supramolecular host-guest interactions represent a promising alternative to porous materials approach to absorb PFAS. PFAS exhibit unique physical properties that are neither hydrophilic nor oleophilic, but fluorophilic, which facilitates aggregation of fluorinated compounds with themselves or other fluorinated compounds. This property was used to improve binding in supramolecular host-guest complexes with PFAS. For example, a β-CD polymer modified with perfluoroarene groups demonstrates a high PFOA affinity (K = 7 × 104M-1), which turned out to be ca.100× times higher than for similar non-perfluorinated cyclodextrines. Calix[5]arenes bearing 5 guanidinium groups form a 1:1 complex with a binding constant of 4.8 × 106M-1. Among all the reported host-guest complexes with PFOA / PFOS, the host-guest ratio always falls within 1:1 - 2:1 ratio. While such host-guest ratios and complexity of host structures limit the absorbing properties of such materials, their excellent sensitivity and selectivity were found to be useful for PFAS detection. Therefore, there is a need for efficient and effective capture of perfluorinated acids such as PFAS, PFOA, PFOS. The present invention aims at obviating or at least reducing the aforementioned problems and to enable efficient and effective capturing of perfluorinated acids such as PFAS, PFOA, PFOS. This objective is achieved with a pillararene comprising n monomers individually selected from formula (I), or a stereoisomer, a tautomer, a racemic, a hydrate, a N-oxide or solvate thereof, wherein: n is an integer in the range of 5 to 8; o is an integer in the range of 1 to 3; p is an integer in the range of 1 to 3; R1is a -C1 to C4 alkyl-, wherein said -C1 to C4 alkyl- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, -SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, - C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen; R2is selected from the group of C, N, or S; R3is selected from the group of C, N, or S; R4is one or more independently selected from the group of hydrogen, -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+, -NR10, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, or R4forms together with R6a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr, wherein said -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen; R5is selected from the group of -O-, -N-, -C-, or a direct bond; R6is absent when R2is selected from N or S, and wherein R6is hydrogen, -C1to C4alkyl-, - C2to C4alkene-, or -C2to C4alkyne- when R2is C, or R6forms together with R4a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr; R7is one or more independently selected from the group of hydrogen, -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne-, -N(R10)2+, -NR10, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, or R7forms together with R9a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr, wherein said -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen; R8is selected from the group of -O-, -N-, -C-, or a direct bond; R9is absent when R3is selected from N or S, and wherein R9is hydrogen, -C1to C4alkyl-, - C2to C4alkene-, or -C2to C4alkyne- when R3is C, or R9forms together with R7a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr; wherein each occurrence of R10is independently selected from the group of hydrogen, -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, -C7 to C12 alkyl, -C7 to C12 alkene, -C7 to C12 alkyne, wherein said -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, -C7 to C12 alkyl, -C7 to C12 alkene, -C7 to C12 alkyne are optionally substituted with a halogen, and wherein at least 1 of the total occurrences of R4and R7being independently selected from - C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N- alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, wherein said -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, -SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen. It is noted that a pillararene is a macrocycle comprising monomeric units, such as the ones herein defined, linked in the para position by alkyl, alkene, alkyne bridges. Formula (VI) provides a schematic overview a pillararene. It is also noted that in embodiment wherein R5and / or R8represents -C- it may include multiple covalent bonds to R4and / or R7respectively. In other words, it includes groups such as - CHR4R4when R5is covalently bound to two R4groups different from hydrogen; -CHR7R7when R8is covalently bound to two R7groups different from hydrogen; CR4R4R4when R5is covalently bound to three R4groups different from hydrogen; -CR7R7R7when R8is covalently bound to three R7groups different from hydrogen. It is also noted that the total occurrences of R4and R7being hydrogen refers to the occurrence of R4and R7not being hydrogen in the pillararene according to the invention. In other words, wherein R4and / or R7are independently selected from -C1to C18alkyl-, -C2to C18alkene-, - C2to C18alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, wherein said -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne- is optionally substituted with one or more substitute selected from the group of - N(R10)2, -OR10, -SO2H, -SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH- NH2, -C≡N, -SH, halogen. When describing the compounds of the invention, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise: The term ‘alkyl’ by itself or as part of another substituent refers to a fully saturated hydrocarbon of Formula CxH2x+1 wherein x is an integer greater than or equal to 1. Generally, alkyl groups of this invention comprise from 1 to 18 carbon atoms. For example, R1may be a -C1 to C4 alkyl-, R4may be a -C1 to C18 alkyl-, and / or R7may be a -C1 to C18 alkyl-. Alkyl groups may be linear or branched and may be substituted as indicated herein. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. Thus, for example, -C1 to C4 alkyl- means an alkyl of one to four carbon atoms. Examples of alkyl groups are methyl, ethyl, n-propyl, i-propyl, butyl, and its isomers (e.g. n-butyl, i-butyl and t-butyl); pentyl and its isomers, hexyl and its isomers, heptyl and its isomers, octyl and its isomers, nonyl and its isomers; decyl and its isomers. For example, -C1 to C6 alkyl- includes all linear, branched, or cyclic alkyl groups with between 1 and 6 carbon atoms, and thus includes methyl, ethyl, n-propyl, i-propyl, butyl and its isomers (e.g. n-butyl, i-butyl and t- butyl); pentyl and its isomers, hexyl and its isomers, cyclopentyl, 2-, 3-, or 4-methylcyclopentyl, cyclopentylmethylene, and cyclohexyl. The term ‘alkenyl’ or ‘alkene’, as used herein, unless otherwise indicated, means straight- chain, cyclic, or branched-chain hydrocarbon radicals containing at least one carbon-carbon double bond. Examples of alkenyl radicals include ethenyl, E- and Z-propenyl, isopropenyl, E- and Z- butenyl, E- and Z-isobutenyl, E- and Z-pentenyl, E- and Z-hexenyl, E,E-, E,Z-, Z,E-, Z,Z- hexadienyl, and the like. An optionally substituted alkenyl refers to an alkenyl having optionally one or more substituents (for example 1, 2, 3 or 4). The term ‘alkynyl’, as used herein, unless otherwise indicated, means straight-chain or branched-chain hydrocarbon radicals containing at least one carbon-carbon triple bond. Examples of alkynyl radicals include ethynyl, E- and Z-propynyl, isopropynyl, E- and Z-butynyl, E- and Z- isobutynyl, E- and Z-pentynyl, E, Z-hexynyl, and the like. An optionally substituted alkynyl refers to an alkynyl having optionally one or more substituents (for example 1, 2, 3 or 4). The term ‘optionally substituted alkyl’, ‘optionally substituted alkene’, or ‘optionally substituted alkyne’ refers to an alkyl group, an alkene group, or alkyne group respectively comprising a carbon chain which is optionally substituted with one or more substituents (for example 1 to 4 substituents, for example 1, 2, 3, or 4 substituents or 1 to 2 substituents) at any available point of attachment. Non-limiting examples of such substituents include a halogen, hydroxyl (-OH), carbonyl (-CO, wherein the carbon of the carbonyl is preferably part of the carbon chain), nitro (-NO2), amino (-NH2), oxime (-C=N−OH, wherein the carbon of the oxime is preferably part of the carbon chain), imino (-C=NH, wherein the carbon of the imino is preferably part of the carbon chain), azido (-N=N+=N−), hydrazine (-NH-NH2), cyano (-C≡N), aryl (Ar), heteroaryl (HetAr), cycloalkyl, acyl, alkylamino, alkoxy, thiol (-SH), alkylthio, carboxylic acid (- COOH), acylamino, esters (-COO, wherein the carbon of the ester is preferably part of the carbon chain), carbamate, thioamido, urea, sullfonamido and the like. Where alkyl groups as defined are divalent, i.e., with two single bonds for attachment to two other groups, they are termed ‘alkylene’ groups. Non-limiting examples of alkylene groups includes methylene, ethylene, methylmethylene, trimethylene, propylene, tetramethylene, ethylethylene, 1,2-dimethylethylene, pentamethylene and hexamethylene. Similarly, where alkenyl groups as defined above and alkynyl groups as defined above, respectively, are divalent radicals having single bonds for attachment to two other groups, they are termed ‘alkenylene’ and ‘alkynylene’ respectively. Generally, alkylene groups of this invention preferably comprise the same number of carbon atoms as their alkyl counterparts. Where an alkylene or cycloalkylene biradical is present, connectivity to the molecular structure of which it forms part may be through a common carbon atom or different carbon atom, preferably a common carbon atom. To illustrate this, a C3 alkylene group may be for example -CH2CH2CH2-, -CH(-CH2CH3)-, or -CH2CH(-CH3)-. The term ‘aryl’ (Ar) as used herein refers to a polyunsaturated, aromatic hydrocarbyl group having a single ring (i.e. phenyl) or multiple aromatic rings fused together (e.g. naphthalene or anthracene) or linked covalently, typically containing 5 to 10 atoms, preferably 5 or 5 atoms; wherein at least one ring is aromatic. The aromatic ring may optionally include one to two additional rings (either cycloalkyl, heterocyclyl, or heteroaryl) fused thereto. Aryl is also intended to include the partially hydrogenated derivatives of the carbocyclic systems enumerated herein. Non-limiting examples of aryl comprise phenyl, biphenylyl, biphenylenyl, 5- or 6-tetralinyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, or 8-azulenyl, 1- or 2-naphthyl, 1-, 2-, or 3-indenyl, 1-, 2-, or 9-anthryl, 1- 2-, 3-, 4-, or 5-acenaphtylenyl, 3-, 4-, or 5-acenaphtenyl, 1-, 2-, 3-, 4-, or 10-phenanthryl, 1- or 2- pentalenyl, 1, 2-, 3-, or 4-fluorenyl, 4- or 5-indanyl, 5-, 6-, 7-, or 8-tetrahydronaphthyl, 1,2,3,4- tetrahydronaphthyl, 1,4-dihydronaphthyl, dibenzo[a,d]cylcoheptenyl, and 1-, 2-, 3-, 4-, or 5- pyrenyl. The aryl ring can optionally be substituted by one or more substituents. An ‘optionally substituted aryl’ refers to an aryl having optionally one or more substituents (for example 1 to 5 substituents, for example 1, 2, 3 or 4) at any available point of attachment. Non-limiting examples of such substituents are selected from halogen, hydroxyl, oxo, nitro, amino, hydrazine, aminocarbonyl, azido, cyano, alkyl, cycloalkyl, alkenyl, alkynyl, cycloalkylalkyl, alkylamino, alkoxy, -SO2-NH2, aryl, heteroaryl, aralkyl, haloalkyl, haloalkoxy, alkoxycarbonyl, alkylaminocarbonyl, heteroarylalkyl, alkylsulfonamide, heterocyclyl, alkylcarbonylaminoalkyl, aryloxy, alkylcarbonyl, acyl, arylcarbonyl, aminocarbonyl, alkylsulfoxide, -SO2Ra, alkylthio, carboxyl, and the like, wherein Rais alkyl or cycloalkyl. Where a carbon atom in an aryl group is replaced with a heteroatom, the resultant ring is referred to herein as a heteroaryl (HetAr) ring. The term ‘heteroaryl’ as used herein by itself or as part of another group refers but is not limited to 4 to 12 carbon-atom aromatic rings, preferably 4 to 5 carbon-atom aromatic rings, or ring systems containing 1 to 3 rings which are fused together or linked covalently, typically containing 5 to 8 atoms; at least one of which is aromatic in which one or more carbon atoms in one or more of these rings can be replaced by oxygen, nitrogen or sulphur atoms where the nitrogen and sulphur heteroatoms may optionally be oxidized and the nitrogen heteroatoms may optionally be quaternized. Such rings may be fused to an aryl, cycloalkyl, heteroaryl or heterocyclyl ring. Non- limiting examples of such heteroaryl, include: pyrrolyl, furanyl, thiophenyl, pyrazolyl, imidazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, oxadiazolyl, thiadiazolyl, tetrazolyl, oxatriazolyl, thiatriazolyl, pyridinyl, pyrimidyl, pyrazinyl, pyridazinyl, oxazinyl, dioxinyl, thiazinyl, triazinyl, imidazo[2,1-b][1,3]thiazolyl, thieno[3,2-b]furanyl, thieno[3,2-b]thiophenyl, thieno[2,3-d][1,3]thiazolyl, thieno[2,3-d]imidazolyl, tetrazolo[1,5-a]pyridinyl, indolyl, indolizinyl, isoindolyl, benzofuranyl, benzopyranyl, 1(4H)-benzopyranyl, 1(2H)-benzopyranyl, 3,4-dihydro- 1(2H)-benzopyranyl, 3,4-dihydro-1(2H)-benzopyranyl, isobenzofuranyl, benzothiophenyl, isobenzothiophenyl, indazolyl, benzimidazolyl, 1,3-benzoxazolyl, 1,2-benzisoxazolyl, 2,1- benzisoxazolyl, 1,3-benzothiazolyl, 1,2-benzoisothiazolyl, 2,1-benzoisothiazolyl, benzotriazolyl, 1,2,3-benzoxadiazolyl, 2,1,3-benzoxadiazolyl, 1,2,3-benzothiadiazolyl, 2,1,3-benzothiadiazolyl, thienopyridinyl, purinyl, imidazo[1,2-a]pyridinyl, 6-oxo-pyridazin-1(6H)-yl, 2-oxopyridin-1(2H)- yl, 6-oxo-pyridazin-1(6H)-yl, 2-oxopyridin-1(2H)-yl, 1,3-benzodioxolyl, quinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl, quinoxalinyl, 7-azaindolyl, 6-azaindolyl, 5-azaindolyl, 4-azaindolyl. It is noted that a C5-Ar refers to an aryl ring comprising 5 carbon atoms, C6-Ar refers to an aryl ring comprising 6 carbon atoms, C5-HetAr refers to a heteroaryl comprising at least one heteroatom and at most 4 carbons atoms, and C6-HetAr refers to a heteroaryl comprising at least one hetero atom and at most 5 carbon atoms. The term ‘halo’ or ‘halogen’ as a group or part of a group is generic for fluoro, chloro, bromo, or iodo. The term ‘haloalkyl’ alone or in combination, refers to an alkyl having the meaning as defined above wherein one or more hydrogens are replaced with a halogen as defined above. Non- limiting examples of such haloalkyl radicals include chloromethyl, 1-bromoethyl, fluoromethyl, difluoromethyl, trifluoromethyl, 1,1,1-trifluoroethyl, and the like. Whenever the term ‘substituted’ is used in the present invention, it is meant to indicate that one or more hydrogens on the atom indicated in the expression using ‘substituted’ is replaced with a selection from the indicated group, provided that the indicated atom’s normal valency is not exceeded, and that the substitution results in a chemically stable compound, i.e. a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into a therapeutic agent. Where groups may be optionally substituted, such groups may be substituted with once or more, and preferably once, twice, or thrice. Substituents may be selected from as indicated throughout this application. As used herein the terms such as ‘alkyl, alkene, alkyne, or aryl each being optionally substituted with” or “alkyl, alkene, alkyne, or aryl, optionally substituted with” refers to optionally substituted alkyl, optionally substituted alkene, optionally substituted alkyne, and optionally substituted. Whenever used in the present invention the term ‘pillararene of the invention’ or a similar term is meant to include compounds of general Formula I and any subgroup thereof. This term also refers to their derivatives, N-oxides, salts, solvates, hydrates, stereoisomeric forms, racemic mixtures, tautomeric forms, optical isomers, analogues, and esters, as well as their quaternized nitrogen analogues. The N-oxide forms of said compounds are meant to comprise compounds wherein one or several nitrogen atoms are oxidized to the so-called N-oxide. As used in the specification and the appended claims, the singular forms ‘a’, ‘an’, and ‘the’ include plural referents unless the context clearly dictates otherwise. By way of example, ‘a pillararene’ means one pillararene or more than one pillararene. The terms described above and others used in the specification are well understood to those in the art. An advantage of the pillararene according to the invention is that said pillararenes combine electrostatic stabilization and fluorous phase stabilisation of polyfluoroalkyl acids efficiently and effectively. As a result, stable supramolecular complexes may be formed. Therefore, said pillararenes may efficiently and effectively bind polyfluoroalkyl acids. It is noted that polyfluoroalkyl acids include but are not limited to PFAS, PFOS, and PFOA. Yet a further advantage of the pillararene according to the invention is that a host-guest ratio of at least 1:4 is achieved, with an overall binding constant in water of up to 106M-1(M is mol L-1). As a result, said pillararene can efficiently and effectively bind polyfluoroalkyl acids, such as PFAS, PFOS, and PFOA. It was found that the host-guest ratio could go to at least 1:10. This enables an efficient and effective formation of (large) supramolecular complexes, wherein a relatively small amount of the pillararene according to the invention can capture / bond with a large amount of polyfluoroalkyl acids. In addition, the inventors found it surprising that a tight binding between the pillararene and perfluoroalkyl acids with a high stoichiometry was achieved. Thus, the pillararene according to the invention may form a supramolecular complex together with the polyfluoroalkyl acids which are dissolved in an aqueous stream. The formed supramolecular complexes may for example precipitate from the aqueous stream and / or bound to a solid support such that said polyfluoroalkyl acids may be efficiently and effectively remove polyfluoroalkyl acids from an aqueous stream. As a result, a long-experienced problem and long felt need for removing said (hazardous) polyfluoroalkyl acids from aqueous streams is resolved. In fact, the pillararenes according to the invention may be used to remove polyfluoroalkyl acids from aqueous streams such as surface water, industrial waste-water, sludge, and the like. Furthermore, the pillararene according to the invention enables to reduce the polyfluoroalkyl acids concentration to less than 70 ng L-1, even less than 40 ng L-1. Therefore, the treated aqueous stream meets the EPA-advised limit, as reductions as low as 15 ng L-1have been demonstrated. It is noted that EPA refers to Environmental Protection Agency. As mentioned before, one of the biggest challenges of water purification from PFAS is the poor efficiency of absorbent in the presence of natural organic co-contaminants, such as alkyl carboxylic acids, which can compete with PFAS for binding. For example, binding with scavengers. Common organic molecules may interact with the cavity of pillararenes. Therefore, without being bound to theory, there is no (strong) interference of said common organic molecules with the binding of PFAS to the rim. It was found that absorbing PFOA (1 μg L-1) in the presence of 10000-fold excess of its non- fluorinated counterpart – octanoic acid (OA) (10 mg L-1), the concentration of PFOA after purification was in range of 1 ng L-1to 5 ng L-1, much lower than the (desired) safety limit. The residual concentration of OA increased after absorbing purifying 150 mL of solution, while the PFOA residual concentration stayed in a low concentration in range of 1 ng L-1to 5 ng L-1, order of magnitude lower than the safety advisory limit. Yet another advantage of the pillararene according to the invention is that material contaminated with polyfluoroalkyl acids could be efficiently and effectively regenerated. Therefore, material such as for example contaminated agricultural land and / or water basins could be recovered efficiently. As a result, said land and / or water may be used for growing food and / or irrigation. Furthermore, said pillararene according to the invention helps to secure freshwater provisions. It was also found that said pillararene according to the invention enables an upconcentration of polyfluoroalkyl acids by a factor of more than 106. Therefore, an efficient and effective treatment of material contaminated with polyfluoroalkyl acids is achieved. In a preferred embodiment according to the invention, each occurrence of R10is independently selected from the group of hydrogen, -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, wherein said -C1to C6alkyl, -C2to C6alkene, -C2to C6alkyne are optionally substituted with a halogen. In a preferred embodiment according to the invention, R6and / or R9are independently selected from hydrogen and -CH3. It was found that R6and / or R9being independently selected from hydrogen and -CH3 enables sufficient space for forming a pillararene according to the invention and provides an efficient and effective binding of PFAS. Said binding of PFAS is enhanced due to the reduced sterically hindrance within the formed pillararene. In a presently preferred embodiment according to the invention, n may be an integer in the range of 5 to 7. Preferably, wherein n may be an integer of 5 or 6. It was found that the pillararene according to the invention comprising n 5 or 6 were more efficient to synthesize compared to pillararene molecules comprising n is 7. Furthermore, pillararene according to the invention comprising n 5 or 6 were most efficient to make. Said efficiency is due to lower kinetic barriers including entropy of ring closing versus enthalpic stabilization. Therefore, pillararene according to the invention comprising n 5 to 6 are most efficient to make. It was also found that the pillararene according to the invention comprising n 5 to 6 enables an efficient and effective balance between ease of formation and stability of the pillararene and formation of a supramolecular complex comprising polyfluoroalkyl acids. In a further presently preferred embodiment according to the invention, the at least 1 of the total occurrences of R4and R7being independently selected from -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, is at least 5, preferably at least 6, more preferably at least 7, even more preferably at least 10, most preferably at least 12. An advantage of reducing the number of R4and R7being hydrogen and / or increasing the number of R4and R7being independently selected from -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, is that the uptake of, or possibility to bind polyfluoroalkyl acids by a single pillararene is increased and / or more efficient. In a further presently preferred embodiment according to the invention, the pillararene comprises at most three different monomers individually selected from formula (I), or a stereoisomer, a tautomer, a racemic, a hydrate, a N-oxide or solvate thereof. Preferably, the pillararene comprises at most two different monomers individually selected from formula (I), or a stereoisomer, a tautomer, a racemic, a hydrate, a N-oxide or solvate thereof. Most preferably, the pillararene comprises one type of monomers selected from formula (I), or a stereoisomer, a tautomer, a racemic, a hydrate, a N-oxide or solvate thereof. A pillararene comprising different type of monomers according to formula (I) enable to combine characteristics of the different monomers. As a result, the electrostatic stabilisation and fluorous stabilisation could be adapted such that the desired properties are achieved. As a result, specific polyfluoroalkyl acids could be targeted to be captured / bond by the pillararene. An advantage of having one type of monomer in the pillararene is that said pillararenes are easier to make compared to pillararenes comprising different monomers individually selected from formula (I). Therefore, a pillararene according to the invention comprising two different monomers individually selected from formula (I) or one type of monomer selected from formula (I) is more economical to manufacture. In a further presently preferred embodiment according to the invention, formula (I) comprises at least 1 positive charge, preferably at least 2 positive charges. An advantage of formula (I) comprising at least 1 positive charge, preferably 2 positive charges, is that said positive charge enables efficient and effective binding of polyfluoroalkyl acids. Said positive charge enables cooperative binding on the rims of the pillararene. In other words, polyfluoroalkyl acids are negatively charged. So, one component of the interactive forces between polyfluoroalkyl acids and the pillararenes according to the invention, for example amino-pillarenes according to the invention, are electrostatic. For example, the amines on the rim of the (amino-)pillararenes are either permanently positive (e.g. by trimethylation) and / or slightly positive in an aqueous medium of use, due to protonation of the amine. This effects a plus- minus attraction between the pillarene and the polyfluoroalkyl acids. In a further presently preferred embodiment according to the invention, R4and / or R7comprises one or more salt forms of -N(R10)2+-, -N(R10)3+, or -P(R10)3+herein represented by - N(R10)2+X-, -N(R10)3+X-, or -P(R10)3+X-, with X- being the counterion, preferably wherein R4and / or R7comprises at least one -N(R10)3+X-. It was found that R4and / or R7comprises one or more of -N(R10)2+X-, -N(R10)3+X-, or - P(R10)3+X-, preferably wherein R4and / or R7comprises at least one -N(R10)3+X-, enables an efficient and effective binding of polyfluoroalkyl acids. In a preferred embodiment, R4and R7comprises at least one -N(R10)3+X-, wherein R10is hydrogen or -CH3. In a further presently preferred embodiment according to the invention, a counterion X- for each positive charge may be independently selected from the group of hydroxide, sulfate, carbonate, phosphate, fluoride, tosylate, tetrafluoroborate, hexafluorophosphate, acetate, trifluoroacetate, a halogen. Preferably, the counterion for each positive charge may be independently selected from the group of carbonate, sulphate, halogen, more preferably each individual counterion is a carbonate or a halogen. It is noted that each counterion X- is individually selected from the abovementioned group and / or options. Thus, the counterions X- may be individually selected from carbonate or halogen. In a preferred embodiment, the carbonate is HCO3-. In a further presently preferred embodiment according to the invention, the halogen may be Br- and / or Cl-, preferably the halogen is Cl-. Having a halogen or a carbonate, preferably a halogen such as Br- and / or Cl-, as counterion enables an interaction between the pillararene, for example R4and / or R7of the pillararene, which is sufficiently strong to provide a stable pillararene but is less preferred compared to an interaction between the pillararene and polyfluoroalkyl acids. In a further presently preferred embodiment according to the invention, R1may be a -C1 to C3 alkyl-, preferably R1may be a -C1 to C2 alkyl-, more preferably R1may be a -CH2-. It was found that a short carbon chain between two adjacent aryl groups forming a backbone of the pillararene enables efficient and effective formation of the pillararene. Furthermore, said R1provides sufficient space for the polyfluoroalkyl acids to form an interaction with R4and / or R7. Said interaction between the polyfluoroalkyl acids and R4and / or R7specifically occurs when R4and / or R7is not hydrogen. Thus, when at least one of the total occurrences of R4and R7being independently selected from -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+-, - NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester. In a further presently preferred embodiment according to the invention, each occurrence of R10may be selected from the group of hydrogen, -C1 to C5 alkyl, -C2 to C5 alkene, -C2 to C5 alkyne, preferably selected from the group of hydrogen, -C1 to C4 alkyl, -C2 to C4 alkene, -C2 to C4 alkyne, more preferably selected from the group of hydrogen, -C1 to C3 alkyl, -C2 to C3 alkene, -C2 to C3 alkyne, even more preferably selected from the group of hydrogen, -C1to C2alkyl, -C2alkene, -C2alkyne, most preferably selected from the group of hydrogen and -CH3. In a preferred embodiment, R10does not include an -OH. In a further presently preferred embodiment according to the invention, the monomer of formula (I) may be a monomer according to formula (II), (II). It is noted that R4is one or more independently selected from the group of hydrogen, -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N- alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, wherein said -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, -SO3H, -COOH, -OH, -CO, -NO2, - C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen. Furthermore, R7is one or more independently selected from the group of hydrogen, -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, wherein said -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, - OR10, -SO2H, -SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen. A pillararene comprising a monomer according to formula (II) provides sufficient space for linking / binding polyfluoroalkyl acids. In a further presently preferred embodiment according to the invention, said -C1to C4alkyl- of R1is substituted with one or more substituent selected from the group of -N(R10)2, -OR10, - SO2H, -SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen. In a further presently preferred embodiment according to the invention, said -C1 to C18 alkyl- , -C2 to C18 alkene-, -C2 to C18 alkyne- of R4is substituted with one or more substituent selected from the group of -N(R10)2, -N(R10)3+, -OR10, -SO2H, -SO3H, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, - C≡N, -SH, halogen. In a preferred embodiment, at least one R4of the pillararene according to the invention comprises a -C1 to C18 alkyl-, -C2 to C18 alkene-, or -C2 to C18 alkyne- substituted with -N(R10)3+and / or -P(R10)3+, preferably the -C1 to C18 alkyl-, -C2 to C18 alkene-, or -C2 to C18 alkyne- is substituted at the terminal end. In a further presently preferred embodiment according to the invention, said -C1 to C18 alkyl- , -C2 to C18 alkene-, -C2 to C18 alkyne- of R7is substituted with one or more substituent selected from the group of -N(R10)2, -N(R10)3+, -OR10, -SO2H, -SO3H, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, - C≡N, -SH, halogen. In a preferred embodiment, at least one R7of the pillararene according to the invention comprises a -C1to C18alkyl-, -C2to C18alkene-, or -C2to C18alkyne- substituted with -N(R10)3+and / or -P(R10)3+, preferably the -C1to C18alkyl-, -C2to C18alkene-, or -C2to C18alkyne- is substituted at the terminal end. It is noted that the terminal end of the -C1 to C18 alkyl-, -C2 to C18 alkene-, or -C2 to C18 alkyne- in this application refers to the carbon atom furthest away from R5or R8. In a preferred embodiment, n is an integer in the range of 5 to 6; o is an integer in the range of 1 to 3; p is an integer in the range of 1 to 3; R1is a -C1 to C4 alkyl-, wherein said -C1 to C4 alkyl- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, -SO3H, -COOH, halogen; R2is selected from the group of C, N, or S; R3is selected from the group of C, N, or S; R4is one or more independently selected from the group of hydrogen, -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, or R4forms together with R6a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr, wherein said -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, halogen; R5is selected from the group of -O-, -N-, -C-, or a direct bond; R6is absent when R2is selected from N or S, and wherein R6is hydrogen, -C1 to C4 alkyl-, - C2 to C4 alkene-, or -C2 to C4 alkyne when R2is C, or R6forms together with R4a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr; R7is one or more independently selected from the group of hydrogen, -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, or R7forms together with R9a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr, wherein said -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, halogen; R8is selected from the group of -O-, -N-, -C-, or a direct bond; R9is absent when R3is selected from N or S, and wherein R9is hydrogen, -C1to C4alkyl-, - C2to C4alkene-, or -C2to C4alkyne when R3is C, or R9forms together with R7a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr; wherein each occurrence of R10is independently selected from the group of hydrogen, -C1to C6alkyl, -C2to C6alkene, -C2to C6alkyne, wherein said -C1to C6alkyl, -C2to C6alkene, -C2to C6alkyne are optionally substituted with a halogen, and wherein at least 1 of the total occurrences of R4and R7being independently selected from -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N- alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, wherein said -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, -SO3H, -COOH, - OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen. In a further presently preferred embodiment according to the invention, the optional -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, -C7 to C12 alkyl, -C7 to C12 alkene, -C7 to C12 alkyne of R10, preferably the optional -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, -C7 to C8 alkyl, -C7 to C8 alkene, -C7 to C8 alkyne of R10, more preferably the optional -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne of R10, are at least partly substituted with fluor. It was found that the partly substituting R10with fluor increases the fluorous phase stabilisation. In a further presently preferred embodiment according to the invention, the monomer of formula (I) is a monomer according to one or more of formula (III), formula (IV), formula (V), It was found that pillararene comprising one or more of the monomers according to formula (III) to (V) provide both electrostatic stabilisation and fluorous phase stabilisation to create stable supramolecular complex when perfluorinated acid molecules are bonded. The invention also relates to a solid support comprising pillararenes according to the invention and a support agent. The solid support according to the invention provides the same or similar effects and advantages as those described for the pillararene according to the invention. It was found that pillararenes according to the invention could be bound with a wide variety of support agents. For example, the pillararenes according to the invention could be bound to support agent such that the formed solid can be filtered off. In addition, or alternatively, the pillararenes according to the invention could be bound to a membrane, or to support agents (like in a packed back) that can be ‘loaded’ with perfluoroalkyl substances, and after the capacity is reached cleaned up again, etc. An advantage of the solid support according to the invention is that formed supramolecular complexes comprising pillararene and multiple perfluorinated acid molecules could be efficiently and effectively removed. Furthermore, it was found that recovering the pillararene part of the solid support was easier compared to pillararenes of supramolecular complexes which were precipitated. In a presently preferred embodiment, the support agent is one or more selected from the group of silica, plastics, ceramics, glass, metals. It is noted that other (similar) solid supports may also be used. The invention also relates to a composition comprising pillararenes according the invention, or solid support according to the invention, and one or more perfluorinated acid. The composition according to the invention provides the same or similar effects and advantages as those described for the pillararene according to the invention and solid support according to the invention. It is noted that that PFAS refers to perfluoroalkyl substances, PFOS refers to perfluorooctane sulfonic acid, and PFOA refers to perfluorooctanoic acid. In a preferred embodiment according to the invention, the counterion of the pillararene according to the invention is a per- and polyfluoroalkyl substance (PFAS). It was found that said PFAS forms a stable composition according to the invention, wherein the PFAS is enabled to act as counterion.In a presently preferred embodiment according to the invention, the perfluorinated acid may be one or more selected from the group of perfluoroalkyl substances, perfluorooctane sulfonic acid, perfluorooctanoic acid. In a further presently preferred embodiment according to the invention, the stoichiometry between the pillararenes and perfluorinated acid may be at least 1 : 3, preferably at least 1 : 4, more preferably at least 1 : 5, even more preferably at least 1 : 6, even more preferably at least 1 : 8, most preferably at least 1 : 10. An advantage of the composition according to the invention is that an efficient and effective ratio between pillararene and perfluorinated acid is achieved. In fact, 1 mol of pillararene could capture at least 6 mol of perfluorinated acid. A further advantage of the pillararenes is that individual PFAS can cluster, such that several clusters of PFAS molecules can be formed. It is noted that upon attachment onto a surface, the stoichiometry is dictated primarily by only one rim. Upon full coverage, this leads to a 1 : 5 or 1 : 10 ratio if the pillararenes comprise five monomers and depending is said pillararenes are bound to a solid support. In addition, by the creation of a fluorous phase, it was found that the (non-covalent) binding of more than five pillararenes per rim is enhanced. This is achieved by complexing PFAS molecules onto a surface, wherein many of the PFAS molecules closely bound together on a surface. This may then lead to a fluorous phase, another PFAS can readily ‘squeeze in’ (in this case likely upside down, so as to minimize electrostatic repulsion to the other negative charges of already bound PFAS and to maximize the interaction with the water solvent while binding to and / or interacting with the pillararene bound fluorous phase. The invention also relates to a method for removing perfluorinated acid from an aqueous stream comprising contacting the pillararene according to the invention, or solid support according to the invention with an aqueous stream comprising perfluorinated acid. The method for removing perfluorinated acid from an aqueous stream according to the invention provides the same or similar effects and advantages as those described for the pillararene according to the invention, solid support according to the invention, and composition according to the invention. It is noted that the method according to the invention enables to provide the composition according to the invention. In other words, the method may comprise the step of providing the composition according to the invention. In a presently preferred embodiment according to the invention, the method further comprises regenerating the pillararenes. Said regenerating of the pillararnes may be performed by washing the pillararenes comprising perfluorinated molecules with organic solvents, in which electrostatic attraction of perfluorinated molecules to pillararenes is weakened and perfluorinated molecules dissociate from pillararenes to the organic solvents. An advantage of regenerating the pillararenes is that the valuable pillararenes can be used multiple times. It was found that said pillararenes could be used at least ten times before degradation occurred. Said regeneration may be performed by washing the (perfluorinated acid saturated) pillararenes with at least 0.1 g L-1NaCl methanol solution. Then the pillararenes are ready to be re- used again. The regeneration may be performed multiple times. The invention also relates to a use of the pillararene according to the invention, or solid support according to the invention to remove perfluorinated acid from an aqueous stream. The use of the pillararene according to the invention, or solid support according to the invention to remove perfluorinated acid from an aqueous stream provides the same or similar effects and advantages as those described for the pillararene according to the invention, solid support according to the invention, composition according to the invention, and method for removing perfluorinated acid from an aqueous stream according to the invention. The use of said pillararene according to the invention enables to solve a long-lasting problem. Said use enables to remove perfluorinated acids from an aqueous stream, such that an aqueous stream comprising perfluorinated acid in a concentration of at most 70 ng L-1, preferably at most 50 ng L-1, more preferably at most 30 ng L-1. Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which: - Figure 1 shows an X-ray crystal structure of a pillararene according to the invention having PFOA bonded thereto (all C-H bonds; MeOH, H2O solvent molecules; and disordered alkyl chains are omitted for clarity); - Figure 2 shows a1H NMR of a pillararene comprising n is 5 monomers of formula V according to the invention having PFOS bonded thereto, 1-bromo-4-fluorobenzene used as internal standard, solvent methanol-d4; - Figure 3 shows a19F NMR of a pillararene comprising n is 5 monomers of formula V according to the invention having PFOS bonded thereto, 1-bromo-4-fluorobenzene used as internal standard, solvent methanol-d4; - Figure 4 shows a1H NMR of a pillararene comprising n is 5 monomers of formula V according to the invention having PFOA bonded thereto, 1-bromo-4-fluorobenzene used as internal standard, solvent methanol-d4; - Figure 5 shows a19F NMR of a pillararene comprising n is 5 monomers of formula V according to the invention having PFOA bonded thereto, 1-bromo-4-fluorobenzene used as internal standard, solvent methanol-d4; - Figure 6A shows the residual concentration PFOS; and - Figure 6B shows the residual concentration of PFOA and octanoic acid (OA). In a first experiment the structure and host-guest arrangement was analysed by crystallization and single-crystal X-Ray diffraction studies (Figure 1). The pillararene shown in figure 1 comprises 5 monomers according to formula V. Said crystal was grown by slow evaporation of solvent from a methanol-water solution. The structure of the complex confirms that the binding between pillararene and perfluorinated acids happens exclusively on the rim of the pillararene, as no PFOA molecule was found in the host cavity. The crystal structure comprises 19 molecules of PFOA per 2 molecules of pillararene. This confirms the overall stoichiometry (pillararene to perfluorinated acid) of at least 1 : 3, preferably at least 1 : 4, more preferably at least 1 : 5, even more preferably at least 1 : 6, even more preferably at least 1 : 8, most preferably of at least 1 : 10. Said crystal structure also shows that the vast majority of perfluorinated acid chains are oriented along the pillararene axis, creating a well- distinct fluorous phase above and below the pillararene ring, and thus a fluorous phase stabilization. Only one perfluorinated acid chain is oriented perpendicular to the pillararene axis and interacts with the perfluorinated phase of a neighbouring pillararene group (Figure 1). In addition, multiple hydrogen bonding interactions between carboxylates, ammonium groups, methanol and water molecules were observed. Thus, it can be concluded that the main driving force for the formation of 1 : 3, preferably 1 : 4, more preferably 1 : 5, even more preferably 1 : 6, even more preferably 1 : 8, most preferably 1 : 10 pillararene- perfluorinated acid adduct is a combination of electrostatic attractions and the fluorophilic interactions between perfluorinated acid guests arranged on the rim. Five ammonium groups on each rim lead to a densely positively charged space for binding of negatively charged perfluorinated acid anions (such as PFAS, PFOS, PFOA). Subsequent stacking of fluorous chains on one side of the rim results in the formation of the local fluorous phase, which stabilizes the 1 : 3, preferably 1 : 4, more preferably 1 : 5, even more preferably 1 : 6, even more preferably 1 : 8, most preferably 1 : 10 adduct. Due to the1H NMR silent feature of at least some perfluorinated acids (for example PFAS), the binding constants were determined by isothermal titration calorimetry (ITC). As mentioned before, it was surprisingly found that an extremely high about 1:10 pillararene – perfluorinated acid (PFAS) binding stoichiometry, suggesting that host-guest interactions occur on the rim rather than in the cavity of pillararene was achieved. Various pillararenes have been tested (see Table 1). For a range of perfluoroalkyl acids guests (entries 1 to 4), including PFOS (entry 1) and PFOA (entry 2), with 11 to 17 fluorine atoms and varying negatively charged end groups (carboxylate, sulfonate, phosphonate; see Table 1), pillararene hosts comprising monomers according to formula III, formula IV, and / or formula V, show an excellent affinity, with a 1:10 stoichiometry and binding constants in the range of 104M-1to 106M-1, up to 5 × 106M-1. The consistently high stoichiometry ratio was further confirmed by isolation of adducts from entry 1, in particular from the perfluorinated acid of entry 1 in combination with formula III or formula IV, and their characterization by quantitative1H NMR and19F NMR (Figures 2 to 5). Thus, the combination of tight binding between perfluoroalkyl acids and a pillararenes (such as deca-ammonium-functionalized pillararenes, preferably wherein n is 5 in said pillararenes) of and the stoichiometry was an unexpected surprise. Table 1: Results of ITC titration of pillararenes comprising 5 monomers according to formula III, formula IV, and formula V respectively, wherein said pillararenes comprise one type of monomers, with different perfluorinated acids. Top value is a host-guest binding ratio; bottom value is a binding constant M-1.[a]Entry perfluorinated acid Formula III Formula IV Formula V 1 : 10±1 1 : 10±1 1 : 13±1 1 C8F17-SO3K (1.3±0.1)×106(5.1±0.4)×106(3.4±0.7)×1061 : 10±1 1 : 10±1 1 : 12±1 2 C7F15-CO2K (1.7±0.5)×105(1.9±0.5)×105(3.9±1.7)×1061 : 10±1 1 : 12±1 3 C5F11-C2H4-PO3K2 (6.6±0.2)×105(1.9±0.4)×105n.d.[b]1 : 8±1 1 : 12±2 1 : 10±1 4 C6F13-SO3K (1.2±0.1)×105(1.4±0.1)×105(3.9±0.9)×1065 C4F9-SO3K n.d.[b]n.d.[b]n.d.[b]1 : 1 1 : 1 6 C7H15-CO2K (1.4±0.1)×104n.d.[b](2.7±0.1)×104[a]All values are average of triplicate experiments, see SI for the full details; [b] n.d. = not detected.It was surprisingly found that shortening the CF2chain from 8 via 6 to 4 carbon atoms in perfluoroalkyl sulfonic acids (entry 1 versus entry 4 versus entry 5) results first in a 10 to 50 fold decrease in the binding constant (entry 1 versus entry 4) for both 1 and 2, and then for entry 5 no interactions are detectable anymore by ITC (i.e., binding constant < 103M-1). This trend is in line with a decrease of fluorophilic interactions occurring due to the shorter length of the fluorinated chain. Perfluoroalkyl acids with longer CF2 chains (e.g. perfluorodecanoic acid) were not measured due to their poor solubility in water. In addition to sulfonic acid PFOS (entry 1) and carboxylic acid PFOA (entry 2), phosphoric acid (entry 3) also form 1:10 complexes with pillararenes with the K values of 1.9 × 105M-1to 6.6 × 105M-1. This highlights that the nature of anion does not significantly affect the resulting pillararene-perfluorinated acid (PFAS) assembly. Similarly, the nature of ammonium cation group on the pillararene was not significant for the 1:10 adduct formation, as R-NH3+(formula III and formula IV) and R-Nme3+(formula V) both showed a similar level of interaction. This example particularly suggests that hydrogen bonding interactions between the pillararene and perfluorinated acid (PFAS) are of less importance for the 1:10 adduct formation. In short: the rim-guest interaction is determined by fluorophilic interactions / attractions and generic electrostatic attractions. In addition, a control experiments with a single monomer of formula V (no pillararene) showed no binding for both PFOS and PFOA, supporting the necessity of multiple interactions to achieve appreciable binding. Similarly, no supramolecular interactions were observed (with ITC) for polyethylenimine in contact with PFOS or PFOA. Therefore, there is a high importance of the pillararene structure for the host-guest interaction. The high 1 : 10 host-guest ratio enables intriguing possibilities for the development of efficient practical absorbents for perfluorinated acid (for example PFAS, PFOS, PFOA), which is an urgent environmental problem. Thus, these positively charged pillararenes would strongly bind to the negatively charged surfaces of e.g. silica and metal oxides, and allowing the cleaning up of perfluorinated acid polluted waters, such as PFAS polluted waters, by filtration. For example through pillararenes loaded columns. In addition, surface immobilization reactions to permanently load the pillararenes according to the invention on the substrate, e.g. resin, gold surface, silicon surface, glasses, may be used. As mentioned before, one of the biggest challenges of water purification from PFAS is the poor efficiency of absorbent in the presence of natural organic co-contaminants, such as alkyl carboxylic acids, which can compete with PFAS for binding. For example, binding with scavengers. Common organic molecules may interact with the cavity of pillararenes. Therefore, without being bound to theory, there is no (strong) interference of said common organic molecules with the binding of PFAS to the rim. It was found that absorbing PFOA (1 μg L-1) in the presence of 10000-fold excess of its non- fluorinated counterpart – octanoic acid (OA) (10 mg L-1), the concentration of PFOA after purification was in range of 1 ng L-1to 5 ng L-1, much lower than the (desired) safety limit. The residual concentration of OA increased after absorbing purifying 150 mL of solution, while the PFOA residual concentration stayed in a low concentration in range of 1 ng L-1to 5 ng L-1, order of magnitude lower than the safety advisory limit (Figure 6B). In a further experiment, a 10 wt% deca-ammonium-functionalized pillararene comprising 5 monomers of formula IV loaded resin column was made (solid support according to the invention) by using the monomer of formula IV to react with the -NH2groups of the substrate, then convert the rest functional groups to formula IV. Next, this column was linked to a peristaltic pump and 1000 mL of a PFOS solution (10 mg L-1, i.e., corresponding to heavily polluted water) was flushed through at a 1 ml min-1flow rate. The residual PFOS concentration was determined by UPLC-MS. The solution after purification exhibited an extremely low concentration of PFOS of only 13 ± 4 ng L-1, significantly lower than the EPA-advised limit of 70 ng L-1(Figure 6A). In other words, the one-time pass reduced the PFOS concentration from 10000000 ng L-1to a concentration between 19 ng L-1to 43 ng L-1(a reduction of no less than six orders of magnitude). It was found that even in the very first fraction collected within the first 5 minutes, the residual concentration was effectively reduced to 49 ng L-1, and at 30 min the optimal performance was reached. Therefore, the pillararenes according to the invention and the use of said pillararenes are more effectively and efficiently compared to conventional materials and methods (e.g. activated carbon, which need at least several hours to reach equilibrium). The initial 5 min to 30 min delay in optimal performance is also in line with the cooperative fluorophilic absorption mechanism as described before. Controlled experiments with activated carbon resulted in residual PFOS concentration of 230 μg L- 1 to 515 μg L-1, four orders of magnitude higher than with the resin functionalized with the pillararenes according to the invention. In a further experiment, the synthesis of the pillararene according to formula VI was performed. Scheme 1: reaction scheme for the synthesis of the pillararene according formula VI The compound according to formula VII (100 mg, 51 µmol) and toluene (1 mL) were added to a 5 mL round bottom flask. Next, an excess of the compound according to formula VIII (1 mL, 4.9 mmol, 95 equivalents) was added to said round bottom flask. The mixture was stirred and heated overnight at 100 °C. After, the reaction was cooled down to room temperature and concentrated under vacuum. The product was precipitated by dissolving the remaining yellow, oily mixture in a minimal amount of methanol followed by the addition of an excess of acetone. The resulting white precipitate was allowed to settle for 24 hours. Subsequently, the solvent was poured off. The remaining white precipitate was dried under vacuum. Yield of the compound according to formula VI: 70 mg, 39%.1H NMR (400 MHz, Methanol-d4) δ 7.00 (s, 10H), 4.17 (bs, 10H), 4.04 (bs, 10H), 3.81 (s, 10H), 3.55 (bs, 20H), 3.17 (bs, 60H), 2.03 (bs, 40H), 1.45-0.99 (m, 140H), 0.91 (t, J = 7.1 Hz, 30H). Table 2: Results of ITC titrations of the compound according to formula VI with different perfluorinated acids (duplicate measurements). The top value is the binding constant and the bottom value (N) is the host-guest stoichiometry. PFAS^^^^-^^^^^^^^[^^^^^^] PFOS ^^^^^− ^^^K 256 ± 25 (N = 10.7 ± 0.8) PFHxS ^^^^^− ^^^K 43.5 ± 4.7 (N = 9.3 ± 0.1) PFBS ^^^^− ^^^K 17.9 ± 3.2 (N = 9.8 ± 0.2) TFMS ^^^^− ^^^K Not detected PFOA ^^^^^− ^^^H 26.5 ± 1.0 (N = 8.9 ± 0.1) PFHxA^^^^^ − ^^^H4.2 ± 0.4 (N = 14.2 ± 1.1) PFBA ^^^^− ^^^H 4.6 ± 0.1 (N = 15.5 ± 0.1) TFA ^^^^− ^^^H Not detected Cheminox FHP 2OH ^^^^^− ^^^^− ^^^^^Not detected GenX ^^^^− ^ − ^^^^− ^^^K Not detected From the ITC data it becomes clear that PFAS adsorption from PFAS-contaminated water was achieved. In a further experiment, the synthesis of the pillararene according to formula IX was performed. (VII) (X) (IX) Scheme 2: reaction scheme for the synthesis of the pillararene according formula IX Compound X was synthesized following the synthesis of scheme 3. Scheme 3: reaction scheme for the synthesis of the compound according formula X Compound XI (851 mg, 12.5 mmol), compound XII-n (wherein n refers to the n as disclosed in the structure of compound XII, see scheme 3) (5 mmol, 0.4 equivalent), and ethyl acetate (15 mL) were added to a 50 mL round bottom flask. The mixture was stirred and refluxed overnight at 80 °C. The resulting yellow mixture was extracted with water (4 x 10 mL) and concentrated under reduced pressure. The product was isolated by column chromatography (petroleum ether:ethyl acetate, 4:1). Yield compound X-1 (wherein n = 1 in compound X) (liquid): 230 mg, 22%.1H NMR (400 MHz, DMSO-d6) δ 7.71 (s, 1H), 7.28 (s, 1H), 6.89 (s, 1H), 4.30 (t, J = 7.2 Hz, 2H), 7.28 (m, 2H).19F NMR δ -83.94 (s, 3F), -117.28 (s, 2F). Yield compound X-5 (wherein n = 5 in compound X): 708 mg, 34%.1H NMR (400 MHz, DMSO-d6) δ 7.71 (s, 1H), 7.28 (s, 1H), 6.88 (s, 0.94), 4.32 (t, J = 7.1 Hz, 2H), 2.82 (m, 2H).19F NMR δ -80.21, -113.47 (m), -121.73, -121.63, -123.11, -125.74 (m). Then compound IX was synthesized. Compound VII (100 mg, 51 µmol) and toluene (1 mL) were added to a 5 mL round bottom flask. Next, an excess of compound X-n (1 mmol, 20 equivalent) was added. The mixture was stirred and heated overnight at 100 °C. After, the reaction was cooled down to room temperature and concentrated under vacuum. The product was precipitated by dissolving the remaining yellow, oily mixture in a minimal amount of methanol, followed by the addition of an excess of acetone. The resulting white precipitate was allowed to settle for 24 hours. Subsequently, the solvent was poured off. The remaining white precipitate was dried under vacuum. Yield of compound IX-1 (wherein n = 1 in compound IX): 203 mg, 97%.1H NMR (400 MHz, DMSO-d6) δ 9.68 (s, 10H), 8.02 (s, 10H), 7.98 (s, 10H), 6.79 (s, 10H), 4.59 (bs, 20H), 4.36 (bs, 20H), 4.03 (bs, 10H), 3.78 (bs, 10H), 3.64 (bs, 10H), 3.03 (m, 20H), 2.08 (bs, 2H), 1.78 (bs, 2H).19F NMR -85.01 (s, 3F), -117.13 (t, 2F). Yield of compound IX-5 (wherein n = 5 in compound IX): 254 mg, 81%.1H NMR (400 MHz, DMSO-d6)) δ 9.71 (s, 10H), 7.99 (s, 10H), 7.98 (s, 10H), 6.80 (s, 10H), 4.61 (bs, 20H), 4.37 (bs, 20H), 4.04 (bs, 10H), 3.77 (bs, 10H), 3.65 (bs, 10H), 3.07 (m, 20H), 2.09 (bs, 20H), 1.80 (bs, 20H).19F NMR δ -80.58 (t), -113.49, -121.94, -122.92, -123.31, -126.07. It was found that PFAS adsorption from PFAS-contaminated water was achieved using compound IX having an n of 1 and / or 5, wherein also a mixture of n = 1 and n = 5 was tested. In addition, excellent PFAS adsorption from PFAS-contaminated water was achieved using compound IX having n = 1. The present invention is by no means limited to the above described preferred embodiments and / or experiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged.

Claims

CLAIMS 1. Pillararene comprising n monomers individually selected from formula (I), or a stereoisomer, a tautomer, a racemic, a hydrate, a N-oxide or solvate thereof,wherein: n is an integer in the range of 5 to 8; o is an integer in the range of 1 to 3; p is an integer in the range of 1 to 3; R1is a -C1 to C4 alkyl-, wherein said -C1 to C4 alkyl- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, -SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, - C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen; R2is selected from the group of C, N, or S; R3is selected from the group of C, N, or S; R4is one or more independently selected from the group of hydrogen, -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, or R4forms together with R6a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr, wherein said -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen; R5is selected from the group of -O-, -N-, -C-, or a direct bond; R6is absent when R2is selected from N or S, and wherein R6is hydrogen, -C1 to C4 alkyl-, -C2 to C4alkene-, or -C2to C4alkyne- when R2is C, or R6forms together with R4a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr; R7is one or more independently selected from the group of hydrogen, -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, or R7forms together with R9a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr,wherein said -C1to C18alkyl-, -C2to C18alkene-, -C2to C18alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen; R8is selected from the group of -O-, -N-, -C-, or a direct bond; R9is absent when R3is selected from N or S, and wherein R9is hydrogen, -C1to C4alkyl-, -C2to C4 alkene-, or -C2 to C4 alkyne- when R3is C, or R9forms together with R7a C5-Ar, a C6-Ar, a 5-HetAr, or a 6-HetAr; wherein each occurrence of R10is independently selected from the group of hydrogen, -C1to C6alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, -C7 to C12 alkyl, -C7 to C12 alkene, -C7 to C12 alkyne, wherein said -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, -C7 to C12 alkyl, -C7 to C12 alkene, -C7 to C12 alkyne are optionally substituted with a halogen, and wherein at least 1 of the total occurrences of R4and R7being independently selected from -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N- alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, wherein said -C1 to C18 alkyl-, -C2 to C18 alkene-, -C2 to C18 alkyne- is optionally substituted with one or more substitute selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen.

2. Pillararene according to claim 1, wherein n is an integer in the range of 5 to 7.

3. Pillararene according to claim 1 or 2, wherein n is an integer of 5 or 6.

4. Pillararene according to any one of the preceding claims, wherein the at least 1 of the total occurrences of R4and R7being independently selected from -C1 to C18 alkyl-, -C2 to C18 alkene-, - C2 to C18 alkyne-, -N(R10)2+-, -NR10-, -N(R10)3+, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, ester, ether, thioether, thioester, is at least 5, preferably at least 6, more preferably at least 7, even more preferably at least 10, most preferably at least 12.

5. Pillararene according to any one of the preceding claims, wherein the pillararene comprises at most three different monomers individually selected from formula (I), or a stereoisomer, a tautomer, a racemic, a hydrate, a N-oxide or solvate thereof.

6. Pillararene according to any one of the preceding claims, wherein the pillararenes comprises at most two different monomers individually selected from formula (I), or a stereoisomer, a tautomer, a racemic, a hydrate, a N-oxide or solvate thereof.

7. Pillararene according to any one of the preceding claims, wherein formula (I) comprises at least 1 positive charge, preferably at least 2 positive charges.

8. Pillararene according to any one of the preceding claims, wherein R4and / or R7comprises one or more salt forms of -N(R10)2+-, -N(R10)3+, or -P(R10)3+herein represented by -N(R10)2+X-, - N(R10)3+X-, or -P(R10)3+X-, with X- being the counterion, preferably wherein R4and / or R7comprises at least one -N(R10)3+X-.

9. Pillararene according to claim 7 or 8, wherein a counterion for each positive charge is independently selected from the group of hydroxide, sulfate, carbonate, phosphate, fluoride, tosylate, tetrafluoroborate, hexafluorophosphate, acetate, trifluoroacetate, a halogen.

10. Pillararene according to claim 9, wherein the counterion for each positive charge is independently selected from the group of carbonate, sulphate, halogen, preferably each individual counterion is a carbonate or a halogen.

11. Pillararene according to claim 9 or 10, wherein the halogen is Br- and / or Cl-.

12. Pillararene according to any one of the preceding claims, wherein R1is a -C1 to C3 alkyl-, preferably R1is a -C1 to C2 alkyl-, more preferably R1is a -CH2-.

13. Pillararene according to any one of the preceding claims, wherein each occurrence of R10is selected from the group of hydrogen, -C1 to C5 alkyl, -C2 to C5 alkene, -C2 to C5 alkyne, preferably selected from the group of hydrogen, -C1 to C4 alkyl, -C2 to C4 alkene, -C2 to C4 alkyne, more preferably selected from the group of hydrogen, -C1 to C3 alkyl, -C2 to C3 alkene, -C2 to C3 alkyne, even more preferably selected from the group of hydrogen, -C1to C2alkyl, -C2alkene, -C2alkyne, most preferably selected from the group of hydrogen and -CH3.

14. Pillararene according to any one of the preceding claims, wherein the monomer of formula (I) is a monomer according to formula (II),(II).

15. Pillararene according to any one of the preceding claims, wherein said -C1to C4alkyl- of R1is substituted with one or more substituent selected from the group of -N(R10)2, -OR10, -SO2H, - SO3H, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen.

16. Pillararene according to any one of the preceding claims, wherein said -C1to C18alkyl-, - C2to C18alkene-, -C2to C18alkyne- of R4is substituted with one or more substituent selected from the group of -N(R10)2, -N(R10)3+, -OR10, -SO2H, -SO3H, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen.

17. Pillararene according to any one of the preceding claims, wherein said -C1to C18alkyl-, - C2to C18alkene-, -C2to C18alkyne- of R7is substituted with one or more substituent selected from the group of -N(R10)2, -N(R10)3+, -OR10, -SO2H, -SO3H, -P(R10)3+, N-alkylpyridinium, imidazolium, guanidinium, -COOH, -OH, -CO, -NO2, -C=N−OH, -C=NH, -N=N+=N−, -NH-NH2, -C≡N, -SH, halogen.

18. Pillararene according to any one of the preceding claims, wherein the optional -C1 to C6 alkyl, -C2 to C6 alkene, -C2 to C6 alkyne, -C7 to C12 alkyl, -C7 to C12 alkene, -C7 to C12 alkyne of R10are at least partly substituted with fluor.

19. Pillararene according to any one of the preceding claims, wherein the monomer of formula (I) is a monomer according to one or more of formula (III), formula (IV), formula (V),20. Solid support comprising pillararenes according to any one of the preceding claims and a support agent.

21. Solid support according to claim 20, wherein the support agent is one or more selected from the group of silica, plastics, ceramics, glass, metals.

22. Composition comprising pillararenes according to any one of the claims 1 to 19, or solid support according to claim 20 or 21, and one or more perfluorinated acid.

23. Composition according to claim 22, wherein the perfluorinated acid is one or more selected from the group of perfluoroalkyl substances, perfluorooctane sulfonic acid, perfluorooctanoic acid.

24. Composition according to claim 22 or 23, wherein the stoichiometry between the pillararenes and perfluorinated acid is at least 1 : 3, preferably at least 1 : 4, more preferably at least 1 : 5, even more preferably 1 : 6, even more preferably at least 1 : 8, most preferably at least 1 :

10.

25. Method for removing perfluorinated acid from an aqueous stream comprising contacting the pillararene according to any one of the claims 1 to 19, or solid support according to claim 20 or 21 with an aqueous stream comprising perfluorinated acid.

26. Method according to claim 25, further comprising regenerating the pillararenes.

27. Use of the pillararene according to any one of the claims 1 to 19, or solid support according to claim 20 or 21 to remove perfluorinated acid from an aqueous stream.

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