Compounds and uses thereof

Abstract

Disclosed herein is a compound or salt thereof comprising: (a) a first polymer; (b) a second polymer operably linked to the first polymer; and (c) a metal complex operably linked to the second polymer. Also disclosed herein are devices and materials comprising the compound as well as methods of using the compound, devices and materials for detecting ions such as phosphate, methods for removing ions such as phosphate from aqueous solutions or mixtures, and methods for treating hyperphosphatemia.

Description

[0001] COMPOUNDS AND USES THEREOF CROSS REFERENCE TO RELATED APPLICATION This application claims priority to United States Provisional Application Number 63 / 676,236 that was filed on July 26, 2024. The entire content of the application referenced above is hereby incorporated by reference herein. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with government support under DK124333 awarded by the National Institutes of Health. The government has certain rights in the invention. BACKGROUND OF THE INVENTION Phosphate pollution is a leading cause of eutrophication, which further leads to biodiversity loss, water quality degradation and economic expenses (Dodds, W. K.; et al., Environ. Sci. Technol.2009, 43 (1), 12–19). The excess phosphate mainly comes from phosphorus rocks mining and subsequent production and consumption of phosphate containing products such as fertilizers or civil products (Fink, G.; et al., Global Biogeochemical Cycles 2018, 32 (4), 617–634). To remediate phosphate pollution numerous phosphate absorbates have been reported. These materials usually are incorporated with hydrogen bonding, positive charges (such as quaternary amine or applied electric field) capable of absorbing phosphate via electrostatic interaction and hard metal cations (such as Fe3+or La3+) forming strong complexation with phosphate (He, Y.; et al., Water Research 2023, 246, 120699). Despite that there are excellent absorbates with high selectivity and adsorption capacity, the regeneration of materials remains a problem. Due to the strong phosphate-metal complexation, phosphate desorption is challenging and usually requires concentrated acid or base, which is not environmentally friendly and may degenerate the material; however, easy regeneration of material for cycles is required to reuse the wasted phosphate sustainably and avoid further mining activities. To circumvent this issue, it is proposed to use metal complexes which can bind phosphate reversibly. An iron (III) based phosphate receptor, FeBisHOPO, which binds phosphate in ethanolic solution with high affinity and selectivity over common ions such as halides, sulfate, nitrate and arsenate has been reported; meanwhile, it also has very weak affinity towards oxyanions such as bicarbonate or acetate (Huang, S.-Y.; Pierre, V. C. JACS Au 2022, 2 (7), 1604–1609). Chemically it means that although these oxyanions do not interfere with phosphate binding at environmentally relevant concentrations, at high enough concentration they will exchange with the phosphate. Considering that the iron complexes easily dimerize in water and are hard to recover once dissolved, we hypothesize that by immobilizing molecules onto porous nylon membranes via a polymer linker, we can avoid dimerization by physically setting receptors apart and have enough receptors to achieve phosphate removal by placing membrane in polluted water and phosphate recovery / material regeneration by washing membrane with more concentrated bicarbonate solution. Hyperphosphatemia is a condition whereby phosphate concentration in the blood reaches levels above 1.46 mmol / L. It appears primarily in patients with chronic kidney diseases (CKD) and those undergoing dialysis because the latter is inefficient at removing phosphate from the blood (Desoi, C. A.; et al., J. Am. Soc. Nephrol.1993, 4, 1214-1218). If left untreated, the condition leads to vascular calcification, up to 200 mg / week, and thus, in the long term, increased morbidity and mortality (Cupisti, A.; et al., Int. J. Nephrol. Renovasc. Dis.2013, 193- 205). Hyperphosphatemia is currently managed by phosphate binders, oral salts such as CaCO3 or La2(CO3)2, or polymers such as Sevelamer®, that bind phosphate in the gut (G. London.; et al. Clin. Nephrol.2010, 74, 423-432; Zhang, C.; et al., BMC Nephrol.2013, 14, 226; Steven Fishbane; Am. J. of Kidney Dis.2009, 55, 307-315). Beyond significant side effects and poor patient compliance due to the high pill burden, phosphate binders have limited success rates. For instance, in one study only 17% of patients taking La2(CO3)3achieved target blood phosphate levels (Bhargava, R.; et al., BMC Nephrol.2019, 20, 37). An alternative to using oral phosphate binders is to directly scrub the blood from excess phosphate. With the goal of developing a new paradigm to the treatment of hyperphosphatemia via blood filtration, inorganic phosphate receptors capable of removing phosphate from complex aqueous systems such as blood with high affinity and high selectivity over other endogenous anions have been developed (Pierre, V. C.; et al., . Front. Chem.2022, 10, 821020). Due to their high oxophilicity and lability, lanthanide complexes (Martinon, T. L. M.; et al., Chem. Asian J. 2022, 17, e202200495; Ramakrishnam Raju, M. V.; et al., Chem. Soc. Rev.2020, 49, 1090- 1108; Harris, S. M.; et al., Environ. Sci. Technol.2017, 51, 4549-4558) are better suited for this application than other metals such as copper(Tobey, S. L.; et al., J. Am. Chem. Soc.2003, 125, 4026-4027; Goswami, S.; et al., Tetrahedron Lett.2010, 51, 6707-6710), zinc (Singh, R.; et al., RSC Adv.2016, 6, 112246-112252; Shi, B.; et. al., Sens. Actuators B Chem.2014, 190, 555-561; Lee, H. N.; et al., Org. Lett.2007, 9, 243-246), and iron (Huang, S.-Y.; et al., JACS Au 2022, 2, 1604-1609). The key to achieving both sensitivity and selectivity in a flexible lanthanide(III) receptor (Wilharm, R. K.; et al., Inorg. Chem.2022, 61, 4130-4142) is to optimize the basicity of the chelating podand (Ramakrishnam Raju; et al., Inorg. Chem.2019, 58, 15189-15201) and the geometry of the ligand (Huang, S.-Y.; et al., Inorg. Chem.2020, 59, 4096-4108). Affinity for phosphate can then be fine-tuned without affecting selectivity by either changing the lanthanide ion (Wilharm, R. K.; et al., Inorg. Chem.2021, 60, 15808-15817) or the charge of the complex (Huang, S.-Y.; et al., Inorg. Chem.2019, 58, 16087-16099). Although these phosphate receptors are intended for ex-vivo use while immobilized on a polymer support in conjunction with dialysis, for safety reasons no lanthanide ion must leach from the receptor during the procedure. Indeed, uncomplexed or “free” gadolinium(III) ions released by weak gadolinium-based MRI contrast agents have been linked to nephrogenic system fibrosis and brain deposits (Weller, A.; et al., Pediatr. Nephrol.2014, 29, 1927-1937); similar toxicity is anticipated for the other lanthanide ions. Therefore, both the thermodynamic stability and the kinetic inertness of the complexes are important parameters to consider in the design of the receptor. Accordingly, there is an ongoing need for compounds and materials (e.g., membranes) that comprise metal complexes (e.g., iron and rare earth metal complexes such as EuIIIcomplexes), for capturing and / or removing ions (e.g., anions such as phosphate) from aqueous solutions or mixtures (e.g., aqueous mixtures), and / or for treating hyperphosphatemia or treating wastewater or waste activated sludge. SUMMARY OF THE INVENTION One embodiment provides a compound or salt thereof comprising: (a) a first polymer; (b) a second polymer operably linked to the first polymer; and (c) a metal complex operably linked to the second polymer. One embodiment provides a material or device comprising one or more compounds or a salt thereof as described herein. One embodiment provides a method to detect or capture inorganic phosphate, comprising contacting the phosphate with a compound or a salt thereof, or a material or device as described herein. One embodiment provides a method to treat wastewater or waste activated sludge comprising contacting the wastewater or waste activated sludge with a compound or salt thereof, or a material or device as described herein. One embodiment provides a method to treat hyperphosphatemia in a mammal (e.g., a human) in need thereof comprising contacting the blood of the mammal in need thereof, with a compound or salt thereof, or a material or device as described herein. One embodiment provides the use of a compound or salt thereof or a material or device as described herein for the treatment of hyperphosphatemia in a mammal (e.g., a human) in need thereof. One embodiment provides use of a compound or salt thereof, or a material or device as described herein for medical therapy. One embodiment provides the use of a compound or salt thereof, as described herein to prepare a device or material for the treatment of hyperphosphatemia. One embodiment provides a solid support in contact with a compound of formula I or a salt thereof as described herein. BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the structure of FeBisHOPO. Figure 2 shows a scheme for phosphate removal and recovery as well as material regeneration via a receptor-polymer-membrane system. Figures 3 shows an adsorption kinetics curve and fitting. Figure 4 shows an adsorption isotherm fitted with hill equation. Figures 5A-5B show an isotherm curve and fitting of thermodynamic parameters. Figure 5A shows an isotherm curve under different temperatures. Figure 5B shows fitting of thermodynamic parameters using data points from Regime A Figure 6 shows phosphate adsorption capacity over multiple adsorption cycles in 50 ppm phosphate solution. Figures 7A-7B show regeneration of membranes and recovery of phosphate. Figure 7A shows regeneration of membranes in wastewater activated sludge (WAS). Figures 7B shows recovery of phosphate in wastewater activated sludge (WAS) elution. Figures 8A-8B show cation and anion impact on phosphate adsorption capacity. Figure 8A shows cation impact on phosphate adsorption capacity. Figure 8B shows anion impact on phosphate adsorption capacity. The phosphate concentration is 50 ppm (1.615mM) and anion concentration is 5 mM. Figures 9 shows a collapse mechanism and proposed location of adsorption sites. Figure 10 shows the preparation of nylon-pGMA-FeBisHOPO. Figures 11A-11B show an adsorption isotherm fitted by Langmuir and Freundlich isotherm Model. Figure 12 shows phosphate adsorption capacity with 0.1 M NaCl and glucose background and adsorption capacity as a function of NaCl concentration. Figure 13 shows the adsorption capacity of nylon-pGMA-FeBisHOPO in different media. The theoretical q is calculated from the isotherm curve referring to the corresponding Ce value. The variation in adsorption capacity across medium is due to the different starting phosphate concentrations. Figures 14A -14 B shows water droplet photos and contact angle. Figure 14A shows photos of water droplet during contact angle measurements at t=0 (left top – water treated at t=0 s; left bottom – 0.1M NaCl treated at t=0 s) and 25 seconds (right top – water treated at t=25 s); right bottom – 0.1M NaCl treated at t=25 s). Figure 14B shows contact angle as a function of time(right). Contact angle is measured by FAMAS software. Measurements are performed on three sites of the membrane and average contact angle is calculated Figure 15 shows the adsorption kinetics of nylon-poly (glycidyl methyl acrylate)- EuLysHOPO. Figure 16 shows the adsorption isotherm of nylon-poly (glycidyl methyl acrylate)- EuLysHOPO. Figures 17 shows the adsorption thermodynamics of nylon-poly(glycidyl methyl acrylate)-EuLysHOPO. Figures 18A and 18B show the regeneration of nylon-poly(glycidyl methyl acrylate)- EuLysHOPO in phosphate solution and in wastewater activated sludge. Figure 18A shows the regeneration of nylon-poly(glycidyl methyl acrylate)-EuLysHOPO in 50 ppm phosphate solution. Figure 18B shows the regeneration of nylon-poly(glycidyl methyl acrylate)- EuLysHOPO in wastewater activated sludge (WAS) (Figure 18B Figures 19A and 19B show phosphate recovery efficiency of nylon-poly(glycidyl methyl acrylate)-EuLysHOPO membrane and analysis. Figure 19A shows phosphate recovery efficiency of nylon-poly(glycidyl methyl acrylate)-EuLysHOPO membrane. Figure 19B shows ICP-MS analysis of recovered phosphate solution (Figure 19B) In the phosphate recovery measurement, 1 cm2material (16 mg) was placed 2 ml WAS solution for 3 hours. Then the membrane was taken out, wiped dry, and placed in 2 mL 50 mM bicarbonate solution for 3 hours for phosphate release and material regeneration. Phosphate concentrations before and after adsorption, and phosphate in the 2 ml 50 mM bicarbonate regeneration solutions were measured. Recovery rate is calculated as the ratio of amount of phosphate released to adsorbed. The data show recovery rate is 86% on average, which is smaller than FeBisHOPO (95%), and that metals of significant presence (Mg, Mn, Zn) were reduced in recovered solution compared to WAS. Figure 20 shows the adsorption kinetics of PES-poly(glycidyl methyl acrylate)- FEBisHOPO. Figure 21 shows the adsorption isotherm of PES-poly(glycidyl methyl acrylate)- FeBisHOPO. Figure 22 shows the regeneration of PES-poly(glycidyl methyl acrylate)-FeBisHOPO in 50 ppm phosphate. Figures 23A and 23B show the regeneration and phosphate recovery of PES- poly(glycidyl methyl acrylate)-FeBisHOPO in wastewater activated sludge (WAS). Figure 23A shows the regeneration of PES-poly(glycidyl methyl acrylate)-FeBisHOPO in WAS. Figure 23B shows phosphate recovery rate of PES-poly(glycidyl methyl acrylate)-FeBisHOPO in WAS. DETAILED DESCRIPTION The following definitions are used, unless otherwise described: halo or halogen is fluoro, chloro, bromo, or iodo. Alkyl and alkoxy, etc. denote both straight and branched groups but reference to an individual radical such as propyl embraces only the straight chain radical (a branched chain isomer such as isopropyl being specifically referred to). As used herein, the term "(Ca-Cb)alkyl" wherein a and b are integers refers to a straight or branched chain alkyl radical having from a to b carbon atoms. Thus when a is 1 and b is 6, for example, the term includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t- butyl, n-pentyl and n-hexyl. The term “alkoxy” refers to -O(alkyl) and the term “haloalkoxy” refers to an alkoxy that is substituted with one or more (e.g., 1, 2, 3, or 4) halo. Specific values listed below for radicals, substituents, and ranges, are for illustration only; they do not exclude other defined values or other values within defined ranges for the radicals and substituents. Specifically, (C1-C6)alkyl can be methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec- butyl, pentyl, 3-pentyl, or hexyl; (C1-C6)alkoxy can be methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, sec-butoxy, pentoxy, 3-pentoxy, or hexyloxy. Operably Linked, and Linker As used herein, the term “operably linked” refers to the linkage of two elements (e.g., entities or moieties such as molecular entities or molecular moieties) in a manner wherein each of the elements function as designed or desired (e.g., function in their usual manner). Thus, the linkage can be variable and not limited in any specific manner, provided the elements function as desired or designed. The linkage also refers to embodiments wherein the two elements are directly connected or attached to each other (e.g., connected or attached through chemical bond). Thus, the term operably linked refers to the linkage of two elements through a linker between the two elements or a direct connection or attachment between the two elements. The term operably linked may refer to a linkage of a first polymer to a second polymer in any manner that preserves the function of the polymers. The term operably linked may also refer to a linkage of a metal complex (e.g., a ligand moiety of a metal complex) to a second polymer in any manner that preserves the function of the polymer and metal complex. In one embodiment the term “operably-linked” refers to the association of two elements so that the function of an element is affected by another element. As described herein, the term linker refers to any molecular moiety that connects two elements (e.g., entities or moieties such as molecular entities or molecular moieties). The elements include but are not limited to polymers (e.g., first polymers and second polymers) and metal complexes (ligands of metal complexes). The term linker also includes linkers which include within the linker one or more reactive groups that are useful to connect elements to the linker. The linkers may also connect a compound or another material as described herein to another material or a device. The linker can be variable, provided it functions to connect one element to another element so that the elements function as desired (e.g., function in their usual manner). The linker can be covalently bonded to the elements at any suitable atom such as a carbon atom or heteroatom (e.g., a nitrogen, oxygen, sulfur or phosphorus atom). The linker can vary in length and atom composition (e.g., C, H, N, O, S, halo, P) and can be branched or non- branched or saturated or unsaturated or a combination thereof. In one embodiment a linker connects the first polymer to one or more second polymers. In one embodiment a linker connects the second polymer to one or more metal complexes. In one embodiment the linker includes one or more reactive groups. The reactive group is useful for covalently bonding the remainder of the linker to one or more elements such as a polymer or metal complex. Examples of reactive groups include amines, alcohols, thiols, amides, esters, carboxylic acids, aldehydes and epoxides. In one embodiment a compound or a salt thereof as described herein can be combined with one or more other materials (e.g., a solid support or device) without being bonded (e.g., covalently bonded) to the material(s). Metal Complex The term metal complex as used herein refers to a metal ion such an iron ion (iron II or iron III) or a rare earth metal ion that is associated with one or more molecules also known as ligands. The ligands are typically bonded to the metal ion through bonds (e.g., bonds formed by the interaction of electron pairs (e.g., lone electron pairs) of the ligand with the metal). In one embodiment the ligand comprises one or more heteroatoms (e.g., nitrogen, oxygen, phosphorus). In one embodiment the ligand is bonded to the metal ion through one or more heteroatoms of the ligand. In one embodiment the metal complex comprises one or more ligands, wherein at least one ligand is linked to the second polymer Metal complexes have been described in various documents including International Application Publication WO 2017 / 106425, US Patent No.11,136,251, and International Application Publication WO 2023 / 244831. Each of these documents is hereby incorporated by reference in their entirety. First Polymer The term “first polymer” as used herein referrers to a polymer that is operably linked (either through a linker or directly attached) to one or more second polymers. In one embodiment the first polymer refers to a polymer comprising a polyamide, polysulfone or a polyether sulfone. The first polymer also includes polymers that comprise one or more functional groups on the polymer; for example, polymers comprising a polyamide, polysulfone or a polyether sulfone, wherein the polyamide, polysulfone or a polyether sulfone comprise one or more functional groups. These function groups may serve as points of attachment for other elements (e.g., entities or moieties such as molecular entities or molecular moieties including linkers and polymers) including attachment of a linker, wherein the linker is attached to another element (e.g., a polymer such as a second polymer). Second Polymer The term “second polymer” as used herein refers to a polymer that is operably linked to a first polymer. In one embodiment the second polymer is operably linked to a first polymer through a linker. In one embodiment second polymer is also operably linked to one or more metal complexes. In one embodiment the second polymer is operably linked to the metal complex through a linker. The second polymer can be variable in nature provided that it functions to connect the first polymer to one or more metal complexes wherein each of the first polymer and metal complex function as desired. Polymer endcap. The term “polymer endcap” as used herein refers to any molecular moiety or molecular group or atom that terminates a polymer (e.g., is at the end of a propagating monomer). In one embodiment the endcap is H, OH, or halo (e.g., bromo or fluoro, bromo, or iodo). In one embodiment the endcap is (C1-C6)alkyl. Certain embodiments are provided herein below. It is to be understood that two or more embodiments may be combined. One embodiment provides a compound or salt thereof comprising: (a) a first polymer; (b) a second polymer operably linked to the first polymer; and (c) a metal complex operably linked to the second polymer. One embodiment provides a compound or salt thereof comprising: (a) a first polymer; (b) one or more second polymers operably linked to the first polymer; and (c) one or more metal complexes operably linked to one or more of the second polymers. In one embodiment the first polymer is linked to 20 or more second polymers. In one embodiment the first polymer is linked to 200 or more second polymers. In one embodiment the first polymer is linked to 1 or more second polymers. In one embodiment the first polymer is linked to 5 or more second polymers. In one embodiment the first polymer is linked to 10 or more second polymers. In one embodiment the first polymer is linked to 50 or more second polymers. In one embodiment the first polymer is linked to 100 or more second polymers. In one embodiment the first polymer is linked to 500 or more second polymers. In one embodiment the first polymer is linked to 1000 or more second polymers. In one embodiment the first polymer is linked to 2000 or more second polymers. In one embodiment the first polymer is linked to the second polymer through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 20 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1- C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl. In one embodiment the first polymer is linked to the second polymer through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 10 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1- C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl. In one embodiment 20 or more of the second polymers are linked to one or more metal complexes. In one embodiment 200 or more of the second polymers are linked to one or more metal complexes. In one embodiment 1 or more of the second polymers are linked to one or more metal complexes. In one embodiment 5 or more of the second polymers are linked to one or more metal complexes. In one embodiment 10 or more of the second polymers are linked to one or more metal complexes. In one embodiment 50 or more of the second polymers are linked to one or more metal complexes. In one embodiment 100 or more of the second polymers are linked to one or more metal complexes. In one embodiment 500 or more of the second polymers are linked to one or more metal complexes. In one embodiment 1000 or more of the second polymers are linked to one or more metal complexes. In one embodiment 2000 or more of the second polymers are linked to one or more metal complexes. In one embodiment the second polymer is linked to the metal complex through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 40 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1- C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl. In one embodiment the second polymer is linked to the metal complex through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 25 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1- C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl. One embodiment provides a compound or a salt thereof comprising a first polymer (P1) substituted with one or more moieties of formula I: wherein the D group of formula I is attached to the first polymer; R1is (C1-C6)alkyl; R2is (C1-C6)alkyl; D is (C1-C6)alkyl or D is absent; and Q is a second polymer (P2) comprising one or more moieties of formula II: wherein the carbonyl group of formula II is attached to the second polymer; X is O or NRa; Y is (C1-C6)alkyl; Z is OH or NHRb; Rais H or (C1-C6)alkyl; Rbis H or (C1-C6)alkyl; and L is a linker or L is absent; W is a metal complex. In one embodiment R1is methyl. In one embodiment R2is methyl. In one embodiment D is -CH2-. In one embodiment D is absent. In one embodiment the more moiety of formula I is: In one embodiment the more moiety of formula I is: . In one embodiment the more moiety of formula I is: . In one embodiment X is O. In one embodiment Y is -CH2-. In one embodiment Z is -OH. In one embodiment L is (C1-C6)alkyl or -NH(C1-C6)alkyl-. In one embodiment L is -CH2- or -NH(-CH2-)3-. In one embodiment L is absent. In one embodiment the more moiety of formula II is: . In one embodiment the more moiety of formula II is: . In one embodiment the more moiety of formula I is: . In one embodiment the second polymer comprises a hydrocarbon polymer. In one embodiment the second polymer comprises polyethylene, wherein the polyethylene is optionally substituted with one or more (C1-C6)alkyl. In one embodiment the second polymer comprises polypropylene. In one embodiment the second polymer has a molecular weight of about 500 to about 600,000. In one embodiment the second polymer has a molecular weight of about 1000 to about 800,000. In one embodiment the second polymer has a molecular weight of about 1000 to about 600,000. In one embodiment the second polymer has a molecular weight of about 1000 to about 400,000. In one embodiment the second polymer comprises about 20 to about 20,000 monomer residues. In one embodiment the second polymer comprises about 20 to about 10,000 monomer residues. In one embodiment the second polymer comprises about 100 to about 20,000 monomer residues. In one embodiment the second polymer comprises about 100 to about 10,000 monomer residues. In one embodiment the monomer residue comprises ethyl or propyl. In one embodiment the monomer residue comprises . In one embodiment the second polymer comprises about 20 to about 20,000 moieties of formula II. In one embodiment the second polymer comprises one or more monomers (monomer residues) of formula IIIa: IIIa. One embodiment provides a compound comprising a first polymer (P1) substituted with one or more moieties of formula I comprising one or more moieties of formula III’ III’ wherein, each M is a monomer (monomer residue), wherein at least one (e.g., on or more, 10 or more, 50 or more, 100 or more, 1000 or more, 2000 or more) M is a monomer (monomer residue) of formula III: n is 20 – 20,0000 (or 20-50,000, 20 -100,000, or 20-100,000 or more) and R4is a polymer endgroup. In one embodiment the remaining M groups of formula III’ are hydrocarbon monomer residues. In one embodiment the remaining M groups of formula III’ are ethylene (monomer residue of polyethylene) or propylene (monomer residue of polypropyl). In one embodiment each M is independently IIIa IIIb IIIc wherein one or more of M is IIIa; and Z1is O or NRb. In one embodiment Z1is O. In one embodiment R1is methyl. In one embodiment R2is methyl. In one embodiment X is O. In one embodiment Y is -CH2-. In one embodiment Z is -OH. One embodiment provides a compound of formula V: (M-Lm-P2-Ln)x-P1V wherein: each M is a metal complex each Lmis independently a linker that operably links the metal complex to P2; each P2is a second polymer; each Lnis independently a linker that operably links the P2to P1x is an integer of 2 or more; and P1is a first polymer. In one embodiment P2-Lnis a moiety of formula I. In one embodiment M-Lmis a moiety of formula II. In one embodiment x is 2-200, 2-500, 2-100, 2-5000, 2-5000 or more. In one embodiment x is > 5, >20, > 50, > 1000, > 200, >500, > 1000, >5000. In one embodiment the first polymer comprises a polyamide, a polysulfone, a polyether sulfone, or polymethyl methacrylate. In one embodiment the first polymer comprises a polyamide, a polysulfone, polyether sulfone or polymethyl methacrylate; wherein the second polymer is linked to an amide nitrogen of the polyamide; wherein the second polymer is linked to a phenyl of the polysulfone or the polyether sulfone; wherein the second polymer is linked to the oxygen or the carbonyl of the polymethyl methacrylate. In one embodiment the first polymer comprises a polyamide, a polysulfone or a polyether sulfone; wherein the one or more moieties of formula I is attached to an amide nitrogen of the polyamide and D is (C1-C6)alkyl; and wherein the one or more moieties of formula I is attached to a phenyl of the polysulfone or the polyether sulfone and D is absent. In one embodiment the first polymer comprises a polyamide, a polysulfone or a polyether sulfone; wherein the one or more moieties of formula I is attached to one or more amide nitrogen of the polyamide and D is -(CH2)-; and wherein the one or more moieties of formula I is attached to one or more phenyls of the polysulfone or the polyether sulfone and D is absent. In one embodiment the polyamide is nylon In one embodiment the nylon is nylon 6,6 or nylon 6. In one embodiment the first polymer comprises wherein m1, m2, m3 and m4 are each independently about 100 to about 250,000. In one embodiment m1, m2, m3 and m4 are each independently about 100 to 500,000. In one embodiment m1, m2, m3 and m4 are each independently about 100 to 100,000. In one embodiment m is about 100 to 500,000. In one embodiment m is about 100 to 100,000. In one embodiment the first polymer comprises one or more monomer residues selected from wherein m1, m2, m3 and m4 are each independently about 100 to about 250,000 (e.g., +-10%, .+-20%, +-50%, +-75%) In one embodiment the first polymer has a molecular weight of about 1000 to about 2,500,000. In one embodiment the first polymer has a molecular weight of about 1000 to about 2,000,000. In one embodiment the first polymer has a molecular weight of about 1000 to about 1,000,000. In one embodiment the first polymer has a molecular weight of about 1000 to about 500,000. In one embodiment L is absent or L comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 20 carbon atoms, wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, wherein each Rais independently H or (C1-C6)alkyl. In one embodiment L is absent or L comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 10 carbon atoms, wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, wherein each Rais independently H or (C1-C6)alkyl. In one embodiment L is a absent or L is –(CH2)n-V- wherein n is one to ten and V is O, S or -N(Ra)-, wherein Rais H or (C1-C6)alkyl. In one embodiment L is a absent or L is –(CH2)nN(Ra)-, -wherein n is one to ten and Rais H or (C1-C6)alkyl. In one embodiment L is a absent or L is –(C1-C6)alkylN(Ra)-, -wherein Rais H or (C1- C6)alkyl. In one embodiment L is a absent or L is –(CH2)3N(Ra)-, -wherein Rais H or (C1-C6)alkyl. In one embodiment L is a absent or L is –(CH2)3NH-. In one embodiment L is a absent. In one embodiment L is –(C1-C6)alkylN(Ra)-, -wherein Rais H or (C1-C6)alkyl. In one embodiment L is –(CH2)3N(Ra)-, -wherein Rais H or (C1-C6)alkyl. In one embodiment L is –(CH2)3NH-. In one embodiment the metal complex comprises iron or a rare earth metal. In one embodiment the metal complex is:

[0002] wherein M is a rare earth metal In one embodiment metal complex is an iron or rare earth metal complex, wherein the rare earth metal is LaIII, CeIII, PrIII, NdIII, SmIII, EuIII, GdIII, TbIII, DyIII, HoIII, ErIII, TmIII, YbIII, LuIII, ScIII, YIIIor PmIII. One embodiment provides a material or device comprising one or more compounds or a salt thereof as described herein. In one embodiment the material or device is a hydrogel, membrane, nanoparticle, or other material. In one embodiment the material or device is a membrane. One embodiment provides a method to detect or capture inorganic phosphate in a sample, comprising contacting the phosphate in the sample with a compound or a salt thereof, or a material or device as described in herein. In one embodiment the phosphate is selectively detected or captured in the presence of other anions. In one embodiment the other anions are selected from the group consisting of carbonate, nitrate, sulfate, halides, arsenate and pyrophosphate. In one embodiment the phosphate is contacted with a compound or a salt thereof, or a material or device as described herein, as a liquid or liquid mixture or a mixture (e.g., at about neutral pH). In one embodiment the liquid or liquid mixture or a mixture is an aqueous liquid or aqueous liquid mixture or aqueous mixture. In one embodiment the is a liquid or liquid mixture or a mixture is an aqueous liquid or aqueous liquid mixture or aqueous mixture. In one embodiment the sample is blood or serum. In one embodiment the sample is blood. In one embodiment the sample is wastewater. In one embodiment the sample is waste activated sludge. In one embodiment the phosphate is captured by the compound or a salt thereof, or the material or the device. In one embodiment the phosphate is captured from an aqueous mixture, aqueous solution, waste water or waste activated sludge. In one embodiment the phosphate that is captured by the compound or a salt thereof, or the material or the device is essentially removed from the compound or a salt thereof, or the material or the device by contacting the compound or a salt thereof, or the material or the device with bicarbonate (e.g., sodium bicarbonate). In embodiment the material or the device that is essentially free of phosphate is contacted again with phosphate (e.g., as an aqueous mixture, aqueous solution, wastewater or waste activated sludge containing phosphate). One embodiment provides a method to treat hyperphosphatemia in a mammal in need thereof comprising contacting the blood of the mammal in need thereof, with a compound or salt thereof, or a material or device as described herein. In one embodiment the mammal has kidney disease (e.g., chronic, advanced, acute or advanced / acute kidney disease). A method to treat wastewater or waste activated sludge comprising contacting the wastewater or waste activated sludge with a compound or salt thereof, or a material or device as described herein. In one embodiment the phosphate concentration of the wastewater or waste activated sludge is lowered after contacting the wastewater or waste activated sludge with the compound or salt thereof, or a material or device. In one embodiment the compound or salt thereof, or the material or device is further contacted with bicarbonate (e.g., sodium bicarbonate). In one embodiment the compound or salt thereof, or the material or device is further contacted with wastewater or waste activated sludge. In one embodiment the compound or salt thereof, or the material or device, after being contacted with phosphate, is further contacted with a base such as bicarbonate (e.g., sodium bicarbonate) to regenerate the compound or salt thereof, or the material or device, by reducing the amount phosphate on the compound or salt thereof, or the material or device. This process of contacting with phosphate followed by regeneration with a base can repeated one or more (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or more) times In one embodiment, phosphate refers to either PO43-, HPO42-, H2PO4-, HP2O73-, P2O74-. In one embodiment the rare earth metal is EuIII. In one embodiment the metal complex is an FeIIIcomplex. One embodiment provides a material or device comprising one or more compounds or a salt thereof as described herein. In one embodiment the material or device is a hydrogel, membrane, nanoparticle, or other material. One embodiment provides a method to reduce the concentration of phosphate in wastewater or waste activated sludge comprising contacting the wastewater or waste activated sludge with a compound, or salt thereof, or material, or device as described herein, under conditions where the concentration of phosphate in the wastewater or the waste activated sludge is reduced. One embodiment further comprising contacting the compound or salt thereof, or a material with bicarbonate (e.g., sodium bicarbonate) after the contacting with phosphate. In one embodiment the phosphate is reduced 1% or more, 2% or more, 5% or more, 10% or more 20% or more 50% or more 70% or more 90% or more, or 95% or more. The invention will now be illustrated by the following non-limiting examples. Example 1. CHEMICAL REAGENTS & EXPERIMENTAL Chemical Reagents and Water Sample Acquisition The purity of the chemical reagents used herein was ≥ 99% purity. The chemical reagents were purchased from common commercial reagent companies. Baking soda for regeneration was purchased from grocery stores. Nylon membranes with 0.45 µm pore size and 90 mm diameter were purchased from GVS (Part No.1213778). Prior to use, membranes were cut into 1 cm2pieces. Waste activated sludge (WAS) and influent were obtained from a wastewater treatment plant under Twin Cities’ Metropolitan Council. The phosphate of the semi-solid WAS was eluted by soaking the WAS in water for 24 h. Elution was filtered through a P8 filter paper (20 µm pore size). Mississippi river was sampled from East River Flats Park and spiked with phosphate. All water samples were stored in a 4 °C refrigerator for use. Preparation of Nylon-pGMA-FeBisHOPO Membrane The synthesis of BisHOPO ligand has been previously reported. The ligand was converted to the Na2BisHOPO salt before use (Huang, S.-Y.; Pierre, V. C. JACS Au 2022, 2 (7), 1604–1609). Nylon-pGMA was prepared by surface-initiated atomic radical transfer polymerization (SI-ATRP) as shown in Figure 10 using a previously reported procedure (Xu, F. J.; et al., Langmuir 2007, 23 (16), 8585–8592.). A detailed preparation is described herein below. Briefly, methylol group was added to the nylon’s amide moiety by reacting with formaldehyde; the ATRP initiator, BIBB, was further conjugated to the membrane by reacting with the alcohol group. For metal mediated ATRP, nylon-pGMA was synthesized by mixing GMA (monomer), CuBr(metal) and HMTETA (ligand) in water with BIBB-modified nylon. The polymerization was carried under nitrogen for 2 hours. In the immobilization reaction, the FeBisHOPO was chemically functionalized to the polymer by amine-epoxide ring opening reaction in DMSO / MeOH under 60oC for 1 day. Adsorption Kinetics Nine pieces of 1 cm2nylon-pGMA-FeBisHOPO membrane (10 mg each) were placed in 18 ml, 50 ppm phosphate solution. Aliquots of solution in the amount of 0.1 ml were taken at various time intervals for phosphate analysis. Adsorption capacity at time t, qt, was calculated using the equation below, where m is mass of membrane in gram and C0 and Ct is phosphate concentration at time zero and time of phosphate analysis. Phosphate was analyzed by the molybdenum blue method. Adsorption Isotherm and Thermodynamics One piece of nylon-pGMA-FeBisHOPO membrane was placed in a 2 ml solution of varying phosphate concentrations at 20 °C, 37 °C and 60 °C. The phosphate concentration in solution was analyzed after 3 hours based on kinetics measurement. Experiments were all done in triplicate using three membranes from the same batch. Equilibrium adsorption capacity(qe) was calculated using the same mathematical equation below. Membrane Regeneration and Phosphate Recovery In each adsorption cycle, 1 piece nylon-pGMA-FeBisHOPO membrane was placed in 2 ml 50 ppm phosphate solution or 2 ml WAS elution for 3 hours. Between each adsorption cycle the membranes were rinsed with a 50 mM bicarbonate solution once and soaked in 50 mM bicarbonate for 3 hours; membranes were air-dried for the next adsorption cycle. Ten cycles were performed for the 50 ppm phosphate solution and 15 cycles for the WAS elution. Phosphate recovery was also measured for 11th-15thcycles in WAS experiments, in which membranes were taken from WAS elution and surface liquid was wiped out and placed in 2ml 50mM bicarbonate for 3 hours; phosphate concentration in the bicarbonate solution was measured after 3 hours. Recovery rate was calculated using the equation below, where the VWAS and VNaHCO3is volume of WAS and bicarbonate solution and C is the phosphate concentration in each solution. The heavy metal concentration in the original WAS elution and recovered phosphate solution was measured by ICP-MS by Research Analytical Laboratory in University of Minnesota. Interference Studies To investigate the impact of NaCl and glucose on phosphate adsorption, 1 piece of nylon-pGMA-FeBisHOPO membrane was placed in 2 ml 50 ppm phosphate solutions with varying NaCl concentrations (0, 1, 2.5, 5, 7.5, 10, 25 and 100 mM) and in 2 ml 50 ppm phosphate solution with 0.1M glucose. Phosphate was analyzed after 3 hours. For the study of specific ion effect on membrane’s phosphate adsorption, 1 piece of 1 cm2nylon-FeBisHOPO membrane was placed in 2 ml 50 ppm phosphate solutions with 5 mM of different salts (NaCl, NH4Cl, LiCl, KCl, NaHCO3, NaF, NaBr, NaI, Na2SO4). Phosphate was analyzed after 3 hours. The membrane’s adsorption capacity for chloride and sulfate alone was also measured by placing 1 piece membrane in a 2 ml solution with varying Cl- and SO42-concentration. Chloride and SO42-concentrations before and after adsorption were measured by a Thermo-Fisher Scientific Integrion HPIC equipped with ADRS600 suppressor, CFD200 carbonate removal device, EGC500KOH eluent generator cartridge, RFIC eluent degasser, IonPac AG 18-4 mm 4x50 mm guard column, and IonPac 18-4 mm 4x250 mm analytical column by Research Analytical Laboratory in University of Minnesota. RESULTS AND DISCUSSION Adsorption Kinetics Adsorption kinetics of the nylon-pGMA-FeBisHOPO is shown in Figure 3. Adsorption equilibrium is reached at 180 min with adsorption capacity of 4.4 mg P / g membrane. At 60 min, 70% of qe (3.1 mg / g) is achieved. The first order and second order kinetics model were used to fit the kinetics curve and first order fits better due to the better agreement with experimental and fitted qevalue and higher R2. It has been proposed that the 1st order usually indicates the adsorption process is diffusion controlled as the 1storder kinetics equation shares the same mathematical form as external diffusion model (Wang, J.; Guo, X. Journal of Hazardous Materials 2020, 390, 122156) and more likely to be observed when there is a polarity mismatch between absorbate and adsorbent (Guo, X.; et al., Chemosphere 2019, 228, 300–308). In this case, phosphate is a hydrophilic molecule with high hydration energy(-522 kJ / mol for H2PO4- and -1170 kJ / mol for HPO42-)4while the substrate is nonpolar; thus, diffusion of phosphate in water into membrane phase is difficult and slow due to the high energy barrier of overcoming hydration. Adsorption Isotherm and Thermodynamics The adsorption isotherm is shown in Figure 4. Experimentally, the maximum adsorption capacity is around 4.8 mg P / g membrane. Although Langmuir and Freundlich are the two most common isotherm models (Wang, J.; Guo, X. Chemosphere 2020, 258, 127279), neither of them could fit the experimental data satisfactorily (Figures 11A-11B). This is attributed to the presence of the cooperativity at initial stage of adsorption isotherm. Langmuir and Freundlich do not have parameters to account for this. To better describe the adsorption process, a less popular three-parameter model, Hill isotherm, was used to fit the experimental data with high goodness of fit (R2=0.993) and qmaxvalue that matches experimental result well (qmaxfit= 4.9 vs qmaxexp= 4.8 mg P / g membrane). Hill isotherm is not usually used to describe an adsorption process, but is commonly applied to biochemistry to describe the host-guest interaction in solution, such as oxygen binding to hemoglobin. Considering that in solution the receptor binds phosphate also via host-guest interaction, the Hill isotherm was used to model the adsorption data. The expression of Hill isotherm is very similar to the Langmuir model, but it has an exponential term n, known as the Hill coefficient, that accounts for the fact that each adsorption site (the molecular receptor in this case) can bind more than one absorbate and that the adsorption of the first absorbate can impact the favorability of binding the subsequent absorbates. A coefficient larger than 1 means positive cooperativity while less than 1 indicates negative cooperativity. An earlier study also suggests that despite the value of n not being an estimate on the number of guests per host, it provides a minimum value of the stoichiometry (Weiss, J. N. The FASEB Journal 1997, 11 (11), 835–841). In this case, considering there are only 2 available coordination sites on the iron center and a fitted n value of 1.88, it is likely that each binding site can bind two phosphates with positive cooperativity. Of notice, similar positive cooperativity was also commonly observed on previously developed lanthanide based phosphate receptors using the same chelating unit (HOPO) (Huang, S.-Y.; et al., Inorg. Chem.2019, 58 (23), 16087– 16099). To further investigate the thermodynamic driving force of the adsorption process, isotherm curves for nylon-pGMA-FeBisHOPO were measured under 20 °C, 37 °C and 60 °C (Figure 5A). The graph can be divided into two regions. The first region (rising zone) is where adsorption capacity rises quickly as phosphate concentration increases, and usually this indicates the rapid saturation of adsorption sites by phosphate at low concentration. As temperature increases, the curve rises at lower concentrations and the isotherm curve is essentially shifting to the left from 20 °C to 60 °C, suggesting the affinity for phosphate increases. The affinity constants obtained by fitting the isotherm in rising zone also supported this, as K increases from 1.36 x 104at 20 °C to 7.61 x 104at 60 °C (Figure 5B). The enthalpy and entropy change calculated from the Van’t Hoff equation for this process is 34.8 kJ / mol and 198 J / mol-K respectively, with ΔG being -23.2 kJ / mol at room temperature. Overall, this is an entropy-driven spontaneous process with large a enthalpy penalty. The positive entropy may be due to the release of the weakly bound bicarbonate, of which hydration number is only 5-6 (Vchirawongkwin, V.; et al., Journal of Computational Chemistry 2010, 31 (2), 249–257; .Dopieralski, P. D.; et al., Chemical Physics Letters 2011, 507 (1), 89–95) compared to 10 and 20 for H2PO4- and HPO42-respectively (Eiberweiser, A.; et al., J. Phys. Chem. B 2015, 119 (16), 5270–5281), resulting in higher freedom for water molecules in the solution. A similar entropy driven process has also been noted in another phosphate removal material by ligand exchange (Zhang, B.; et al.,. Chemical Engineering Journal 2018, 353, 361–372; Kumar, I. A.; Viswanathan, N. Carbohydrate Polymers 2018, 183, 173–182). The second region, known as saturation zone, shows some interesting features. After adsorption sites are quickly occupied in the first stage, nearly all isotherm models either predict slowly increasing qe(physisorption models such as Freundlich and BET) or constant qe(chemosorption models such as Langmuir and Redlich-Peterson) (Wang, J.; Guo, X. Chemosphere 2020, 258, 127279). However, in this case, at higher temperatures (37 °C and 60 °C) adsorption capacity abnormally decreases when Ceis larger than 40 ppm, not following a typical adsorption behavior. This can be attributed to the temperature’s effect on polymer brush conformation. The polymer brush with receptor possesses thermoresponsive characters due to the hydroxyl and ester group; polymer brushes with similar moieties are known to collapsxe with higher temperature and kosmotropic ion concentration (Johnson, E. C.; et al., Polymer 2021, 214, 123287; Murdoch, T. J.; et al., Journal of Colloid and Interface Science 2017, 490, 869–878; Robertson, H.; et al., Journal of Colloid and Interface Science 2021, 586, 292–304). While increasing the temperature promotes the adsorption process itself, increasing temperature and phosphate concentration also induces the polymer brush’s collapse, which makes receptors folded in the polymer cluster and no longer available for binding. Regeneration of Membranes and Phosphate Removal Performance in Water and WAS Elution From a sustainability and economy perspective, easy regeneration of absorbate and full recovery of absorbed phosphate are desired for applications. The adsorption capacity was measured for 10 cycles for the membrane in 50 ppm phosphate solution at 1 hour and 3 hours. The adsorption capacity at 1 and 3 hours stays constant over cycles and does not decrease (Figure 4), with the average adsorption capacity at 3 hours(q3h) being 4.51 mg P / g membrane and at 1 hour(q1h) 3.22 mg P / g membrane, 70% of q3h. This agrees well with the previously measured adsorption isotherm and kinetics. Besides simple phosphate solution, the same regeneration experiment was performed for 15 cycles in elution of WAS obtained from wastewater treatment plant (Figure 7A). The phosphate concentration in WAS elution is 54.3 ppm and 38.6 ppm before and after adsorption respectively. Again, the adsorption capacity stays constant, with an average adsorption capacity of 3.1 mg P / g membrane. In addition to regeneration, in the 11-15thcycle the amount of absorbed and desorbed phosphate was measured (Figure 7B); over the 5 cycles an average recovery rate of 95% is achieved. It is also important that the recovered phosphate solution should be clean, so a 27-element ICP-MS analysis was used to detect the presence of contaminants (Table 1) in both WAS elution and recovered phosphate solution. Of elements surveyed, Ca, Cu, Fe, K, Mg, Mn, Na, Sr, Zn were detected. Except for sodium where the increase is due to sodium bicarbonate, all other metal contents decreases by 80-85% in concentration, suggesting that the membrane can be used to remove and recover phosphate in a relatively clean manner in real life samples. Table 1 Interference Studies and Adsorption Mechanism Despite the good regeneration and recovery performance, it was also observed that when equilibrium phosphate concentration is the same, adsorption capacity for phosphate decreases in WAS elution compared to pure phosphate solution. At Ceof 38.6 ppm, qeis 3.1 mg / g in WAS elution and 4.7 mg / g in pure phosphate solution; about 34% adsorption capacity is lost. The same trend also happened when nylon-pGMA-FeBisHOPO was tested in other matrices (Figure 13). About 20% adsorption capacity is lost in Mississippi river sample spiked with 60 ppm phosphate and nearly 75% is lost in wastewater influent. To figure out the interfering factors, two representative species, NaCl and glucose, were tested. NaCl is a typical ionic species existing in nearly all water samples while glucose is a common organic compound with high water solubility and hydrogen bonding characters. In competitive adsorption experiments with 1.615 mM(50 ppm) phosphate, 0.1 M glucose has no effect on adsorption while the presence of 0.1 M NaCl reduces adsorption by more than 90% (Figure 12). In a subsequent phosphate-NaCl titration, the phosphate adsorption capacity also decreases to 75%, 50%, 25% with 5mM, 10 mM and 25 mM NaCl background respectively (Figure 12). In a further adsorption experiment of 50 ppm phosphate in the presence of 5 mM of various salts, it can be seen that while keeping the anion the same (Cl-), varying the cation (NH4+, K+, Na+, Li+) does not impact the adsorption capacity (Figure 8A); however, varying anions has significant effects. As shown in Figure 8B, for monovalent species, going from F- to I-, the adsorption capacity decreases from 3.55 to 1.4 mg P / g. The NaCl and anions’ impact on adsorption actually correspond to the commonly seen specific ion effect on polymer brush or similar systems (Willott, J. D.; et al., Progress in Polymer Science 2017, 64, 52–75; Yokokura, T. J.; et al., Biomacromolecules 2024, 25 (1), 328–337). For a charged polymer brush, high ionic strength will cause it to collapse due to the ion pairing and charge screening. For example, in the contact angle measurement for nylon- pGMA-FeBisHOPO, the membrane soaked in water shows much better wettability and smaller contact angle (76°) compared to the one soaked in 100 mM NaCl solution (100°, Figures 14A and 14B), indicating a more hydrophobic surface with high salt concentration and commonly seen as a result of polymer collapse (Moya, S.; et al., Angewandte Chemie International Edition 2005, 44 (29), 4578–4581). In addition to concentration, the ability to screen charge and induce polymer collapse also depends on ion types. Following the Hofmeister series, I- is a poorly solvated chaotropic anion with a higher tendency to enter the polymer phase and pair with the charge on the polymer brush. As a result, the polymer brush’s positive charges are screened by I- and hydrophilicity decreases significantly, which further causes the collapse of polymer and reduces the accessibility of the receptor towards phosphate. Fluoride (F-), on the other hand, is tightly hydrated and less likely to interact with charges on polymers so it has the least impact on adsorption capacity (Kou, R.; et al., Langmuir 2015, 31 (38), 10461–10468). Here a reverse effect is also seen for sulfate, a kosmotropic and strongly hydrated species yet reducing adsorption capacity even more than the chaotropic iodide does. This is due to that while concentration is the same, the divalent anion renders three times higher ionic strength which inherently induces polymer brush collapse. Moreover, divalent anions increase the hydrophobicity of polymer more effectively by cross-linking multiple cationic polymer brush and dehydrating the polymer (Moya, S.; et al., Angewandte Chemie International Edition 2005, 44 (29), 4578–4581; Wang, X.; et al., Langmuir 2011, 27 (16), 9895–9901). The most direct evidence for polymer collapse is the measurement of polymer brush thickness by ellipsometry, atomic force microscopy or quartz crystal microbalance with dissipation (QCM-D) measurements. These techniques require the polymer brush to be developed in a special substrate such as silicon wafer or metal surface. The porous nylon described herein is not suitable for these techniques. Although the collapse of polymer chain has not be probed directly, the ion pairing effect and qualitatively the collapse of polymer brush can be assessed by measuring the membrane’s adsorption capacity not only towards phosphate but also other anions. The material’s adsorption capacity of sulfate and chloride was measured using ion chromatography at two different starting concentrations and phosphate adsorption at pH = 9 (Table 2). Table 2 Comparison between the adsorption capacity of phosphate and chloride / sulfate at two different concentrations For sulfate, the adsorption capacity decreases from 2.84 mg / g to 1.5 mg / g as Ceincreases from 42.2 to 85 ppm. This again indicates the collapse of polymer chain, which happens when ionic strength is at least 8.67 mM (corresponding to 92.5 ppm sulfate’s ionic strength). Interestingly, when Ceis the same, the adsorption capacity, without polymer brush collapse, of either chloride or sulfate, in μmol / g, is always about half of that of phosphate. When pH=9, the phosphate adsorption also decrease to 50% value of q at pH=7.2. Considering the value of Hill’s coefficient (n=1.88 and ≥ number of adsorption sites) described earlier and based on the adsorption data, it is proposed that there are actually two adsorption sites per complex (Figure 9). The first adsorption site is the positively charged tertiary amine and the second one is the iron center of the complex. Since the first site on a tertiary amine is simply a positive charge under neutral pH, it can bind any anion, especially chaotropic and divalent anions via electrostatic interaction. Such binding, along with increasing ionic strength, reduces phosphate adsorption capacity. When pH is elevated, the tertiary amine is not charged and only complex is available for phosphate binding, so adsorption capacity reduces to about 50% of original value. Preparation of nylon-pGMA membrane Nylon-OH was prepared from pristine nylon by soaking 40 pcs of 1 cm2nylon membranes in 20 ml 85% phosphoric acid with 0.8 ml formalin in a vial. Reaction was carried for 12 hours at 60 °C with gentle stirring. After reaction membranes were rinsed by water to remove excess reagent and air dried. Then nylon-OH was made into nylon-Br by placing 40 pcs nylon-OH membranes in 50 ml chloroform with 0.8 ml α-bromoisobutyryl bromide and 2 ml triethylamine; reaction was carried in a round bottom flask in ice bath for 15 min and room temperature for 45 min. Nylon- Br was rinsed by acetone and water multiple times and dried for use. In surface-initiated atomic transfer radical polymerization, 2ml glycidyl methacrylate was mixed with 100 ml water in a round bottom flask. The solution was purged with nitrogen for 40 min with vigorous stirring. After purging, 40 pcs of nylon-Br, 15 mg CuBr, and 24 uL HMTETA were quickly added. The reaction was run under nitrogen atmosphere for 3 hours with gentle stirring. The product (nylon-pGMA) was rinsed by water. For the immobilization reaction of FeBisBOPO, 30 mg Na2BisHOPO (71.2 µmol) was dissolved in 6 ml 2:1 MeOH: DMSO.1.1 molar equivalence of FeCl3·6H2O, 10 molar equivalence of triethylamine and 9 pieces of nylon-pGMA membranes were added to the solution and reaction was carried at 60 °C for 24 hours. The membranes were then rinsed with water and stored in 50 mM bicarbonate. Scheme 1 shows the preparation of nylon-pGMA-FeBisHOPO from nylon.

[0003] Scheme 1 Phosphate Adsorption Data in Blood Experimental conditions: A 1 cm2membrane as described above was placed in 1 ml serum at 37oC for 1 hour. The serum was then analyzed for phosphate. In summary, a phosphate receptor functionalized polymer brush on nylon membrane has been prepared The material is able to catch and release phosphate in relatively simple environments such as wastewater activated sludge and phosphate solutions as well as blood and serum. Example 2. EXPERIMENTAL Nylon-pGMA-EuLysHOPO preparation protocol is shown in Scheme 2. The pGMA- nylon was prepared in the same way as described for nylon-pGMA-FeBisHOPO above. The final step, conjugation of EuLysHOPO onto pGMA-nylon, was performed as follows: 30mg EuLysHOPO was dissolved in 6 mL 2:1 MeOH: DMSO solution with 10 molar equivalence of triethylamine added.9 pieces membrane (1cm2each) were placed in this solution for 24 hours under 60 °C. After reaction membrane was washed thoroughly by MeOH and 50 mM sodium bicarbonate solution and dried prior to use. Scheme 2 shows the preparation of nylon-pGMA-EuLysHOPO from nylon. Scheme 2 After material preparation, adsorption kinetics, isotherm, thermodynamics, regeneration of materials, recovery of phosphate from WAS were performed for this material. Except for kinetics, all experiments were done in triplicates using three pieces of membrane. The experimental procedure for adsorption is similar to that of nylon-pGMA-FeBisHOPO reported above. In adsorption kinetics, 9 pieces membranes (1cm2, 16mg each) were placed in 18 mL 50 ppm phosphate solution; aliquots of solution were taken out and analyzed at different time intervals. Adsorption isotherm was performed by placing 1 cm2membrane in 2 mL solution of various phosphate concentrations and phosphate in solution was analyzed after 3 hours to calculate adsorption capacity. Adsorption thermodynamics is the same as adsorption isotherm but performed at elevated temperatures (37 °C and 60 °C). In material regeneration, 1 cm2membrane was placed in either 50 ppm phosphate solution or WAS for 3 hours.10 adsorption cycles were performed for 50 ppm phosphate solution and 15 cycles were performed for WAS. Between each cycle membrane was washed by 50 mM bicarbonate solution for regeneration. For phosphate recovery measurement, the phosphate released into 2 mL 50 mM bicarbonate during regeneration was measured for 11thto 15thcycle of the WAS regeneration. The amount of released phosphate was compared to that of absorbed phosphate in adsorption cycle. Elemental analysis for the 50 mM bicarbonate solution containing released phosphate was performed by ICP-MS. RESULTS & DISCUSSION Adsorption kinetics was shown in Figure 15. This kinetics pattern is very similar to that of nylon-pGMA-FeBisHOPO, where a diffusion controlled first order kinetics was observed and 3 hours were needed to reach equilibration. The adsorption capacity at equilibration is smaller (1.6 mg / g) compared to the FeBisHOPO counterpart, probably due to less receptors were functionalized to the polymer chain as less molar amount of receptor were used in functionalization. Adsorption isotherm and thermodynamics are shown in Figure 16 and 17, respectively. Similar to its FeBisHOPO counterpart, a Hill isotherm model was used to describe the adsorption behavior with strong positive cooperativity, and thermodynamics analysis also revealed an entropy driven process due to more freed water molecules from phosphate’s hydration sphere. Of notice, despite the adsorption capacity is smaller for this membrane compared to nylon-pGMA-FeBisHOPO, its affinity towards phosphate is comparable or higher than that of nylon-pGMA-FeBisHOPO under all temperatures measured (20°C, 37 °C and 60 °C). This agrees with solution studies of the FeBisHOPO and EuLysHOPO reported earlier, where EuLysHOPO binds phosphate more strongly. (Inorg. Chem.2019, 58, 23, 16087–16099 AND JACS Au 2022, 2, 7, 1604–1609) In addition to adsorption behavior, its reusability for phosphate removal was studied in both ideal 50 ppm phosphate solution and WAS samples from the wastewater treatment plant. As shown in Figure 18A, over 10 adsorption cycles, the membrane’s adsorption capacity stabilized at 1.68 mg / g, indicating the retain of adsorption sites. In WAS where composition is more complicated, still the membrane can be reused for 15 cycles with no adsorption capacity decay, although the adsorption capacity is lower compared to in pure phosphate due to high ionic strength of WAS. The phosphate recovery efficiency and purity analysis of recovered phosphate are shown in Figure 19 A and 19 B respectively. From 11th-15thcycle, on average about 86% phosphate absorbed in WAS can be released in 50 mM bicarbonate solution; this is smaller than the 95% recovery for FeBisHOPO-pGMA-nylon, as stronger affinity towards phosphate means harder release of it under the same regeneration condition. In terms of purity of recovered phosphate. Figure 19 B shows that for metals of significant presence(Mg, Mn, Zn) in WAS, their concentrations decreases significantly by 93%, 87% and 80% in the solution with recovered phosphate, indicating the phosphate was recovered in a much cleaner fashion. In summary, compared to FeBisHOPO-pGMA-nylon reported in Example 1, this material behaves very similar in terms of adsorption mechanism. In application, it is able to be reused for phosphate removal, although due to its higher affinity towards phosphate the recovery rate is lower than the FeBisHOPO counterpart in Example 1. Example 3. EXPERIMENTAL PES-pGMA-FeBisHOPO preparation method is shown in Scheme 3. In the first step, surface hydroxyl group on PES was generated by treating with oxygen plasma instead of using formaldehyde with phosphoric acid. The later step is exactly the same as that of nylon-pGMA- FeBisHOPO, where The experimental procedure for adsorption studies is similar to that of Example 2, where 1 cm2material is placed in 2 mL phosphate solution. Due to the longer equilibration time of this material, all adsorption studies were carried out for 8 hours instead of 3 hours. However, for practical application, the adsorption experiments of materials in WAS and the phosphate recovery process were carried for 3 hours

[0004] Scheme 3 shows the preparation of PES-pGMA-FeBisHOPO from PES. Scheme 3 RESULTS AND DISCUSSION The kinetics behavior of PES-pGMA-FeBisHOPO nylon is shown in Figure 20. It is still a first order diffusion-controlled process; however, the time needed to reach equilibrium is significantly longer (480 min) than the nylon-based material (180min). This much longer adsorption is associated with the charge of plasma treated PES. Plasma treatment is known to produce various oxygen containing groups; in addition to hydroxyl, ester or carboxylate will also be present (Surf. Interface Anal.2007; 39: 476–481). The carboxylate group on the surface, negatively charged under pH 7.2, leads to greater repulsion towards also negatively charged phosphate from diffusion onto the material, increasing the time it takes to reach equilibrium. Nevertheless, despite of slow kinetics, the adsorption capacity at equilibrium is not impacted (4.77 mg / g), similar to that of nylon-pGMA-FeBisHOPO (4.4 mg / g). Figure 21 shows the adsorption isotherm of PES-pGMA-FeBisHOPO. The isotherm is used to describe the adsorption process. Compared to nylon-pGMA-FeBisHOPO, it has higher adsorption capacity (7.75 mg / g) yet lower affinity as all sites are saturated when solution phosphate is more than 125ppm, significantly higher than nylon-based materials (40 ppm). The lower affinity is also attributed to the surface negative charge imposed by carboxylate. In solution chemistry study, it has been well known that negative charge in proximity with binding sites may decrease or even eliminate affinity for the binding ( Org. Biomol. Chem., 2004,2, 1624-1632). Regeneration studies of this material in 50 ppm phosphate solution are shown in Figure 22; 100% of adsorption capacity (4.8 mg / g) is retained over 10 cycles of adsorption, indicating reusability of the material. In WAS regeneration experiments, although adsorption was carried only for 3 hours for application consideration, an average adsorption capacity of 4.34 mg / g was measured across 15 cycles, and a 75% recovery rate was obtained from 11thto 15thcycles. Despite of lower affinity and lower recovery rate, the adsorption capacity in WAS is highest for PES-pGMA-FeBisHOPO compared to the nylon based material in Example 1 and 2. All publications, patents, and patent documents are incorporated by reference herein, as though individually incorporated by reference. The invention has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.

Claims

CLAIMS We claim:

1. A compound or salt thereof comprising: (a) a first polymer; (b) a second polymer operably linked to the first polymer; and (c) a metal complex operably linked to the second polymer.

2. The compound of claim 1, wherein the first polymer is operably linked to 20 or more second polymers.

3. The compound of claim 1, wherein the first polymer is operably linked to 200 or more second polymers.

4. The compound of any one of claims 1-3, wherein the first polymer is linked to the second polymer through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 20 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1-C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl.

5. The compound of any one of claims 1-3, wherein the first polymer is linked to the second polymer through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 10 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1-C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl.

6. The compound of any one of claims 1-5, wherein 20 or more of the second polymers are linked to one or more metal complexes.

7. The compound of any one of claims 1-5, wherein 200 or more of the second polymers are linked to one or more metal complexes.

8. The compound of any one of claims 1-7, wherein the second polymer is linked to the metal complex through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 40 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1-C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl.

9. The compound of any one of claims 1-7, wherein the second polymer is linked to the metal complex through a linker that comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 25 carbon atoms wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, and wherein the chain is optionally substituted with one or more (e.g.1, 2, 3, 4, 5 or more) substituents independently selected from (C1-C4)alkyl, (C1-C6)alkoxy, oxo (=O), and halo, wherein each Rais independently H or (C1-C6)alkyl.

10. A compound or a salt thereof of claim 1 comprising a first polymer (P1) substituted with one or more moieties of formula I:wherein the D group of formula I is attached to the first polymer; R1is (C1-C6)alkyl; R2is (C1-C6)alkyl; D is (C1-C6)alkyl or D is absent; Q is a second polymer (P2) comprising one or more moieties of formula II:II wherein the carbonyl group of formula II is attached to the second polymer; X is O or NRa;Y is (C1-C6)alkyl; Z is OH or NHRb; Rais H or (C1-C6)alkyl; Rbis H or (C1-C6)alkyl; and L is a linker or L is absent; W is a metal complex.

11. The compound of any one of claims 1-10, wherein the second polymer comprises a hydrocarbon polymer.

12. The compound of any one of claims 1-11, wherein the second polymer comprises polyethylene, wherein the polyethylene is optionally substituted with one or more (C1-C6)alkyl.

13. The compound of any one of claims 1-12, wherein the second polymer comprises polypropylene.

14. The compound of any one of claims 1-13, wherein the second polymer has a molecular weight of about 500 to about 600,000.

15. The compound of any one of claims 1-14, wherein the second polymer comprises about 20 to about 20,000 monomer residues.

16. The compound of claim 15, wherein the monomer comprises an ethyl group or propyl group.

17. The compound of claim 16, wherein each monomer comprises.

18. The compound of any one of claims 10-17, wherein the second polymer comprises about 20 to about 20,000 moieties of formula II.

19. The compound of any one of claims 1-17, wherein the second polymer comprises one or more monomers (e.g., monomer residues) of formula IIIa:IIIa.

20. The compound of any one of claims 10-19, comprising one or more moieties of formula III’wherein, each M is a monomer, wherein at least one M is a monomer (monomer residue) of formula III’:III n is 20 – 20,0000; and R4is a polymer endgroup.

21. The compound of claim 20, wherein each M is independentlywherein one or more of M is IIIa; and Z1is O or NRb.

22. The compound of any one of claims claim 21, wherein Z1is O.

23. The compound of any one of claims 10-22, wherein R1is methyl.

24. The compound of any one of claims 10-23, wherein R2is methyl.

25. The compound of any one of claims 10-24, wherein X is O.

26. The compound of any one of claims 10-25, wherein Y is -CH2-.

27. The compound of any one of claims 10-26, wherein Z is -OH.

28. The compound of any one of claims 1-27, wherein the first polymer comprises a polyamide, a polysulfone a polyether sulfone, or polymethyl methacrylate.

29. The compound of any one of claims 1-27, wherein the first polymer comprises a polyamide, a polysulfone, polyether sulfone or polymethyl methacrylate; wherein the second polymer is linked to an amide nitrogen of the polyamide; wherein the second polymer is linked to a phenyl of the polysulfone or the polyether sulfone; wherein the second polymer is linked to the oxygen or the carbonyl of the polymethyl methacrylate.

30. The compound of any one of claims 10-29, wherein the first polymer comprises a polyamide, a polysulfone or a polyether sulfone; wherein the one or more moieties of formula I is attached to an amide nitrogen of the polyamide and D is (C1-C6)alkyl; and wherein the one or more moieties of formula I is attached to a phenyl of the polysulfone or the polyether sulfone and D is absent.

31. The compound of any one of claims 10-29, wherein the first polymer comprises a polyamide, a polysulfone or a polyether sulfone;wherein the one or more moieties of formula I is attached to an amide nitrogen of the polyamide and D is -(CH2)-; and wherein the one or more moieties of formula I is attached to a phenyl of the polysulfone or the polyether sulfone and D is absent.

32. The compound of any one of claims 28-31, wherein the polyamide is nylon.

33. The compound of claim 32, wherein the nylon is nylon 6,6 or nylon 6.

34. The compound of any one of claims 1-31, wherein the first polymer compriseswherein m1, m2, m3 and m4 are each independently about 100 to about 250,000.

35. The compound of any one of claims 1-34, wherein the first polymer has a molecular weight of about 1000 to about 2,500,000.

36. The compound of any one of claims 10-27, wherein the L is absent or L comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 20 carbon atoms, wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, wherein each Rais independently H or (C1-C6)alkyl.

37. The compound of any one of claims 10-27, wherein the L is absent or L comprises a branched or unbranched, saturated or unsaturated, hydrocarbon chain, having from 1 to 10carbon atoms, wherein one or more of the carbon atoms is optionally replaced independently by -O-, -S, -N(Ra)-, wherein each Rais independently H or (C1-C6)alkyl.

38. The compound of any one of claims 10-27, wherein the L is absent or L is –(CH2)n-V- wherein n is one to ten and V is O, S or -N(Ra)-, wherein Rais H or (C1-C6)alkyl.

39. The compound of any one of claims 1-38, wherein the metal complex comprises iron or a rare earth metal.

40. The compound of any one of claims 1-39, wherein the metal complex is:

41. The compound or a salt thereof of claim 1 wherein the metal complex is an iron or rare earth metal complex and claim 40 wherein the rare earth metal is LaIII, CeIII, PrIII, NdIII, SmIII, EuIII, GdIII, TbIII, DyIII, HoIII, ErIII, TmIII, YbIII, LuIII, ScIII, YIIIor PmIII.

42. A material or device comprising one or more compounds or a salt thereof as described in any one of claims 1-41.

43. The material or device of claim 42, wherein the material or device is a hydrogel, membrane, nanoparticle, or other material.

44. The material or device of claim 42, wherein the material or device is a membrane.

45. A method to detect or capture inorganic phosphate, comprising contacting the phosphate (e.g., a sample comprising phosphate) with a compound or a salt thereof, or a material or device as described in any one of claims 1-44.

46. The method of claim 45, wherein the phosphate is selectively detected or captured in the presence of other anions.

47. The method of claim 46, wherein the other anions are selected from the group consisting of carbonate, nitrate, sulfate, halides, arsenate and pyrophosphate.

48. The method of any one of claims 45-47, wherein the phosphate (e.g., a sample comprising phosphate) is contacted with the compound or a salt thereof, or a material or device as a liquid or liquid mixture or a mixture (e.g., at about neutral pH).

49. The method of claim 48, wherein the liquid or liquid mixture or a mixture is an aqueous liquid or aqueous liquid mixture or aqueous mixture.

50. The method of any one of claims 48-49, wherein the liquid or liquid mixture or a mixture or aqueous liquid or aqueous liquid mixture or aqueous mixture is blood or serum.

51. The method of any one of claims 48-49, wherein the liquid or liquid mixture or a mixture or aqueous liquid or aqueous liquid mixture or aqueous mixture is wastewater.

52. The method of any one of claims 48-49, wherein the liquid or liquid mixture or a mixture or aqueous liquid or aqueous liquid mixture or aqueous mixture is waste activated sludge.

53. The method of any one of claims 45-52, wherein the phosphate is captured by the compound or a salt thereof, or the material or the device.

54. The method of claim 53, wherein the phosphate is captured from an aqueous mixture, aqueous solution, wastewater or waste activated sludge.

55. The method of any one of claims 53-54, wherein the phosphate that is captured by the compound or a salt thereof, or the material or the device is essentially removed from the compound or a salt thereof, or the material or the device by contacting the compound or a salt thereof, or the material or the device with bicarbonate (e.g., sodium bicarbonate).

56. The method of claim 55, wherein the compound or a salt thereof, or the material or the device that is essentially free of phosphate is contacted again with phosphate as described in any one of claims 45-52.

57. A method to treat hyperphosphatemia in a mammal in need thereof comprising contacting the blood of the mammal in need thereof, with a compound or salt thereof, or a material or device as described in any one of claims 1-44.

58. The method of claim 56, wherein the mammal has kidney disease (e.g., chronic, advanced, acute or advanced / acute kidney disease).

59. A method to treat wastewater or waste activated sludge comprising contacting the wastewater or waste activated sludge with a compound or salt thereof, or a material or device as described in any one of claims 1-44.

60. The method of claim 59, wherein phosphate concentration of the wastewater or waste activated sludge is lowered after contacting the wastewater or waste activated sludge with the compound or salt thereof, or a material or device.

61. The method of any one of claims 59-60, further comprising contacting the compound or salt thereof, or a material with bicarbonate (e.g., sodium bicarbonate).

62. The method of claim 61, further comprising contacting the compound or salt thereof, or the material with wastewater or waste activated sludge.

63. A method to reduce the concentration of phosphate in wastewater or waste activated sludge comprising contacting the wastewater or waste activated sludge with a compound, or salt thereof, or material, or device as described in any one of claims 1-44, under conditions where the concentration of phosphate in the wastewater or the waste activated sludge is reduced.

64. The method of claim 63, further comprising contacting the compound or salt thereof, or a material with bicarbonate (e.g., sodium bicarbonate).

65. The method of claim 64, further comprising contacting the compound or salt thereof, or the material with wastewater or waste activated sludge.

66. The method of claim 60 or 63, wherein the phosphate is reduced 1% or more, 2% or more, 5% or more, 10% or more 20% or more 50% or more 70% or more 90% or more, or 95% or more.

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