Compounds for the selective solid-liquid extraction and liquid-liquid extraction of lithium chloride

Abstract

The present disclosure relates to calixpyrrole compounds and compositions thereof. The calixpyrrole compounds are chemical groups which are located in such a manner so as to be useful for the selective extraction of specific salts. Also provided herein are compositions and methods of use thereof.

Description

[0001] DESCRIPTION COMPOUNDS FOR THE SELECTIVE SOLID-LIQUID EXTRACTION AND LIQUID-LIQUID EXTRACTION OF LITHIUM CHLORIDE This application claims the benefit of priority to United States Provisional Application No. 63 / 680,349, filed on August 7, 2024, the entire contents of which is hereby incorporated by reference. This invention was made with government support under Grant No. DE-FG02- 01ER15186 and Grant No. DE-SC0024393 awarded by the Department of Energy. The government has certain rights in the invention BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates generally to the fields of chemistry, metal extraction, and macrocycles. The present disclosure relates to calixpyrrole compounds and methods for selective extraction of salts such as lithium salts. 2. Description of Related Art The lithium ion (Li+) supports key features of modern life; it is an essential component in lithium ion batteries (LIBs), ceramics, and lubricating greases, and is used as a pharmaceutical agent in treating depressive illness (Armand and Tarascon, 2008; Oruch et al., 2014; Evarts, 2015; Martin et al., 2017; Kavanagh et al., 2018; Saraim and Lippmann, 2018). Currently rechargeable LIBs account for approximately 80% of the end use of lithium (U.S. Geological Survey: Reston, VA, 2022). According to U.S. Geological Survey (USGS), global consumption of lithium rose from approximately 95,000 tons in 2021 to 134,000 tons in 2022.7 While the global demand for lithium is increasing, the available lithium reserves remain limited. In addition, selective separation of the lithium ion from its sources requires an energy- and labor-intensive process, and can be time-consuming (Swain, 2017; Haddad et al., 2023). In principle, lithium may be separated from rocky ores, salt lakes, brines, and sea water (Swain, 2017; Haddad et al., 2023; Meshram et al., 2014). When rocky ores or clays -1-4917-6162-2874, v. 1 are used as the lithium source, roasting at a high temperature (1,100 °C) is followed by baking at 250 °C in acid (Swain, 2017). Undesired salts are then removed via several energy- and water-intensive steps that are a source of environmental concern (Vieceli et al., 2017; Yelatontsev and Mukhachev, 2021; Gao et al., 2023). The ocean is the largest source of lithium; however, selective extraction of lithium from seawater is challenging because of the very low concentration of the lithium cation amounting to only 0.1 ~ 0.2 ppm while other potentially competitive ions exist at much higher concentrations (Nishihama et al., 2011; Loganathan et al., 2017; Yang et al., 2018; Harvianto et al., 2016; Liu et al., 2020; He et al., 2020). At present, salt lake brines supply the majority of the commercial lithium. However, the extraction of lithium from brine However, the extraction of lithium from brine reservoirs typically requires evaporation of residual water over a period of months to years (Flexer et al., 2018; Liu et al., 2019; Xu et al., 2021; Sun et al., 2021; Zhao et al., 2020; Khalil et al., 2022; Ying et al., 2023). A huge amount of water is also necessary to remove unwanted ions and contaminants. Because of the shortcomings of conventional extraction processes efforts are being devoted increasingly to so-called direct lithium extraction (DLE) methods. In this context, the use of porous lithium sorbents and ion exchange materials has attracted attention because of their relative simplicity and potential to operate at relatively low levels of environmental stress (Stringfellow and Dobson, 2021; Vera et al., 2023). Unfortunately, most DLE methods developed thus far require additional processing steps to free the lithium ions from the lithium adsorbing materials. (Stringfellow and Dobson, 2021; Vera et al., 2023). Therefore, so-called liquid-liquid extraction (LLE) and solid-liquid extraction (SLE), wherein an extractant capable of selectively complexing lithium salts is used to promote DLE, continue to attract interest. In principle, these approaches could enable the direct and selective extraction of lithium salts from a mixed salt solid phases or brines. Nevertheless, it remains challenging to design and construct an extractant possessing the ability to extract selectively lithium salts due to the small size of the lithium cation and its relatively high hydration energy (ΔhydG* = -475 kJ / mol), as well as the interference of other competing cations, such as Na+, K+, Mg2+, and Ca2+(Marcus, 1991; Xu et al., 2021; Zhang et al., 2023). For instance, Mg2+not only has a similar ionic radius (72 pm for Mg2+vs 69 pm for Li+), it also has a higher net charge, and is typically present at ≥8x the concentration of Li+in most salt lake brines (Sun et al., 2021; Marcus, 1991). The likely presence of Mg2+and other potential interferants underscores the challenge associated with designing Li+-selective extractants. Therefore, new compounds and methods for binding Li+are needed, particularly -2-4917-6162-2874, v. 1 for ameliorating the unmet challenge of direct separation of LiCl from mixtures, either in brine form or after evaporation to a solid salt mixture or from a liquid to another liquid composition. -3-4917-6162-2874, v. 1 SUMMARY OF THE INVENTION In some aspects, the present disclosure relates to compounds that show improved selectivity for lithium in aqueous media. In some aspects, the present disclosure provides compounds of the formula: , wherein: R1, R1′, R2, R2′, R3, R3′, R4, and R4′ are each independently hydrogen, hydroxy, amino, cyano, or halo; or alkyl(C≤6), alkenyl(C≤6), alkynyl(C≤6), acyloxy(C≤6), alkoxy(C≤6), alkylamino(C≤6), dialkylamino(C≤12), amido(C≤6), or a substituted version of any of these groups; or one of these groups is attached to a solid support or a fluorophore; R5, R5′, R6, R6′, R7, and R8 are each independently hydrogen or alkyl(C≤12), cycloalkyl(C≤12), cycloalkenyl(C≤12), alkenyl(C≤12), alkynyl(C≤12), aryl(C≤12), heteroalkyl(C≤12), heterocycloalkyl(C≤12), alkoxy(C≤12), alkylamino(C≤12), dialkylamino(C≤18), amido(C≤12), or a substituted version of any of these groups; or one of these groups is attached to a solid support or a fluorophore; R9, R10, R11, and R12 are hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); L and L′ are taken together and form a group of the formula: , wherein: X and X′ are each independently arenediyl(C≤8) or substituted arenediyl(C≤8); Y and Y′ are each independently −O−, −C(O)−, −C(O)O−, −S(O)−, −S(O)2O−, −C(O)NRa−, or −S(O)2NRb−, wherein: -4- 4917-6162-2874, v.1 Raand Rbare each independently hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); or one or more of these groups is attached to a solid support or a fluorophore; Z is a group of the formula: (Ib), wherein: A1 and A1′ are each independently alkanediyl(C≤8), substituted alkanediyl(C≤8); and A2is heteroarenediyl(C≤24)or substituted heteroarenediyl(C≤24), wherein the group comprises at least 3 fused rings; or or a salt thereof. In some embodiments, the compounds are further defined as: , wherein: R1, R1′, R2, R2′, R3, R3′, R4, and R4′ are each independently hydrogen, hydroxy, amino, cyano, or halo; or alkyl(C≤6), alkenyl(C≤6), alkynyl(C≤6), acyloxy(C≤6), alkoxy(C≤6), alkylamino(C≤6), dialkylamino(C≤12), amido(C≤6), or a substituted version of any of these groups; R5, R5′, R6, R6′, R7, and R8are each independently hydrogen or alkyl(C≤6), alkenyl(C≤6), alkynyl(C≤6), or a substituted version of any of these groups; L and L′ are taken together and form a group of the formula: , wherein: X and X′ are each independently arenediyl(C≤8) or substituted arenediyl(C≤8); -5- 4917-6162-2874, v.1 Y and Y′ are each independently −O−, −C(O)−, −C(O)O−, −S(O)−, −S(O)2O−, −C(O)NRa−, or −S(O)2NRb−, wherein: Ra and Rb are each independently hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); Z is a group of the formula: (Ib), wherein: A1and A1′ are each independently alkanediyl(C≤8), substituted alkanediyl(C≤8); and A2 is heteroarenediyl(C≤24) or substituted heteroarenediyl(C≤24), wherein the group comprises at least 3 fused rings; or or a salt thereof. In some embodiments, the compounds are further defined as: , wherein: R1, R1′, R2, R2′, R3, R3′, R4, and R4′ are each independently hydrogen, hydroxy, amino, cyano, or halo; or alkyl(C≤6), alkenyl(C≤6), alkynyl(C≤6), acyloxy(C≤6), alkoxy(C≤6), alkylamino(C≤6), dialkylamino(C≤12), amido(C≤6), or a substituted version of any of these groups; L and L′ are taken together and form a group of the formula: , wherein: X and X′ are each independently arenediyl(C≤8) or substituted arenediyl(C≤8); -6- 4917-6162-2874, v.1 Y and Y′ are each independently −O−, −C(O)−, −C(O)O−, −S(O)−, −S(O)2O−, −C(O)NRa−, or −S(O)2NRb−, wherein: Ra and Rb are each independently hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); Z is a group of the formula: (Ib), wherein: A1and A1′ are each independently alkanediyl(C≤8), substituted alkanediyl(C≤8); and A2 is heteroarenediyl(C≤24) or substituted heteroarenediyl(C≤24), wherein the group comprises at least 3 fused rings; or or a salt thereof. In some embodiments, the compounds are further defined as: , wherein: L and L′ are taken together and form a group of the formula: , wherein: X and X′ are each independently arenediyl(C≤8) or substituted arenediyl(C≤8); Y and Y′ are each independently −O−, −C(O)−, −C(O)O−, −S(O)−, −S(O)2O−, −C(O)NRa−, or−S(O)2NRb−, wherein:Raand Rbare each independently hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); Z is a group of the formula: , wherein: -7- 4917-6162-2874, v.1 A1and A1′ are each independently alkanediyl(C≤8), substituted alkanediyl(C≤8); and A2 is heteroarenediyl(C≤24) or substituted heteroarenediyl(C≤24), wherein the group comprises at least 3 fused rings; or or a salt thereof. In some embodiments, X and X′ are both the same. In some embodiments, X and X′ are both arenediyl(C≤8) or substituted arenediyl(C≤8). In some embodiments, X and X′ are both arenediyl(C≤8). In some embodiments, X and X′ are both arenediyl(C≤6). In some embodiments, X and X′ are both benzenediyl. In some embodiments, Y and Y′ are both the same. In some embodiments, Y and Y′ are both −O−. In some embodiments, A1and A1′ are both the same. In some embodiments, A1and A1′ are both alkanediyl(C≤8) or substituted alkanediyl(C≤8). In some embodiments, A1 and A1′ are both alkanediyl(C≤8). In some embodiments, A1and A1′ are both methylene. In some embodiments, A2 is heteroarenediyl(C≤18) or substituted heteroarenediyl(C≤18), wherein the group comprises at least 3 fused rings. In some embodiments, A2is heteroarenediyl(C≤18), wherein the group comprises at least 3 fused rings. In some embodiments, A2is heteroarenediyl(C≤24), wherein the group comprises 3 fused rings. In some embodiments, A2 is heteroarenediyl(C≤18), wherein the group comprises 3 fused rings. In some embodiments, A2 is heteroarenediyl(C≤18), wherein the group comprises 3 fused rings and contains at least two nitrogen atoms. In some embodiments, A2 is heteroarenediyl(C≤18), wherein the group comprises 3 fused rings and contains two nitrogen atoms. In some embodiments, A2is phenanthrolinediyl. In some embodiments, A2is phenanthroline-2,9- diyl. In some embodiments, the compounds are further defined as: . -8- 4917-6162-2874, v.1 In other aspects, the present disclosure provides composition comprising a compound described herein and a salt. In some embodiments, the salt comprises an alkali metal cation. In some embodiments, the alkali metal cation is lithium(I). In some embodiments, the salt comprises a halogen anion. In some embodiments, the halogen anion is chloride. In some embodiments, the salt is lithium(I) chloride. In some embodiments, the compound is defined as: . In another aspect, the methods of sequestering a target compound in a first solution comprising contacting the first solution with a compound described herein. In some embodiments, the target compound is a salt. In some embodiments, the salt comprises an alkali metal cation. In some embodiments, the alkali metal cation is lithium(I). In some embodiments, the salt comprises a halogen anion. In some embodiments, the halogen anion is chloride. In some embodiments, the salt is lithium(I) chloride. In some embodiments, the first solution is an aqueous solution. In other embodiments, the compound is dissolved in a solvent prior to contacting the first solution. In some embodiments, the solvent is an organic solvent. In some embodiments, the organic solvent is nitrobenzene. In some embodiments, the organic solvent is chloroform. In some embodiments, the target compound is separated from first solution. In some embodiments, the compound further defined as: -9- 4917-6162-2874, v.1 . In still yet another aspect e provides methods of carrying out a liquid-liquid extraction of a salt from a first solution to form a complex with a compound described herein, wherein the compound is dissolved in a liquid. In yet another aspect, the present disclosure provides methods method of carrying out a solid-liquid extraction of a salt from a solid to form a complex with a compound described herein, wherein the compound is dissolved in a liquid. In some embodiments, the liquid is water. In some embodiments, the methods are carried out in the presence of one or more additional salts. Other objects, features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. Note that simply because a particular compound is ascribed to one particular generic formula doesn’t mean that it cannot also belong to another generic formula. -10- 4917-6162-2874, v.1 BRIEF DESCRIPTION OF THE DRAWINGS The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present disclosure. The disclosure may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein. FIGS. 1A – 1F show partial1H NMR spectra of (FIG. 1A) 2 (3 mM) only, (FIG. 1B) 2 + excess LiCl, (FIG.1C) 2 + excess NaCl, (FIG. 1D) 2 + excess KCl, (FIG. 1E) 2 + excess MgCl2, and (FIG. 1F) 2 + excess CaCl2 in CH3OH / CDCl3 (1:9, v / v). The asterisk (*) denotes the residual CHCl3peak in the NMR solvent. FIG. 2shows binding modes of receptor 2 for LiCl, MgCl2, and CaCl2 in 10% CH3OH in CDCl3as inferred from1H NMR spectroscopic analyses. FIG. 3 shows1H NMR spectra recorded during the titration of 2 (3 mM) with CaCl2 in CH3OH / CDCl3(1:9, v / v). The asterisk (*) denotes the residual CHCl3peak in the NMR solvent FIGS. 4A – 4F show partial1H NMR spectra of (FIG. 4A) 2 (3 mM) only, (FIG. 4B) 2 + excess LiBr, (FIG.4C) 2 + excess NaBr, (FIG.4D) 2 + excess KBr, (FIG.4E) 2 + excess MgBr2, and (FIG. 4F) 2 + excess CaBr2in CH3OH / CDCl3(1:9, v / v). The asterisk (*) denotes the residual CHCl3 peak in the NMR solvent. FIGS.5A-5E show partial1H NMR spectra of (FIG. 5A) 2 (3 mM) only, (FIG. 5B) 2 + excess LiF, (FIG. 5C) 2 + excess LiCl, (FIG. 5D) 2 + excess LiBr, and (FIG. 5E) 2 + excess LiI in CH3OH / CDCl3(1:9, v / v). The asterisk (*) denotes the residual CHCl3peak in the NMR solvent. FIG. 6 shows the1H NMR spectra recorded during the titration of 2 (3 mM) with LiCl in CH3OH / CDCl3 (1:9, v / v). The peaks marked as ▼ represent the proton signals corresponding to the LiCl complex of 2 (2•LiCl). The asterisk (*) denotes the residual CHCl3peak in the NMR solvent. -11- 4917-6162-2874, v.1 FIG.7 shows the1H NMR spectra recorded during the titration of 1 (3mM) with LiCl in CD3OD / CDCl3(1:9, v / v). The asterisk (*) demotes the residual CHCl3peak in the NMR solvent. FIG. 8 shows the1H NMR spectra recorded during the titration of 2 (3 mM) with LiBr in CH3OH / CDCl3(1:9, v / v). The asterisk (*) denotes the residual CHCl3peak in the NMR solvent. FIG.9 shows the1H NMR spectra recorded during the titration of 1 (3mM) with LiBr in CD3OD / CDCl3 (1:9, v / v). The asterisk (*) demotes the residual CHCl3 peak in the NMR solvent. FIGS. 10A – 10E show the partial 1H NMR spectra of (FIG. 10A) 2 (3 mM) only, (FIG. 10B) 2 + excess TBACl, (FIG. 10C) 2 + excess LiClO4, (FIG. 10D) 2 + excess LiClO4+ excess TBACl, and (FIG. 10E) 2 + excess LiCl in CH3OH / CDCl3 (1:9, v / v). The asterisk (*) denotes the residual CHCl3 peak in the NMR solvent. FIGS. 11A-11E show, at top, the partial1H NMR spectra of (FIG. 11A) 2 (3 mM) only, (FIG. 11B) 2 + excess TBABr, (FIG. 11C) 2 + excess LiClO4, (FIG. 11D) 2 + excess LiClO4 + excess TBABr, and (FIG. 11E) 2 + excess LiBr in CH3OH / CDCl3 (1:9, v / v). The asterisk (*) denotes the residual CHCl3 peak in the NMR solvent. The bottom of FIG. 11 shows proposed ion binding modes in the presence of Li+, Br–, and both Li+and Br–, respectively, in CH3OH / CDCl3 (1:9, v / v) as inferred from1H NMR spectroscopic studies. FIG. 12 shows the1H NMR spectra recorded during the titration of 2 (3 mM) with LiClO4 in CH3OH / CDCl3 (1:9, v / v). The asterisk (*) denotes the residual CHCl3 peak in the NMR solvent. FIG. 13 shows the proposed ion binding modes of receptor 2 in the presence of separately Li+and Cl–(added with a non-coordinating counter ion) and in the presence of both Li+and Cl–in CH3OH / CDCl3(1:9, v / v) as inferred from1H NMR spectroscopic studies. FIG. 14 provides1H NMR spectra recorded during the titration of 2 with TBACl in the presence of 5.0 equiv of LiClO4 in CH3OH / CDCl3 (1:9, v / v). The asterisk (*) denotes the residual CHCl3 peak in the NMR solvent. -12- 4917-6162-2874, v.1 FIG. 15 provides1H NMR spectra recorded during the titration of 2 +50 equiv of LiClO4with TBABr in CH3OH / CDCl3(1:9, v / v). The asterisk (*) denotes the residual CHCl3peak in the NMR solvent. FIG. 16 shows1H NMR spectra for the titration of 2 with LiClO4 in the presence of 5.0 equiv of TBACl in CH3OH / CDCl3(1:9, v / v). The asterisk (*) denotes the residual CHCl3peak in the NMR solvent. FIG. 17 shows1H NMR spectra recorded during the titration of 2 with LiClO4in the presence of 50 equiv of TBABr in CH3OH / CDCl3 (1:9, v / v). The asterisk (*) denotes the residual CHCl3 peak in the NMR solvent. FIG. 18 shows two different views of the X-ray crystal structure of the 2•LiBr. Thermal ellipsoids are scaled to the 50% probability level. Most hydrogen atoms are omitted for clarity. FIGS. 19A – 19D show partial1H NMR spectra of CD2Cl2solutions of (FIG. 19A) 2 (3 mM) only, (FIG. 19B) 2 + LiCl (100 equiv), (FIG. 19C) 2 + LiBr (100 equiv), and (FIG. 19D) 2 + LiCl (100 equiv) + LiBr (100 equiv). The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIG. 20 shows, at top, ion binding behavior of receptor 2 that is proposed, without being bound by theory, to occur when receptor 2 is titrated with TBAF in the presence of LiCl. At bottom is shown the1H NMR spectra recorded during the titration of 2•LiCl (3 mM) with TBAF in CD2Cl2 and1H NMR spectrum of receptor 2 recorded in the presence of 20 equiv of TBAF without LiCl. The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIGS. 21A – 21G show partial1H NMR spectra of CD2Cl2solutions of (FIG. 21A) 2 (3 mM) only, (FIG.21B) 2 + LiCl (100 equiv), (FIG.21C) 2 + NaCl (100 equiv), (FIG.21D) 2 + KCl (100 equiv), (FIG. 21E) 2 + MgCl2(100 equiv), (FIG. 21F) 2 + CaCl2(100 equiv), and (FIG. 21G) 2 + LiCl + NaCl + KCl + MgCl2+ CaCl2(100 equiv each). The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. -13- 4917-6162-2874, v.1 FIGS. 22A – 22G show partial1H NMR spectra of CD2Cl2solutions of (FIG. 22A) 2 (3 mM) only, (FIG.22B) 2 + LiBr (100 equiv), (FIG.22C) 2 + NaBr (100 equiv), (FIG.22D) 2 + KBr (100 equiv), (FIG. 22E) 2 + MgBr2 (100 equiv), (FIG. 22F) 2 + CaBr2 (100 equiv), and (FIG. 22G) 2 + LiBr + NaBr + KBr + MgBr2+ CaBr2(100 equiv each). The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIG. 23 shows optimized structures of the complexes of receptor 2 with LiCl, MgCl2, LiBr, MgBr2, and CaBr2 as calculated in the gas phase and the corresponding computed complexation energies for the interaction of receptor 2 with the ion pairs in question. FIGS. 24A - 24E show partial1H NMR spectra of CD2Cl2 solutions of (FIG. 24A) 2 (3 mM) only, (FIG.24B) 2 + MgCl2 (500 equiv.), (FIG.24C) the solution of (FIG.24B) after contacting with 10 M LiCl aqueous solution, (FIG. 24D) the solution of (FIG. 24C) after removing an aqueous phase and then contacting with an ion-free aqueous D2O solution, and (FIG. 24E) a CD2Cl2 solution of free 2 after contacting with an ion-free aqueous D2O solution. The asterisk (*) denotes the residual CH2Cl2peak in the NMR solvent. FIG.25A - 25C provide partial1H NMR spectra of CD2Cl2 solutions of (FIG.25A) 2 (3 mM) only, (FIG. 25B) 2 + LiCl (100 equiv) + MgCl2(100 equiv), and (FIG. 25C) after adding 10% MeOH to (FIG. 25B). The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIGS. 26A – 26C show the partial1H NMR spectra of CD2Cl2 solutions of (FIG. 26A) 2 (3 mM) only, (FIG. 26B) 2 + LiBr (100 equiv) + CaBr2(100 equiv), and (FIG. 26C) after adding 5% MeOH to (FIG. 26B). The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIGS. 27A – 27E show the1H NMR spectra of CD2Cl2 solutions of (FIG. 27A) 2 (3 mM) only, (FIG. 27B) 2 + CaBr2(500 equiv), (FIG. 27C) solution (FIG. 27B) after contacting with a 13 M aqueous D2O LiBr solution, (FIG. 27D) solution (FIG. 27C) after removing of an aqueous source phase and contacting with an ion-free aqueous D2O solution, and (FIG.27E) solution of free 2 after contacting with an ion-free aqueous D2O solution. The asterisk (*) denotes the residual CH2Cl2peak in the NMR solvent. -14- 4917-6162-2874, v.1 FIGS.28A – 28F show partial1H NMR spectra of CD2Cl2organic phases of receptor 2 (3 mM) after contacting with (FIG. 28A) an ion-free aqueous D2O solution, (FIG. 28B) an aqueous D2O solution containing LiCl (excess), (FIG. 28C) an aqueous D2O solution containing NaCl (excess) (FIG. 28D) an aqueous D2O solution containing KCl (excess), (FIG. 28E) an aqueous D2O solution containing MgCl2 (excess), and (FIG. 28F) an aqueous D2O solution containing CaCl2(excess). The asterisk (*) denotes the residual CH2Cl2peak in the NMR solvent. FIGS. 29A - 29F show partial1H NMR spectra of the CD2Cl2organic phases of 2 (3 mM) after contacting with (FIG. 29A) an ion-free aqueous D2O solution, (FIG. 29B) an aqueous D2O solution containing LiBr (excess), (FIG. 29C) an aqueous D2O solution containing NaBr (excess) (FIG. 29D) an aqueous D2O solution containing KBr (excess), (FIG. 29E) an aqueous D2O solution containing MgBr2(excess), and (FIG. 29F) an aqueous D2O solution containing CaBr2 (excess). The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIGS. 30A – 30C show partial1H NMR spectra of CD2Cl2 solutions of 2 (3 mM) after contacting with (FIG. 30A) an ion-free aqueous D2O solution, (FIG. 30B) a 5 M LiCl aqueous D2O solution, and (FIG.30C) a 10 M LiCl aqueous D2O solution. Percentages of the receptor bound to LiCl are estimated to be 24% and ≈ 100%, respectively. The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIG. 31 shows the HRMS spectrum of the organic phase of receptor 2 after contacting with an aqueous D2O solution containing 10 M of LiCl. FIGS. 32A – 32D show partial1H NMR spectra of CD2Cl2solutions of 2 (3 mM) after contacting with (FIG.32A) ion-free D2O, (FIG.32B) a 5 M LiBr aqueous D2O solution, (FIG. 32C) a 10 M LiBr aqueous D2O solution, and (FIG. 32D) a 15 m LiBr aqueous D2O solution. The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIGS. 33A & 33B show partial1H NMR spectra of CD2Cl2solutions of 1 (3 mM) after contacting with (FIG. 33A) ion-free D2O, and (FIG. 33B) a 10 M LiCl aqueous D2O solution. The asterisk (*) denotes the residual CH2Cl2peak in the NMR solvent. -15- 4917-6162-2874, v.1 FIGS. 34A & 34B show partial1H NMR spectra of CD2Cl2solutions of 1 (3 mM) after contacting with (FIG. 34A) ion-free D2O, and (FIG. 34B) a 15 M LiBr aqueous D2O solution. The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIGS. 35A – 35F show partial1H NMR spectra of nitrobenzene-d5 solutions of 2 (3 mM) after contacting with (FIG. 35A) ion-free D2O, (FIG. 35B) an aqueous D2O solution containing LiCl (excess), (FIG. 35C) an aqueous D2O solution containing NaCl (excess) (FIG. 35D) an aqueous D2O solution containing KCl (excess), (FIG. 35E) an aqueous D2O solution containing MgCl2(excess), (FIG. 35F) an aqueous D2O solution containing CaCl2(excess), and an aqueous D2O solution containing all the chloride salts (5 M each). The asterisks (*) denote the residual nitrobenzene peaks in the NMR solvent. FIGS.36A - 36F show partial1H NMR spectra of nitrobenzene-d5 solutions of 2 (3 mM) after contacting with (FIG.36A) ion-free H2O, (FIG.36B) an aqueous H2O solution containing LiBr (excess), (FIG.36C) an aqueous H2O solution containing NaBr (excess) (FIG.36D) an aqueous H2O solution containing KBr (excess), (FIG.36E) an aqueous H2O solution containing MgBr2 (excess), and (FIG.36F) an aqueous H2O solution containing CaBr2(excess). The asterisks (*) denote the residual nitrobenzene peaks in the NMR solvent. FIGS. 37A-37G show, at left, partial1H NMR spectra of nitrobenzene-d5 layers of 2 (3 mM) recorded upon exposure to aqueous D2O phases at concentrations of 0.0 M, 0.5 M, 1 M, 2 M, 3 M, 4 M, and 5 M of LiCl, respectively. Percentages of the receptor loaded with LiCl are estimated to be <10%, 39%, 63%, 74%, 93% and 100% respectively. The asterisks denote the residual nitrobenzene peak in the NMR solvent. At right, FIG. 37 provides plots showing loading percentages of receptor 2 for the metal chloride salts after liquid-liquid extraction. FIGS. 38A – 38E show partial1H NMR spectra of nitrobenzene-d5layers of 2 (3 mM) after contacting with (FIG. 38A) ion-free D2O, (FIG. 38B) an aqueous D2O solution containing 3 M LiBr, (FIG. 38C) an aqueous D2O solution containing 5 M LiBr, (FIG. 38D) an aqueous D2O solution containing 8 M LiBr, and (FIG. 38E) an aqueous D2O solution containing 10 M LiBr. The asterisks denote the residual nitrobenzene peaks in the NMR solvent. -16- 4917-6162-2874, v.1 FIG. 39 shows LiCl loading percentages for receptor 2 after nitrobenzene-d5organic phases were contacted with aqueous D2O phases containing 0.5 M and 1.0 M LiCl in the absence and presence of (concurrently) NaCl, KCl, MgCl2, and CaCl2 at concentrations of 0.5 M and 1.0 M in each additive. FIGS. 40A – 40G show partial1H NMR spectra of nitrobenzene-d5phases of 2 (3 mM) after contacting with (FIG. 40A) ion-free D2O, (FIG. 40B) an aqueous D2O solution containing 0.5 M LiCl, (FIG. 40C) an aqueous D2O solution containing 0.5 M LiCl + 0.5 M NaCl + 0.5 M KCl + 0.5 M MgCl2+ 0.5 M CaCl2, (FIG. 40D) an aqueous D2O solution containing 0.5 M LiCl + 1.0 M NaCl + 1.0 M KCl + 1.0 M MgCl2 + 1.0 M CaCl2, (FIG.40E) an aqueous D2O solution containing 1.0 M LiCl, (FIG. 40F) an aqueous D2O solution containing 1.0 M LiCl + 0.5 M NaCl + 0.5 M KCl + 0.5 M MgCl2 + 0.5 M CaCl2, and (FIG. 40G) an aqueous D2O solution containing 1.0 M LiCl + 1.0 M NaCl + 1.0 M KCl + 1.0 M MgCl2 + 1.0 M CaCl2 FIGS. 41A – 41C show partial1H NMR spectra of CD2Cl2solutions of 2 (3 mM) after contacting with (FIG. 41A) ion-free D2O, (FIG. 41B) an aqueous D2O solution containing 5 M LiCl, and (FIG. 41C) an aqueous D2O solution containing 5 M LiCl + Sat. NaCl. Percentages of the receptor extracting LiCl are estimated to be 24% and 36% respectively. The asterisk (*) denotes the residual CH2Cl2peak in the NMR solvent. FIG.42A – 42C show partial1H NMR spectra of CD2Cl2 solutions of 2 (3 mM) after contacting with (FIG. 42A) ion-free D2O, (FIG. 42B) an aqueous D2O solution containing 5 M LiCl, and (FIG. 42C) an aqueous D2O solution containing 5 M LiCl + Sat. NaI. Percentages of the receptor extracting LiCl are estimated to be 24% and 42% respectively. The asterisk (*) denotes the residual CH2Cl2 peak in the NMR solvent. FIG.43 shows the1H NMR spectrum of 2 recorded in CDCl3. FIG.44 shows the13C NMR spectrum of 2 recorded in CDCl3. FIG.45 shows the high resolution QTOF mass spectrum of receptor 2. -17- 4917-6162-2874, v.1 DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS The present disclosure describes calixpyrrole compounds and compositions and methods of use thereof. One non-limiting example of the use of these compounds is in the selective extraction of LiCl. In another embodiment, the present disclosure provides use of these compounds is in the selective extraction of LiBr. The present disclosure provides calix[4]pyrrole-based ion pair receptors, such as 2, that may selectively bind LiCl or LiBr in the presence of other chloride or bromide salts, respectively, of other alkali and alkaline earth metal cations. Additionally, the present disclosure provides calix[4]pyrrole-based ion pair receptors, such as 2, that selectively bind LiCl or LiBr in the presence of other lithium halide salts. The present disclosure provides the synthesis and analysis of calix[4]pyrrole-based ion pair receptors, such as 2, that allow LiCl to be captured selectively under SLE conditions. Furthermore, in some aspects, receptor 2 also permits the selective LLE extraction of LiCl into an organic phase from an aqueous source phase. Additionally, the compositions herein may have the advantage of separating lithium salts such as lithium chloride or lithium bromide dissolved in an aqueous solution from other alkali or alkaline earth metal salts into an organic solvent. In some embodiments, the compositions herein may have the advantage of separating lithium salts such as lithium chloride or lithium bromide dissolved in an aqueous solution from other halide salts into an organic solvent. Furthermore, receptor 2 is also capable of stabilizing a LiCl complex in the solid state as a receptor system without an intervening water molecule between the Li+cation and Cl–anion. In some embodiments, the present disclosure provides use of calix[4]pyrrole-based ion pair receptors, such as 2, for the selective extraction of LiCl from aqueous solutions containing relatively low concentrations of LiCl, which is an improvement over corresponding methods and compounds known in the art. Further details on these aspects and more may be found below and in the sections that follow. A. Calixpyrroles of the Present Disclosure The compounds of the present invention (also referred to as “compounds of the present disclosure”) are shown, for example, above, in the summary of the invention section, and in the claims below. They may be made using the synthetic methods outlined in the Examples section. These methods can be further modified and optimized using the principles -18- 4917-6162-2874, v.1 and techniques of organic chemistry as applied by a person skilled in the art. Such principles and techniques are taught, for example, in Smith, March’s Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, (2013), which is incorporated by reference herein. In addition, the synthetic methods may be further modified and optimized for preparative, pilot- or large-scale production, either batch or continuous, using the principles and techniques of process chemistry as applied by a person skilled in the art. Such principles and techniques are taught, for example, in Anderson, Practical Process Research & Development – A Guide for Organic Chemists (2012), which is incorporated by reference herein. The calixpyrroles of the present disclosure may include further modifications to allow substitutions on the calixpyrrole core. Such modified calixpyrroles include those described in United States Patent Nos. 6,262,257, 6,984,734, 7,041,819, and 7,122,572 as well as U.S. Patent Application Publication No.2010 / 0129308 and U.S.2010 / 0120958, the entire contents of which are hereby incorporated by reference. The compounds described herein include attachment of the instant calixpyrroles to a solid support or a polymer to better achieve separation of the desired metal ions. Such systems are described in U.S. Patent No. 8,802,074, the entire contents of which are hereby incorporated by reference. Compounds of the present invention may contain one or more asymmetrically- substituted carbon or nitrogen atoms and may be isolated in optically active or racemic form. Thus, all chiral, diastereomeric, racemic form, epimeric form, and all geometric isomeric forms of a chemical formula are intended, unless the specific stereochemistry or isomeric form is specifically indicated. Compounds may occur as racemates and racemic mixtures, single enantiomers, diastereomeric mixtures and individual diastereomers. In some embodiments, a single diastereomer is obtained. The chiral centers of the compounds of the present invention can have the S or the R configuration. In some embodiments, the present compounds may contain two or more atoms which have a defined stereochemical orientation. Chemical formulas used to represent compounds of the present invention will typically only show one of possibly several different tautomers. For example, many types of ketone groups are known to exist in equilibrium with corresponding enol groups. Similarly, many types of imine groups exist in equilibrium with enamine groups. Regardless of which tautomer is depicted for a given compound, and regardless of which one is most prevalent, all tautomers of a given chemical formula are intended. In addition, atoms making up the compounds of the present invention are intended to include all isotopic forms of such atoms. Isotopes, as used herein, include those atoms having the same atomic number but different mass numbers. By way of general example and

[0002] -19- 4917-6162-2874, v.1 without limitation, isotopes of hydrogen include tritium and deuterium, and isotopes of carbon include13C and14C. The calixpyrroles of the present disclosure are useful, in one aspect, in that they facilitate the selective extraction or separation of lithium salts, such as lithium chloride or lithium bromide into the organic phase from an aqueous phase, such as an aqueous phase comprising other alkali or alkaline earth metal salts and / or other lithium halide salts. In some embodiments, the calixpyrroles of the present disclosure have a high binding affinity (Ka) for lithium salts. In some embodiments, the calixpyrroles of the present disclosure have a high binding affinity (Ka) for lithium chloride. In some embodiments, the calixpyrroles of the present disclosure have a high binding affinity (Ka) for lithium bromide. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for a lithium salt that is higher than that of similar compounds or compositions known in the art. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium chloride that is higher than that of similar compounds or compositions known in the art. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity for lithium bromide (Ka) that is higher than that of similar compounds or compositions known in the art. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium chloride that is over about 103M-1. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium chloride that is about 103M-1, about 104M-1, about 105M-1, about 106M-1, about 107M-1, about 108M-1, or any range derivable therein. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium chloride of between about 103M-1and about 107M-1. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium chloride of about 105M-1. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium bromide that is over about 25 M-1. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium bromide that is about 30 M-1, about 35 M-1, about 40 M-1, about 45 M-1, about 50 M-1, about 55 M-1, about 60 M-1, about 65 M-1, about 70 M-1,about 75 M-1, about 80 M-1, about 85 M-1, about 90 M-1, about 95 M-1, about 100 M-1, or any range derivable therein. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium bromide of between about 40 M-1and about 80 M-1. In some embodiments, the calixpyrroles of the present disclosure have a binding affinity (Ka) for lithium chloride of about 63 M-1.

[0003] -20- 4917-6162-2874, v.1 B. Definitions When used in the context of a chemical group: “hydrogen” means −H; “hydroxy” means −OH; “oxo” means =O; “carbonyl” means −C(=O)−; “carboxy” means −C(=O)OH (also written as −COOH or −CO2H); “halo” means independently −F, −Cl, −Br or −I; “amino” means −NH2; “hydroxyamino” means −NHOH; “nitro” means −NO2; imino means =NH; “cyano” means −CN; “isocyanyl” means −N=C=O; “azido” means −N3; in a monovalent context “phosphate” means −OP(O)(OH)2 or a deprotonated form thereof; in a divalent context “phosphate” means −OP(O)(OH)O− or a deprotonated form thereof; “mercapto” means −SH; and “thio” means =S; “sulfonyl” means −S(O)2−; and “sulfinyl” means −S(O)−. In the context of chemical formulas, the symbol “−” means a single bond, “=” meansa double bond, and “≡” means triple bond. The “ ” represents an optional bond,which if present is either single or double. The symbol “ ” represents a single bond or adouble bond. Thus, the covers, for example, , and . And it is understood such ring atom forms part of Furthermore, it is noted that the covalent bond symbol “−”, when connecting one or two stereogenic atoms, does not indicate any preferred stereochemistry. Instead, it covers allstereoisomers as well as mixtures thereof. The symbol “ ”, when drawn perpendicularlyacross a bond (e.g., for methyl) indicates a point of attachment of the group. It isnoted that the point of attachment is typically only identified in this manner for larger groups in order to assist the reader in unambiguously identifying a point of attachment. The symbol“ ” means a single bond where the group attached to the thick end of the wedge is “out ofThe symbol “ ” means a single bond where the group attached to the thick endof the wedge is “into the page”. The symbol “ ” means a single bond where thegeometry around a double bond (e.g., either E or Z) is undefined. Both options, as well as combinations thereof are therefore intended. Any undefined valency on an atom of a structure shown in this application implicitly represents a hydrogen atom bonded to that atom. A bold dot on a carbon atom indicates that the hydrogen attached to that carbon is oriented out of the plane of the paper. When a variable is depicted as a “floating group” on a ring system, for example, the group “R” in the formula:

[0004] -21- 4917-6162-2874, v.1 R , then the variable may replace any to any of the ring atoms, including a depicted, implied, or expressly defined hydrogen, so long as a stable structure is formed. When a variable is depicted as a “floating group” on a fused ring system, as for example the group “R” in the formula: (R)y, then the variable may replace any to any of the ring atoms of either of the fused rings unless specified otherwise. Replaceable hydrogens include depicted hydrogens (e.g., the hydrogen attached to the nitrogen in the formula above), implied hydrogens (e.g., a hydrogen of the formula above that is not shown but understood to be present), expressly defined hydrogens, and optional hydrogens whose presence depends on the identity of a ring atom (e.g., a hydrogen attached to group X, when X equals −CH−), so long as a stable structure is formed. In the example depicted, R may reside on either the 5-membered or the 6- membered ring of the fused ring system. In the formula above, the subscript letter “y” immediately following the R enclosed in parentheses, represents a numeric variable. Unless specified otherwise, this variable can be 0, 1, 2, or any integer greater than 2, only limited by the maximum number of replaceable hydrogen atoms of the ring or ring system. For the chemical groups and compound classes, the number of carbon atoms in the group or class is as indicated as follows: “Cn” defines the exact number (n) of carbon atoms in the group / class. “C≤n” defines the maximum number (n) of carbon atoms that can be in the group / class, with the minimum number as small as possible for the group / class in question. For example, it is understood that the minimum number of carbon atoms in the groups “alkyl(C≤8)”, “cycloalkanediyl(C≤8)”, “heteroaryl(C≤8)”, and “acyl(C≤8)” is one, the minimum number of carbon atoms in the groups “alkenyl(C≤8)”, “alkynyl(C≤8)”, and “heterocycloalkyl(C≤8)” is two, the minimum number of carbon atoms in the group “cycloalkyl(C≤8)” is three, and the minimum number of carbon atoms in the groups “aryl(C≤8)” and “arenediyl(C≤8)” is six. “Cn-n′” defines both the minimum (n) and maximum number (n′) of carbon atoms in the group. Thus, “alkyl(C2-10)” designates those alkyl groups having from 2 to 10 carbon atoms. These carbon number indicators may precede or follow the chemical

[0005] -22- 4917-6162-2874, v.1 groups or class it modifies and it may or may not be enclosed in parenthesis, without signifying any change in meaning. Thus, the terms “C5 olefin”, “C5-olefin”, “olefin(C5)”, and “olefinC5” are all synonymous. When any of the chemical groups or compound classes defined herein is modified by the term “substituted”, any carbon atom in the moiety replacing the hydrogen atom is not counted. Thus methoxyhexyl, which has a total of seven carbon atoms, is an example of a substituted alkyl(C1-6).Unless specified otherwise, any chemical group or compound class listed in a claim set without a carbon atom limit has a carbon atom limit of less than or equal to twelve. The term “saturated” when used to modify a compound or chemical group means the compound or chemical group has no carbon-carbon double and no carbon-carbon triple bonds, except as noted below. When the term is used to modify an atom, it means that the atom is not part of any double or triple bond. In the case of substituted versions of saturated groups, one or more carbon oxygen double bond or a carbon nitrogen double bond may be present. And when such a bond is present, then carbon-carbon double bonds that may occur as part of keto-enol tautomerism or imine / enamine tautomerism are not precluded. When the term “saturated” is used to modify a solution of a substance, it means that no more of that substance can dissolve in that solution. The term “aliphatic” signifies that the compound or chemical group so modified is an acyclic or cyclic, but non-aromatic compound or group. In aliphatic compounds / groups, the carbon atoms can be joined together in straight chains, branched chains, or non-aromatic rings (alicyclic). Aliphatic compounds / groups can be saturated, that is joined by single carbon-carbon bonds (alkanes / alkyl), or unsaturated, with one or more carbon-carbon double bonds (alkenes / alkenyl) or with one or more carbon-carbon triple bonds (alkynes / alkynyl). The term “aromatic” signifies that the compound or chemical group so modified has a planar unsaturated ring of atoms with 4n +2 electrons in a fully conjugated cyclic π system. The term “alkyl” when used without the “substituted” modifier refers to a monovalent saturated aliphatic group with a carbon atom as the point of attachment, a linear or branched acyclic structure, and no atoms other than carbon and hydrogen. The groups −CH3(Me), −CH2CH3 (Et), −CH2CH2CH3 (n-Pr or propyl), −CH(CH3)2 (i-Pr,iPr or isopropyl), −CH2CH2CH2CH3(n-Bu), −CH(CH3)CH2CH3(sec-butyl), −CH2CH(CH3)2(isobutyl), −C(CH3)3 (tert-butyl, t-butyl, t-Bu ortBu), and −CH2C(CH3)3 (neo-pentyl) are non-limiting examples of alkyl groups. The term “alkanediyl” when used without the “substituted” modifier refers to a divalent saturated aliphatic group, with one or two saturated carbon atom(s) as the point(s) of attachment, a linear or branched acyclic structure, no carbon-carbon

[0006] -23- 4917-6162-2874, v.1 double or triple bonds, and no atoms other than carbon and hydrogen. The groups −CH2− (methylene), −CH2CH2−, −CH2C(CH3)2CH2−, and −CH2CH2CH2− are non-limiting examples of alkanediyl groups. The term “alkylidene” when used without the “substituted” modifier refers to the divalent group =CRR′ in which R and R′ are independently hydrogen or alkyl. Non-limiting examples of alkylidene groups include: =CH2, =CH(CH2CH3), and =C(CH3)2. An “alkane” refers to the class of compounds having the formula H−R, wherein R is alkyl as this term is defined above. When any of these terms is used with the “substituted” modifier, one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The following groups are non-limiting examples of substituted alkyl groups: −CH2OH, −CH2Cl, −CF3, −CH2CN, −CH2C(O)OH, −CH2C(O)OCH3, −CH2C(O)NH2, −CH2C(O)CH3, −CH2OCH3, −CH2OC(O)CH3, −CH2NH2, −CH2N(CH3)2, and −CH2CH2Cl. The term “haloalkyl” is a subset of substituted alkyl, in which the hydrogen atom replacement is limited to halo (i.e. −F, −Cl, −Br, or −I) such that no other atoms aside from carbon, hydrogen and halogen are present. The group, −CH2Cl is a non-limiting example of a haloalkyl. The term “fluoroalkyl” is a subset of substituted alkyl, in which the hydrogen atom replacement is limited to fluoro such that no other atoms aside from carbon, hydrogen and fluorine are present. The groups −CH2F, −CF3, and −CH2CF3are non-limiting examples of fluoroalkyl groups. The term “cycloalkyl” refers to a monovalent saturated aliphatic group with a carbon atom as the point of attachment, said carbon atom forming part of one or more non-aromatic ring structures, no carbon-carbon double or triple bonds, and no atoms other than carbon and hydrogen. Non-limiting examples include: −CH(CH2)2(cyclopropyl), cyclobutyl, cyclopentyl, or cyclohexyl (Cy). As used herein, the term does not preclude the presence of one or more alkyl groups (carbon number limitation permitting) attached to a carbon atom of the non-aromatic ring structure. The term “cycloalkanediyl” refers to a divalent saturated aliphatic group with two carbon atoms as points of attachment, no carbon-carbon double or triple bonds, and no atoms other than carbon and hydrogen. The is a non-limiting example of cycloalkanediyl group. A “cycloalkane” of compounds having the formula H−R, wherein R is cycloalkyl as this term is defined above. When any of these terms are used with the “substituted” modifier one or more hydrogen atom hasbeen independently replaced by−OH, −F, −Cl, −Br, −I, −NH2,−NO2,−CO2H,−CO2CH3,−CN, −SH,

[0007] -24- 4917-6162-2874, v.1 −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The term “alkenyl” when used without the “substituted” modifier refers to a monovalent unsaturated aliphatic group with a carbon atom as the point of attachment, a linear or branched, acyclic structure, at least one nonaromatic carbon-carbon double bond, no carbon-carbon triple bonds, and no atoms other than carbon and hydrogen. Non-limiting examples include: −CH=CH2(vinyl), −CH=CHCH3, −CH=CHCH2CH3, −CH2CH=CH2(allyl),−CH2CH=CHCH3, and−CH=CHCH=CH2. The term “alkenediyl” when used without the “substituted” modifier refers to a divalent unsaturated aliphatic group, with two carbon atoms as points of attachment, a linear or branched, a linear or branched acyclic structure, at least one nonaromatic carbon-carbon double bond, no carbon-carbon triple bonds, and no atoms other than carbon and hydrogen. The groups −CH=CH−, −CH=C(CH3)CH2−, −CH=CHCH2−, and −CH2CH=CHCH2− are non-limiting examples of alkenediyl groups. It is noted that while the alkenediyl group is aliphatic, once connected at both ends, this group is not precluded from forming part of an aromatic structure. The terms “alkene” and “olefin” are synonymous and refer to the class of compounds having the formula H−R, wherein R is alkenyl as this term is defined above. Similarly, the terms “terminal alkene” and “α-olefin” are synonymous and refer to an alkene having just one carbon-carbon double bond, wherein that bond is part of a vinyl group at an end of the molecule. When any of these terms are used with the “substituted” modifier one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The groups −CH=CHF, −CH=CHCl and −CH=CHBr are non-limiting examples of substituted alkenyl groups. The term “cycloalkenyl” refers to a monovalent saturated aliphatic group with a carbon atom as the point of attachment, said carbon atom forming part of one or more non- aromatic ring structures, one or more carbon-carbon double bonds provided the group is not aromatic, no carbon-carbon triple bonds, and no atoms other than carbon and hydrogen. Non-limiting examples include: cyclopropenyl, cyclobutenyl, cyclopentenyl, or cyclohexenyl. As used herein, the term does not preclude the presence of one or more alkyl groups (carbon number limitation permitting) attached to a carbon atom of the non-aromatic ring structure. A “cycloalkene” refers to the class of compounds having the formula H−R,

[0008] -25- 4917-6162-2874, v.1 wherein R is cycloalkenyl as this term is defined above. When any of these terms are used with the “substituted” modifier one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The term “alkynyl” when used without the “substituted” modifier refers to a monovalent unsaturated aliphatic group with a carbon atom as the point of attachment, a linear or branched acyclic structure, at least one carbon-carbon triple bond, and no atoms other than carbon and hydrogen. As used herein, the term alkynyl does not preclude the presence of one or more non-aromatic carbon-carbon double bonds. The groups −C≡CH, −C≡CCH3, and −CH2C≡CCH3 are non-limiting examples of alkynyl groups. The term “alkynediyl” when used without the “substituted” modifier refers to a divalent unsaturated aliphatic group, with two carbon atoms as points of attachment, a linear or branched acyclic structure, at least one nonaromatic carbon-carbon triple bond, no carbon-carbon double bonds, and no atoms other than carbon and hydrogen. The groups −C≡C−, −C≡CCH2−, and −CH2C≡CCH2− are non-limiting examples of alkynediyl groups. It is noted that while the alkynediyl group is aliphatic, once connected at both ends, this group is not precluded from forming part of an aromatic structure. An “alkyne” refers to the class of compounds having the formula H−R, wherein R is alkynyl. When any of these terms are used with the “substituted” modifier one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The term “aryl” when used without the “substituted” modifier refers to a monovalent unsaturated aromatic group with an aromatic carbon atom as the point of attachment, said carbon atom forming part of a one or more aromatic ring structures, each with six ring atoms that are all carbon, and wherein the group consists of no atoms other than carbon and hydrogen. If more than one ring is present, the rings may be fused or unfused. Unfused rings are connected with a covalent bond. As used herein, the term aryl does not preclude the presence of one or more alkyl groups (carbon number limitation permitting) attached to the first aromatic ring or any additional aromatic ring present. Non-limiting examples of aryl groups include phenyl (Ph), methylphenyl, (dimethyl)phenyl, −C6H4CH2CH3 (ethylphenyl),

[0009] -26- 4917-6162-2874, v.1 naphthyl, and a monovalent group derived from biphenyl (e.g., 4-phenylphenyl). The term “arenediyl” when used without the “substituted” modifier refers to a divalent aromatic group with two aromatic carbon atoms as points of attachment, said carbon atoms forming part of one or more six-membered aromatic ring structures, each with six ring atoms that are all carbon, and wherein the divalent group consists of no atoms other than carbon and hydrogen. As used herein, the term arenediyl does not preclude the presence of one or more alkyl groups (carbon number limitation permitting) attached to the first aromatic ring or any additional aromatic ring present. If more than one ring is present, the rings may be fused or unfused. Unfused rings are connected with a covalent bond. Non-limiting examples of arenediyl groups include: An as that term is defined above. Benzene and toluene are non-limiting examples of arenes. When any of these terms are used with the “substituted” modifier one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The term “heteroaryl” when used without the “substituted” modifier refers to a monovalent aromatic group with an aromatic carbon atom or nitrogen atom as the point of attachment, said carbon atom or nitrogen atom forming part of one or more aromatic ring structures, each with three to eight ring atoms, wherein at least one of the ring atoms of the aromatic ring structure(s) is nitrogen, oxygen or sulfur, and wherein the heteroaryl group consists of no atoms other than carbon, hydrogen, aromatic nitrogen, aromatic oxygen and aromatic sulfur. If more than one ring is present, the rings are fused; however, the term heteroaryl does not preclude the presence of one or more alkyl or aryl groups (carbon number limitation permitting) attached to one or more ring atoms. Non-limiting examples of heteroaryl groups include furanyl, imidazolyl, indolyl, indazolyl (Im), isoxazolyl, methylpyridinyl, oxazolyl, phenylpyridinyl, pyridinyl (pyridyl), pyrrolyl, pyrimidinyl,

[0010] -27- 4917-6162-2874, v.1 pyrazinyl, quinolyl, quinazolyl, quinoxalinyl, triazinyl, tetrazolyl, thiazolyl, thienyl, and triazolyl. The term “N-heteroaryl” refers to a heteroaryl group with a nitrogen atom as the point of attachment. The term “heteroarenediyl” when used without the “substituted” modifier refers to a divalent aromatic group, with two aromatic carbon atoms, two aromatic nitrogen atoms, or one aromatic carbon atom and one aromatic nitrogen atom as the two points of attachment, said atoms forming part of one or more aromatic ring structures, each with three to eight ring atoms, wherein at least one of the ring atoms of the aromatic ring structure(s) is nitrogen, oxygen or sulfur, and wherein the divalent group consists of no atoms other than carbon, hydrogen, aromatic nitrogen, aromatic oxygen and aromatic sulfur. If more than one ring is present, the rings are be fused; however, the term heteroarenediyl does not preclude the presence of one or more alkyl or aryl groups (carbon number limitation permitting) attached to one or more ring atoms. Non-limiting examples of heteroarenediyl groups include: N N . A “heteroarene” refers −R, wherein R is H heteroaryl. Pyridine and quinoline are non-limiting examples of heteroarenes. When these terms are used with the “substituted” modifier one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2,−C(O)NHCH3,−C(O)N(CH3)2,−OC(O)CH3,−NHC(O)CH3,−S(O)2OH, or−S(O)2NH2.The term “heterocycloalkyl” refers to a monovalent non-aromatic group with a carbon atom or nitrogen atom as the point of attachment, said carbon atom or nitrogen atom forming part of one or more non-aromatic ring structures, each with three to eight ring atoms, wherein at least one of the ring atoms of the non-aromatic ring structure(s) is nitrogen, oxygen or sulfur, and wherein the heterocycloalkyl group consists of no atoms other than carbon, hydrogen, nitrogen, oxygen and sulfur. If more than one ring is present, the rings are fused. As used herein, the term does not preclude the presence of one or more alkyl groups (carbon number limitation permitting) attached to one or more ring atoms. Also, the term does not preclude the presence of one or more double bonds in the ring or ring system, provided that the resulting group remains non-aromatic. Non-limiting examples of heterocycloalkyl groups include aziridinyl, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, tetrahydrofuranyl, tetrahydrothiofuranyl, tetrahydropyranyl, pyranyl,

[0011] -28- 4917-6162-2874, v.1 oxiranyl, and oxetanyl. The term “N-heterocycloalkyl” refers to a heterocycloalkyl group with a nitrogen atom as the point of attachment. N-pyrrolidinyl is an example of such a group. When any of these terms are used with the “substituted” modifier one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The term “acyl” when used without the “substituted” modifier refers to the group −C(O)R, in which R is a hydrogen, alkyl, cycloalkyl, or aryl as those terms are defined above. The groups, −CHO, −C(O)CH3(acetyl, Ac), −C(O)CH2CH3, −C(O)CH(CH3)2, −C(O)CH(CH2)2, −C(O)C6H5, and −C(O)C6H4CH3 are non-limiting examples of acyl groups. A “thioacyl” is defined in an analogous manner, except that the oxygen atom of the group −C(O)R has been replaced with a sulfur atom, −C(S)R. The term “aldehyde” corresponds to an alkyl group, as defined above, attached to a −CHO group. When any of these terms are used with the “substituted” modifier one or more hydrogen atom (including a hydrogen atom directly attached to the carbon atom of the carbonyl or thiocarbonyl group, if any) has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The groups, −C(O)CH2CF3, −CO2H (carboxyl), −CO2CH3 (methylcarboxyl), −CO2CH2CH3, −C(O)NH2(carbamoyl), and −CON(CH3)2, are non-limiting examples of substituted acyl groups. The term “alkoxy” when used without the “substituted” modifier refers to the group −OR, in which R is an alkyl, as that term is defined above. Non-limiting examples include: −OCH3(methoxy), −OCH2CH3(ethoxy), −OCH2CH2CH3, −OCH(CH3)2(isopropoxy), or −OC(CH3)3 (tert-butoxy). The terms “cycloalkoxy”, “alkenyloxy”, “alkynyloxy”, “aryloxy”, “aralkoxy”, “heteroaryloxy”, “heterocycloalkoxy”, and “acyloxy”, when used without the “substituted” modifier, refers to groups, defined as −OR, in which R is cycloalkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heterocycloalkyl, and acyl, respectively. The term “alkylthio” and “acylthio” when used without the “substituted” modifier refers to the group −SR, in which R is an alkyl and acyl, respectively. The term “alcohol” corresponds to an alkane, as defined above, wherein at least one of the hydrogen atoms has been replaced with a hydroxy group. The term “ether” corresponds to an alkane, as defined above, wherein at least one of the hydrogen atoms has been replaced with an alkoxy group. When any of these terms

[0012] -29- 4917-6162-2874, v.1 is used with the “substituted” modifier, one or more hydrogen atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The term “alkylamino” when used without the “substituted” modifier refers to the group −NHR, in which R is an alkyl, as that term is defined above. Non-limiting examples include: −NHCH3 and −NHCH2CH3. The term “dialkylamino” when used without the “substituted” modifier refers to the group −NRR′, in which R and R′ can be the same or different alkyl groups. Non-limiting examples of dialkylamino groups include: −N(CH3)2 and −N(CH3)(CH2CH3). The terms “cycloalkylamino”, “alkenylamino”, “alkynylamino”, “arylamino”, “aralkylamino”, “heteroarylamino”, “heterocycloalkylamino”, and “alkoxyamino” when used without the “substituted” modifier, refers to groups, defined as −NHR, in which R is cycloalkyl, alkenyl, alkynyl, aryl, aralkyl, heteroaryl, heterocycloalkyl, and alkoxy, respectively. A non-limiting example of an arylamino group is −NHC6H5. The term “amido” (acylamino), when used without the “substituted” modifier, refers to the group −NHR, in which R is acyl, as that term is defined above. A non-limiting example of an amido group is −NHC(O)CH3. When any of these terms is used with the “substituted” modifier, one or more hydrogen atom attached to a carbon atom has been independently replaced by −OH, −F, −Cl, −Br, −I, −NH2, −NO2, −CO2H, −CO2CH3, −CN, −SH, −OCH3, −OCH2CH3, −C(O)CH3, −NHCH3, −NHCH2CH3, −N(CH3)2, −C(O)NH2, −C(O)NHCH3, −C(O)N(CH3)2, −OC(O)CH3, −NHC(O)CH3, −S(O)2OH, or −S(O)2NH2. The groups −NHC(O)OCH3 and −NHC(O)NHCH3 are non-limiting examples of substituted amido groups. The use of the word “a” or “an,” when used in conjunction with the term “comprising” in the claims and / or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects or patients. The terms “comprise,” “have” and “include” are open-ended linking verbs. Any forms or tenses of one or more of these verbs, such as “comprises,” “comprising,” “has,” “having,” “includes” and “including,” are also open-ended. For example, any method that

[0013] -30- 4917-6162-2874, v.1 “comprises,” “has” or “includes” one or more steps is not limited to possessing only those one or more steps and also covers other unlisted steps. The term “effective,” as that term is used in the specification and / or claims, means adequate to accomplish a desired, expected, or intended result. The term “hydrate” when used as a modifier to a compound means that the compound has less than one (e.g., hemihydrate), one (e.g., monohydrate), or more than one (e.g., dihydrate) water molecules associated with each compound molecule, such as in solid forms of the compound. An “isomer” of a first compound is a separate compound in which each molecule contains the same constituent atoms as the first compound, but where the configuration of those atoms in three dimensions differs. As used herein, the term “ligand” references to a chemical group which coordinates to a metal center through a bond. The bond between the ligand and the metal center in some cases is either an ionic or a coordination bond. A ligand can be monovalent, divalent, trivalent or have a greater valency. In some cases, a ligand may be negatively charged. Some exemplary examples of ligands include, but are not limited to, halide (F-, Cl-, Br-, or I-), a carbonate (CO32-), bicarbonate (HCO3-), hydroxide (-OH), perchlorate (ClO4-), nitrate (NO3-), sulfate (SO42-), acetate (CH3CO2-), trifluoroacetate (CF3CO2-), acetylacetonate (CH3COCHCOCH3-), trifluorosulfonate (CF3SO2-), phosphate (PO43-), oxalate, ascorbate, or gluconate. A ligand could also be a neutral species that contains a lone pair of electrons. Some examples of neutral ligands include but are not limited to aqua (H2O) or ammonia (NH3). Additionally, a neutral ligand can include groups such as an alkylamine or a dialkylamine. A “stereoisomer” or “optical isomer” is an isomer of a given compound in which the same atoms are bonded to the same other atoms, but where the configuration of those atoms in three dimensions differs. “Enantiomers” are stereoisomers of a given compound that are mirror images of each other, like left and right hands. “Diastereomers” are stereoisomers of a given compound that are not enantiomers. Chiral molecules contain a chiral center, also referred to as a stereocenter or stereogenic center, which is any point, though not necessarily an atom, in a molecule bearing groups such that an interchanging of any two groups leads to a stereoisomer. In organic compounds, the chiral center is typically a carbon, phosphorus or

[0014] -31- 4917-6162-2874, v.1 sulfur atom, though it is also possible for other atoms to be stereocenters in organic and inorganic compounds. A molecule can have multiple stereocenters, giving it many stereoisomers. In compounds whose stereoisomerism is due to tetrahedral stereogenic centers (e.g., tetrahedral carbon), the total number of hypothetically possible stereoisomers will not exceed 2n, where n is the number of tetrahedral stereocenters. Molecules with symmetry frequently have fewer than the maximum possible number of stereoisomers. A 50:50 mixture of enantiomers is referred to as a racemic mixture. Alternatively, a mixture of enantiomers can be enantiomerically enriched so that one enantiomer is present in an amount greater than 50%. Typically, enantiomers and / or diastereomers can be resolved or separated using techniques known in the art. It is contemplated that that for any stereocenter or axis of chirality for which stereochemistry has not been defined, that stereocenter or axis of chirality can be present in its R form, S form, or as a mixture of the R and S forms, including racemic and non-racemic mixtures. As used herein, the phrase “substantially free from other stereoisomers” means that the composition contains ≤ 15%, more preferably ≤ 10%, even more preferably ≤ 5%, or most preferably ≤ 1% of another stereoisomer(s). The above definitions supersede any conflicting definition in any reference that is incorporated by reference herein. The fact that certain terms are defined, however, should not be considered as indicative that any term that is undefined is indefinite. Rather, all terms used are believed to describe the invention in terms such that one of ordinary skill can appreciate the scope and practice the present invention.

[0015] -32- 4917-6162-2874, v.1 EXAMPLES The following examples are included to demonstrate preferred embodiments of the disclosure. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the disclosure, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the disclosure. Example 1: Results and Discussion Scheme 1: Known ion pair receptor (1) and an ion pair receptor of the present disclosure (2) Recently, an ion pair strapped calix[4]pyrrole with ester linkers; see Scheme 1) was shown to be able to extract LiCl from a LiCl-saturated aqueous solutions into a chloroform layer (He et al., 2018). However, receptor 1 failed to extract LiCl from aqueous solutions containing relatively low concentrations of LiCl. Moreover, receptor 1 was not examined for its LiCl selectivity in the presence of MgX2, CaX2, NaX, or KX (X = Cl and Br), which coexist in most lithium sources, under liquid-liquid extraction conditions (He et al., 2018). Receptor 2 (see Scheme 1), wherein relatively rigid phenoxy groups serve to link the phenanthroline cation and calix[4]pyrrole anion recognition subunits, was prepared in an effort to address these shortcomings. The synthesis of receptor 2 is summarized in Scheme 2. Briefly, phenanthroline ditosylate 3 and cis-bisphenolic calix[4]pyrrole 4 were prepared following known literature procedures (Scheme 1) (Wang et al., 2016; Yoo et al., 2010). Reaction of compound 3 with calix[4]pyrrole 4 in the presence of K2CO3as a base in acetonitrile gave the desired ion pair receptor 2 in 11% yield. Receptor 2 was characterized by means of1H and13C NMR -33- 4917-6162-2874, v.1 spectroscopies and high resolution QTOF (quadrupole time of flight) mass spectrometry, as well as a single crystal X-ray diffraction analysis of its LiBr complex. Scheme 2: Synthesis of exemplary receptor 2 Initially, the and alkaline earth metal chloride salts, including LiCl, NaCl, KCl, MgCl2, and CaCl2 in CH3OH / CDCl3 (1:9, v / v) was examined using1H NMR spectroscopy. This specific solvent system was chosen with consideration of the solubility of both the receptor and the test salts. Upon exposure of receptor 2 to excess LiCl (ca. 100 equiv.), noticeable chemical shift changes were observed in the proton signals of both the calix[4]pyrrole subunit and the phenanthroline group, findings leading us to conclude that receptor 2 forms an ion pair complex with LiCl (FIG.1 and FIG.2). By contrast, no chemical shift movements took place in the presence of NaCl and KCl, which was taken as evidence, without being bound, for receptor 2 incapable of complexing NaCl and KCl. In contrast, in the presence of MgCl2 (ca. 100 equiv.), roughly 16% of receptor 2 forms a complex with MgCl2under these conditions (CH3OH / CDCl3; 1:9, v / v), which leads us to suggest, without being bound by theory, that the affinity of receptor 2 for MgCl2 is very low (Ka <5 M-1) (FIG. 1)). (Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987. Association constants (Ka) were evaluated using BindFit v0.5 available from URL: app.supramolecular.org / bindfit / ). In analogy to what was seen with LiCl, Mg2+is presumed, without being bound by theory, to be bound to the phenanthroline unit while one of two Cl–anions is bound to the calix[4]pyrrole moiety via hydrogen bonds (FIG. 1, FIG. 2). Distinct chemical shift changes were also observed in the1H NMR spectrum when receptor 2 was treated with CaCl2in CH3OH / CDCl3 (1:9, v / v) (FIG. 1). These1H NMR spectral changes are consistent with the Ca2+cation only, and not the Cl–anion, being complexed within receptor 2 (FIG. 2). A follow up1H NMR spectral titration with CaCl2 provided further support for this binding mode (FIG. 3; see below for additional details). This non-ion pair binding mode stands in contrast to what was seen in the cases of LiCl and MgCl2 (FIG.2). Taken in concert, these findings are thought, without being bound by theory,

[0016] -34- 4917-6162-2874, v.1 to reflect a cation recognition site that is near-optimal for Li+cation complexation, somewhat small for fully effective Na+and K+recognition, and essentially able to accommodate only Ca2+without Cl- being co-bound. The capability of receptor 2 to complex the bromide salts of alkali and alkaline earth metal cations, including LiBr, NaBr, KBr, MgBr2 and CaBr2, was investigated in 10% methanol in chloroform-d. In contrast to what was seen with the corresponding chloride salts, upon exposure of receptor 2 to the respective bromide salts, only LiBr gave rise to chemical shift movements attributable to ion pair complexation (FIG. 4). This finding is taken as evidence, without being bound, that receptor 2 is capable of binding LiBr selectively over other test bromide salts. We also examined the binding selectivity of receptor 2 for the lithium halide salts, i.e., LiF, LiCl, LiBr, and LiI, in CH3OH / CDCl3 (1:9, v / v). Addition of LiCl and LiBr produced chemical shift changes for the signals of receptor 2 in the1H NMR spectra ascribable to co-binding of the lithium cations and the halide anions while LiF caused no appreciable chemical shift changes (FIG. 5). When receptor 2 was exposed to LiI, only the lithium cation was bound to the phenanthroline moiety without the iodide anion being co-complexed by the calix[4]pyrrole subunit (FIG. 5). When exposed to LiI, the pyrrolic NH proton of receptor 2 underwent a very small downfield shift as compared to treatment with LiCl and LiBr. By contrast, the proton peaks assignable to the phenanthroline CH protons were shifted to lowerF field in analogy to what was seen upon exposure to LiCl and LiBr. These findings are interpreted in terms of the lithium cation binding to the phenanthroline moiety without the iodide anion being co-complexed by the calix[4]pyrrole subunit. To quantify the ability of receptor 2 to bind cations and anions as well as various test ion pairs,1H NMR spectroscopic titrations were performed in CH3OH / CDCl3 (1:9, v / v). For instance, upon the titration of receptor 2 with LiCl, the resulting1H NMR spectral changes support the conclusion receptor 2 binds LiCl quantitatively with a 1:1 binding stoichiometry via a binding-release equilibrium that is slow on the NMR time scale (FIG. 6). The association constant for LiCl approximated from this titration experiment was found to be Ka>105M-1. This value is at least three orders of magnitude larger than what was found in the case of receptor 1 (Table 1 and FIG. 7) (Approximate binding constant from: Connors, Binding

[0017] -35- 4917-6162-2874, v.1 Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987). When receptor 2 was subjected to titration with LiCl in 10% CH3OH in CDCl3, two distinguishable sets of proton signals emerged in the1H NMR spectrum before saturation was achieved upon addition of 1.0 equiv of LiCl. These sets of proton signals correspond to the ion-free form of receptor 2 and its LiCl complex form, respectively. These1H NMR spectral changes support the conclusion, without being bound, that receptor 2 binds LiCl quantitatively with a 1:1 binding stoichiometry via a binding-release equilibrium that is slow on the NMR time scale. Table 1. Association constants (Ka, M-1)acorresponding to the interaction of receptor 2 with the lithium cation and selected halide anion salts as determined in CH3OH / CDCl3 (1:9, v / v). HostbGuest Ka(M-1) 2 Cl- No Binding 2 Br- No Binding 2 Li+<5c1 LiCl 180 ± 7c2 LiCl >1051 LiBr 24 ± 1c2 LiBr 63 ± 3c2 + Li+Cl- >1052 + Li+Br- 148 ± 5c2 + Cl- Li+>1052 + Br- Li+95 ± 3caValues were obtained from1H NMR spectroscopic titrations of 2.bUnless otherwise indicated, the anions and lithium cations were used in the forms of their respective tetrabutylammonium and perchlorate salts.cThe Ka value was approximated using BindFit v0.5 available from https: / / app.supramolecular.org / bindfit. Receptor 2 was also found to bind LiBr, albeit with low affinity relative to LiCl and via an equilibrium process that is fast on the NMR timescale (FIG. 8). The corresponding LiBr association constant was calculated to be Ka = 63 ± 3 M-1(Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987. Association constants (Ka) were evaluated using BindFit v0.5 available from URL: https: / / app.supramolecular.org / bindfit / ). The relatively low affinity for LiBr is presumably, without being bound by theory, because the Br–anion is too large to be co-complexed with the Li+cation effectively within the receptor cavity. However, this

[0018] -36- 4917-6162-2874, v.1 association constant for LiBr is 2.6x larger than that of receptor 1 (Table 1 and FIG. 9). The association constants for MgCl2and CaCl2were likewise determined to be Ka<5 M-1for both salts in 10% CH3OH in CDCl3 (FIG.1, FIG.3) (Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987. Association constants (Ka) were evaluated using BindFit v0.5 available from URL: https: / / app.supramolecular.org / bindfit / ). Again, this finding is ascribed, without being bound by theory, to a mismatch with the binding cavity present in receptor 2 as well as to larger solvation energies of the divalent cations. Different chemical shift changes in the receptor proton signals took place when receptor 2 was titrated with LiBr in 10% CH3OH in CDCl3. The proton signals of the receptor appeared to be gradually shifted towards either downfield or upfield and saturation was accomplished upon addition of 73 equiv of LiBr. These spectral changes are consistent, without being bound, with receptor 2 binding LiBr with low affinity relative to LiCl and via an equilibrium process that is fast on the NMR timescale. The interactions of receptor 2 with Cl–, Br–, and Li+with non-coordinating counter ions were investigated in 10% CH3OH in CDCl3. When receptor 2 was treated with excess Cl–and Br–(as their TBA+(tetrabutylammonium) salts), no appreciable chemical shift changes were observed in the1H NMR spectrum, a finding taken as evidence, without being bound, that receptor 2 fails to bind these halide anion salts in this protic solvent system (FIG.10, FIG.11). In contrast, in the presence of excess Li+(as its ClO4–(perchlorate anion) salt), the CH proton signal (Ha) of the phenanthroline subunit of receptor 2 underwent a slight downfield shift (Δδ = 0.04 ppm). Although modest, this change is thought to reflect Li+cation complexation by the phenanthroline group (FIG 10). The addition of Cl–and Br–(as their TBA+salts) to receptor 2 in the presence of Li+(as its ClO4–salt) induced significant chemical shift changes in the receptor proton signals giving rise to1H NMR spectra closely analogous to those obtained when receptor 2 was treated with LiCl and LiBr, respectively. These results are consistent, without being bound by theory, with Cl–and Br–binding to the receptor in the presence of the Li+cation in 10% CH3OH in CDCl3 forming LiCl and LiBr ion pair complexes, respectively (FIG.9, FIG.10). This stands in sharp contrast to what is observed in the absence of a Li+cation source. The association constant of receptor 2

[0019] -37- 4917-6162-2874, v.1 for LiClO4was calculated from this1H NMR spectral titration to be <5 M-1(FIG. 12) (Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987. Association constants (Ka) were evaluated using BindFit v0.5 available from URL: https: / / app.supramolecular.org / bindfit / ). These studies support that receptor 2 binds the LiCl and LiBr ion pairs far more effectively than the individual ions, Cl–, and Br–, and Li+, when the latter were tested using a non-coordinating counter ion. These findings are rationalized, without being bound by theory, in terms of the ion pair complexes with LiCl and LiBr being stabilized by electrostatic attractions between the co-bound anion and cation. Consistent with the above conclusion, the ability of receptor 2 to bind the Cl–and Br–anions was markedly improved in the presence of the Li+cation and vice versa (FIG.13). For instance, when receptor 2 was titrated with Cl–in the presence of Li+in 10% CH3OH in CDCl3, a new set of proton signals attributable to the LiCl complex of receptor 2 emerged with saturation being achieved upon the addition of 1.0 equiv. of Cl–(FIG.14). The association constant of receptor 2 for Cl–in the presence of Li+was found to be >105M-1on the basis of this1H NMR spectral titration experiment (Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987). Receptor 2 was also found to bind the Br–anion in the presence of the Li+cation (ca. 50 equiv.) with an association constant of Ka= 148 ± 5 M-1(FIG. 15 (Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987. Association constants (Ka) were evaluated using BindFit v0.5 available from URL: https: / / app.supramolecular.org / bindfit / ). This value is considerably larger than what was seen in its absence (no affinity for Br-; vide supra). The co-complexation of Cl–and Br–with Li+appears, without being bound by theory, to significantly enhance the affinity of presently disclosed compounds such as 2 for these two halide anions, which are otherwise incapable of binding to the receptor (FIG.13). The affinity of receptor 2 for Li+was also found to be significantly enhanced in the presence of Cl–and Br–. On the basis of the1H NMR spectral titration of receptor 2 with LiClO4 in the presence of TBACl (5.0 equiv.), the association constant of

[0020] -38- 4917-6162-2874, v.1 receptor 2 for Li+was estimated to be >105M-1(FIG. 16), a value that is higher than that measured in the absence of Cl–by >100,000-fold (Table 1) (Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987). In contrast, the affinity of receptor 2 for Li+was enhanced in the presence of Br–by only approx. 20-fold (FIG. 17 and Table 1). Therefore, cooperativity between the cation and anion binding sites within presently disclosed compounds such as receptor 2 appears to play, without being bound by theory, a crucial role in regulating the ion binding affinity of the receptor for appropriately chosen lithium halide ion pairs, with the effect being particularly dramatic in the case of LiCl, but also noteworthy for LiBr. During the titration of receptor 2 with Li+in a solution of CH3OH / CDCl3 (1 / 9, v / v) containing 5.0 equiv of Cl-, two sets of proton signals appeared upon the addition of 0.20 - 0.8 equiv of Cl–. However, upon the addition of ≥1.00 equiv of Cl–only one set of proton signals is seen. On the basis of this1H NMR spectral titration, the association constant of receptor 2 for Li+was estimated to be >105M-1. Further evidence that receptor 2 forms an ion pair complex with LiBr came from a single crystal X-ray diffraction analysis. Single crystals of the complex 2•LiBr appropriate for an X-ray diffraction analysis were grown by allowing a mixture of CHCl3and CH3OH containing 2 and an excess LiBr to evaporate slowly. The resulting crystal structure revealed that the Br–anion is bound to the calix[4]pyrrole moiety via hydrogen bonds with N-H···Br–distances of 2.50 ~ 2.51 Å while the Li+cation is coordinated not only to the phenanthroline nitrogen atoms but also to the ether oxygenatoms with N·· ·Li+ distances of 1.91 Å and 2.34 Å and O·· ·Li+ distances of 2.627 Åand 3.269 Å, respectively (FIG. 18). The Li+cation is further stabilized by the coordination of two methanol molecules. The Li+cation was also found to interact directly with the co-bound Br–anion at a distance of 4.02 Å. Receptor 2 was also tested for its ability to solubilize and extract the solid LiCl and LiBr into dichloromethane-d2(CD2Cl2). When receptor 2 along with LiCl or LiBr (ca. 100 equiv.) was subjected to sonication for 1 hour in CD2Cl2, distinct1H NMR spectral changes attributable to the formation of ion pair complexes 2•LiCl and 2•LiBr were seen (FIG. 19). These ion pair complexes proved soluble in CD2Cl2 enabling receptor 2 to extract LiCl and LiBr into this organic phase under solid-liquid extraction conditions. When an equimolar ratio of LiCl and LiBr (ca.100 equiv. each)

[0021] -39- 4917-6162-2874, v.1 was used, receptor 2 was found to complex both LiCl and LiBr at a nearly 1:1 ratio in CD2Cl2. This proved true, surprisingly, in spite of the greater affinity displayed for LiCl over LiBr in CH3OH / CDCl3; 1 / 9, v / v (Table 1). This seeming disparity is rationalized, without being bound by theory, in terms of the relatively small lattice energy of LiBr in CD2Cl2. On the other hand, release of the lithium cation from 2•LiCl could be, again without being bound by theory, triggered in CD2Cl2via the addition of the fluoride anion (as its tetrabutylammonium (TBA+) salt). This treatment enables recovery of Li+in the form of its insoluble LiF salt by filtration (FIG.20). The process could be monitored by1H NMR spectroscopy (FIG. 20; see below for additional details). When TBAF was gradually added to a CD2Cl2 solution containing 2•LiCl, a new set of proton signals completely emerged and, after the addition of 1.2 equiv of F–, the spectrum evolved to one nearly identical to that of the ion-free receptor 2. Further addition of F–led to formation of the fluoride anion complex of 2 featuring a doublet for the NH signal at δ = 12.4 ppm. The selectivity of 2 for the chloride and bromide salts of alkali and alkaline earth cations was also evaluated under a solid-liquid extraction conditions using dichloromethane-d2 as the receiving phase. Receptor 2 is soluble in this solvent, whereas the test salts are insoluble. In this aprotic solvent, receptor 2 exhibited different binding behavior as compared to 10% CH3OH in CDCl3. Upon treatment of receptor 2 with approx. 500 equiv. each of LiCl, NaCl, KCl, MgCl2, and CaCl2in CD2Cl2 (separate studies), only LiCl induced chemical shift changes in the spectrum that could be readily interpreted in terms of LiCl complexation (FIG. 21). In contrast, NaCl, KCl, and CaCl2 gave rise to no appreciable chemical shift changes in the1H NMR spectrum of 2. Meanwhile, treatment with MgCl2produced an orange precipitate (FIG.21). This latter finding is interpreted, without being bound by theory, in terms of receptor 2 forming an ion pair complex with MgCl2 that is insoluble in CD2Cl2. The changes in the1H NMR spectrum of 2 when treated with a mixture of LiCl, NaCl, KCl, MgCl2, and CaCl2 salts (ca. 100 equiv. each) in CD2Cl2 were also monitored. Under these conditions, an orange precipitate was formed with no discernable proton signals being seen in the1H NMR spectrum of the residual CD2Cl2 layer. Given the analogy to what was seen when receptor 2 was treated with MgCl2alone, these findings appear, without being bound by theory, to indicate receptor 2

[0022] -40- 4917-6162-2874, v.1 capturing MgCl2in preference to the other chloride salts with this nominal selectivity being driven in part by solubility considerations (FIG.22). For the corresponding bromide salts, receptor 2 was found to extract LiBr and MgBr2in the solid state into CD2Cl2but via different apparent binding modes. For instance, when exposed to LiBr in CD2Cl2, receptor 2 exhibited1H NMR spectral changes consistent with the formation of 2•LiBr where the Li+and Br- are bound to the phenanthroline nitrogen atoms and the calix[4]pyrrole NH protons, respectively (Figure 21). In contrast, exposure of 2 to MgBr2led the signal assignable to the calix[4]pyrrole NH protons to undergo a relatively small downfield shift (Δδ = 0.26 ppm for MgBr2vs Δδ = 3.31 ppm for LiBr, respectively) while the proton signals of the phenanthroline and the phenoxy CH hydrogens were seen to undergo noticeable downfield shifts (FIG. 22). These1H NMR spectral changes provide support for the notion that only the Mg2+cation is bound to the receptor with the two Br–counter anions being located outside the receptor cavity. In contrast, treatment of receptor 2 with CaBr2 led to formation of a white solid with no observable proton signals appearing in the1H NMR spectrum of 2. Again, this finding is consistent with the formation of a strong, insoluble complex with CaBr2(FIG.22). A similar phenomenon took place when receptor 2 in CD2Cl2 was treated with an equimolar mixture of LiBr, NaBr, KBr, MgBr2, and CaBr2(ca. 100 equiv. each) (FIG. 22). Therefore, the present disclosure provides compounds such as receptor 2 that complex CaBr2 with high selectivity among the various test bromide salts. The high selectivity of receptor 2 for MgCl2 over LiCl and for CaBr2 over LiBr and MgBr2observed in CD2Cl2was rationalized, without being bound by theory, in terms of the associated binding energies and geometries of the resulting complexes obtained via density functional theory (DFT) calculations carried out in the gas phase at the X3LYP / 6-31g*level (FIG. 23). For instance, the complexation energies of receptor 2 for LiCl and MgCl2 were computed to be -57.17 kcal / mol and -71.23 kcal / mol, respectively. In case of the optimized structure of the MgCl2complex, one of two chloride anions was bound to the calix[4]pyrrole subunit of receptor 2 interacting directly with the magnesium cation coordinated by the phenanthroline nitrogen atoms as well as one ether oxygen atom (FIG.23; cf. FIG.1 and FIG. 2). In contrast, the other chloride anion was located outside the receptor cavity forming a contact ion pair with the magnesium cation. The complexation energy of receptor 2 for MgCl2 proved larger than that for LiCl by -14.06 and could, without being bound by theory,

[0023] -41- 4917-6162-2874, v.1 account for the selective binding of the receptor for MgCl2over LiCl; however, solubility considerations are ignored in this analysis. The stabilization energies of receptor 2 upon complexing various bromide salts were similarly calculated to be -56.95 kcal / mol for LiBr, - 57.99 kcal / mol for MgBr2, and -71.35 kcal / mol for CaBr2, respectively (FIG. 24). These computed values could account for the selectivity seen for CaBr2 over LiBr or MgBr2; however, as above, effects such as solvation and solubility are not considered. The selectivity of receptor 2 seen in 10% CH3OH in CDCl3 is considered to reflect solvation effects. Based on their respective hydration energies (ΔhydG* = -1,830 kJ / mol for Mg2+, ΔhydG* = -1,505 kJ / mol for Ca2+, and ΔhydG* = -475 kJ / mol for Li+), Mg2+and Ca2+are presumed to be more strongly solvated by methanol molecules than Li+(Marcus, 1991). This strong solvation is thought, without being bound by theory, to reduce the binding interactions with receptor 2 leading to the observed selective binding of LiCl and LiBr in CH3OH / CDCl3 (1 / 9, v / v). Support for this presumption came from a1H NMR spectroscopic analysis. For instance, when receptor 2 was treated with an mixture of LiCl and MgCl2 (ca.100 equiv. each) in CD2Cl2, orange solids corresponding to 2•MgCl2 precipitated out with no proton signals of the receptor appearing in the1H NMR spectrum of the residual solvent phase (FIG. 25). Adding methanol (10% by volume relative to CD2Cl2) to the sample caused the precipitates to dissolve and produced a spectrum analogous to that of 2•LiCl (FIG. 25). The reversal in selectivity seen for receptor 2 from MgCl2to LiCl upon moving to a more polar medium is rationalized in terms of MgCl2 being more strongly solvated than LiCl by methanol. Similarly, the apparent high selectivity of receptor 2 for CaBr2over LiBr in CD2Cl2 was also reversed when methanol (5% by volume) was added to a CD2Cl2 solution containing precipitated 2•CaBr2(FIG.26). The solvation effects on the receptor selectivity were further supported by two-phase liquid-liquid extraction experiments using CD2Cl2as the organic receiving phase and an aqueous D2O solution as the lithium salt source. For instance, when CD2Cl2 solutions containing precipitates of the respective 2•MgCl2 and 2•CaBr2 complexes were contacted with aqueous solutions of LiCl (10 M) and LiBr (13 M), respectively, complete dissolution ensued (FIG. 24, FIG. 27). The1H NMR spectra of the organic phases exhibited proton signals consistent with those of the LiCl and LiBr complexes, respectively (FIG.24, FIG.27). These findings indicate, without being bound by theory, that MgCl2 and CaBr2 are released from receptor 2 in the organic phase into the aqueous phases while LiCl and LiBr initially present in the aqueous phase form complexes with receptor 2 that are soluble in the organic

[0024] -42- 4917-6162-2874, v.1 phase. This permits the selective extraction of these two lithium salts from an aqueous source phase into a CD2Cl2receiving phase. When the resulting organic phases containing the respective LiCl and LiBr complexes of receptor 2 were further contacted with ion-free D2O, release of LiCl and LiBr into the aqueous D2O phase occurs. This produces receptor 2 in its ion-free form (FIG.24, FIG.27). In order to obtain further insights into the ability of presently disclosed compounds such as receptor 2 to extract the metal chloride and bromide salts from an aqueous phase, liquid-liquid extraction experiments were carried out using CD2Cl2 / D2O. For instance, when an CD2Cl2 layer containing receptor 2 (3 mM) was contacted with aqueous solution layers containing excess LiCl, NaCl, KCl, MgCl2, and CaCl2, respectively, only in the case of LiCl were chemical shift changes seen in the1H NMR spectrum of the organic layer consistent with effective extraction (FIG. 28). The resulting1H NMR spectrum was almost identical to that seen upon complexation of receptor 2 with LiCl (cf. FIG. 21). This finding was taken, without being bound, as evidence that presently disclosed compounds such as receptor 2 are able to extract LiCl with high selectivity from an aqueous source phase into a CD2Cl2 organic layer. Upon exposure of a CD2Cl2 solution of receptor 2 (3 mM) to aqueous solutions containing various respective bromide salts, as above, only the lithium salt (LiBr) induced chemical shift changes attributable to LiBr complex formation (FIG.29). To evaluate further the extraction capacity of receptor 2 for LiCl and LiBr, we determined the percentages of the receptor loaded with LiCl and LiBr in the CD2Cl2 organic phase after contacting with aqueous solutions containing different concentrations of LiCl and LiBr, respectively. When receptor 2 was contacted with an aqueous D2O solution containing 5 M of LiCl, two sets of proton signals were visible in the1H NMR spectrum of the organic phase (FIG. 30). Based on integrations, ca. 24% of the receptor was presumed to participate in the LiCl extraction (FIG.30). In contrast, the LiCl loading percentage of the receptor from an aqueous solution containing 10 M of LiCl was calculated to be ca. ≈ 100% (FIG. 30). Further evidence for the ability of receptor 2 to extract LiCl came from a high resolution ESI mass spectrometric analysis. A major peak at m / z = 795.4105, a value corresponding to [M + Li]+, was seen (FIG. 31). On the other hand, the corresponding receptor loading levels for LiBr were estimated to be ca. (70 ± 10) % and ca. 100% when a CD2Cl2solution containing receptor 2 (3 mM) was contacted with aqueous solutions containing 10 M and 15 M concentrations of LiBr, respectively (FIG. 32). These findings stand in sharp contrast to what was seen with receptor 1 that fails to extract LiCl or LiBr under the same LLE conditions

[0025] -43- 4917-6162-2874, v.1 (FIG. 33, FIG. 34). Both the LiCl and LiBr complexes of receptor 2 could be separated off and washed with D2O to release the bound salts into an aqueous D2O layer (FIG.24, FIG.27), thereby freeing up receptor 2 for possible reuse. In some embodiments, the extraction efficiency of presently disclosed compounds such as receptor 2 for LiCl and LiBr is improved by employing relatively polar nitrobenzene- d5as the organic receiving phase instead of CD2Cl2. For instance, after a nitrobenzene-d5solution containing receptor 2 was contacted with an aqueous source phase containing an excess of the respective LiCl, NaCl, KCl, MgCl2, and CaCl2, it was found that 100% of the receptor in the organic phase existed in the form of the LiCl complex (FIG.35). In the case of NaCl and KCl, less than 30% of the receptor was loaded with these salts in the organic phase while no evidence for MgCl2 and CaCl2 extraction by receptor 2 was found (FIG. 35). In contrast, when a nitrobenzene-d5 organic layer of receptor 2 (3 mM) was contacted with an aqueous layer containing all five test chloride anion salts (LiCl, NaCl, KCl, MgCl2, and CaCl2) at a concentration of ≈ 5.0 M each, the resulting1H NMR spectrum of the nitrobenzene layer was consistent with that recorded after receptor 2 was treated with LiCl only (FIG. 35). This finding was taken as evidence, without being bound, that presently disclosed compounds such as receptor 2 are capable of extracting LiCl with high selectivity from a mixed salt aqueous solution. In analogy to what was seen in the case of the metal chloride salts, receptor 2 was found to extract LiBr selectively from an aqueous solution over other test bromide salts. For instance, upon subjecting the nitrobenzene-d5 layer containing receptor 2 to contact with a D2O layer containing an excess amount of LiBr, NaBr, KBr, MgBr2, and CaBr2, respectively, only LiBr gave rise to a1H NMR spectrum of the organic layer consistent with formation of an ion pair complex (FIG.36). The capacity of receptor 2 to extract LiCl and LiBr into nitrobenzene-d5 from an aqueous D2O solution containing various concentrations of LiCl or LiBr was examined. For instance, when a nitrobenzene-d5 phase containing receptor 2 (3 mM) was contacted with aqueous D2O layers containing 0.5 M ~ 5.0 M of LiCl, the resulting1H NMR spectra of the nitrobenzene-d5phase exhibited two distinguishable sets of proton signals that could be assigned to the ion-free form and the LiCl complex of receptor 2, respectively. The LiCl loading percentages of the receptor in the organic layer were determined to be <10%, 39%, 63%, 74%, 93%, and 100% when nitrobenzene-d5 phases containing the receptor were contacted with D2O solutions containing 0.5 M, 1.0 M, 2.0 M, 3.0 M, 4.0 M, and 5.0 M of LiCl, respectively (FIG. 37). The LiCl loading levels for receptor 2 were compared to those

[0026] -44- 4917-6162-2874, v.1 achieved by receptor 1. For instance, the LiCl loading percentage of receptor 1 from a 10 M LiCl aqueous solution was 15% (He et al., 2018). In case of LiBr, when nitrobenzene-d5solutions of receptor 2 were treated with D2O aqueous solutions containing LiBr at concentrations of 3.0 M, 5.0 M, and 8.0 M, respectively, 21%, 53%, and 100% of the receptor molecules formed a LiBr complex within the organic phase (FIG.38). The ability of receptor 2 to extract LiCl selectively was evaluated under liquid-liquid extraction conditions using aqueous solutions containing other competitive chloride salts including NaCl, KCl, MgCl2, and CaCl2. In the case of the individual salts, receptor 2 failed to extract chloride salts other than LiCl under otherwise identical liquid-liquid extraction conditions when aqueous solutions containing 5.0 M of the metal cation chloride anion salts in question were tested (FIG. 37). This selectivity was retained when mixtures of salts were tested. However, unexpectedly, the extraction efficiency of the receptor for LiCl was boosted in the presence of the other test chloride salts. For instance, the proton integration ratios corresponding to the 2·LiCl complex in the1H NMR spectra of the nitrobenzene-d5 phases increased as the concentration of the other chloride salts increased (FIG. 39, FIG. 40). By way of a specific example, when a nitrobenzene-d5 phase containing receptor 2 (3 mM) was contacted with an aqueous solution containing 0.5 M of LiCl in the absence of the other salts, <10% of the receptor was loaded with LiCl in the organic layer (FIG. 39, FIG. 40). By contrast, the LiCl loading percentages of receptor 2 were enhanced up to 54% and 78% when the aqueous LiCl source phase (0.5 M) consisted of a mixture of NaCl, KCl, MgCl2, and CaCl2at concentrations of 0.5 M each and 1.0 M each, respectively. This loading increased to nearly 100% when each of the salts, including LiCl, was present at 1.0 M (FIG. 39, FIG. 36). Similar results were observed in liquid-liquid extraction studies involving dichloromethane- d2 as the receiving phase. For instance, upon contacting an organic dichloromethane-d2 phase containing receptor 2 with an aqueous D2O phase containing 5.0 M LiCl, 24% of the receptor in the organic phase was loaded with LiCl. In the presence of excess NaCl and NaBr along with 5.0 M LiCl in the aqueous phase, the LiCl loading percentages improved to 36% and 42%, respectively (FIG.41, FIG.42). Example 2: Synthesis, Characterization, and Methodology a. General experimental and synthetic details Solvents and reagents used for the synthetic work were purchased from Aldrich, TCI, or Alfa Aesar and used without further purification. NMR spectra were recorded on a Bruker Advance-300 MHz instrument. NMR spectra were referenced to residual solvent peaks. The

[0027] -45- 4917-6162-2874, v.1 spectroscopic solvents were purchased from either Cambridge Isotope Laboratories or Aldrich. Quadrupole time-of-flight (QTOF) mass spectra were recorded on a VG ZAB-2E instrument or a VG AutoSpec apparatus. TLC analyses were carried out using Sorbent Technologies silica gel (200 mm) sheets. Column chromatography was performed on Sorbent Technologies silica gel 60 (40–63 mm). Theoretical calculations evaluating the stability of various putative structures were carried out with the Gaussian 09 suite (Gaussian et al., 2009) of programs using the X3LYP density functional (Xu and Goddard, 2004). Structural optimization was performed using a 6–31G* basis set. Complexation energies were corrected for basis set superposition error (BSSE) using the counterpoise correction method (Boys and Bernardi, 2002; van Duijneveldt et al., 2002). b. Liquid-liquid extraction of the salts using the ion pair receptors To 5 mL vials containing 2 mL of dichloromethane-d2or nitrobenzene-d5solutions of the receptors (3 mM) vials were added 2 mL of aqueous solutions of the salts in question. The resulting two-phase solutions were vigorously shaken for 10 min and then allowed to stand for 1~2 hours until the two phases are clearly separated. The aqueous phase was removed, and 1 ml of the organic phase was transferred to an NMR tube. The organic solution was then monitored by1H NMR spectroscopy. The integrations corresponding to the ion free forms and the salt complex forms of the receptor, respectively, were compared to determine the loading percentages of the receptor with salts. c. Synthesis of Receptor 2 Compound 3 (1.36 g, 2.48 mmol) (Wang et al., 2016), compound 4 (1.45 g, 2.48 mmol) (Yoo et al., 2010) and K2CO3(1.71 g, 12.37 mmol) were dissolved in 80 mL of acetonitrile and heated to reflux under a nitrogen atmosphere. After the resulting reaction mixture was stirred at reflux for 24 hours, the volatiles were removed in vacuo. To the resulting brown solid, CH2Cl2(100 mL) was added and the organic layer was separated off and washed three times with 200 mL of water. The organic layer was dried over anhydrous MgSO4and the solvent was evaporated in vacuo to give a brown solid. Column chromatography over silica gel (eluent: acetone / dichloromethane (1:70)) gave 0.22 g (11.25% yield) of 2 as a white solid.1H NMR (300 MHz, chloroform-d) δ 8.28 (d, J = 8.3 Hz, 2H), 7.88 (d, J = 8.3 Hz, 2H), 7.81 (s, 2H), 7.21 – 7.10 (m, 4H), 7.05 – 6.95 (m, 4H), 6.63 (s, 4H), 5.93 – 5.85 (m, 4H), 5.78 (dd, J = 3.4, 2.8 Hz, 4H), 5.66 (s, 4H), 1.89 (s, 6H), 1.42 (s, 6H), 1.23 (s, 6H).13C NMR (75 MHz, chloroform-d) δ 157.9, 145.3, 138.5, 137.3, 136.9, 128.3,

[0028] -46- 4917-6162-2874, v.1 126.6, 122.84, 115.6, 104.2, 73.7, 44.0, 35.3, 29.9, 29.5. HRMS (QTOF) m / z 788.3839 [M]+calcd for C52H48N6O2, found 788.3917. d. Determination of association constants for host-guest association / dissociation equilibria that are slow on the NMR time scale using 1H NMR spectral titrations Equilibrium: A + B AB [^^] [^^] Equilibrium constant: Ka = [^][^] = (^(^^^[^^]^(^(^^^[^^]^ (1) c(A) and c(B) are the A and and [A], [B] and [AB] are the equilibrium A and B is in slow exchange with the complex AB on the1H NMR time scale. Two signals for one specific proton on A can be seen in the spectrum, corresponding to complexed and uncomplexed forms of A: Single-point Methods Ka is determined from the integrals of complexed and uncomplexed A. If I(A) denotes the integral of a signal for one specific proton of A and I(AB) the integral for the same proton in the complex, the concentration of AB at equilibrium is shown by eq 2. The equilibrium expression (eq 3) is obtained after substituting into eq (1): ^ [AB]=(^^^^^(A^(2) Upon exposure of receptor 2 to excess LiCl (ca.100 equiv), the proton signals (Ha, Hb, and Hc) in the1H NMR spectrum corresponding to the phenanthroline unit underwent noticeable downfield shifts presumably due to the complexation of the lithium cation with the phenanthroline nitrogen atoms. A more significant downfield shift (Δδ = 3.23 ppm) was seen for the NH proton signal of the calix[4]pyrrole unit, a finding attributed to the formation of hydrogen bonds between the NH protons and the chloride anion. These chemical shift

[0029] -47- 4917-6162-2874, v.1 changes are distinct from those taking place when either the lithium cation (as its perchlorate (ClO4-) salt) or the chloride anion (as its tetrabutylammonium (TBA+) salt) was added to receptor 2 (vide infra). These findings led us to conclude that receptor 2 forms an ion pair complex with LiCl. By contrast, no appreciable chemical shift changes were observed in the1H NMR spectra in the presence of NaCl or KCl, a finding interpreted in terms of receptor 2 failing to complex these salts. In contrast, upon the addition of excess MgCl2(ca. 100 equiv) to receptor 2, two distinguishable sets of proton signals appeared that corresponded to the ion-free receptor and its MgCl2complex, respectively. In analogy to what was seen with LiCl, Mg2+is presumed to be bound to the phenanthroline unit while one of two Cl–anions is bound to the calix[4]pyrrole moiety via hydrogen bonds (FIG. 13). Based on the integration ratios of the proton signals of the ion-free receptor and the MgCl2 complex, roughly 16% of receptor 2 forms a complex with MgCl2 under these conditions (CH3OH / CDCl3; 1:9, v / v). Distinct chemical shift changes were also observed in the1H NMR spectrum when receptor 2 was treated with CaCl2 in CH3OH / CDCl3 (1:9, For instance, the proton peaks corresponding to the phenanthroline unit experienced relatively small downfield shifts as compared to LiCl and MgCl2 while the pyrrolic NH proton signal disappeared. A follow up1H NMR spectral titration with CaCl2revealed that the pyrrolic NH proton signal of receptor 2 was only slightly downfield shifted upon addition of up to 5.6 equiv of CaCl2 before it disappeared in the presence of > 9.6 equiv of CaCl2(FIG. 2). These1H NMR spectral changes are consistent with the Ca2+cation only, and not the Cl–anion, being complexed within receptor 2. * * * * * * * * * * * * * All of the compositions and / or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this disclosure have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and / or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the disclosure. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the disclosure as defined by the appended claims.

[0030] -48- 4917-6162-2874, v.1 References The following references, to the extent that they provide exemplary procedural or other details supplementary to those set forth herein, are specifically incorporated herein by reference. Anderson, Practical Process Research & Development – A Guide for Organic Chemists, 2nded., Academic Press, New York, 2012. U.S. Patent No.6,262,257 U.S. Patent No.6,984,734 U.S. Patent No.7,041,819 U.S. Patent No.7,122,572 U.S. Patent No.8,802,074 U.S. Patent App. Pub. No.2010 / 0129308 U.S. Patent App. Pub. No.2010 / 0120958 1 Armand and Tarascon, Nature, 451, 652-657, 2008. 2 Oruch et al., Eur. J. Pharmacol., 740, 464-473, 2014. 3 Evarts, Nature, 526, S93-S95, 2015. 4 Martin et al., Energy Storage Mater., 6, 171-179, 2017. 5 Kavanagh et al., Resources, 7, 57, 2018. 6 Saraim and Lippmann, Innov Clin Neurosci., 15, 30-32, 2018. 7 U.S. Geological Survey: Reston, VA, 2022. 8 Swain, Sep. Purif. Technol., 172, 388-403, 2017. 9 Haddad et al., Nature, 616, 245-248, 2023. 10 Meshram et al., Hydrometallurgy, 150, 192-208, 2014. 11 Vieceli et al., Miner. Eng., 102, 1-14, 2017. 12 Yelatontsev and Mukhachev, Hydrometallurgy, 201, 105578, 2021. 13 Gao et al., China Geology, 6, 137-153, 2023. 14 Nishihama et al., Solvent Extr. Ion Exch., 29, 421-431, 2011. 15 Loganathan et al., Environ. Sci.: Water Res. Technol., 3, 37-53, 2017. -49- 4917-6162-2874, v.1 16 Yang et al., Joule, 2, 1648-1651, 2018. 17 Harvianto et al., Rare Met., 35, 948–953, 2016. 18 Liu et al., Joule, 4, 1459-1469, 2020. 19 He et al., Joule, 4, 1357-1368, 2020. 20 Flexer et al., Sci. Total Environ., 639, 1188-1204, 2018. 21 Liu et al., Hydrometallurgy, 187, 81-100, 2019. 22 Xu et al., Mater. Sci., 56, 16-63, 2021. 23 Sun et al., Sep. Purif. Technol., 256, 117807, 2021. 24 Zhao et al., Desalination, 481, 114360, 2020. 25 Khalil et al., Desalination, 528, 115611, 2022. 26 Ying et al., ACS ES&T Water, 3, 1720-1739, 2023. 27 Stringfellow and Dobson, Energies, 14, 6805, 2021. 28 Vera et al., Nat. Rev. Earth Environ., 4, 149-165, 2023. 29 Marcus, J. Chem. Soc., Faraday Trans., 87, 2995-2999, 1991. 30 Xu et al., J. Mater. Sci., 56, 16-63, 2021. 31 Zhang et al., Angew. Chem. Int. Ed., 62, e202216011, 2023. 32 Kim and Sessler, Chem. Soc. Rev., 39, 3784-3809, 2010. 33 Kim and Sessler, Acc. Chem. Res., 47, 2525-2536, 2014. 34 He et al., Chem. Rev., 119, 9753-9835, 2019. 35 McConnell and Beer, Angew. Chem., Int. Ed., 51, 5052-5061, 2012. 36 McConnell et al., ChemPlusChem, 2020, 85, 1824-1841, 2020. 37 He et al., J. Am. Chem. Soc., 138, 9779-9782, 2016. 38 Hong et al., Chem. Commun., 56, 10541-10544, 2020. 39 He et al., Angew. Chem. Int. Ed., 57, 11924-11928, 2018. 40 Wang et al., Chem. Sci., 7, 2787-2792, 2016. 41 Yoo et al., Bull. Korean Chem. Soc., 31, 630-634, 2010. 42 Approximate binding constant from: Connors, Binding Constants: The Measurement of Molecular Complex Stability; Wiley-Interscience: New York, 1987. Association constants (Ka) were evaluated using BindFit v0.5 available from URL: https: / / app.supramolecular.org / bindfit / . 1. Gaussian et al., Gaussian, Inc., Wallingford CT, 2009. Xu and Goddard, P. Natl. Acad. Sci. USA, 101, 2673-2677, 2004.

[0031] -50- 4917-6162-2874, v.1 3. Boys and Bernardi, Mol. Phys., 100, 65-73, 2002. 4. van Duijneveldt et al., Chem. Rev., 94, 1873-1885, 1994. 5. Wang et al., Chem. Sci.7, 2787-2792, 2016. 6. Yoo et al., Bull. Korean Chem. Soc.31, 630-634, 2010. Practical Process Research & Development – A Guide for Organic Chemists, 2012.

[0032] -51- 4917-6162-2874, v.1

Claims

CLAIMS What is claimed is:

1. A compound of the formula: , wherein:R1, R1′, R2, R2′, R3, R3′, R4, and R4′ are each independently hydrogen, hydroxy, amino, cyano, or halo; or alkyl(C≤6), alkenyl(C≤6), alkynyl(C≤6), acyloxy(C≤6), alkoxy(C≤6), alkylamino(C≤6), dialkylamino(C≤12), amido(C≤6), or a substituted version of any of these groups; or one of these groups is attached to a solid support or a fluorophore; R5, R5′, R6, R6′, R7, and R8 are each independently hydrogen or alkyl(C≤12), cycloalkyl(C≤12), cycloalkenyl(C≤12), alkenyl(C≤12), alkynyl(C≤12), aryl(C≤12), heteroalkyl(C≤12), heterocycloalkyl(C≤12), alkoxy(C≤12), alkylamino(C≤12), dialkylamino(C≤18), amido(C≤12), or a substituted version of any of these groups; or one of these groups is attached to a solid support or a fluorophore; R9, R10, R11, and R12 are hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); L and L′ are taken together and form a group of the formula:, wherein:X and X′ are each independently arenediyl(C≤8)or substituted arenediyl(C≤8); Y and Y′ are each independently −O−, −C(O)−, −C(O)O−, −S(O)−, −S(O)2O−, −C(O)NRa−, or −S(O)2NRb−, wherein: -52- 4917-6162-2874, v.1Raand Rbare each independently hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); or one or more of these groups is attached to a solid support or a fluorophore; Z is a group of the formula: (Ib), wherein:A1and A1′ are each independently alkanediyl(C≤8), substituted alkanediyl(C≤8); and A2 is heteroarenediyl(C≤24) or substituted heteroarenediyl(C≤24), wherein the group comprises at least 3 fused rings; or or a salt thereof.

2. The compound of claim 1, wherein the compound is further defined as: , wherein:L and L′ are taken together and form a group of the formula: , wherein:X and X′ are each independently arenediyl(C≤8) or substituted arenediyl(C≤8); Y and Y′ are each independently −O−, −C(O)−, −C(O)O−, −S(O)−, −S(O)2O−, −C(O)NRa−, or −S(O)2NRb−, wherein: Ra and Rb are each independently hydrogen, alkyl(C≤6), or substituted alkyl(C≤6); Z is a group of the formula: (Ib), wherein:-53- 4917-6162-2874, v.1A1and A1′ are each independently alkanediyl(C≤8), substituted alkanediyl(C≤8); and A2 is heteroarenediyl(C≤24) or substituted heteroarenediyl(C≤24), wherein the group comprises at least 3 fused rings; or or a salt thereof.

3. The compound of either claim 1 or claim 2, wherein X and X′ are both arenediyl(C≤8) or substituted arenediyl(C≤8).

4. The compound according to any one of claims 1-3, wherein X and X′ are both benzenediyl.

5. The compound according to any one of claims 1-4, wherein Y and Y′ are both the same.

6. The compound according to any one of claims 1-5, wherein Y and Y′ are both −O−.

7. The compound according to any one of claims 1-6, wherein A1and A1′ are both alkanediyl(C≤8)or substituted alkanediyl(C≤8).

8. The compound according to any one of claims 1-7, wherein A1 and A1′ are both methylene.

9. The compound according to any one of claims 1-8, wherein A2is heteroarenediyl(C≤18)or substituted heteroarenediyl(C≤18), wherein the group comprises at least 3 fused rings.

10. The compound according to any one of claims 1-9, wherein A2 is heteroarenediyl(C≤18), wherein the group comprises 3 fused rings.

11. The compound according to any one of claims 1-10, wherein A2 is heteroarenediyl(C≤18), wherein the group comprises 3 fused rings and contains at least two nitrogen atoms.

12. The compound according to any one of claims 1-11, wherein A2is phenanthrolinediyl.

13. The compound according to any one of claims 1-12, wherein A2 is phenanthroline- 2,9-diyl.-54- 4917-6162-2874, v.

114. The compound according to any one of claims 1-13, wherein the compound is further defined as: .

15. A compositionto any one of claims 1-14 and a salt.

16. The composition of claim 15, wherein the salt is lithium(I) chloride.

17. A method of carrying out a liquid-liquid extraction of a salt from a first solution to form a complex with a compound according to any one of claims 1-14, wherein the compound is dissolved in a liquid.

18. A method of carrying out a solid-liquid extraction of a salt from a solid to form a complex with a compound according to any one of claims 1-14, wherein the compound is dissolved in a liquid.

19. The method of either claim 17 or claim 18, wherein the liquid is water.

20. The method according to any one of claims 17-19, wherein the method is carried out in the presence of one or more additional salts.-55- 4917-6162-2874, v.1

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