CHELATING MOLECULES

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/401,687, filed on Sept. 29, 2016, which is hereby incorporated by reference in its entirety. STATEMENT OF GOVERNMENT SUPPORT

[0002] This invention was made with government support under DE-AC02- 05CH11231 awarded by the Department of Energy. The government has certain rights in the invention.

FIELD OF THE DISCLOSURE

[0003] The present disclosure provides various metal chelators. BACKGROUND OF THE DISCLOSURE

[0004] Metal-binding ligands have a variety of uses, from medical to environmental and numerous other applications. SUMMARY OF THE DISCLOSURE

[0005] In some embodiments, a composition having a structure is provided that comprises:

, wherein:

(i) A1, A2, A3, and A4, individually, comprise a CAM group, a 1,2-HOPO group, or a HA group; (ii) B1, B2, B3, and B4, individually, comprise an amide group or an amine group; (iii) at least one of C1, C2, C3, C4, C5, or C6, individually, comprise NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

(iv) at least another one of C1, C2, C3, C4, C5, or C6 is optional; (v) at least one of L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, or L13, individually, comprise H, an alkyl group having no greater than 10 carbon atoms, an alkylamino group having no greater than 10 carbon atoms and no greater than 2 nitrogen atoms; an alkylamido group having no greater than 10 carbon atoms and no greater than 2 nitrogen atoms; an alkyl ether group having no greater than 10 carbon atoms, a hydroxy ester group, or an alkyl ester group having no greater than 10 carbon atoms; and (vi) at least one of L1, L5, L6, L7, L8, L9, L10, L11, L12, or L13 is optional. [0006] In some embodiments a composition is provided that comprises a structure:

,

wherein: at least one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, comprise a CAM group, a HA group, or a 1,2-HOPO group; at least another one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, comprise H or an alkyl group having from 1 to 10 carbon atoms; R ₆ comprises (i) H, (ii) an alkyl group having from 1 to 10 carbon atoms, or (iii) an alkyl group having from 1 to 10 carbon atoms and substituted by at least one of NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; m can be from 1 to 6; n can be from 1 to 6; o can be from 1 to 6.

[0007] In some embodiments, a composition is provided that comprises a structure:

,

wherein: at least one of R ₁₁ , R ₁₂ , R ₁₃ , or R ₁₅ , individually, comprise a CAM group, a HA group, or a 1,2-HOPO group; optionally, at least another one of R ₁₁ , R ₁₂ , R ₁₃ , or R ₁₅ , individually, comprise H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ comprises NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; R ₂ , R ₁₄ , and R ₁₆ , individually, comprise H, OH, or an alkyl group having from 1 Page 3 of 109 to 10 carbon atoms; and r can be from 0 to 6.

[0008] In some embodiments, a composition is provided comprising a structure:

,

wherein: R ₂₁ and R ₂₂ , individually, comprise H, OH, or an alkyl group having from 1 to 10 carbon atoms; R ₂₃ comprises H, OH, an alkyl group having from 1 to 10 carbon atoms, or (CH ₂ ) _e R _a , where R _a is NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; R ₂₄ comprises a substituent having a CAM group, a 1,2-HOPO group, or a HA group; a, b, and c, individually, are from 1 to 10; d is from 1 to 4; and e is from 1 to 10.

[0009] In some embodiments, a composition is provided that comprises a structure:

,

wherein: A, B, C, and D, individually, comprise one or more amide groups, one or more amine groups, or an alkyl group having from 1 to 10 carbon atoms; R ₃₃ , R ₃₄ , R ₃₅ , and R ₃₆ , individually, comprise a CAM group, a 1,2-HOPO group, or a HA group; and g, h, i, and j, individually, are from 1 to 10. [0010] In some embodiments, a composition is provided that comprises a structure:

wherein: at least one of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , individually, comprise a CAM group, a HA group, or a 1,2-HOPO group; at least another one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, comprise H or an alkyl group having from 1 to 10 carbon atoms; R ₆ comprises (i) H, (ii) an alkyl group having from 1 to 10 carbon atoms, or (iii) an alkyl group having from 1 to 10 carbon atoms and substituted by at least one of NH ₂ , C(=O)OH, maleimide, dibromo- maleimide, isothiocyanate, alkyne, or azide; m can be from 1 to 6; n can be from 1 to 6; o can be from 1 to 6; p can be from 1 to 6; q can be from 1 to 6; r can be from 1 to 6; s can be from 1 to 6; and t can be from 1 to 6. BRIEF DESCRIPTION OF THE FIGURES

[0011] FIG. 1. Complexation of M(III) and M(IV) by the hexadentate siderophore enterobactin or the octadentate synthetic analogs 3,4,3-LI(CAM) or 3,4,3-LI(1,2-HOPO), when deprotonated.

[0012] FIGs.2A and 2B.3,4,3-LI(2,2-diphenylbenzo[d][1,3]-2,3-catecholamide) (5)– NMR Spectra.

[0013] FIGs.3A and 3B.3,4,3-LI(CAM) (6)– NMR Spectra.

[0014] FIG.4.3,4,3-LI(CAM) (6)– Mass Spectrum, Positive Mode.

[0015] FIGs.5A and 5B. (5A) Example of spectrophotometric competition titration of Th(IV)-CAM complexes. Starting conditions: 50 µM 3,4,3-LI(CAM), 50 µM Th(IV), 112 µM DTPA, 3 mM CHES, 3 mM TRIS, 3 mM MES, 10 mM HCl. I = 0.1 M (KCl). T = 25 °C. 130 spectra measured between pH 2.4 and 11.5. Path length = 10 mm. Spectra corrected for dilution. Inset: Change in absorbance 360 nm (squares), 340 nm (crosses), 280 nm (circles) and 265 nm (diamonds) as a function of pH. (5B) Speciation diagram of the 3,4,3-LI(CAM) ligand in the presence of Th(IV). [Th] = [CAM] = 10 μΜ. T = 25°C, I = 0.1 M. Species: CAMH ₈ , CAMH/, [CAMHTh] ^3" and [CAMTh] ^4" . Calculations performed with Hyss software.

[0016] FIGs. 6A and 6B. (6A) Example of spectrophotometric competition titration of Zr(IV)-CAM complexes. Starting conditions: 50 μΜ 3,4,3-LI(CAM), 50 μΜ Zr(IV), 56 μΜ DTPA, 5 mM CHES, 5 mM TRIS, 5 mM MES, 45 mM HCI. I = 0.1 M (KCI). T = 25 °C. 230 spectra measured between pH 1.4 and 11.8. Path length = 10 mm. Spectra corrected for dilution. Inset: Change in absorbance 360 nm (squares), 340 nm (crosses) and 265 nm (diamonds) as a function of pH. (6B) Speciation diagram of the 3,4,3- LI(CAM) ligand in the presence of Zr(IV). [Zr] = [CAM] = 10 μΜ. T = 25°C, I = 0.1 M. Species: CAMH ₈ , CAMH ₇ ^" , [CAMHZr] ^3" and [CAMZr] ^4" . Calculations performed with Hyss software.

[0017] FIGs. 7A and 7B. (7A) Example of spectrophotometric competition titration of Eu(lll)-CAM complexes. Starting conditions: 50 μΜ 3,4,3-LI(CAM), 50 μΜ Eu(IV), 10 mM CHES, 10 mM MES, 10 mM acetic acid, 10 mM HCI. I = 0.1 M (KCI). T = 25 °C. 215 spectra measured between pH 2.0 and 11.9. Path length = 10 mm. Spectra corrected for dilution. Inset: Change in absorbance 360 nm (squares), 340 nm (crosses) and 265 nm (diamonds) as a function of pH. (7B) Speciation diagram of the 3,4,3-LI(CAM) ligand in the presence of Eu(lll). [Eu] = [CAM] = 10 μΜ. T = 25°C, I = 0.1 M. Species: CAMHg, CAMH ₇ ^" , CAMH ₆ ^2" , [CAMH ₂ Eu] ^3" , [CAMHEu] ^4" and [CAMEu] ^5" . Calculations performed with Hyss software.

[0018] FIG. 8. Synthesis of 3,4,3-LI(CAM). (A) H ₂ S0 ₄ , MeOH, 65°C, 16h (88%). (B) dichlorodiphenylmethane, 160°C, 1 h. (C) 50/50 THF/H ₂ 0, reflux 5 h (81 % over 2 steps). (D) (COCI) ₂ , toluene, cat. DMF; then spermine, Et ₃ N, THF, 50°C, O/N (78%). (E) AcOH/H ₂ 0 + cone. HCI, 16h (90%).

[0019] FIG. 9. Protonation and Eu(lll), Zr(IV), and Th(IV) Complex Formation Constants for 3,4,3-LI(CAM) ^{a a} / = 0.1 M (KCI), 7 = 25 °C. Errors correspond to standard deviations from at least three independent titrations. Protonation and Eu(lll), Zr(IV), and Th(IV) complex formation constants previously reported for 3,4,3-LI(1 ,2-HOPO) are also given for comparison. [0020] FIG.10A depicts an embodiment of a general peptoid synthesis.

[0021] FIG.10B depicts an embodiment of a general peptoid synthesis.

[0022] FIG.10C depicts some embodiments of a general peptoid synthesis.

[0023] FIG.10D depicts some embodiment of a general peptoid synthesis.

[0024] FIG. 10E depicts some embodiments of a combination of products obtained from a general peptoid synthesis scheme.

[0025] FIG.10F depicts some embodiments of a fluorescent tag.

[0026] FIG.11A depicts some embodiments of a conjugation pathway.

[0027] FIG.11B depicts some embodiments of a conjugation pathway.

[0028] FIG.12A depicts reaction schemes for conjugation.

[0029] FIG.12B depicts reaction schemes for a conjugation.

[0030] FIG.13 depicts some embodiments of a fluorescent tag incorporation.

[0031] FIG.14 depicts a representative reversed-phase HPLC trace

[0032] FIG.15A depicts the mass spectra (HHHC Peptoid. MS1: free peptoid, MS2: peptoid-Na, MS3: peptoid-Fe and peptoid-Fe-K.

[0033] FIG.15B depicts the mass spectra for CHHH Peptoid. MS1: free peptoid and peptoid-K, MS2: peptoid-Na, peptoid-Fe, and possible impurity.

[0034] FIG.15C depicts the mass spectra for HCHH Peptoid. MS1: free peptoid and peptoid-K, MS2: peptoid-Na, peptoid-Fe.

[0035] FIG.15D depicts the mass spectra for HHCH Peptoid. MS1: free peptoid and possible impurity, MS2: peptoid-Na, MS3: Peptoid-Fe.

[0036] FIG. 15E depicts the mass spectra for CHHC Peptoid. MS1: free peptoid only and peptoid-K, MS2: peptoid-Na and peptoid-Fe.

[0037] FIG.15F depicts the mass spectra for HHCC Peptoid. MS1: free peptoid and peptoid-Na, MS2: peptoid-Na, free peptoid, and peptoid-Fe.

[0038] FIG.15G depicts the mass spectra for CCHH Peptoid. MS1: free peptoid and peptoid-Na, MS2: Peptoid-Fe and possible trimer.

[0039] FIG. 15H depicts the mass spectra for HCHC Peptoid. MS1: free peptoid, MS2: peptoid-Fe and peptoid-Na.

[0040] FIG.15I depicts the mass spectra for HCCH Peptoid. MS1: free peptoid and small amount trimer, MS2: peptoid-Fe, MS3: peptoid-Na and possible fragments. [0041] FIG.15J depicts the mass spectra for CHCH Peptoid. MS1: free peptoid and peptoid-K, MS2: peptoid-Fe.

[0042] FIG.15K depicts the mass spectra for HCCC Peptoid. MS1: free peptoid and trimer-Fe trace, MS2: free peptoid and peptoid-Fe.

[0043] FIG.15L depicts the mass spectra for CHCC Peptoid. MS1: free peptoid and peptoid-Na, MS2: free peptoid and unidentified masses.

[0044] FIG. 15M depicts the mass spectra for CCHC Peptoid. MS1: free peptoid, MS2: free peptoid and peptoid-Na.

[0045] FIG.15N depicts the mass spectra for CCCH Peptoid. MS1: free peptoid and peptoid-Na, MS2: free peptoid and peptoid-K/Na.

[0046] FIG.15O depicts the mass spectra for CCCH Peptoid. MS1: free peptoid and peptoid-Na, MS2: free peptoid and peptoid-K/Na.

[0047] FIG. 15P is the mass spectra for HHHH Peptoid. MS1: free peptoid, MS2: peptoid-Fe/Na, MS3: Peptoid-Fe-Na.

[0048] FIGs. 16A-16C depict the spectra that were obtained in negative mode. All peptoids are 1:1 Fe ³⁺ complexes except for CCCC and HHHH. Top spectrum is calculated and bottom is obtained.

[0049] FIG.17 depicts the TOF MSMS of select peptoids.

[0050] FIGs.18A-18D depict NMR results of select peptoids.

DETAILED DESCRIPTION

[0051] Chelators. Chelators are molecules that can bind metals. Chelators can include organic molecules that covalently bond with a metal. As used herein, a covalent bond describes the sharing of one or more pairs of electrons between atoms. In some instances, chelators are agents that bind to metal.

[0052] In particular embodiments, chelators can include a number of metal- coordinating atoms that bond with a metal. The metal-coordinating atoms can bond with metals having cations with a +1 charge. The metal-coordinating atoms can also bond with metals having cations with a +2 charge. Additionally, the metal-coordinating atoms can bond with metals having cations with a +3 charge. Further, the metal-coordinating atoms can bond with metals having cations with a +4 charge. The chelators described herein can, in some cases, include siderophores.

[0053] In particular embodiments, the metal-coordinating atoms of the chelators described herein can be included in one or more functional groups of the chelators. In some examples, the metal-coordinating atoms of the chelators can be included in one or more catecholate (CAM) groups. A CAM group can include at least a phenyl ring substituted by hydroxyl groups on adjacent carbon atoms. According to some illustrative

AM group can include:

.

[0054] In some embodiments, the metal-coordinating atoms of the chelators can be included in one or more hydroxamate (HA) groups. According to some embodiments, a clude:

,

where R _a can include H or an alkyl group including no greater than 5 carbon atoms. For example, R _a can include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an iso-butyl group, a tert-butyl group, a pentyl group, a tert-pentyl group, a neopentyl group, or an iso-pentyl group.

[0055] In some embodiments, the metal-coordinating atoms of the chelators can be included in one or more hydroxypyridinone (HOPO) groups. A HOPO group can include a pyridinone ring substituted by a hydroxyl group on the N atom. In some cases, a HOPO group can include a 1,2-HOPO group. According to some illustrative embodiments, a 1,2-HOPO group can include:

.

[0056] The metal-coordinating atoms of the chelators can be included in combinations of two or more of one or more CAM groups, one or more HA groups, or one or more HOPO groups. In illustrative examples, the metal-coordinating atoms of the chelators can be included in one or more CAM groups and one or more HA groups. In other illustrative examples, the metal-coordinating atoms of the chelators can be included in one or more CAM groups and one or more HOPO groups. In additional illustrative examples, the metal-coordinating atoms of the chelators can be included in one or more HA groups and one or more HOPO groups. In further illustrative examples, the metal-coordinating atoms of the chelators can be included in one or more HA groups, one or more CAM groups, and one or more HOPO groups.

[0057] The chelators can include a number of functional groups having metal- coordinating atoms with the functional groups being bonded to a linear scaffold or a branched scaffold. The functional groups and/or substituents described herein may be substituted or unsubstituted. Substituted functional groups and/or substituents can be substituted by one or more hydroxyl groups, one or more alkyl groups having no greater than 10 carbon atoms, one or more amine groups, one or more thiol groups, one or more ester groups, or combinations thereof.

[0058] The scaffold can include one or more amine groups. An amine group can include a nitrogen atom bonded to three substituents. In particular embodiments, an amine group can include a nitrogen atom bonded at least one carbon atom of substituent. In various embodiments, an amine group can include a nitrogen atom bonded to at least a first carbon atom of a first substituent and a second carbon atom of a second substituent. In further embodiments, an amine group can include a nitrogen atom bonded to a first carbon atom of a first substituent, a second carbon atom of a second substituent and a third carbon atom of a third substituent. In certain embodiments, an amine group can include a nitrogen atom bonded to one or more hydrogen atoms.

[0059] In some embodiments, the scaffold can include one or more amide groups. An amide group can include a nitrogen atom bonded to a carbonyl group and two additional substituents. In various examples, an amide group can include a nitrogen atom bonded to a carbonyl group and a carbon atom of a first additional substituent. In other examples, an amide group can include a nitrogen atom bonded to a carbonyl group and a first carbon atom of a first additional substituent and a second carbon atom of a second additional substituent. In certain embodiments, an amine group can include a nitrogen atom bonded to one or more hydrogen atoms.

[0060] In particular embodiments, the scaffold can include one or more amine groups and one or more amide groups. The scaffold can include one or more carbon- based chains bonded between amine groups, a carbon-based chain bonded between amide groups, or one or more carbon-based chains bonded between a combination of one or more amine groups and one or more amide groups. The carbon-based chains can include at least one carbon atom, at least 2 carbon atoms, at least 3 carbon atoms, at least 4 carbon atoms, or at least 5 carbon atoms. In addition, the carbon-based chains can include no greater than 10 carbon atoms, no greater than 9 carbon atoms, no greater than 8 carbon atoms, no greater than 7 carbon atoms, or no greater than 6 carbon atoms. In various embodiments, the carbon-based chains can include from 1 carbon atom to 10 carbon atoms, from 2 carbon atoms to 7 carbon atoms, or from 3 carbon atoms to 6 carbon atoms. In illustrative embodiments, the carbon-based chains can include alkane chains having carbon-carbon single bonds. In some cases, the carbon-based chains can include alkene chains having at least one carbon-carbon double bond. The carbon-based chains can be substituted or unsubstituted.

[0061] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure I:

.   

In some examples, A1, A2, A3, and A4 can, individually, include a CAM group, a HOPO group, or a HA group. Additionally, B1, B2, B3, and B4 can, individually, include an amide group or an amine group. Further, at least one of C1, C2, C3, C4, C5, or C6 can, individually, include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. Also, in various examples, at least another one of C1, C2, C3, C4, C5, or C6 can be optional. In particular examples, at least one of L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, or L13 can, individually, include H, an alkyl group having no greater than 10 carbon atoms, an alkylamino group having no greater than 10 carbon atoms and no greater than 2 nitrogen atoms; an alkylamido group having no greater than 10 carbon atoms and no greater than 2 nitrogen atoms; an alkyl ether group having no greater than 10 carbon atoms, a hydroxy ester group, or an alkyl ester group having no greater than 10 carbon atoms. In certain examples, at least one of L1, L5, L6, L7, L8, L9, L10, L11, L12, or L13 can be optional.

[0062] In illustrative examples, at least another one of L2, L3, or L4, can, individually, include an amine group or an amide group. In additional illustrative examples, L1, C1, L7, C2, L9, C3, L11, C4, and L13, C5 can be absent, L5 can include an alkyl group having no greater than 5 carbon atoms, and C6 can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. In further illustrative examples, L2, L3, L4, L6, L8, L10, and L12 can, individually, include an alkyl group having no greater than 5 carbon atoms. Also, A1 can include a CAM group or a 1, 2-HOPO group; A2 can include a HA group, A3 can include a HA group, and A4 can include a CAM group, a 1,2-HOPO group, or a HA group. In other illustrative examples, at least one of L2, L3, or L4 includes an alkylamino or alkylamido group.

[0063] In various illustrative examples, B1, B2, and B3 can, individually, include an amide group and B4 can include an amino group, L2 and L3 can include an amino group, and L4 can include an alky group having no greater than 5 carbon atoms. Additionally, C1, C2, C3, C4, C5, L1, A1, A2, A3, L1, L6, L7, L8, L9, L10, L11, L12, and L13 can be absent; A4 can include a CAM group, a 1,2-HOPO group, or a HA group; and L5 can include an alkyl group having no greater than 5 carbon atoms.

[0064] In certain illustrative examples, B1, B2, and B3 can include an amide group and B4 can include an amide group; L2 and L3 can, individually, include an amino group; and L4 includes an alky group having no greater than 5 carbon atoms. Further, C1, C2, C3, C4, C5, A1, A2, A3, L1, L6, L7, L8, L9, L10, L11, and L13 can be absent, L12 can include an amino group, L5 can include an ether group having no greater than 10 carbon atoms, and A4 can include a CAM group, a 1,2-HOPO group, or a HA group.

[0065] In particular illustrative examples, C1, C2, C5, C6, L1, L2, L3, L4, L5, L7, L13, B2, and B4 can be absent; B1 and B3 can, individually, include an amide group; L6, L8, L10, and L12 can, individually, include an amino group, A1, A2, A3, and A4 can, individually, include a CAM group, a 1,2-HOPO group, or a HA group; and L9 and L11 can, individually, include an alkyl group having no greater than 5 carbon atoms.

[0066] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure II:

.

R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ can, individually, include H, an alkyl group having from 1 to 10 carbon atoms, a CAM group, a HA group, or a 1,2-HOPO group. R ₆ can include H, an alkyl group having from 1 to 10 carbon atoms, or an alkyl group having from 1 to 10 carbon atoms and substituted by at least one of NH ₂ , C(=O)OH, maleimide, dibromo- maleimide, isothiocyanate, alkyne, or azide. m can be from 1 to 6; n can be from 1 to 6; and o can be from 1 to 6. In particular embodiments, at least one of R ₁ , R ₂ , R ₃ , R ₄ , or R ₅ can, individually, include a CAM group, a HA group, or a 1,2-HOPO group. In various embodiments, Structure II can include a linear, spermine-based backbone.

[0067] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure III:

. At least one of R ₁ , R ₃ , R ₄ , or R ₅ can, individually, include a CAM group, a HA group, or a 1,2-HOPO group. Optionally, another one of R ₁ , R ₃ , R ₄ , or R ₅ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂ can include H, OH, or an alkyl group including from 1 to 5 carbon atoms. p can be from 0 to 4. R ₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. In illustrative embodiments, R ₁ can include a CAM group or a 1,2-HOPO group, R ₃ and R ₄ can, individually, include a HA group, and R ₅ can include a CAM group, a 1,2-HOPO group, or a HA group.

[0068] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure IV:

.

R ₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R _2, R _8, and R ₉ can, individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms. p can be from 0 to 4.

[0069] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure V:

.

R ₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R _2, R _8, and R ₉ can, individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms. p can be from 0 to 4.

[0070] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure VI:

.

R ₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R _2, R _8, R ₉ , and R ₁₀ can, individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms. p can be from 0 to 4.

[0071] In particular embodiments, compositions that function as chelators for radionuclides can have the followin structure, referred to herein as Structure VII:

.

R ₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R _2, R _8, and R ₉ can, individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms. p can be from 0 to 4.

[0072] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure VIII:

.

R ₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R _2, R _8, and R ₉ can, individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms. p can be from 0 to 4.

[0073] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure IX:

.

R ₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R _2, R _8, R ₉ , and R ₁₀ can, individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms. p can be from 0 to 4.

[0074] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure X:

.

[0075] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XI:

.

[0076] In particular embodiments, compositions can have a branched backbone rather than the linear, spermine-based backbone of Structures III-XI. In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XII:

. At least one of R ₁₁ , R ₁₂ , R ₁₃ , or R ₁₅ , can, individually, include a CAM group, a HA group, or a 1,2-HOPO group. Optionally, at least another one of R ₁₁ , R ₁₂ , R ₁₃ , or R ₁₅ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₁₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. r can be from 0 to 6. R ₂ , R ₁₄ , and R ₁₆ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. In illustrative embodiments, R ₁₁ can include a CAM group or a 1,2-HOPO group, R ₁₂ and R ₁₅ can, individually, include a HA group, and R ₁₃ can include a CAM group, a 1,2-HOPO group, or a HA group.

[0077] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XIII:

.

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₁₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. r can be from 0 to 4.

[0078] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XIV:

.

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₁₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. r can be from 0 to 4.

[0079] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XV:

.

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , R ₁₉ , and R ₂₀ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₁₇ can include NH ₂ , C(=O)OH, maleimide, dibromo- maleimide, isothiocyanate, alkyne, or azide. r can be from 0 to 4.

[0080] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XVI:

.

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , R ₁₉ , and R ₂₀ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₁₇ can include NH ₂ , C(=O)OH, maleimide, dibromo- maleimide, isothiocyanate, alkyne, or azide. r can be from 0 to 4. [0081] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XVII:

.

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₁₇ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. r can be from 0 to 4.

[0082] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XVIII:

.

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ can include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₁₇ can, individually, include NH ₂ , C(=O)OH, maleimide, dibromo- maleimide, isothiocyanate, alkyne, or azide. r can be from 0 to 4.

[0083] In particular embodiments, compositions can have a backbone that includes a number of amide groups and a number of amine groups. In some embodiments, the backbone of compositions that function as chelators for radionuclides can be based on Desferrioxamine B. In particular embodiments, compositions that function as chelators can have the following structure, referred to herein as Structure XIX:

.

R ₂₁ and R ₂₂ can include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂₃ can include H, OH, an alkyl group having from 1 to 10 carbon atoms, or (CH ₂ ) _e R _a , where R _a is NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide and e is from 1 to 10. R ₂₄ can include a substituent that includes a CAM group, a 1,2-HOPO group, or a HA group. Optionally, R ₂₄ can include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide _. a, b, and c can include from 1 to 10 and d can include from 1 to 4.

[0084] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XX:

. R ₂₅ , R ₂₆ , and R ₂₇ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂₈ can include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. s can be from 0 to 4. [0085] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXI:

.

R ₂₅ , R ₂₆ , R _27, and R ₃₀ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂₈ and R ₂₉ can, individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. s can be from 0 to 4. t can be from 0 to 4.

[0086] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXII:

.

R ₂₅ , R ₂₆ , R _27, and R ₃₀ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂₈ and R ₂₉ can, individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. s can be from 0 to 4. t can be from 0 to 4.

[0087] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXIII:

. R ₂₅ , R ₂₆ , R _27, R ₃₀ , and R ₃₁ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂₈ and R ₂₉ can, individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. s can be from 0 to 4. t can be from 0 to 4.

[0088] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXIV:

O .

R ₂₅ , R ₂₆ , and R ₂₇ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂₈ can include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. s can be from 0 to 4.

[0089] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXV:

.

R ₂₅ , R ₂₆ , R ₂₇ , and R ₃₂ can, individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms. R ₂₈ can include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. s can be from 0 to 4.

[0090] In particular embodiments, compositions can have an amide-based backbone. In particular embodiments, compositions that function as chelators can have the following structure, referred to herein as Structure XXVI:

.

A, B, C, and D can, individually, include one or more amide groups, one or more amine groups, or an alkyl group having from 1 to 10 carbon atoms. R ₃₃ , R ₃₄ , R ₃₅ , and R ₃₆ can, individually, include a CAM group, a 1,2-HOPO group, or a HA group. g, h, i, and j can, individually, be from 1 to 10.

[0091] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXVII:

.

R ₃₇ and R ₄₂ can, individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R ₃₈ , R ₃₉ , R ₄₀ , and R ₄₁ can, individually, include H, OH, or an alkyl group having from 1 to 5 carbon atoms. u and v can, individually, be from 0 to 5.

[0092] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXVIII:

.

R ₃₇ and R ₄₂ can, individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R ₃₈ , R ₃₉ , R ₄₀ , and R ₄₁ can, individually, include H, OH, or an alkyl group having from 1 to 5 carbon atoms. u and v can, individually, be from 0 to 5.

[0093] In particular embodiments, compositions that function as chelators for radionuclides can have the following structure, referred to herein as Structure XXIX:

.

R ₃₇ and R ₄₂ can, individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide. R ₃₈ , R ₃₉ , R ₄₀ , and R ₄₁ can, individually, include H, OH, or an alkyl group having from 1 to 5 carbon atoms. u and v can, individually, be from 0 to 5.

In particular embodiments, compositions that function as chelators for radionuclides can have the followin structure, referred to herein as Structure L:

wherein: at least one of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , individually, comprise a CAM group, a HA group, or a 1,2-HOPO group; at least another one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, comprise H or an alkyl group having from 1 to 10 carbon atoms; R ₆ comprises (i) H, (ii) an alkyl group having from 1 to 10 carbon atoms, or (iii) an alkyl group having from 1 to 100 carbon atoms and no greater than 2 nitrogen atoms, and substituted by at least one of NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, amide, fluorescent moiety, or azide; m can be from 1 to 6; n can be from 1 to 6; o can be from 1 to 6; p can be from 1 to 6; q can be from 0 to 6; r can be from 1 to 6; s can be from 1 to 6; t can be from 1 to 6.

[0094] In some embodiments, the chelator is any one or more of the chelators in any of the figures. In some embodiments, the chelator has a structure as depicted in FIG. 10E. In some embodiments, the chelator is made by any one or more of the flow charts provided in the present figures. In some embodiments, the chelator is a peptoid chelator.  

[0095] Examples of radioisotopes useful include ²²⁵ Ac, ²²⁶ Ac, ²²⁸ Ac, ¹⁰⁵ Ag, ¹⁰⁶ mAg, ¹¹⁰ mAg, ¹¹¹ Ag, ¹¹² Ag, ¹¹³ Ag, ²³⁹ Am, ²⁴⁰ Am, ²⁴² Am, ²⁴⁴ Am, ³⁷ Ar, ⁷¹ As, ⁷² As, ⁷³ As, ⁷⁴ As, ⁷⁶ As, ⁷⁷ As, ²⁰⁹ At, ²¹⁰ At, ¹⁹¹ Au, ¹⁹² Au, ¹⁹³ Au, ¹⁹⁴ Au, ¹⁹⁵ Au, ¹⁹⁶ Au, ¹⁹⁶ m ² Au, ¹⁹⁸ Au, ¹⁹⁸ mAu, ¹⁹⁹ Au, ²⁰⁰ mAu, ¹²⁸ Ba, ¹³¹ Ba, ¹³³ mBa, ¹³⁵ mBa, ¹⁴⁰ Ba, ⁷ Be, ²⁰³ Bi, ²⁰⁴ Bi, ²⁰⁵ Bi, ²⁰⁶ Bi, ²¹⁰ Bi, ²¹² Bi, ²⁴³ Bk, ²⁴⁴ Bk, ²⁴⁵ Bk, ²⁴⁶ Bk, ²⁴⁸ mBk, ²⁵⁰ Bk, ⁷⁶ Br, ⁷⁷ Br, ⁸⁰ mBr, ⁸² Br, ¹¹ C, ¹⁴ C, ⁴⁵ Ca, ⁴⁷ Ca, ¹⁰⁷ Cd, ¹¹⁵ Cd, ¹¹⁵ mCd, ¹¹⁷ mCd, ¹³² Ce, ¹³³ mCe, ¹³⁴ Ce, ¹³⁵ Ce, ¹³⁷ Ce, ¹³⁷ mCe, ¹³⁹ Ce, ¹⁴¹ Ce, ¹⁴³ Ce, ¹⁴⁴ Ce, ²⁴⁶ Cf, ²⁴⁷ Cf, ²⁵³ Cf, ²⁵⁴ Cf, ²⁴⁰ Cm, ²⁴¹ Cm, ²⁴² Cm, ²⁵² Cm, ⁵⁵ Co, ⁵⁶ Co, ⁵⁷ Co, ⁵⁸ Co, ⁵⁸ mCo, ⁶⁰ Co, ⁴⁸ Cr, ⁵¹ Cr, ¹²⁷ Cs, ¹²⁹ Cs, ¹³¹ Cs, ¹³² Cs, ¹³⁶ Cs, ¹³⁷ Cs, ⁶¹ Cu, ⁶² Cu, ⁶⁴ Cu, ⁶⁷ Cu, ¹⁵³ Dy, ¹⁵⁵ Dy, ¹⁵⁷ Dy, ¹⁵⁹ Dy, ¹⁶⁵ Dy, ¹⁶⁶ Dy, ¹⁶⁰ Er, ¹⁶¹ Er, ¹⁶⁵ Er, ¹⁶⁹ Er, ¹⁷¹ Er, ¹⁷² Er, ²⁵⁰ Es, ²⁵¹ Es, ²⁵³ Es, ²⁵⁴ Es, ²⁵⁴ mEs, ²⁵⁵ Es, ²⁵⁶ mEs, ¹⁴⁵ Eu, ¹⁴⁶ Eu, ¹⁴⁷ Eu, ¹⁴⁸ Eu, ¹⁴⁹ Eu, ¹⁵⁰ mEu, ¹⁵² mEu, ¹⁵⁶ Eu, ¹⁵⁷ Eu, ⁵² Fe, ⁵⁹ Fe, ²⁵¹ Fm, ²⁵² Fm, ²⁵³ Fm, ²⁵⁴ Fm, ²⁵⁵ Fm, ²⁵⁷ Fm, ⁶⁶ Ga, ⁶⁷ Ga, ⁶⁸ Ga, ⁷² Ga, ⁷³ Ga, ¹⁴⁶ Gd, ¹⁴⁷ Gd, ¹⁴⁹ Gd, ¹⁵¹ Gd, ¹⁵³ Gd, ¹⁵⁹ Gd, ⁶⁸ Ge, ⁶⁹ Ge, ⁷¹ Ge, ⁷⁷ Ge, ¹⁷⁰ Hf, ¹⁷¹ Hf, ¹⁷³ Hf, ¹⁷⁵ Hf, ¹⁷⁹ m ² Hf, ¹⁸⁰ mHf, ¹⁸¹ Hf, ¹⁸⁴ Hf, ¹⁹² Hg, ¹⁹³ Hg, ¹⁹³ mHg, ¹⁹⁵ Hg, ¹⁹⁵ mHg, ¹⁹⁷ Hg, ¹⁹⁷ mHg, ²⁰³ Hg, ¹⁶⁰ mHo, ¹⁶⁶ Ho, ¹⁶⁷ Ho, ¹²³ I, ¹²⁴ I, ¹²⁶ I, ¹³⁰ I, ¹³² I, ¹³³ I, ¹³⁵ I, ¹⁰⁹ In, ¹¹⁰ In, ¹¹¹ In, ¹¹⁴ mIn, ¹¹⁵ mIn, ¹⁸⁴ Ir, ¹⁸⁵ Ir, ¹⁸⁶ Ir, ¹⁸⁷ Ir, ¹⁸⁸ Ir, ¹⁸⁹ Ir, ¹⁹⁰ Ir, ¹⁹⁰ m ² Ir, ¹⁹² Ir, ¹⁹³ mIr, ¹⁹⁴ Ir, ¹⁹⁴ m ² Ir, ¹⁹⁵ mIr, ⁴² K, ⁴³ K, ⁷⁶ Kr, ⁷⁹ Kr, ⁸¹ mKr, ⁸⁵ mKr, ¹³² La, ¹³³ La, ¹³⁵ La, ¹⁴⁰ La, ¹⁴¹ La, ²⁶² Lr, ¹⁶⁹ Lu, ¹⁷⁰ Lu, ¹⁷¹ Lu, ¹⁷² Lu, ¹⁷⁴ mLu, ¹⁷⁶ mLu, ¹⁷⁷ Lu, ¹⁷⁷ mLu, ¹⁷⁹ Lu, ²⁵⁷ Md, ²⁵⁸ Md, ²⁶⁰ Md, ²⁸ Mg, ⁵² Mn, ⁹⁰ Mo, ⁹³ mMo, ⁹⁹ Mo, ¹³ N, ²⁴ Na, ⁹⁰ Nb, ⁹¹ mNb, ⁹² mNb, ⁹⁵ Nb, ⁹⁵ mNb, ⁹⁶ Nb, ¹³⁸ Nd, ¹³⁹ mNd, ¹⁴⁰ Nd, ¹⁴⁷ Nd, ⁵⁶ Ni, ⁵⁷ Ni, ⁶⁶ Ni, ²³⁴ Np, ²³⁶ mNp, ²³⁸ Np, ²³⁹ Np, ¹⁵ O, ¹⁸² Os, ¹⁸³ Os, ¹⁸³ mOs, ¹⁸⁵ Os, ¹⁸⁹ mOs, ¹⁹¹ Os, ¹⁹¹ mOs, ¹⁹³ Os, ³² P, ³³ P, ²²⁸ Pa, ²²⁹ Pa, ²³⁰ Pa, ²³² Pa, ²³³ Pa, ²³⁴ Pa, ²⁰⁰ Pb, ²⁰¹ Pb, ²⁰² mPb, ²⁰³ Pb, ²⁰⁹ Pb, ²¹² Pb, ¹⁰⁰ Pd, ¹⁰¹ Pd, ¹⁰³ Pd, ¹⁰⁹ Pd, ¹¹¹ mPd, ¹¹² Pd, ¹⁴³ Pm, ¹⁴⁸ Pm, ¹⁴⁸ mPm, ¹⁴⁹ Pm, ¹⁵¹ Pm, ²⁰⁴ Po, ²⁰⁶ Po, ²⁰⁷ Po, ²¹⁰ Po, ¹³⁹ Pr, ¹⁴² Pr, ¹⁴³ Pr, ¹⁴⁵ Pr, ¹⁸⁸ Pt, ¹⁸⁹ Pt, ¹⁹¹ Pt, ¹⁹³ mPt, ¹⁹⁵ mPt, ¹⁹⁷ Pt, ²⁰⁰ Pt, ²⁰² Pt, ²³⁴ Pu, ²³⁷ Pu, ²⁴³ Pu, ²⁴⁵ Pu, ²⁴⁶ Pu, ²⁴⁷ Pu, ²²³ Ra, ²²⁴ Ra, ²²⁵ Ra, ⁸¹ Rb, ⁸² Rb, ⁸² mRb, ⁸³ Rb, ⁸⁴ Rb, ⁸⁶ Rb, ¹⁸¹ Re, ¹⁸² Re, ¹⁸² mRe, ¹⁸³ Re, ¹⁸⁴ Re, ¹⁸⁴ mRe, ¹⁸⁶ Re, ¹⁸⁸ Re, ¹⁸⁹ Re, ¹⁹⁰ mRe, ⁹⁹ Rh, ⁹⁹ mRh, ¹⁰⁰ Rh, ¹⁰¹ mRh, ¹⁰² Rh, ¹⁰³ mRh, ¹⁰⁵ Rh, ²¹¹ Rn, ²²² Rn, ⁹⁷ Ru, ¹⁰³ Ru, ¹⁰⁵ Ru, ³⁵ S, ¹¹⁸ mSb, ¹¹⁹ Sb, ¹²⁰ Sb, ¹²⁰ mSb, ¹²² Sb, ¹²⁴ Sb, ¹²⁶ Sb, ¹²⁷ Sb, ¹²⁸ Sb, ¹²⁹ Sb, ⁴³ Sc, ⁴⁴ Sc, ⁴⁴ mSc, ⁴⁶ Sc, ⁴⁷ Sc, ⁴⁸ Sc, ⁷² Se, ⁷³ Se, ⁷⁵ Se, ¹⁵³ Sm, ¹⁵⁶ Sm, ¹¹⁰ Sn, ¹¹³ Sn, ¹¹⁷ mSn, ¹¹⁹ mSn, ¹²¹ Sn, ¹²³ Sn, ¹²⁵ Sn, ⁸² Sr, ⁸³ Sr, ⁸⁵ Sr, ⁸⁹ Sr, ⁹¹ Sr, ¹⁷³ Ta, ¹⁷⁵ Ta, ¹⁷⁶ Ta, ¹⁷⁷ Ta, ¹⁸⁰ Ta, ¹⁸² Ta, ¹⁸³ Ta, ¹⁸⁴ Ta, ¹⁴⁹ Tb, ¹⁵⁰ Tb, ¹⁵¹ Tb, ¹⁵² Tb, ¹⁵³ Tb, ¹⁵⁴ Tb, ¹⁵⁴ mTb, ¹⁵⁴ m ² Tb, ¹⁵⁵ Tb, ¹⁵⁶ Tb, ¹⁵⁶ mTb, ¹⁵⁶ m ² Tb, ¹⁶⁰ Tb, ¹⁶¹ Tb, ⁹⁴ Tc, ⁹⁵ Tc, ⁹⁵ mTc, ⁹⁶ Tc, ⁹⁷ mTc, ⁹⁹ mTc, ¹¹⁸ Te, ¹¹⁹ Te, ¹¹⁹ mTe, ¹²¹ Te, ¹²¹ mTe, ¹²³ mTe, ¹²⁵ mTe, ¹²⁷ Te, ¹²⁷ mTe, ¹²⁹ mTe, ¹³¹ mTe, ¹³² Te, ²²⁷ Th, ²³¹ Th, ²³⁴ Th, ⁴⁵ Ti, ¹⁹⁸ Tl, ¹⁹⁹ Tl, ²⁰⁰ Tl, ²⁰¹ Tl, ²⁰² Tl, ²⁰⁴ Tl, ¹⁶⁵ Tm, ¹⁶⁶ Tm, ¹⁶⁷ Tm, ¹⁶⁸ Tm, ¹⁷⁰ Tm, ¹⁷² Tm, ¹⁷³ Tm, ²³⁰ U, ²³¹ U, ²³⁷ U, ²⁴⁰ U, ⁴⁸ V, ¹⁷⁸ W, ¹⁸¹ W, ¹⁸⁵ W, ¹⁸⁷ W, ¹⁸⁸ W, ¹²² Xe, ¹²⁵ Xe, ¹²⁷ Xe, ¹²⁹ mXe, ¹³¹ mXe, ¹³³ Xe, ¹³³ mXe, ¹³⁵ Xe, ⁸⁵ mY, ⁸⁶ Y, ⁸⁷ Y, ⁸⁷ mY, ⁸⁸ Y, ⁹⁰ Y, ⁹⁰ mY, ⁹¹ Y, ⁹² Y, ⁹³ Y, ¹⁶⁶ Yb, ¹⁶⁹ Yb, ¹⁷⁵ Yb, ⁶² Zn, ⁶⁵ Zn, ⁶⁹ mZn, ⁷¹ mZn, ⁷² Zn, ⁸⁶ Zr, ⁸⁸ Zr, ⁸⁹ Zr, ⁹⁵ Zr, and ⁹⁷ Zr.

[0096] It can be helpful to classify cytotoxic radionuclides into groups, for example, metals (e.g., ⁹⁰ Y, ⁶⁷ Cu, ²¹³ Bi, ²¹² Bi), and transitional elements (e.g., ¹⁸⁶ Re). Further, examples of pure β-emitters include ⁶⁷ Cu and ⁹⁰ Y; and examples of α-emitters include ²¹³ Bi. β-emitters that emit γ-radiation include ¹⁷⁷ Lu and ¹⁸⁶ Re, while Auger emitters and radionuclides that decay by internal conversion include ⁶⁷ Ga.

[0097] As will be appreciated by one of ordinary skill in the art, more than one radioisotope may be chosen and used, for example, in particular nuclear medicine indications. Thus, embodiments can include a single species of radioisotope, two species of radioisotopes, or a population of a plurality of species of radioisotopes combined in various proportions. In this manner the useful properties of different radioisotopes can be combined. For example, a single radioisotope decays at a defined exponential rate. By combining radioisotopes of different half-lives, it is possible to create a new decay rate.

[098] In particular embodiments, targeting domains can be derived from whole proteins or protein fragments with an affinity for particular tissues and/or cell types of interest. In particular embodiments, targeting domains can be derived from whole antibodies or binding fragments of an antibody, e.g., Fv, Fab, Fab', F(ab') ₂ , Fc, and single chain Fv fragments (scFvs) or any biologically-effective fragments of an immunoglobulin that bind specifically to, for example, a cancer antigen epitope. Antibodies or antigen binding fragments include all or a portion of polyclonal antibodies, monoclonal antibodies, human antibodies, humanized antibodies, synthetic antibodies, chimeric antibodies, bispecific antibodies, mini bodies, and linear antibodies.

[099] Targeting domains from human origin or humanized antibodies have lowered or no immunogenicity in humans and have a lower number of non-immunogenic epitopes compared to non-human antibodies. Antibodies and their fragments will generally be selected to have a reduced level or no antigenicity in human subjects. Targeting domains can particularly include any peptide that specifically binds a selected unwanted cell epitope. Sources of targeting domains include antibody variable regions from various species (which can be in the form of antibodies, sFvs, scFvs, Fabs, scFv- based grababody, or soluble VH domain or domain antibodies). These antibodies can form antigen-binding regions using only a heavy chain variable region, i.e., these functional antibodies are homodimers of heavy chains only (referred to as "heavy chain antibodies") (Jespers et al., Nat. Biotechnol. 22:1161, 2004; Cortez-Retamozo et al., Cancer Res.64:2853, 2004; Baral et al., Nature Med.12:580, 2006; and Barthelemy et al., J. Biol. Chem.283:3639, 2008).

[0100] Phage display libraries of partially or fully synthetic antibodies are available and can be screened for an antibody or fragment thereof that can bind a selected epitope. For example, targeting domains may be identified by screening a Fab phage library for Fab fragments that specifically bind to a target of interest (see Hoet et al., Nat. Biotechnol. 23:344, 2005). Phage display libraries of human antibodies are also available. Additionally, traditional strategies for hybridoma development using a target of interest as an immunogen in convenient systems (e.g., mice, HuMAb mouse®, TC mouse™, KM-mouse ^® , llamas, chicken, rats, hamsters, rabbits, etc.) can be used to develop targeting domains. In particular embodiments, antibodies specifically bind to selected epitopes expressed by targeted cells and do not cross react with nonspecific components or unrelated targets. Once identified, the amino acid sequence or polynucleotide sequence coding for the antibody can be isolated and/or determined.

[0101] An alternative source of targeting domains includes sequences that encode random peptide libraries or sequences that encode an engineered diversity of amino acids in loop regions of alternative non-antibody scaffolds, such as scTCR (see, e.g., Lake et al., Int. Immunol.11:745, 1999; Maynard et al., J. Immunol. Methods 306:51, 2005; U.S. Patent No. 8,361,794), mAb ² or Fcab™ (see, e.g., PCT Patent Application Publication Nos. WO 2007/098934; WO 2006/072620), affibody, avimers, fynomers, cytotoxic T-lymphocyte associated protein-4 (Weidle et al., Cancer Gen. Proteo.10:155, 2013), or the like (Nord et al., Protein Eng. 8:601, 1995; Nord et al., Nat. Biotechnol. 15:772, 1997; Nord et al., Euro. J. Biochem. 268:4269, 2001; Binz et al., Nat. Biotechnol. 23:1257, 2005; Boersma and Plückthun, Curr. Opin. Biotechnol. 22:849, 2011).

[0102] An "antibody fragment" denotes a portion of a complete or full length antibody that retains the ability to bind to an epitope. Examples of antibody fragments include Fv, scFv, Fab, Fab', Fab'-SH, F(ab') ₂ ; diabodies; and linear antibodies.

[0103] A single chain variable fragment (scFv) is a fusion protein of the variable regions of the heavy and light chains of immunoglobulins connected with a short linker peptide. Fv fragments include the VL and VH domains of a single arm of an antibody. Although the two domains of the Fv fragment, VL and VH, are coded by separate genes, they can be joined, using, for example, recombinant methods, by a synthetic linker that enables them to be made as a single protein chain in which the VL and VH regions pair to form monovalent molecules (single chain Fv (scFv)). For additional information regarding Fv and scFv, see e.g., Bird, et al., Science 242 (1988) 423-426; Huston, et al., Proc. Natl. Acad. Sci. USA 85 (1988) 5879-5883; Plueckthun, in The Pharmacology of Monoclonal Antibodies, vol. 113, Rosenburg and Moore (eds.), Springer-Verlag, New York), (1994) 269-315; WO1993/16185; US Patent 5,571,894; and US Patent 5,587,458.

[0104] A Fab fragment is a monovalent antibody fragment including VL, VH, CL and CH1 domains. A F(ab') ₂ fragment is a bivalent fragment including two Fab fragments linked by a disulfide bridge at the hinge region. For discussion of Fab and F(ab') ₂ fragments having increased in vivo half-life, see U.S. Patent 5,869,046. Diabodies include two epitope-binding sites that may be bivalent. See, for example, EP 0404097; WO1993/01161; and Holliger, et al., Proc. Natl. Acad. Sci. USA 90 (1993) 6444-6448. Dual affinity retargeting antibodies (DART™; based on the diabody format but featuring a C-terminal disulfide bridge for additional stabilization (Moore et al., Blood 117, 4542-51 (2011))) can also be used. Antibody fragments can also include isolated CDRs. For a review of antibody fragments, see Hudson, et al., Nat. Med.9 (2003) 129- 134.

[0105] Antibody fragments can be made by various techniques, including proteolytic digestion of an intact antibody as well as production by recombinant host-cells (e.g. E. coli or phage), as described herein. Antibody fragments can be screened for their binding properties in the same manner as intact antibodies.

[0106] In particular embodiments, targeting domains can also include a natural receptor or ligand for an epitope. For example, if a target for binding includes PD-L1, the binding domain can include PD-1 (including, e.g., a PD-1/antiCD3 fusion). One example of a receptor fusion for binding is Enbrel ^® (Immunex). Natural receptors or ligands can also be modified to enhance binding. For example, betalacept is a modified version of abatacept.

[0107] Binding can also be enhanced through increasing avidity. Any screening method known in the art can be used to identify increased avidity to an antigen epitope.

[0108] As used herein, an epitope denotes the binding site on a protein target bound by a corresponding targeting domain. The targeting domain either binds to a linear epitope, (e.g., an epitope including a stretch of 5 to 12 consecutive amino acids), or the targeting domains binds to a three-dimensional structure formed by the spatial arrangement of several short stretches of the protein target. Three-dimensional epitopes recognized by a targeting domain, e.g. by the epitope recognition site or paratope of an antibody or antibody fragment, can be thought of as three-dimensional surface features of an epitope molecule. These features fit precisely (in)to the corresponding binding site of the targeting domains and thereby binding between the targeting domains and its target protein is facilitated.

[0109] "Bind" means that the targeting domain associates with its target epitope with a dissociation constant (1(D) of 10 ^-8 M or less, in one embodiment of from 10 ^-5 M to 10- ¹³ M, in one embodiment of from 10 ^-5 M to 10 ^-10 M, in one embodiment of from 10 ^-5 M to 10 ^-7 M, in one embodiment of from 10 ^-8 M to 10 ^-13 M, or in one embodiment of from 10 ^-9 M to 10 ^-13 M. The term can be further used to indicate that the targeting domains does not bind to other biomolecules present, (e.g., it binds to other biomolecules with a dissociation constant (KD) of 10 ^-4 M or more, in one embodiment of from 10 ^-4 M to 1 M.

[0110] Methods of Synthesizing Chelators. In some embodiments, compositions of chelators described herein can be synthesized using techniques that are simpler and less harsh than conventional techniques. In particular, the use of dichlorophenylmethane improves the synthesis of natural siderophores and analogs, such as 3,4,3-LI(CAM), by minimizing the use of harsh, toxic substances in the synthesis of siderophores and siderophore-like ligands. Additionally, the reaction conditions are improved when dichlorophenylmethane is used in the synthesis of siderophores and siderophore-like ligands.

[0111] Methods of Making Radionuclides. Radioisotopes can be obtained in solution in water or other polar fluid in elemental form (i.e., uncharged) or ionic form. As appreciated by the skilled artisan, when in ionic form, radioisotopes may occur in various different valence states, as anions, or as cations, depending upon the particular radioisotope being considered.

[0112] Methods of Charging Chelators with Radionuclides. In particular embodiments, chelators can be charged with radionuclides by contacting the chelators with metallic radioisotopes and allowing complexes between the two molecules to form.

[0113] A prodrug includes an active ingredient which is converted into a therapeutically active or more therapeutically active compound after administration, such as by cleavage of a protein.

[0114] A pharmaceutically acceptable salt includes any salt that retains the activity of the active ingredient and is acceptable for pharmaceutical use. A pharmaceutically acceptable salt also refers to any salt which may form in vivo as a result of administration of an acid, another salt, or a prodrug which is converted into an acid or salt. Suitable pharmaceutically acceptable acid addition salts can be prepared from an inorganic acid or an organic acid. Examples of inorganic acids include hydrochloric, hydrobromic, hydroiodic, nitric, carbonic, sulfuric and phosphoric acid. Appropriate organic acids can be selected from aliphatic, cycloaliphatic, aromatic, arylaliphatic, heterocyclic, carboxylic and sulfonic classes of organic acids. Suitable pharmaceutically acceptable base addition salts include metallic salts made from aluminum, calcium, lithium, magnesium, potassium, sodium and zinc or organic salts made from N,N'- dibenzylethylene-diamine, chloroprocaine, choline, diethanolamine, ethylenediamine, N- methylglucamine, lysine, arginine and procaine.

[0115] The term analog (also structural analog or chemical analog) is used to refer to a compound that is structurally similar to another compound but differs with respect to a certain component, such as an atom, a functional group, or a substructure. The term derivative refers to a compound that is obtained from a similar compound or a precursor compound by a chemical reaction. As used herein, analogs and derivatives retain the therapeutic effectiveness of the parent compound (i.e., there is no statistically significant difference in therapeutic activity according to an imaging assay or assessment of clinical improvement) or have improved therapeutic effectiveness as defined elsewhere herein.

[0116] Active ingredients are formulated into compositions for administration to subjects. Compositions include at least one active ingredient and at least one pharmaceutically acceptable carrier. In particular embodiments, compositions include active ingredients of at least 0.1% w/v or w/w of the composition; at least 1% w/v or w/w of composition; at least 10% w/v or w/w of composition; at least 20% w/v or w/w of composition; at least 30% w/v or w/w of composition; at least 40% w/v or w/w of composition; at least 50% w/v or w/w of composition; at least 60% w/v or w/w of composition; at least 70% w/v or w/w of composition; at least 80% w/v or w/w of composition; at least 90% w/v or w/w of composition; at least 95% w/v or w/w of composition; or at least 99% w/v or w/w of composition.

[0117] Exemplary generally used pharmaceutically acceptable carriers include any and all absorption delaying agents, antioxidants, binders, buffering agents, bulking agents or fillers, chelating agents, coatings, disintegration agents, dispersion media, gels, isotonic agents, lubricants, preservatives, salts, solvents or co-solvents, stabilizers, surfactants, and/or delivery vehicles.

[0118] Exemplary antioxidants include ascorbic acid, methionine, and vitamin E.

[0119] Exemplary buffering agents include citrate buffers, succinate buffers, tartrate buffers, fumarate buffers, gluconate buffers, oxalate buffers, lactate buffers, acetate buffers, phosphate buffers, histidine buffers, and/or trimethylamine salts.

[0120] An exemplary chelating agent for use as a pharmaceutically acceptable carrier is EDTA. Other chelating agents disclosed herein may also be used.

[0121] Exemplary isotonic agents include polyhydric sugar alcohols including trihydric or higher sugar alcohols, such as glycerin, erythritol, arabitol, xylitol, sorbitol, or mannitol.

[0122] Exemplary preservatives include phenol, benzyl alcohol, meta-cresol, methyl paraben, propyl paraben, octadecyldimethylbenzyl ammonium chloride, benzalkonium halides, hexamethonium chloride, alkyl parabens such as methyl or propyl paraben, catechol, resorcinol, cyclohexanol, and 3-pentanol.

[0123] Stabilizers refer to a broad category of excipients which can range in function from a bulking agent to an additive which solubilizes the active ingredient or helps to prevent denaturation or adherence to the container wall. Typical stabilizers can include polyhydric sugar alcohols; amino acids, such as R, K, G, Q, N, H, A, ornithine, L- leucine, 2-F, E, and T; organic sugars or sugar alcohols, such as lactose, trehalose, stachyose, mannitol, sorbitol, xylitol, ribitol, myoinisitol, galactitol, glycerol, and cyclitols, such as inositol; PEG; amino acid polymers; sulfur-containing reducing agents, such as urea, glutathione, thioctic acid, sodium thioglycolate, thioglycerol, alpha- monothioglycerol, and sodium thiosulfate; low molecular weight polypeptides (i.e., <10 residues); proteins such as human serum albumin, bovine serum albumin, gelatin or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; monosaccharides such as xylose, mannose, fructose and glucose; disaccharides such as lactose, maltose and sucrose; trisaccharides such as raffinose, and polysaccharides such as dextran. Stabilizers are typically present in the range of from 0.1 to 10,000 parts by weight based on active ingredient weight.

[0124] In particular embodiments, the compositions disclosed herein can be formulated for administration by injection (e.g., intravenous injection). Compositions can also be formulated for administration by, for example, inhalation, infusion, perfusion, lavage, or ingestion. The compositions disclosed herein can further be formulated for intradermal, intraarterial, intranodal, intralymphatic, intraperitoneal, intralesional, intraprostatic, intravaginal, intrarectal, topical, intrathecal, intravesicular, oral and/or subcutaneous administration and more particularly by intravenous, intradermal, intraarterial, intranodal, intralymphatic, intraperitoneal, intralesional, intraprostatic, intravaginal, intrarectal, intrathecal, intramuscular, intravesicular, and/or subcutaneous injection.

[0125] For injection, compositions can be formulated as aqueous solutions, such as in buffers including Hanks' solution, Ringer's solution, or physiological saline. The aqueous solutions can contain formulatory agents such as suspending, stabilizing, and/or dispersing agents. Alternatively, the formulation can be in lyophilized and/or powder form for constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use. Particular embodiments are formulated for intravenous or intramuscular administration.

[0126] For oral administration, the compositions can be formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions and the like. Compositions can be formulated as an aerosol for inhalation. In one embodiment, the aerosol is provided as part of an anhydrous, liquid or dry powder inhaler. Compositions can also be formulated as depot preparations. Depot preparations can be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salts. Additionally, compositions can be formulated as sustained- release systems utilizing semipermeable matrices of solid polymers containing at least one active ingredient.

[0127] Any composition disclosed herein can advantageously include any other pharmaceutically acceptable carriers which include those that do not produce significantly adverse, allergic, or other untoward reactions that outweigh the benefit of administration. Exemplary pharmaceutically acceptable carriers and formulations are disclosed in Remington's Pharmaceutical Sciences, 18th Ed. Mack Printing Company, 1990. Moreover, formulations can be prepared to meet sterility, pyrogenicity, general safety, and purity standards as required by U.S. FDA Office of Biological Standards and/or other relevant foreign regulatory agencies.

[0128] Kits. Also disclosed herein are kits including one or more containers including one or more of the active ingredients, compositions, chelators, and/or radionuclides described herein. In various embodiments, the kits may include one or more containers containing one or more portions of active ingredients and/or compositions to be used in combination with other portions of the active ingredients and/or compositions described herein. Associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use, or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use, or sale for human administration.

[0129] Optionally, the kits described herein further include instructions for using the kit in the methods disclosed herein. In various embodiments, the kit may include instructions regarding preparation of the active ingredients and/or compositions for administration; administration of the active ingredients and/or compositions; appropriate reference levels to interpret results associated with using the kit; proper disposal of the related waste; and the like. The instructions can be in the form of printed instructions provided within the kit or the instructions can be printed on a portion of the kit itself. Instructions may be in the form of a sheet, pamphlet, brochure, CD-Rom, or computer-readable device, or can provide directions to instructions at a remote location, such as a website. The instructions may be in English and/or in any national or regional language. In various embodiments, possible side effects and contraindications to further use of components of the kit based on a subject’s symptoms can be included.

[0130] In various embodiments, the kits described herein include some or all of the necessary medical supplies needed to use the kit effectively, thereby eliminating the need to locate and gather such medical supplies. Such medical supplies can include syringes, ampules, tubing, facemasks, protective clothing, a needleless fluid transfer device, an injection cap, sponges, sterile adhesive strips, Chloraprep, gloves, and the like. Variations in contents of any of the kits described herein can be made. Particular kits provide materials to administer compositions through intravenous administration.

[0131] Methods of Use. Methods disclosed herein include treating subjects (humans, veterinary animals (dogs, cats, reptiles, birds, etc.) livestock (horses, cattle, goats, pigs, chickens, etc.) and research animals (monkeys, rats, mice, fish, etc.) with therapeutic compositions disclosed herein. Treating subjects includes delivering therapeutically effective amounts. Therapeutically effective amounts include those that provide effective amounts and therapeutic treatments.

[0132] An "effective amount" is the amount of a composition necessary to result in a desired physiological change in the subject. Effective amounts are often administered for research purposes. Effective amounts disclosed herein can cause a statistically- significant effect in an animal model assessing a use of nuclear medicine.

[0133] A "therapeutic treatment" can include a treatment administered to a subject in need of imaging. The subject can be in need of imaging to aid in diagnosis; to locate a position for a therapeutic intervention; to assess the functioning of a body part; and/or to assess the presence or absence of a condition. The effectiveness of a therapeutic imaging treatment can be confirmed based on the capture of an image sufficient for its intended purpose.

[0134] Exemplary types of imaging that utilize nuclear medicine include: positron emission tomography (PET), single photon emission computed tomography, radioisotope renography, and scintigraphy.

[0135] A "therapeutic treatment" can also include a treatment administered to a subject with a condition. The therapeutic treatment reduces, controls, or eliminates the condition or a symptom associated with the condition. Conditions treated with nuclear medicine include those associated with the proliferation of unwanted cells.

[0136] In particular embodiments, therapeutic treatments reduce cellular proliferation. Cellular proliferation refers to the process of cellular division, either through mitosis or meiosis, whereby increased cell numbers result. In particular embodiments, therapeutic treatments reduce cellular growth. Cellular growth refers both to an increase in cell mass or size, as well as cellular physiological processes necessary to support a cell's life.

[0137] Particular conditions that can be treated include various cancers, thyroid diseases (e.g., hyperthyroidism or thyrotoxicosis), blood disorders (e.g., Polycythemia vera, an excess of red blood cells produced in the bone marrow), and cellular proliferation in blood vessels following balloon angioplasty and/or stent placement (known as restenosis).

[0138] The effectiveness of a therapeutic treatment can be confirmed based on a beneficial change related to the condition following the treatment.

[0139] In the context of cancers, therapeutic treatments can decrease the number of cancer cells, decrease the number of metastases, decrease tumor volume, increase life expectancy, induce chemo- or radiosensitivity in cancer cells, inhibit angiogenesis near cancer cells, inhibit cancer cell proliferation, inhibit tumor growth, prevent or reduce metastases, prolong a subject’s life, reduce cancer-associated pain, and/or reduce relapse or re-occurrence of cancer following treatment. In particular embodiments, therapeutic treatments reduce, delay, or prevent further metastasis from occurring.

[0140] For hyperthyroidism or thyrotoxicosis, therapeutic treatments can aid in the return of thyroid secreted hormones, such as T3 and T4, to more normal levels. These hormones can be measured from patient blood samples. In particular embodiments, a therapeutic treatment returns serum levels of T3 and/or T4 to within a normal range (80- 180 ng/dl and 4.6-12 µg/dl, respectively).

[0141] For Polycythemia vera, therapeutic treatments can aid in the return of red blood cell counts to more normal levels. In particular embodiments, a therapeutic treatment returns the red blood cell count to within a normal range (4.7 to 6.1 million cells/µl).

[0142] For restenosis, therapeutic treatments can include the placement of radionuclides in the region of a vessel where a stent was placed or balloon angioplasty was performed, in order to inhibit the narrowing of the vessel due to proliferation of blood vessel cells. Treatment for restenosis can be deemed effective if normal blood flow through the affected blood vessel is restored. One test that can be used to diagnose improper blood flow is a stress test, which involves physical exercise while blood pressure and heart rate are measured. A normal stress test result means that the patient was able to exercise for a normal length of time and at a normal intensity level for their age and gender. Another test that can be performed to diagnose improper blood flow is a CT or MRI angiogram, which involves placement of a dye into the bloodstream and imaging of blood vessels. If restenosis treatment is effective, the CT or MRI angiogram will reveal normal blood flow through the affected vessel.

[0143] As indicated previously, particular uses of the chelating platforms disclosed herein include in imaging and treatment in the same subject.

[0144] The actual dose amount administered to a particular subject can be determined by a physician, veterinarian, or researcher taking into account parameters such as physical and physiological factors including body weight; severity of condition; previous or concurrent therapeutic interventions; idiopathy of the subject; and route of administration.

[0145] In particular embodiments, the total dose of absorbed radiation may include 10-3 grays (Gy), 10-2 Gy, 10-1 Gy, 1 Gy, 5 Gy, 10 Gy, 25 Gy, 50 Gy, 75 Gy, 100 Gy, 200 Gy, 300 Gy, 400 Gy, 500 Gy, 600 Gy, 700 Gy, 800 Gy, 900 Gy, or 1000 Gy. [0146] Doses of absorbed radiation can be achieved by delivering an appropriate amount of a composition. Exemplary amounts of compositions can include 0.05 mg/kg to 5.0 mg/kg administered to a subject per day in one or more doses. For certain indications, the total daily dose can be 0.05 mg/kg to 3.0 mg/kg administered intravenously to a subject one to three times a day, including administration of total daily doses of 0.05-3.0, 0.1-3.0, 0.5-3.0, 1.0-3.0, 1.5-3.0, 2.0-3.0, 2.5-3.0, and 0.5-3.0 mg/kg/day of composition using 60-minute QD, BID, or TID intravenous infusion dosing. Additional useful doses can often range from 0.1 to 5 µg/kg or from 0.5 to 1 µg/kg. In other examples, a dose can include 1 µg/kg, 20 µg/kg, 40 µg/kg, 60 µg/kg, 80 µg/kg, 100 µg/kg, 200 µg/kg, 350 µg/kg, 500 µg/kg, 700 µg/kg, 0.1 to 5 mg/kg, or from 0.5 to 1 mg/kg. In other examples, a dose can include 1 mg/kg, 10 mg/kg, 20 mg/kg, 40 mg/kg, 60 mg/kg, 80 mg/kg, 100 mg/kg, 200 mg/kg, 400 mg/kg, 500 mg/kg, 700 mg/kg, 750 mg/kg, 1000 mg/kg, or more.

[0147] Therapeutically effective amounts can be achieved by administering single or multiple doses during the course of an imaging or treatment regimen (e.g., daily, every other day, every 3 days, every 4 days, every 5 days, every 6 days, weekly, every 2 weeks, every 3 weeks, monthly, every 2 months, every 3 months, every 4 months, every 5 months, every 6 months, every 7 months, every 8 months, every 9 months, every 10 months, every 11 months, or yearly).

[0148] In some embodiments, the 1,2-HOPO chelating agent include, but are not limited to, molecules i ures, including:

,

; wherein l, m and n are integers between one and twenty. In some embodiments, there can be 5 HOPO groups instead of 4 (shown above).

In some embodiments, the -(CH2)m- chains can contain ether bonds -(CH2-O-CH2)- or ramifications. -(CH2-CHR’-CH2)-, or hydroxyl groups -(CH2-CH(OH)’-CH2)- etc. In some embodiments, one can substitute one or both of the oxygens on the HOPO ring (shown in any of the embodiments herein) with a sulfur.

In a particular embodiment of the invention, m is three. In a particular embodiment of the invention, m is three and n is four. In a particular embodiment of the invention, l and n are three, and m is four. Various 1,2-HOPO and 3,2-HOPO chelating agents suitable for various uses, as well as methods of making them, are also taught in U.S. Pat. Nos. 4,698,431 ("Hydroxypyridonate Chelating Agents"), 5,634,901 ("3-Hydroxy-2(1H)- pyridonate Chelating Agents"), and 5,892,029 ("3-Hydroxy-2(1H)-pyridonate Chelating Agents"), all of which are hereby incorporated by reference. [0149] Exemplary Embodiments.

1. A composition having a structure including:

,  wherein:

(i) A1, A2, A3, and A4, individually, include a CAM group, a 1,2-HOPO group, or a HA group;

(ii) B1, B2, B3, and B4, individually, include an amide group or an amine group;

(iii) at least one of C1, C2, C3, C4, C5, or C6, individually, include NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

(iv) at least another one of C1, C2, C3, C4, C5, or C6 is optional;

(v) at least one of L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, or L13, individually, include H, an alkyl group having no greater than 10 carbon atoms, an alkylamino group having no greater than 10 carbon atoms and no greater than 2 nitrogen atoms; an alkylamido group having no greater than 10 carbon atoms and no greater than 2 nitrogen atoms; an alkyl ether group having no greater than 10 carbon atoms, a hydroxy ester group, or an alkyl ester group having no greater than 10 carbon atoms; and (vi) at least one of L1, L5, L6, L7, L8, L9, L10, L11, L12, or L13 is optional. 2. A composition of embodiment 1, wherein at least another one of L2, L3, or L4, individually, include an amine group or an amide group.

3. A composition of embodiment 1 or embodiment 2, wherein L1, C1, L7, C2, L9, C3, L11, C4, and L13, C5 are absent, L5 includes an unsubstituted alkyl group having no greater than 5 carbon atoms, and C6 includes NH ₂ , C(=O)OH, maleimide, dibromo- maleimide, isothiocyanate, alkyne, or azide.

4. A composition of embodiment 3, wherein L2, L3, L4, L6, L8, L10, and L12, individually, include an unsubstituted alkyl group having no greater than 5 carbon atoms.

5. A composition of embodiment 4, wherein A1 includes a CAM group or a HOPO group; A2 includes a HA group, A3 includes a HA group, and A4 includes a CAM group, a HOPO group, or a HA group.

6. A composition of any one of embodiments 1-5, wherein at least one of L2, L3, or L4, individually, include an alkylamino or alkylamido group.

7. A composition of embodiment 1, wherein B1, B2, and B3, individually, include an amide group and B4 includes an amino group, L2 and L3 include an amino group, and L4 includes an alky group having no greater than 5 carbon atoms

8. A composition of embodiment 7, wherein:

C1, C2, C3, C4, C5, L1, A1, A2, A3, L1, L6, L7, L8, L9, L10, L11, L12, and L13 are absent,

A4 includes a CAM group, a HOPO group, or a HA group; and

L5 includes an alkyl group having no greater than 5 carbon atoms.

9. A composition of embodiment 1, wherein B1, B2, and B3, individually, include an amide group and B4 includes an amide group, L2 and L3, individually, include an amino group, and L4 includes an alky group having no greater than 5 carbon atoms.

10. A composition of embodiment 9, wherein C1, C2, C3, C4, C5, A1, A2, A3, L1, L6, L7, L8, L9, L10, L11, and L13 are absent, L12 includes an amino group, L5 includes an ether group having no greater than 10 carbon atoms, and A4 includes a CAM group, a HOPO group, or a HA group.

11. A composition of embodiment 1, wherein C1, C2, C5, C6, L1, L2, L3, L4, L5, L7, L13, B2, and B4 are absent, B1 and B3, individually, include an amide group, L6, L8, L10, and L12, individually, include an amino group, A1, A2, A3, and A4, individually, include a CAM group, a HOPO group, or a HA group, L9 and L11, individually, include an alkyl group having no greater than 5 carbon atoms.

12. A composition, including a structure:

,

wherein:

at least one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, include a CAM group, a HA group, or a 1,2-HOPO group;

at least another one of R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, include H or an alkyl group having from 1 to 10 carbon atoms;

R ₆ includes (i) H, (ii) an alkyl group having from 1 to 10 carbon atoms, or (iii) an alkyl group having from 1 to 10 carbon atoms and substituted by at least one of NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

m can be from 1 to 6;

n can be from 1 to 6;

o can be from 1 to 6.

13. A composition of embodiment 12, including a structure:

, wherein:

at least one of R ₁ , R ₃ , R ₄ , or R ₅ R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, include a CAM group, a HA group, or a 1,2- HOPO group;

optionally, another one of R ₁ , R ₃ , R ₄ , or R ₅ R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ , individually, include H or an alkyl group having from 1 to 10 carbon atoms;

R ₂ includes H or an alkyl group including from 1 to 5 carbon atoms;

R ₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

p is from 0 to 4.

14. A composition of embodiment 13, wherein:

R ₁ includes a CAM group or a 1,2-HOPO group;

R ₃ and R ₄ , individually, include a HA group; and

R ₅ includes a CAM group, a 1,2-HOPO group, or a HA group.

15. A composition of embodiment 12, including a structure:

, wherein:

R ₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R _2, R _8, and R ₉ , individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms; and

p is from 0 to 4.

16. A composition of embodiment 12, including a structure:

, wherein:

R ₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R _2, R _8, and R ₉ , individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms; and

p is from 0 to 4.

17. A composition of embodiment 12, including a structure:

, wherein:

R ₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R _2, R _8, R ₉ , and R ₁₀ , individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms; and

p is from 0 to 4. 18. A com osition of embodiment 12, includin a structure:

, wherein:

R ₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R _2, R _8, and R ₉ , individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms; and

p is from 0 to 4.

19. A com osition of embodiment 12, includin a structure:

, wherein:

R ₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; R _2, R _8, and R ₉ , individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms; and

p is from 0 to 4.

20. A composition of embodiment 12, including a structure:

, wherein:

R ₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R _2, R _8, R ₉ , and R ₁₀ , individually, include H, OH, or an alkyl group including from 1 to 5 carbon atoms; and

p is from 0 to 4.

21. A com osition of embodiment 12, includin a structure:

.

22. A composition of embodiment 12, including a structure:

.

23. A composition, including a structure:

,

wherein:

at least one of R ₁₁ , R ₁₂ , R ₁₃ , or R ₁₅ , individually, include a CAM group, a HA group, or a 1,2-HOPO group;

optionally, at least another one of R ₁₁ , R ₁₂ , R ₁₃ , or R ₁₅ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R ₂ , R ₁₄ , and R ₁₆ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms; and

r can be from 0 to 6.

24. A composition of embodiment 23, wherein:

R ₁₁ includes a CAM group or a 1,2-HOPO group;

R ₁₂ and R ₁₅ , individually, include a HA group; and R ₁₃ includes a CAM group, a 1,2-HOPO group, or a HA group.

25. A composition of embodiment 23, including a structure:

, wherein:

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

r can be from 0 to 4.

26. A composition of embodiment 23, including a structure:

, wherein

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

r is from 0 to 4.

27. A composition of embodiment 23, including a structure:

, wherein:

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , R ₁₉ , and R ₂₀ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

r can be from 0 to 4.

28. A composition of embodiment 23, including a structure:

, wherein:

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , R ₁₉ , and R ₂₀ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

r can be from 0 to 4.

29. A composition of embodiment 23, including a structure:

, wherein:

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

r is from 0 to 4.

30. A composition of embodiment 23, including a structure:

, wherein:

R ₂ , R ₁₄ , R ₁₆ , R ₁₈ , and R ₁₉ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₁₇ includes NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

r is from 0 to 4.

31. A composition, including a structure:

,

wherein:

R ₂₁ and R ₂₂ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₂₃ includes H, OH, an alkyl group having from 1 to 10 carbon atoms, or (CH ₂ ) _e R _a , where R _a is NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R ₂₄ includes a substituent having a CAM group, a 1,2-HOPO group, or a HA group; a, b, and c, individually, are from 1 to 10;

d is from 1 to 4; and

e is from 1 to 10.

32. A composition of embodiment 31, wherein R ₂₄ includes a substituent having NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide _.

33. A composition of embodiment 31, including a structure:

, wherein:

R ₂₅ , R ₂₆ , and R ₂₇ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₂₈ includes H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

s is from 0 to 4.

34. A composition of embodiment 31, including a structure:

, wherein: R ₂₅ , R ₂₆ , R _27, and R ₃₀ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₂₈ and R ₂₉ , individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

s is from 0 to 4; and

t is from 0 to 4.

35. A composition of embodiment 31, including a structure:

, wherein:

R ₂₅ , R ₂₆ , R _27, and R ₃₀ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₂₈ and R ₂₉ , individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, or azide;

s is from 0 to 4; and

t is from 0 to 4.

36. A composition of embodiment 31, including a structure:

, wherein:

R ₂₅ , R ₂₆ , R _27, R ₃₀ , and R ₃₁ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₂₈ and R ₂₉ , individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, or azide;

s is from 0 to 4; and

t is from 0 to 4.

37. A composition of embodiment 31, including a structure:

,

wherein

R ₂₅ , R ₂₆ , and R ₂₇ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₂₈ includes H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

s is from 0 to 4.

38. A composition of embodiment 31, including a structure: , wherein:

R ₂₅ , R ₂₆ , R ₂₇ , and R ₃₂ , individually, include H, OH, or an alkyl group having from 1 to 10 carbon atoms;

R ₂₈ includes H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide; and

s is from 0 to 4.

39. A composition, including a structure:

,

wherein:

A, B, C, and D, individually, include one or more amide groups, one or more amine groups, or an alkyl group having from 1 to 10 carbon atoms;

R ₃₃ , R ₃₄ , R ₃₅ , and R ₃₆ , individually, include a CAM group, a 1,2-HOPO group, or a HA group; and

g, h, i, and j, individually, are from 1 to 10.

40. A composition of embodiment 39, including a structure:

, wherein:

R ₃₇ and R ₄₂ , individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R ₃₈ , R ₃₉ , R ₄₀ , and R ₄₁ , individually, include H, OH, or an alkyl group having from 1 to 5 carbon atoms; and

u and v, individually, are from 0 to 5.

41. A composition of embodiment 39, including a structure:

wherein:

R ₃₇ and R ₄₂ , individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R ₃₈ , R ₃₉ , R ₄₀ , and R ₄₁ , individually, include H, OH, or an alkyl group having from 1 to 5 carbon atoms; and

u and v, individually, are from 0 to 5.

42. A composition of embodiment 39, including a structure:

,

wherein:

R ₃₇ and R ₄₂ , individually, include H, an alkyl group having from 1 to 5 carbon atoms, NH ₂ , C(=O)OH, maleimide, dibromo-maleimide, isothiocyanate, alkyne, or azide;

R ₃₈ , R ₃₉ , R ₄₀ , and R ₄₁ , individually, include H, OH, or an alkyl group having from 1 to 5 carbon atoms; and

u and v, individually, are from 0 to 5.

43. A method of synthesizing a siderophore using dichlorodiphenylmethane.

44. A method of embodiment 43, wherein a siderophore or siderophore-like ligand is synthesized according to the following pathway:

. 45. A composition of any one of embodiment s1-42, wherein the metal is a radionuclide.

46. A composition of embodiment 53, wherein the radionuclide includes ²²⁵ Ac, ²²⁶ Ac, ²²⁸ Ac, ¹⁰⁵ Ag, ¹⁰⁶ mAg, ¹¹⁰ mAg, ¹¹¹ Ag, ¹¹² Ag, ¹¹³ Ag, ²³⁹ Am, ²⁴⁰ Am, ²⁴² Am, ²⁴⁴ Am, ³⁷ Ar, ⁷¹ As, ⁷² As, ⁷³ As, ⁷⁴ As, ⁷⁶ As, ⁷⁷ As, ²⁰⁹ At, ²¹⁰ At, ¹⁹¹ Au, ¹⁹² Au, ¹⁹³ Au, ¹⁹⁴ Au, ¹⁹⁵ Au, ¹⁹⁶ Au, ¹⁹⁶ m ² Au, ¹⁹⁸ Au, ¹⁹⁸ mAu, ¹⁹⁹ Au, ²⁰⁰ mAu, ¹²⁸ Ba, ¹³¹ Ba, ¹³³ mBa, ¹³⁵ mBa, ¹⁴⁰ Ba, ⁷ Be, ²⁰³ Bi, ²⁰⁴ Bi, ²⁰⁵ Bi, ²⁰⁶ Bi, ²¹⁰ Bi, ²¹² Bi, ²⁴³ Bk, ²⁴⁴ Bk, ²⁴⁵ Bk, ²⁴⁶ Bk, ²⁴⁸ mBk, ²⁵⁰ Bk, ⁷⁶ Br, ⁷⁷ Br, ⁸⁰ mBr, ⁸² Br, ¹¹ C, ¹⁴ C, ⁴⁵ Ca, ⁴⁷ Ca, ¹⁰⁷ Cd, ¹¹⁵ Cd, ¹¹⁵ mCd, ¹¹⁷ mCd, ¹³² Ce, ¹³³ mCe, ¹³⁴ Ce, ¹³⁵ Ce, ¹³⁷ Ce, ¹³⁷ mCe, ¹³⁹ Ce, ¹⁴¹ Ce, ¹⁴³ Ce, ¹⁴⁴ Ce, ²⁴⁶ Cf, ²⁴⁷ Cf, ²⁵³ Cf, ²⁵⁴ Cf, ²⁴⁰ Cm, ²⁴¹ Cm, ²⁴² Cm, ²⁵² Cm, ⁵⁵ Co, ⁵⁶ Co, ⁵⁷ Co, ⁵⁸ Co, ⁵⁸ mCo, ⁶⁰ Co, ⁴⁸ Cr, ⁵¹ Cr, ¹²⁷ Cs, ¹²⁹ Cs, ¹³¹ Cs, ¹³² Cs, ¹³⁶ Cs, ¹³⁷ Cs, ⁶¹ Cu, ⁶² Cu, ⁶⁴ Cu, ⁶⁷ Cu, ¹⁵³ Dy, ¹⁵⁵ Dy, ¹⁵⁷ Dy, ¹⁵⁹ Dy, ¹⁶⁵ Dy, ¹⁶⁶ Dy, ¹⁶⁰ Er, ¹⁶¹ Er, ¹⁶⁵ Er, ¹⁶⁹ Er, ¹⁷¹ Er, ¹⁷² Er, ²⁵⁰ Es, ²⁵¹ Es, ²⁵³ Es, ²⁵⁴ Es, ²⁵⁴ mEs, ²⁵⁵ Es, ²⁵⁶ mEs, ¹⁴⁵ Eu, ¹⁴⁶ Eu, ¹⁴⁷ Eu, ¹⁴⁸ Eu, ¹⁴⁹ Eu, ¹⁵⁰ mEu, ¹⁵² mEu, ¹⁵⁶ Eu, ¹⁵⁷ Eu, ⁵² Fe, ⁵⁹ Fe, ²⁵¹ Fm, ²⁵² Fm, ²⁵³ Fm, ²⁵⁴ Fm, ²⁵⁵ Fm, ²⁵⁷ Fm, ⁶⁶ Ga, ⁶⁷ Ga, ⁶⁸ Ga, ⁷² Ga, ⁷³ Ga, ¹⁴⁶ Gd, ¹⁴⁷ Gd, ¹⁴⁹ Gd, ¹⁵¹ Gd, ¹⁵³ Gd, ¹⁵⁹ Gd, ⁶⁸ Ge, ⁶⁹ Ge, ⁷¹ Ge, ⁷⁷ Ge, ¹⁷⁰ Hf, ¹⁷¹ Hf, ¹⁷³ Hf, ¹⁷⁵ Hf, ¹⁷⁹ m ² Hf, ¹⁸⁰ mHf, ¹⁸¹ Hf, ¹⁸⁴ Hf, ¹⁹² Hg, ¹⁹³ Hg, ¹⁹³ mHg, ¹⁹⁵ Hg, ¹⁹⁵ mHg, ¹⁹⁷ Hg, ¹⁹⁷ mHg, ²⁰³ Hg, ¹⁶⁰ mHo, ¹⁶⁶ Ho, ¹⁶⁷ Ho, ¹²³ I, ¹²⁴ I, ¹²⁶ I, ¹³⁰ I, ¹³² I, ¹³³ I, ¹³⁵ I, ¹⁰⁹ In, ¹¹⁰ In, ¹¹¹ In, ¹¹⁴ mIn, ¹¹⁵ mIn, ¹⁸⁴ Ir, ¹⁸⁵ Ir, ¹⁸⁶ Ir, ¹⁸⁷ Ir, ¹⁸⁸ Ir, ¹⁸⁹ Ir, ¹⁹⁰ Ir, ¹⁹⁰ m ² Ir, ¹⁹² Ir, ¹⁹³ mIr, ¹⁹⁴ Ir, ¹⁹⁴ m ² Ir, ¹⁹⁵ mIr, ⁴² K, ⁴³ K, ⁷⁶ Kr, ⁷⁹ Kr, ⁸¹ mKr, ⁸⁵ mKr, ¹³² La, ¹³³ La, ¹³⁵ La, ¹⁴⁰ La, ¹⁴¹ La, ²⁶² Lr, ¹⁶⁹ Lu, ¹⁷⁰ Lu, ¹⁷¹ Lu, ¹⁷² Lu, ¹⁷⁴ mLu, ¹⁷⁶ mLu, ¹⁷⁷ Lu, ¹⁷⁷ mLu, ¹⁷⁹ Lu, ²⁵⁷ Md, ²⁵⁸ Md, ²⁶⁰ Md, ²⁸ Mg, ⁵² Mn, ⁹⁰ Mo, ⁹³ mMo, ⁹⁹ Mo, ¹³ N, ²⁴ Na, ⁹⁰ Nb, ⁹¹ mNb, ⁹² mNb, ⁹⁵ Nb, ⁹⁵ mNb, ⁹⁶ Nb, ¹³⁸ Nd, ¹³⁹ mNd, ¹⁴⁰ Nd, ¹⁴⁷ Nd, ⁵⁶ Ni, ⁵⁷ Ni, ⁶⁶ Ni, ²³⁴ Np, ²³⁶ mNp, ²³⁸ Np, ²³⁹ Np, ¹⁵ O, ¹⁸² Os, ¹⁸³ Os, ¹⁸³ mOs, ¹⁸⁵ Os, ¹⁸⁹ mOs, ¹⁹¹ Os, ¹⁹¹ mOs, ¹⁹³ Os, ³² P, ³³ P, ²²⁸ Pa, ²²⁹ Pa, ²³⁰ Pa, ²³² Pa, ²³³ Pa, ²³⁴ Pa, ²⁰⁰ Pb, ²⁰¹ Pb, ²⁰² mPb, ²⁰³ Pb, ²⁰⁹ Pb, ²¹² Pb, ¹⁰⁰ Pd, ¹⁰¹ Pd, ¹⁰³ Pd, ¹⁰⁹ Pd, ¹¹¹ mPd, ¹¹² Pd, ¹⁴³ Pm, ¹⁴⁸ Pm, ¹⁴⁸ mPm, ¹⁴⁹ Pm, ¹⁵¹ Pm, ²⁰⁴ Po, ²⁰⁶ Po, ²⁰⁷ Po, ²¹⁰ Po, ¹³⁹ Pr, ¹⁴² Pr, ¹⁴³ Pr, ¹⁴⁵ Pr, ¹⁸⁸ Pt, ¹⁸⁹ Pt, ¹⁹¹ Pt, ¹⁹³ mPt, ¹⁹⁵ mPt, ¹⁹⁷ Pt, ²⁰⁰ Pt, ²⁰² Pt, ²³⁴ Pu, ²³⁷ Pu, ²⁴³ Pu, ²⁴⁵ Pu, ²⁴⁶ Pu, ²⁴⁷ Pu, ²²³ Ra, ²²⁴ Ra, ²²⁵ Ra, ⁸¹ Rb, ⁸² Rb, ⁸² mRb, ⁸³ Rb, ⁸⁴ Rb, ⁸⁶ Rb, ¹⁸¹ Re, ¹⁸² Re, ¹⁸² mRe, ¹⁸³ Re, ¹⁸⁴ Re, ¹⁸⁴ mRe, ¹⁸⁶ Re, ¹⁸⁸ Re, ¹⁸⁹ Re, ¹⁹⁰ mRe, ⁹⁹ Rh, ⁹⁹ mRh, ¹⁰⁰ Rh, ¹⁰¹ mRh, ¹⁰² Rh, ¹⁰³ mRh, ¹⁰⁵ Rh, ²¹¹ Rn, ²²² Rn, ⁹⁷ Ru, ¹⁰³ Ru, ¹⁰⁵ Ru, ³⁵ S, ¹¹⁸ mSb, ¹¹⁹ Sb, ¹²⁰ Sb, ¹²⁰ mSb, ¹²² Sb, ¹²⁴ Sb, ¹²⁶ Sb, ¹²⁷ Sb, ¹²⁸ Sb, ¹²⁹ Sb, ⁴³ Sc, ⁴⁴ Sc, ⁴⁴ mSc, ⁴⁶ Sc, ⁴⁷ Sc, ⁴⁸ Sc, ⁷² Se, ⁷³ Se, ⁷⁵ Se, ¹⁵³ Sm, ¹⁵⁶ Sm, ¹¹⁰ Sn, ¹¹³ Sn, ¹¹⁷ mSn, ¹¹⁹ mSn, ¹²¹ Sn, ¹²³ Sn, ¹²⁵ Sn, ⁸² Sr, ⁸³ Sr, ⁸⁵ Sr, ⁸⁹ Sr, ⁹¹ Sr, ¹⁷³ Ta, ¹⁷⁵ Ta, ¹⁷⁶ Ta, ¹⁷⁷ Ta, ¹⁸⁰ Ta, ¹⁸² Ta, ¹⁸³ Ta, ¹⁸⁴ Ta, ¹⁴⁹ Tb, ¹⁵⁰ Tb, ¹⁵¹ Tb, ¹⁵² Tb, ¹⁵³ Tb, ¹⁵⁴ Tb, ¹⁵⁴ mTb, ¹⁵⁴ m ² Tb, ¹⁵⁵ Tb, ¹⁵⁶ Tb, ¹⁵⁶ mTb, ¹⁵⁶ m ² Tb, ¹⁶⁰ Tb, ¹⁶¹ Tb, ⁹⁴ Tc, ⁹⁵ Tc, ⁹⁵ mTc, ⁹⁶ Tc, ⁹⁷ mTc, ⁹⁹ mTc, ¹¹⁸ Te, ¹¹⁹ Te, ¹¹⁹ mTe, ¹²¹ Te, ¹²¹ mTe, ¹²³ mTe, ¹²⁵ mTe, ¹²⁷ Te, ¹²⁷ mTe, ¹²⁹ mTe, ¹³¹ mTe, ¹³² Te, ²²⁷ Th, ²³¹ Th, ²³⁴ Th, ⁴⁵ Ti, ¹⁹⁸ Tl, ¹⁹⁹ Tl, ²⁰⁰ Tl, ²⁰¹ Tl, ²⁰² Tl, ²⁰⁴ Tl, ¹⁶⁵ Tm, ¹⁶⁶ Tm, ¹⁶⁷ Tm, ¹⁶⁸ Tm, ¹⁷⁰ Tm, ¹⁷² Tm, ¹⁷³ Tm, ²³⁰ U, ²³¹ U, ²³⁷ U, ²⁴⁰ U, ⁴⁸ V, ¹⁷⁸ W, ¹⁸¹ W, ¹⁸⁵ W, ¹⁸⁷ W, ¹⁸⁸ W, ¹²² Xe, ¹²⁵ Xe, ¹²⁷ Xe, ¹²⁹ mXe, ¹³¹ mXe, ¹³³ Xe, ¹³³ mXe, ¹³⁵ Xe, ⁸⁵ mY, ⁸⁶ Y, ⁸⁷ Y, ⁸⁷ mY, ⁸⁸ Y, ⁹⁰ Y, ⁹⁰ mY, ⁹¹ Y, ⁹² Y, ⁹³ Y, ¹⁶⁶ Yb, ¹⁶⁹ Yb, ¹⁷⁵ Yb, ⁶² Zn, ⁶⁵ Zn, ⁶⁹ mZn, ⁷¹ mZn, ⁷² Zn, ⁸⁶ Zr, ⁸⁸ Zr, ⁸⁹ Zr, ⁹⁵ Zr, and/or ⁹⁷ Zr.

47. A composition of embodiment 46, wherein the radionuclide includes ⁹⁰ Y, ⁶⁷ Cu, ²¹³ Bi, ²¹² Bi, ¹⁸⁶ Re, ⁶⁷ Cu ⁹⁰ Y, ²¹³ Bi, ¹⁷⁷ Lu, ¹⁸⁶ Re, and/or ⁶⁷ Ga.

48. A composition of embodiment 46, wherein the radionuclide includes ⁸⁹ Zr, ²²⁵ Ac, and/or ²²⁷ Th.

49. A composition of any one of embodiments 1-42, wherein the metal includes a daughter isotope of a radionuclide. 50. A composition of embodiment 49, wherein the daughter isotope of the radionuclide includes ⁸⁹ Y, ¹⁸ O, ²²¹ Fr, ²¹³ Bi, and/or ²⁰⁹ Pb.

51. A method of treating a subject in need thereof comprising administering a therapeutically effective amount of a composition of any of embodiments 1-42 to the subject thereby treating the subject.

52. A method of embodiment 51 wherein the treating provides imaging to aid in diagnosis; to locate a position for a therapeutic intervention; to assess the functioning of a body part; and/or to assess the presence or absence of a condition.

53. A method of embodiment 64 wherein the imaging is through positron emission tomography (PET), single photon emission computed tomography, radioisotope renography, or scintigraphy.

54. A method of any of embodiments 63-65 wherein the treating reduces cellular proliferation.

55. A method of embodiment 66 wherein the cellular proliferation is due to cancer, a thyroid disease, a blood disorder, and/or restenosis.

56. A method of embodiment 67 wherein the cancer is adrenal cancer, bladder cancer, blood cancer, bone cancer, brain cancer, breast cancer, carcinoma, cervical cancer, colon cancer, colorectal cancer, corpus uterine cancer, ear, nose and throat (ENT) cancer, endometrial cancer, esophageal cancer, gastrointestinal cancer, head and neck cancer, Hodgkin's disease cancer, intestinal cancer, kidney cancer, larynx cancer, leukemia, liver cancer, lymph node cancer, lymphoma, lung cancer, melanoma, mesothelioma, myeloma, nasopharynx cancer, neuroblastoma, non-Hodgkin's lymphoma, oral cancer, ovarian cancer, pancreatic cancer, penile cancer, pharynx cancer, prostate cancer, rectal cancer, sarcomcancer, seminomcancer, skin cancer, stomach cancer, teratomcancer, testicular cancer, thyroid cancer, uterine cancer, vaginal cancer, vascular tumor cancer, and/or cancer from metastases thereof.

57. A method of embodiment 67 wherein the thyroid disease is hyperthyroidism or thyrotoxicosis.

58. A method of embodiment 67 wherein the blood disorder is Polycythemia vera. 59. A method of embodiment 67 wherein the restenosis follows balloon angioplasty and/or stent placement. 60. A method of any of embodiments 72-76 wherein the metal is a radionuclide.

61. A method of any of embodiments 72-76 wherein the metal is a radionuclide of embodiment 55.

62. A method of any of embodiments 72-76 wherein the metal is a radionuclide selected from ⁹⁰ Y, ⁶⁷ Cu, ²¹³ Bi, ²¹² Bi, ¹⁸⁶ Re, ⁶⁷ Cu ⁹⁰ Y, ²¹³ Bi, ¹⁷⁷ Lu, ¹⁸⁶ Re, and ⁶⁷ Ga.

63. A method of any of embodiments 72-76 wherein the metal is a radionuclide selected from ⁸⁹ Zr, ²²⁵ Ac, and ²²⁷ Th.

[0150] The chelator 3,4,3-LI(1,2-HOPO) is an octadentate, tetraprotic compound including 4 bidentate 1,2-HOPO metal binding units attached onto a spermine (“3,4,3- LI”) scaffold (FIG. 1), which was recently modified to enable monoclonal antibody attachment and form a bioconjugate chelator that displayed great properties for positron emission tomography (PET) when bound to ⁸⁹ Zr (Deri, et al., Bioconjugate Chemistry, 2015, 26 (12): 2579-2591; Deri, et al., J. Med. Chem., 2014, 57 (11): 4849-4860). Methyl 2,3-dihydroxybenzoate (2). A stirred suspension of 1 (8.06 g, 52.3 mmol) in 100 mL of MeOH was treated with 2.00 mL of concentrated sulfuric acid. The suspension warmed and clarified 2 minutes after the addition. The reaction was equipped with a reflux condenser and was heated to 65 °C overnight. The next morning the conversion was verified by LC-MS and the volatiles were removed under reduced pressure. The crude was partitioned between H ₂ O (100 mL) and ethyl acetate (100 mL) and the aqueous layer was extracted with ethyl acetate (3x50 mL). The organic extracts were combined, dried over MgSO ₄ , and concentrated under reduced pressure. The crude was passed through a plug of silica using 10% ethyl acetate in hexanes as eluent. The eluent was concentrated under reduced pressure and dried under high vacuum for 2 hours to yield 2 (7.66 g, 45.6 mmol, 88%) as a white solid, the spectral properties of which matched previous reports (Weitl, et al., J. Am. Chem. Soc., 1980, 102 (7): 2289- 2293).

[0151] Methyl 2,2-diphenylbenzo[d][1,3]dioxole-4-carboxylate (3). Precursor 2 (5.00 g, 29.7 mmol) was mixed with dichlorodiphenylmethane (8.56 mL, 44.6 mmol) under an argon atmosphere; the resulting suspension was stirred and heated to 160 °C for 1 hour. The mixture was allowed to cool to room temperature and was diluted with 100 mL of ethyl acetate. The solution was washed with sat. NaHCO ₃ (30 mL), brine (30 mL), dried over MgSO ₄ , and then concentrated under reduced pressure. The ensuing greyish oil was dissolved in 30 mL of hot MeOH (65 °C) and was slowly cooled to 5 °C, which resulted in the formation of white crystals. The crystals were a mixture of 3 and benzophenone that could not be easily separated; the crude product was used as is for the subsequent step.

[0152] 2,2-diphenylbenzo[d][1,3]dioxole-4-carboxylic acid (4). The mixture from the previous step was dissolved in 100 mL of THF and was treated with 100 mL of 0.9 M LiOH. The emulsion was rapidly stirred and heated to reflux for 5 hours. Conversion was verified by LC-MS and the reaction was cooled to room temperature. The solution was neutralized with 10% v/v aqueous acetic acid and was extracted with ethyl acetate (3x50 mL). The organic extracts were combined, dried over MgSO ₄ , and concentrated under reduced pressure. The crude was chromatographed using 25% ethyl acetate in hexanes as eluent. Volatiles were then removed under reduced pressure followed by high vacuum to yield 4 (7.6 g, 24 mmol, 81% over 2 steps) as a white solid, the spectral properties of which matched previous reports (Weitl, et al., J. Am. Chem. Soc., 1980, 102 (7): 2289-2293).

[0153] 3,4,3-LI(2,2-diphenylbenzo[d][1,3]-2,3-catecholamide) (5). Precursor 4 (746 mg, 2.33 mmol) was suspended in 10 mL of dry toluene under an argon atmosphere and was treated with oxalyl chloride (220 µL, 2.55 mmol). Catalytic N,N- dimethylformamide was added and the suspension was heated to 40 °C. The solution was stirred until the evolution of gas ceased and was concentrated on the manifold vacuum at the same temperature. The resulting brown oil was dissolved in 10 mL of dry THF. In a separate container a solution of spermine (118 mg, 0.583 mmol), triethylamine (356 µL, 2.56 mmol), and THF (5 mL) was prepared. The solutions were combined and heated to 50°C overnight in a sealed flask. The following day the reaction was filtered and concentrated under reduced pressure. The resulting crude oil was chromatographed using 3% MeOH in CH ₂ Cl ₂ as eluent. The volatiles were then removed under reduced pressure and dried under vacuum, yielding 5 as a white foam (641 mg, 0.457 mmol, 78 % yield). ¹ H NMR (300 MHz, CDCl ₃ ) δ 7.88 (1H, t, J = 5.7 Hz), 7.66-7.76 (6H, br t), 7.60 (1H, br s), 7.57 (1H, br s), 7.43-7.53 (10H, br s), 7.33-7.40 (4H, br s), 7.19-7.31 (20H, br s), 7.01 (2H, d, J = 7.6 Hz), 6.91 (4H, dd, J = 12.1 Hz, 8.0 Hz), 6.80 (2H, br s), 6.72 (2H, br s), 3.85 (4H, br s), 3.43 (2H br s), 3.21 (2H, br s), 3.06 (1H, br s), 2.96 (1H, br s), 2.80 (2H, br s), 1.81 (4H, br s), 1.54 (1H, br s), 1.43 (1H, br s), 1.19 (1H, br s), 0.89 (2H, br s). ¹³ C NMR (75 MHz, CDCl ₃ ) δ 167.5, 163.7, 147.3, 147.1, 145.0, 142.8, 139.7, 139.4, 138.9, 129.7, 129.2, 128.4, 128.3, 126.4, 126.3, 126.1, 126.0, 122.3, 122.2, 121.7, 120.4, 118.4, 118.1, 116.0, 111.8, 111.4, 111.3, 109.4, 47.9, 41.8, 36.5, 27.9, 25.5 (FIG.2A and 2B).

[0154] 3,4,3-LI(CAM) (6). The protected chelator 5 (411 mg, 0.293 mmol) was dissolved in a mixture of 5 mL acetic acid, 0.5 mL H ₂ O, and 0.1 mL concentrated HCl. The solution was stirred in a sealed container at 60°C overnight. The next day the conversion was confirmed by LC-MS and the volatiles were removed under vacuum. A portion of the crude was purified using reverse-phase prep-HPLC using at 10→50% MeOH in H ₂ O + 0.1 % trifluoroacetic acid as eluent. The solvent was removed on a Genevac centrifugal evaporator followed by lyophilization of residual H ₂ O. 6 was obtained as a pure white powder (90% yield). ¹ H NMR (600 MHz, DMSO-d ₆ ) δ 12.82 (1H, br s), 12.69 (1H, br s), 9.52 (2H, br s), 9.11 (2H, br s), 8.78 (1H, br s), 8.60 (3H, br s), 7.26 (1H, br s), 7.12 (1H, br s), 6.90 (2H, br s), 6.77 (1H, br s), 6.66 (4H, br s), 6.56 (2H, br s), 6.44 (1H, br s), 2.88-3.52 (12H, overlapping aliphatic signals), 1.16-1.83 (8H, overlapping aliphatic signals); ¹³ C NMR (125 MHz, MeOD-d ₄ ) δ 172.9, 171.5, 150.4, 147.3, 146.6, 125.6, 125.4, 121.0, 119.6, 119.1, 118.8, 118.6, 116.9, 116.6, 47.7, 44.9, 43.2, 37.8, 37.5, 29.3, 28.2, 26.5, 25.5 (FIGs.3A and 3B). MS-ESI (m/z) [M + H] Calcd for C ₃₈ H ₄₃ N ₄ O ₁₂ , 747.2878; found 747.2922 and [M– H] Calcd. for C ₃₈ H ₄₁ N ₄ O ₁₂ , 745.2721; found 745.2774 (FIG.4).

[0155] Another pathway for synthesizing a chelator that includes a carboxyl group for binding with another compound, such as a protein or a dye, can include:

. [0156] Metal, Chelator Solutions. The trivalent lanthanide Ln(III) working stock solutions were prepared in standardized 0.1 M HCl. A Zr(IV) stock solution was prepared by dissolving ZrCl ₄ in 3.0 M H ₂ SO ₄ , to prevent hydrolysis. The metal salt ZrCl ₄ was handled and stored in a glovebox kept under inert atmosphere. The Zr(IV) stock solution was standardized against EDTA, with xylene orange as the indicator (Welcher, F. J. The analytical uses of ethylenediamine tetraacetic acid; 1958). A Th(IV) stock solution was prepared in 0.1 M H ₂ SO ₄ . Stock solutions (4 mM) of Ent, and 3,4,3- LI(CAM) were prepared by direct dissolution of a weighed portion of chelator in DMSO and aliquots were removed prior to each set of experiments.

[0157] Solution Thermodynamics. All titrant solutions were degassed by boiling for 1 h while being purged under Ar. Carbonate-free 0.1 M KOH was prepared from concentrate (J.T Baker Dilut-It) and was standardized by titrating against 0.1 M potassium hydrogen phthalate (99.95%, Sigma Aldrich). Solutions of 0.1 M HCl were similarly prepared and were standardized by titrating against TRIS (99.9%, J.T. Baker). The glass electrode (Metrohm - Micro Combi - response to [H+]) used for the pH measurements was calibrated at 25.0°C and at an ionic strength of 0.1 M (KCl) before each potentiometric or spectrophotometric titration. The calibration data were analyzed using the program GLEE (Gans & O’Sullivan, Talanta, 2000, 51 (1): 33-37) to refine for the E° and slope. All thermodynamic measurements were conducted at 25.0°C, in 0.1 M KCl supporting electrolyte under positive Ar gas pressure. The automated titration system was controlled by an 867 pH Module (Metrohm). Two-milliliter Dosino 800 burets (Metrohm) dosed the titrant (0.1 M KOH or 0.1 M HCl) into the thermostated titration vessel (5−90 mL). UV−visible spectra were acquired with an Ocean Optics USB4000-UV−vis spectrometer equipped with a TP-300 dip probe (Ocean Optics; path length of 10 mm), fiber optics and a DH-2000 light source (deuterium and halogen lamps). The fully automated titration system and the UV-vis spectrophotometer were coordinated by LBNL titration system, a computer program developed in house.

[0158] Incremental Spectrophotometric Titrations. This method was used to determine the protonation constants of 3,4,3-LI(CAM) as well as the stability constants of its complexes formed with Eu(III), Zr(IV) and ²³² Th(IV). The experimental titration setup is similar to previously described systems (Sturzbecher-Hoehne, et al., Radiochimica Acta., 2013, 101 (6): 359-366). For the 3,4,3-LI(CAM) protonation (and Eu(III)-3,4,3-LI(CAM) complexes), titrations were performed with an initial concentration of 50 μM of 3,4,3-LI(CAM) (and 50 μM of Eu(III)) resulting in absorbance values included between 0 and 1.0 throughout the titration. Typically, 9 mL of a sample containing 3,4,3-LI(CAM) (and Eu(III)) and the supporting electrolyte (KCl/HCl) were incrementally perturbed by addition of 0.025 mL of carbonate-free 0.1 M KOH followed by a time delay of 80 s. Buffering of the solution was ensured by the addition of 10 mM of HEPES, 10 mM of CHES and 10 mM of MES. Between 130 and 250 data points were collected per titration, each data point including a pH measurement and a UV-Vis spectrum (250-450 nm) over the pH range 1.5 to 12.0. All spectra were corrected for dilution before data fitting. The entire procedure (electrode calibrate, titration and data treatment) was performed independently five times for the protonation constants and four times for the Eu(III)-3,4,3-LI(CAM) complexes. For the Zr(IV) and Th(IV) complexes, titrations were performed similarly but in the presence of DTPA to avoid the formation of metal hydroxides at low pH, before the uptake by 3,4,3-LI(CAM). For each metal, three titrations were performed independently in the presence of 1.1 to 40 equivalents of DTPA. Examples of titrations are displayed in the Supporting Information (FIGs.5-7).

[0159] Data Treatment. Thermodynamic constants and spectral deconvolution were refined using the nonlinear least-squares fitting program HypSpec (Gans, et al., Talanta, 1996, 43 (10): 1739-1753). All equilibrium constants were defined as cumulative formation constants, β _mlh according to Equation (1), where the metal and chelator are designated as M and L, respectively. All metal and chelator concentrations were held at estimated values determined from the volume of standardized stock solutions. All species formed with 3,4,3-LI(CAM) were considered to have significant absorbance to be observed in the UV-vis spectra and were therefore included in the refinement process. The refinements of the overall formation constants β included in each case with previously determined chelator protonation constants and the metal hydrolysis products, whose equilibrium constants were fixed to the literature values (Smith, et al., NIST standard reference database 46. NIST Critically selected stability constants of metal complexes database ver 2004, 2) The speciation diagrams were calculated using the modeling program Hyss (Alderighi, et al., Coordination Chemistry Reviews, 1999, 184 (1): 311-318). Errors on log β _mlh and pK _a values presented in this Example correspond to the standard deviation observed over the n replicates (n = 3 to 5) of the entire procedure (electrode calibrate, titration and data treatment).

mM+lL+hH⇌^[M _m L _l H _h ]; β _mlh =[M _m L _l H _h ]/([M] ^m [L] ^l [H] ^h )

[0160] 3,4,3-LI(CAM) was synthesized from readily available building blocks using a process shown in FIG. 8. The new preparation moves away from using harsh reaction conditions by using the protected diphenylmethylene acetal derivative (5), which greatly simplifies purification of the final product.

[0161] Affinity of 3,4,3-LI(CAM) Toward 3+ and 4+ Metals. A comprehensive solution thermodynamic analysis was performed to characterize the affinity of 3,4,3- LI(CAM) for trivalent and tetravalent metals and the effect of substituting 1,2-HOPO for CAM binding units on the octadentate spermine scaffold. The protonation constants of 3,4,3-LI(CAM) were determined by spectrophotometric titrations, and eight protonation equilibria were assigned to sequential removal of two protons from each of the four CAM units (FIG. 9). Previous studies of Ent and other CAM-containing synthetic analogs established that the protonation constants (pK _a1 -pK _a4 ) of the meta-hydroxyl oxygen atoms are well separated from the ortho-hydroxyl oxygen atoms (pK _a5 -pK _a8 ) (Loomis & Raymond, Inorganic Chemistry, 1991, 30 (5): 906-911). The last four pK _a values are most relevant to metal binding as moieties corresponding to these values have to be deprotonated at physiological pH in order to bind the metal ions. The overall acidity of 3,4,3-LI(CAM) can be defined as∑pK _a5-8 = 45.4 versus 3,4,3-LI(1,2-HOPO)’s 21.2 (Abergel, et al., Inorganic chemistry 2009, 48 (23): 10868-10870) with lower values representing higher acidity. 3,4,3-LI(CAM) is therefore less prone to bind hard Lewis acids at low pH than its 1,2-HOPO analog, due to competition between metal uptake and protonation of the CAM moieties.

[00162] Incremental spectrophotometric titrations were then carried out to determine the formation of Eu ^III , Zr ^IV or Th ^IV complexes with 3,4,3-LI(CAM). Because of the very short half-life of ²²⁵ Ac and the scarce availability of the longer-lived ²²⁷ Ac, Eu ^III was used here as a non-radioactive Ln surrogate for Ac ^III . Based on previous solution thermodynamic studies of Ln ^III complexes of 3,4,3-LI(1,2-HOPO) and other common polyaminocarboxylate chelators,15 it is reasonable to expect similar stability constants for Eu ^III and Ac ^III complexes of 3,4,3-LI(CAM). The CAM octadentate chelator showed a very high affinity for both 3+ and 4+ ions (FIG. 9). The stability constants of [Eu-3,4,3- LI(CAM)] ^5- , [Th-3,4,3-LI(CAM)] ^4- and [Zr-3,4,3-LI(CAM)] ^4- are several orders of magnitude higher than those of their 1,2-HOPO counterparts, with log β110 values of 29.7, 47.7 and 57.3, respectively. Consequently, 3,4,3-LI(CAM) is one of the strongest chelators ever reported for the chelation of both trivalent and tetravalent f-elements. For comparison, a cyclic octadentate terephthalamide derivative was recently designed to bind Th4+ in vivo and showed an unprecedented affinity for Th4+ with a log β110 (ThL4-) value of 53.7 (Pham, et al., J. Am. Chem. Soc., 2014, 136 (25): 9106-9115). To inspect the pH dependency of metal complex formation, speciation diagrams were calculated for 3,4,3-LI(CAM) in the presence of 1 equivalent of Eu(III), Zr(IV) or Th(IV) (FIGs. 5-7). Both Zr(IV) and Th(IV) complexes start forming at around pH 3, with the mono and fully deprotonated species, [MIVLH] ^3- and [MIVL] ^4- , being predominant at physiological pH (7.4). This behavior departs from that of 3,4,3-LI(1,2-HOPO), with which 4+ metal complexes are formed even under very acidic conditions (pH < 0) (Deblonde, et al., Inorganic chemistry, 2013, 52 (15); 8805-8811; Sturzbecher-Hoehne, et al., Inorganic chemistry, 2015, 54 (7): 3462-3468). For Eu(III), complexation by 3,4,3- LI(CAM) starts at pH 5 and the mono-protonated complex, [Eu ^III LH] ^4- , is the only species present at pH 7.4. Similar to what is observed with 4+ metals, the pH at which Eu(III)- 3,4,3-LI(CAM) complexes start forming is higher than in the case of Eu(III)-3,4,3-LI(1,2- HOPO) species that already appear at pH 1 under those same conditions (Abergel, et al., Inorganic chemistry, 2009, 48 (23): 10868-10870). Additional embodiments of various chelators are shown in FIG. 10A, which depicts an embodiment of a general peptoid synthesis. Submonomer units are generally depicted as“R” group, and can be metal chelating units substituted with an available primary amine. These submonomer units can be used to prepare the peptoids on Rink Amide resin employing standard coupling chemistry. An unlimited number of submonomer units can be added, with each submonomer unit providing 1, 2, 3, or more metal chelating atoms such as oxygen, nitrogen, or sulfur donors. Peptoid structures formed with one, two, three, four, or five submonomer CAM- or HOPO-based units will result in bidentate, tetradentate, hexadentate, Octadentate, or pentadentate ligands. Unless noted otherwise, all synthetic aspects may be carried out in fritted polypropylene syringes, which allowed for recovery of submonomer for re-use. Synthesis can include: 1. Adding 100-150 mg of Rink amide resin to a fritted syringe. Swelling the resin by adding 2 mL of DMF and rock for 30 minutes. Ejecting the solution to isolate the swelled resin. 2.

[00163] Adding 1 mL of 20 % 4-methylpiperidine in DMF (v/v) to deprotect the Fmoc group. Agitating for 2 minutes, draining, and repeating for 12 minutes.3. Rinsing the resin with DMF (2 mL, 5 times for 1 minute). 4. Bromoacetylation. Premixing 0.8 M bromoacetic acid in DMF with 0.8 M N,N-diisopropylcarbodiimide (DIC), 2 mL total solution with 0.4 M of each reagent. Drawing the solution into the syringe, agitating for 5 minutes, and rinsing (2 mL DMF 5x1 minute). 5. Displacement. Drawing in 1.5 mL of submonomer solution (0.2 M in DMF), agitating for 1 hour at 45 ^o C, then rinsing (DMF 5x1 minute). 6. Repeating bromoacetylation and displacement until synthesis is finished. Washing with DCM (2 mL 3x1 minute) after last DMF wash and drying resin by pulling the plunger out and applying a gentle vacuum onto the syringe needle.

[00164] FIG. 10B depicts an embodiment of a general peptoid synthesis, where only one same submonomer unit is used throughout four coupling steps. The submonomer unit comprises a 1,2-HOPO chelating functionality linked to a primary amine through an ethylene bridge to allow for coupling to the peptoid scaffold. The resulting peptoid ligand is octadentate, with four HOPO chelating units available for metal binding. In some embodiments, different units can be added for different functionality, such as to allow cross-linking or other functions.

[00165] FIG. 10C depicts an embodiment of a general peptoid synthesis where two different submonomer units are used throughout four coupling steps. The submonomer units comprise either a 1,2-HOPO or CAM chelating functionality linked to a primary amine through an ethylene bridge to allow for coupling to the peptoid scaffold. The combinatorial nature of peptoid synthesis provides a unique opportunity to control binding moiety sequence. The modularity of the scaffold allows for the preparation of up to 16 possible tetrapeptoid, octadentate ligands, with zero, one, two, three, or four HOPO or CAM chelating units available for metal binding. “H” and“C” are defined in FIG. 10D. The option of this approach allows for the generation of a wide variety of resulting chelators.

[00166] FIG. 10D depicts an embodiment of a general peptoid synthesis, where two different submonomer units are each used throughout two coupling steps. The submonomer units can comprise a 1,2-HOPO or CAM chelating functionality linked to a primary amine through an ethylene bridge to allow for coupling to the peptoid scaffold. The particular embodiment depicts the“CHHC” peptoid ligand, which incorporates directionally from the rink amide resin a CAM, two HOPO, and a CAM chelating units available for metal binding.

[00167] FIG.10E depicts an embodiment of the 16 products obtained from a general peptoid synthesis, where two different submonomer units are used throughout four coupling steps. The submonomer units comprise a 1,2-HOPO or CAM chelating functionality linked to a primary amine through an ethylene bridge to allow for coupling to the peptoid scaffold. The modularity of the scaffold allows for the preparation of up to 16 possible tetrapeptoid, octadentate ligands, with zero, one, two, three, or four HOPO or CAM chelating units available for metal binding.

[00168] FIG. 10F depicts an embodiment of an organic fluorophore, FITC, that can be used as a fluorescent tag. The tag, similarly to the majority of well-characterized commercially-available fluorophores, can be incorporated onto the peptoid structures through standard amine coupling conditions, using its available primary-amine-reactive isothiocyanate functionality. [00169] FIG.11A depicts an embodiment of a conjugation pathway for attachment to biologically-relevant targeting molecules, solid resins, or nanoparticles, that contain thiol reactive sites (such as those in cysteine residues). A maleimide or dibromo-maleimide functionality can be attached to the peptoid ligands through standard amide coupling conditions as a subsequent step following the addition of the last chelating submonomer. This embodiment specifically depicts the functionalization of the available peptoid secondary amine by a carboxylic group linked to maleimide or di- bromomaleimide groups through an alkyl chain. In this case, the alkyl chain comprises 5 carbons, but its length can vary from 2 to 10 carbon atoms.

[00170] FIG. 11B depicts an embodiment of conjugation pathways that use click chemistry methods for attachment to biologically-relevant targeting molecules, solid resins, or nanoparticles. A functionality comprising of isothiocyanate, azide, or alkyne, can be attached to the peptoid ligands through standard amide coupling conditions as a subsequent step following the addition of the last chelating submonomer. This embodiment specifically depicts the addition of an available peptoid primary amine linked to the scaffold through an alkyl chain and its subsequent reaction to form the isothiocyanate, azide, or alkyne moiety. In this case, the alkyl chain comprises 5 carbons, but its length can vary from 2 to 10 carbon atoms.

[00171] FIG. 12A depicts reaction schemes for the conjugation of maleimide- or dibromomaleimide-substituted peptoids to the disulfide bridges available on antibodies. Reduction of the disulfide bridges results in the formation of thiol functionalities on the targeting antibodies, which then readily react with the substituted peptoid.

[00172] FIG.12B depicts the reaction schemes for the conjugation of isothiocyanate- or azide-substitued peptoids to antibody substitutions sites through standard click chemistry methods.

[00173] FIG. 13 depicts some embodiments of a fluorescent tag incorporation. A fluorophore can be attached to the peptoid ligands through standard amide coupling conditions as a subsequent step following the addition of the last chelating submonomer. This embodiment specifically depicts the functionalization of the peptoid through additional bromoacetylation and displacement steps with the FITC fluorophore that is substituted with a primary amine through an alkyl chain. In this case, the alkyl chain comprises 2 carbons, but its length can vary from 2 to 10 carbon atoms. Any fluorophore can be used in some embodiments. Examples

Example 1

Experimental Procedures

[00174] General Considerations. Chemicals were obtained from commercial suppliers and were used as received unless stated otherwise. ¹ H NMR spectra were recorded on Bruker instruments; ¹³ C NMR spectra were recorded on Bruker instruments with tetramethylsilane as an internal reference. SilicaFlash G60 (particle size 60-200 µm) was used for flash column chromatography. LC-MS was performed on an Agilent LC/MS system consisting of an Agilent 1200 binary LC pump, a temperature-controlled autosampler, a PDA UV detector, and a 6530 Accurate Mass Q-TOF mass spectrometer (Wilmington, DE, USA). The mass spectrometer was equipped with a JetStream® ESI probe operating at atmospheric pressure. The ESI source parameter settings were: mass range m/z 100–1200, gas temperature 350 °C, gas flow 10 L/min, nebulizer 50 psi, sheath gas temperature 400 °C, sheath gas flow 12 L/min, capillary voltage (Vcap) 3500 V, nozzle voltage 500 V, fragmentor 200 V, skimmer 65 V, octopole RF (OCT 1 RF Vpp) 750 V. Reverse phase preparatory HPLC was performed on a Varian ProStar system with a Vydac C18 column. HRMS and MS-MS were obtained on a Waters Xevo G2 Qtof mass spectrometer, leucine encephalin lockspray with mass correction was used for HRMS. Example 2--Synthetic Procedures--Submonomer

[00175] Methyl 2,3-dihydroxybenzoate, 4. A stirred suspension of 3 (8.06 g, 52.3 mmol) in 100 mL of methanol was treated with 2.00 mL of concentrated sulfuric acid. The suspension warmed and clarified 2 minutes after the addition. The reaction was equipped with a reflux condenser and was heated to 65 ^o C overnight. The next morning the conversion was verified by LC-MS and the volatiles were removed under reduced pressure. The crude was partitioned between water (100 mL) and ethyl acetate (100 mL) and the aqueous layer was extracted with ethyl acetate (3x50 mL). The organic extracts were combined, dried over MgSO ₄ , and concentrated under reduced pressure. The crude was passed through a plug of silica using 10% ethyl acetate in hexanes as eluent. The eluent was concentrated under reduced pressure and dried under high vacuum for 2 hours to yield 4 (7.66g, 45.6 mmol, 88%) as a white solid, the spectral properties of which matched previous reports. ¹ [00176] Methyl 2,2-diphenylbenzo[d][1,3]dioxole-4-carboxylate, 5.4 (5.00 g, 29.7 mmol) was mixed with dichlorodiphenylmethane (8.56 ml, 44.6 mmol) under an argon atmosphere, the resulting suspension was stirred and heated to 160 ^o C for 1 hour. The mixture was allowed to cool to room temperature and was diluted with 100 ml of ethyl acetate. The solution was washed with sat. NaHCO ₃ (30 mL) then brine (30 mL), dried over MgSO ₄ , then concentrated under reduced pressure. The ensuing greyish oil was dissolved in 30 mL of hot methanol (65 ^o C) and was slowly cooled to 5 ^o C, which resulted in the formation of white crystals. The crystals were a mixture of 5 and benzophenone dimethyl acetal that could not be easily separated; product was used as is for the subsequent step.

[00177] 2,2-diphenylbenzo[d][1,3]dioxole-4-carboxylic acid, 6. The mixture from the previous step was dissolved in 100 mL of THF and was treated with 100 mL of 0.9 M LiOH. The emulsion was rapidly stirred and heated to reflux for 5 hours. Conversion was verified by LC-MS and the reaction was cooled to room temperature. The solution was neutralized with 10 % v/v aqueous acetic acid and was extracted with ethyl acetate (3x50 mL). The organic extracts were combined, dried over MgSO ₄ , and concentrated under reduced pressure. The crude was chromatographed using 25% ethyl acetate in hexanes as eluent. Volatiles were then removed under reduced pressure followed by high vacuum to yield 6 ( 7.6 g, 24 mmol, 81% over 2 steps) as a white solid, the spectral properties of which matched previous reports. ¹

[00178] “CAM Submonomer, 2.” 1(3.84 g, 12.1 mmol) was suspended in 30 mL of toluene under an argon atmosphere. Oxalyl chloride (1.14 mL, 13.3 mmol) was then added followed by a catalytic amount of N,N-dimethylformamide. The suspension was heated to 40 ^o C and was stirred until it became clear and the evolution of gas has ceased (~1 hour). The volatiles were then removed under reduced pressure and the resulting white solid was dissolved in dry dichloromethane. A separate 1 L roundbottom flask outfitted with an addition funnel was charged with ethylenediamine (8 mL, 120 mmol) and 50 mL dry dichloromethane; the resulting solution was cooled to 0 ^o C using an ice bath. The aforementioned solution of acyl chloride was transferred into the addition funnel and was diluted with dichloromethane to a total volume of 700 mL. The acyl chloride solution was then added into the vigorously stirred ethylenediamine over 1.5 hours at 0 ^o C. Following the addition, the reaction solution was transferred into a separatory funnel and was washed with 0.5 M NaOH in 50% saturated aq. NaCl (50 mL x2). The organic phase was dried over MgSO ₄ and was concentrated on a rotary evaporator yielding the crude. The crude was purified using silica column chromatography (5 ^10% MeOH in DCM with 1% Et ₃ N, R _f = 0.35 in 10% MeOH in DCM). The desired fractions were combined, concentrated under reduced pressure, and dried under vacuum yielding the CAM submonomer as a sticky yellow oil (3.49 g, 9.68 mmol, 80% yield). ¹ H NMR (300 MHz, CDCl ₃ ) δ 7.64 (1H, br s, NH), 7.56-7.61 (5H, m, ArH), 7.37-7.42 (6H, m, ArH), 7.01 (1H, dd, J = 7.7, 1.4 Hz, ArH), 6.94 (1H, t, J = 7.9 Hz, ArH), 3.56 (2H, q, J = 6.0 Hz, NHCH ₂ ), 2.97 (2H, t, J = 6.0 Hz, NH ₂ CH ₂ ), 2.75 (2H, s, NH ₂ ). ¹³ C NMR (75 MHz, CDCl ₃ ) δ 163.7, 147.2, 144.7, 139.4, 129.5, 128.4, 126.2, 122.4, 122.0, 118.0, 116.0, 111.6, 42.3, 41.5. HRMS-ESI (m/z) [M+H] Calcd. For C ₂₂ H ₂₀ N ₂ O ₃ +H, 361.1563; found, 361.1581.

[00179] “HOPO Submonomer, 3.” 3 was synthesized in an identical fashion to 2 above, using 1-benzyloxy-6-carboxy-2 (1H) pyridinone (J. Labelled Cpd. Radiopharm. 2001, 44, 13-19, CAS 210366-15-7, US Patent US6846915) as the starting material. The crude product was purified using silica column chromatography (10% NH ₄ OH (10%) in MeOH) in DCM, R _f = 0.08). The desired fractions were combined, concentrated under reduced pressure, and dried under vacuum yielding the HOPO submonomer 3 as a sticky yellow oil in ~80% yield). ¹ H NMR (300 MHz, CDCl ₃ ) δ 7.40- 7.48 (3H, m, ArH), 7.35-7.38 (3H, m, ArH and NH), 7.24-7.29 (1H, m, ArH), 6.66 (1H, dd, J = 9.0, 1.5 Hz, CHCHCH), 6.45 (1H, dd, J = 6.9, 1.8 Hz, CHCHCH), 5.29 (2H, s, CH ₂ Ph), 3.36 (2H, q, J = 6.0 Hz, NHCH ₂ ), 2.80 (2H, t, J = 6.0 Hz, NH ₂ CH ₂ ). ¹³ C NMR (75 MHz, CDCl ₃ ) δ 160.3, 158.5, 142.5, 138.0, 133.2, 130.1, 129.4, 128.6, 124.0, 106.4, 79.3, 77.4, 77.0, 76.6, 42.7, 40.7. Calcd. For C ₁₅ H ₁₇ N ₃ O ₃ +H, 288.1328; found, 288.1361. Example 2--Synthesis of Peptoids

[00180] Unless noted otherwise, all steps were carried out in fritted polypropylene syringes, which allowed for recovery of submonomer for re-use. Automatic peptoid synthesis was not an option for this work due to difficulty of sub-monomer preparation. 1. Add 100-150 mg of Rink amide resin to a fritted syringe. Swell the resin by adding 2 mL of DMF and rock for 30 minutes. Eject the solution to isolate the swelled resin.

2. Add 1 mL of 20 % 4-methylpiperidine in DMF (v/v) to deprotect the Fmoc group.

Agitate for 2 minutes, drain, and repeat for 12 minutes.

3. Rinse the resin with DMF (2 mL, 5 times for 1 minute)

4. Bromoacetylation. Premix 0.8 M bromoacetic acid in DMF with 0.8 M N,N- diisopropylcarbodiimide (DIC), 2 mL total solution with 0.4 M of each reagent. Draw the solution into the syringe, agitate for 5 minutes, and rinse (2 mL DMF 5x1 minute).

5. Displacement. Draw in 1.5 mL of submonomer solution (0.2 M in DMF), agitate for 1 hour at 45 ^o C, then rinse (2 mL DMF 5x1 minute).

6. Repeat bromoacetylation and displacement until synthesis is finished. Wash with DCM (2 mL 3x1 minute) after last DMF wash and dry resin by pulling the plunger out and applying a gentle vacuum onto the syringe needle. Example 3--Deprotection, cleavage, and purification [00181] Dry resin (100-150 mg) was placed into a scintillation vial and was swollen in 9 mL of DCM by shaking for 30 minutees.1 mL of 1.0 M BBr ₃ in hexanes was added via a syringe, the vial was capped and shaken for 60 minutes ensuring that all of the resin was thoroughly submerged; this removes benzyl protecting groups from HOPO units. The solvent was carefully removed with a glass pipette and the resin was washed with DCM (2 mL) methanol (2x2 mL) followed by DCM (2x2 mL). The peptoid was then cleaved from resin by treatment with cleavage cocktail for 60 minutes (the treatment also deprotects CAM units). The cleavage cocktail (95 % trifluoroacetic acid, 2.5 % water, 2.5% triethylsilane) was filtered from resin and a small aliquot was removed and diluted with methanol for LC-MS analysis (1 ^30% MeCN in H ₂ O over 20 minutes, both with 0.1 % formic acid); the resin was washed of TFA traces and discarded. Most LC- MS analyses showed a relatively clean desired compound; iron complexes were sometimes seen, which we believe came from stainless steel components of the instrument. Volatiles were then removed from the filtrate using a vacuum pump. The resulting residue was dissolved in 90/10 acetic acid/water (0.5-1 mL) and the resulting clear solution was stirred at 42 ^o C and treated with water in 0.5 mL increments. The solution turned turbid upon addition of water and slowly clarified with continued stirring (5-15 min between additions). A total of ~2.5 mL of water was added, at which point the solution remained turbid even with prolonged stirring.

The turbid solution was taken up into a syringe and injected onto reverse-phase prep- HPLC through a 0.45 µm filter in no more than 2.0 mL batches (~ 2 injections per peptoid). Example 4--Reversed-Phase Preparative HPLC Method

[00182] Most peptoids had peak maxima between 20 and 40 minutes, methods were typically terminated once the target material was collected. The column was flushed with 50/50 solvent composition for 5 minutes and equilibrated to initial condition for at least 20 minutes before every injection; insufficient equilibration leads to low column loading and very low yields. Peptoids with higher CAM compositions tended to be less polar and thus came out later than HOPO-heavy analogs. A representative reversed- phase preparative HPLC trace is presented in FIG.14. Example 5--Peptoid LC-MS of purified peptoids: [00183] LC traces of peptoids A@320. Ion counts along the entire peak including shoulders were used to generate mass spectra. Spectra were obtained in negative mode on Agilent 6530 mass spectrometer.

[00184] MS labels from left to right and are shown in FIG.15A (HHHC Peptoid. MS1: free peptoid, MS2: peptoid-Na, MS3: peptoid-Fe and peptoid-Fe-K. FIG. 15B is the mass spectra for CHHH Peptoid. MS1: free peptoid and peptoid-K, MS2: peptoid-Na, peptoid-Fe, and possible impurity. FIG. 15C is the mass spectra for HCHH Peptoid. MS1: free peptoid and peptoid-K, MS2: peptoid-Na, peptoid-Fe. FIG. 15D is the mass spectra for HHCH Peptoid. MS1: free peptoid and possible impurity, MS2: peptoid-Na, MS3: Peptoid-Fe. FIG. 15E is the mass spectra for CHHC Peptoid. MS1: free peptoid only and peptoid-K, MS2: peptoid-Na and peptoid-Fe. FIG.15F is the mass spectra for HHCC Peptoid. MS1: free peptoid and peptoid-Na, MS2: peptoid-Na, free peptoid, and peptoid-Fe. FIG. 15G is the mass spectra for CCHH Peptoid. MS1: free peptoid and peptoid-Na, MS2: Peptoid-Fe and possible trimer. FIG. 15H is the mass spectra for HCHC Peptoid. MS1: free peptoid, MS2: peptoid-Fe and peptoid-Na. FIG. 15I is the mass spectra for HCCH Peptoid. MS1: free peptoid and small amount trimer, MS2: peptoid-Fe, MS3: peptoid-Na and possible fragments. FIG.15J is the mass spectra for CHCH Peptoid. MS1: free peptoid and peptoid-K, MS2: peptoid-Fe. FIG. 15K is the mass spectra for HCCC Peptoid. MS1: free peptoid and trimer-Fe trace, MS2: free peptoid and peptoid-Fe. FIG. 15L is the mass spectra for CHCC Peptoid. MS1: free peptoid and peptoid-Na, MS2: free peptoid and unidentified masses. FIG. 15M is the mass spectra for CCHC Peptoid. MS1: free peptoid, MS2: free peptoid and peptoid-Na. FIG. 15N is the mass spectra for CCCH Peptoid. MS1: free peptoid and peptoid-Na, MS2: free peptoid and peptoid-K/Na. FIG.15O is the mass spectra for CCCH Peptoid. MS1: free peptoid and peptoid-Na, MS2: free peptoid and peptoid-K/Na. FIG. 15P is the mass spectra for HHHH Peptoid. MS1: free peptoid, MS2: peptoid-Fe/Na, MS3: Peptoid-Fe-Na.

Example 6--High Resolution Mass Spectrometry Data [00185] FIGs. 16A-16C depict the spectra that were obtained in negative mode. All peptoids are 1:1 Fe ³⁺ complexes except for CCCC and HHHH. Top spectrum is calculated and bottom is obtained.

Example 7--TOF MSMS of Select Peptoids

[00186] FIG.17 depicts the positive mode, fragmentation of molecular ion, masses of interest. Differences in peptoids are illustrated based on both composition and sequence. H and C units differ by a mass of 1 amu. FIGs. 18A-18D depict the NMR results. References

(1) Baco, E.; Hoegy, F.; Schalk, I. J.; Mislin, G. L. A. Org Biomol Chem 2014, 12 (5), 749.

  [0187] As will be understood by one of ordinary skill in the art, each embodiment disclosed herein can comprise, consist essentially of, or consist of its particular stated element, step, ingredient or component. Thus, the terms“include” or“including” should be interpreted to recite:“comprise, consist of, or consist essentially of.” The transition term“comprise” or“comprises” means includes, but is not limited to, and allows for the inclusion of unspecified elements, steps, ingredients, or components, even in major amounts. The transitional phrase“consisting of” excludes any element, step, ingredient or component not specified. The transition phrase“consisting essentially of” limits the scope of the embodiment to the specified elements, steps, ingredients or components and to those that do not materially affect the embodiment.

[0188] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. When further clarity is required, the term“about” has the meaning reasonably ascribed to it by a person skilled in the art when used in conjunction with a stated numerical value or range, i.e. denoting somewhat more or somewhat less than the stated value or range, to within a range of ±20% of the stated value; ±19% of the stated value; ±18% of the stated value; ±17% of the stated value; ±16% of the stated value; ±15% of the stated value; ±14% of the stated value; ±13% of the stated value; ±12% of the stated value; ±11% of the stated value; ±10% of the stated value; ±9% of the stated value; ±8% of the stated value; ±7% of the stated value; ±6% of the stated value; ±5% of the stated value; ±4% of the stated value; ±3% of the stated value; ±2% of the stated value; or ±1% of the stated value.

[0189] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0190] The terms“a,”“an,”“the”, and similar referents used in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g.,“such as”) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0191] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[0192] Certain embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above- described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0193] Furthermore, numerous references have been made to patents, printed publications, journal articles and other written text throughout this specification (referenced materials herein). Each of the referenced materials is individually incorporated herein by reference in their entirety for their referenced teaching.

[0194] The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings and/or examples making apparent to those skilled in the art how the several forms of the invention can be embodied in practice.

[0195] Definitions and explanations used in the present disclosure are meant and intended to be controlling in any future construction unless clearly and unambiguously modified in the following examples or when application of the meaning renders any construction meaningless or essentially meaningless. In cases where the construction of the term would render it meaningless or essentially meaningless, the definition should be taken from Webster's Dictionary, 3rd Edition or a dictionary known to those of ordinary skill in the art, such as the Oxford Dictionary of Biochemistry and Molecular Biology (Ed. Anthony Smith, Oxford University Press, Oxford, 2004).

[0196] In closing, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the present invention. Other modifications that can be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the present invention can be utilized in accordance with the teachings herein. Accordingly, the present invention is not limited to that precisely as shown and described.