Patent Number: 
Section: claims

1. A composition, comprising:a support material; andan extractant having a structure satisfying Formula Iwherein each Ra independently is hydrogen, aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic; and each Rb independently is hydrogen, aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic, provided that at least one Ra or one Rb is aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic. 2. The composition of claim 1, wherein each Ra independently is aliphatic, heteroaliphatic, aryl, aliphatic-aryl, or heteroaliphatic-aryl. 3. The composition of claim 1, wherein each Rb independently is aliphatic, heteroaliphatic, aryl, aliphatic-aryl, or heteroaliphatic-aryl. 4. The composition of claim 1, wherein each Ra independently is alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, aryl, alkyl-aryl, alkenyl-aryl, alkynyl-aryl, heteroalkyl-aryl, heteroalkenyl-aryl, or heteroalkynyl-aryl. 5. The composition of claim 1, wherein each Rb independently is alkyl, alkenyl, alkynyl, heteroalkyl, heteroalkenyl, heteroalkynyl, aryl, alkyl-aryl, alkenyl-aryl, alkynyl-aryl, heteroalkyl-aryl, heteroalkenyl-aryl, or heteroalkynyl-aryl. 6. The composition of claim 1, wherein each Ra independently is decyl, nonyl, octyl, septyl, or hexyl. 7. The composition of claim 1, wherein each Rb independently is decyl, nonyl, octyl, septyl, or hexyl. 8. The composition of claim 1, wherein each Ra and Rb independently are octyl, 2-ethylhexyl, cyclohexyl, methyl, ethyl, or isopropyl. 9. The composition of claim 1, wherein each Ra is the same and each Rb is the same. 10. The composition of claim 1, wherein each Ra is the same as each Rb. 11. The composition of claim 1, wherein the support material is an organic resin or an inorganic, particle-based medium. 12. The composition of claim 1, wherein the support material is an organic acrylic-based resin. 13. The composition of claim 1, wherein the support material is a silica-based support. 14. The composition of claim 13, wherein the extractant is covalently bound to the silica-based support. 15. The composition of claim 1, wherein the extractant is 16. A method, comprising:exposing a liquid sample to an extractant composition comprising a support material and an extractant having a structure satisfying Formula Iwherein each Ra independently is hydrogen, aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic; and each Rb independently is hydrogen, aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic, provided that at least one Ra or one Rb is aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic; and wherein the liquid sample is exposed to the composition for a time sufficient to promote formation of a complex between the extractant composition and a radioisotope, a metal, and/or any ion thereof present in the liquid sample;separating the complex from the liquid sample;exposing the complex to a solution having a pH sufficient to promote dissociation of the radioisotope, the metal, or any ion thereof from the extractant composition; andisolating the radioisotope, the metal, or any ion thereof. 17. The method of claim 16, wherein the radioisotope is protactinium, niobium, a protactinium ion, a niobium ion, or any combination thereof; and wherein the sample comprises thorium, iron, zinc, any ion thereof, or any combination thereof. 18. The method of claim 16, wherein the metal is gold, platinum, silver, palladium, any ion thereof, or any combination thereof; and wherein the sample comprises thorium, iron, zinc, any ion thereof, or any combination thereof. 19. A compound having a structure satisfying Formula Iwherein each Ra independently is hydrogen, aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic; and each Rb independently is hydrogen, aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic, provided that at least one Ra or one Rb is aliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, or heteroaliphatic-aromatic and further provided that the compound is not or is other than 20. The compound of claim 19, wherein the compound is 21. The composition of claim 1, wherein the extractant is not or is other than