Stabilized semiconductor nanocrystals

1. A polydentate ligand of formula:

wherein n is 1, 2, 3, 4 or 5, m is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, each k is 1, 2, 3, or 4, each X independently is a donor group selected from the group consisting of N, P, P═O, and N═O, each Y is substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, or substituted or unsubstituted aryloxy, and L is a linking group optionally terminated by O and includes at least one carbonate, carbamate, amide, ester or ether linkage.

2. A polydentate ligand of formula:

wherein n is 1, 2 or 3, m is 1, 2, 3,4, or 5, each k is 1 or 2, each X independently is a donor group selected from the group consisting of N, P, P═O, and N═O, each Y is substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, or substituted or unsubstituted aryloxy, and L is a linking group optionally terminated by O and includes at least one carbonate, carbamate, amide, ester or ether linkage.

3. A distribution of polydentate ligands of formula:

wherein n is 1, 2 or 3, m is 1, 2, 3, 4, or 5, each k is 1 or 2, each X independently is a donor group selected from the group consisting of N, P, P═O, and N═O, each Y is substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, or substituted or unsubstituted aryloxy, L is a linking group optionally terminated by O and includes at least one carbonate, carbamate, amide, ester or ether linkage, and the distribution includes at least two members with different values of m.

4. A polydentate ligand of formula:

wherein p is 1 or 2, each m is 1, 2, 3, 4, or 5, each k is 1 or 2, each j is 0 or 1, each p is 0 or 1, q is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, each X independently is a donor group selected from the group consisting of N, P, P═O, and N═O, each Y is substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryl, or substituted or unsubstituted aryloxy, and L is a linking group optionally terminated by O and includes at least one carbonate, carbamate, amide, ester or ether linkage.

5. A polydentate ligand of formula:

wherein n is 1, 2 or 3, m is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, each k is 1 or 2, each x independently is 0 or 1, each of Z 1 and Z 2 , independently, is an ether, amide, ester, carbamate or carbonate linkage, each R 1 and R 2 , independently, is an alkylene optionally interrupted by S, O, NH, N-lower alkyl, arylene, heteroarylene, or aralkylene and optionally terminated by S, O, NH, N-lower alkyl, arylene, heteroarylene, or aralkylene, and each R is substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, or substituted or unsubstituted aryl.

6. A polydentate ligand of formula:

wherein n is 1, 2 or 3, m is 1, 2, 3, 4, or 5, each k is 1 or 2, each x independently is 0 or 1, Z is an ether, carbamate, amide, ester or carbonate linkage, each R 1 and each R 2 , independently, is an alkylene optionally interrupted by S, O, NH, N-lower alkyl, arylene, heteroarylene, or aralkylene, and optionally terminated by S, O, NH, N-lower alkyl, arylene, heteroarylene, or aralkylene, and each R is substituted or unsubstituted alkyl, or substituted or unsubstituted aryl, and each R is bonded to R 1 via an ether, ester, amide, carbamate or carbonate linkage.

7. A polydentate ligand of formula:

wherein n is 1, 2 or 3, m is 1, 2, 3, 4, or 5, each k is 1 or 2, each x independently is 0 or 1, and each R is substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, or substituted or unsubstituted aryl.

8. The ligand of claim 7 , wherein at least one x is 0.

9. The ligand of claim 7 , wherein each x is 0.

10. The ligand of claim 7 , wherein each R is unsubstituted alkyl.

11. The ligand of claim 7 , wherein each R includes a carboxylic acid group.

12. The ligand of claim 7 , wherein each R includes an acrylate group.

13. A method of making a polydentate ligand comprising contacting a monomeric, polyfunctional phosphine with a polyfunctional oligomerization reagent to form an oligomeric phosphine.

14. The method of claim 13 , wherein the monomeric, polyfunctional phosphine is trishydroxypropylphosphine.

15. The method of claim 14 , wherein the polyfunctional oligomerization reagent is a diisocyanate.

16. The method of claim 13 , further comprising contacting the oligomeric phosphine with an isocyanate of formula: R′—L—NCO, wherein L is C 2 –C 24 alkylene, and R′ has the formula:

R′ has the formula:

or R′ is hydrogen, wherein R a is hydrogen or C 1 –C 4 alkyl.

17. A method of making a nanocrystal-biomolecule conjugate comprising contacting a nanocrystal including a polydentate ligand including a reactive group with a biomolecule.

18. The method of claim 17 , wherein the biomolecule is a polypeptide.

19. The method of claim 17 , further comprising contacting the nanocrystal and the biomolecule with a cross-linking agent.

20. The method of claim 19 , wherein the reactive group is a carboxylic acid.

21. The method of claim 20 , wherein the biomolecule includes an amino group and the cross-linking agent is a carbodiimide.