Ultrastable silver nanoparticles
Ultrastable silver nanoparticles, methods of making the same, and methods of using the same, are disclosed.
1. A compound comprising the formula M 4 Ag 44 (SR) 30 wherein:
M is a metal selected from the group consisting of Cs, Na, K, Li, Fr, and Rb; and
SR is a mercaptophenyl ligand; and salts and isomers thereof.
2. The compound of claim 1 , wherein the mercaptophenyl ligand is selected from the group consisting of p-mercaptobenzoic acid, p-mercaptophenyl alcohol, and 4-mercaptophenol.
3. The compound of claim 1 , further comprising coordinating molecules selected from the group consisting of: deprotonated methanol ions, deprotonated ethanol ions, hydroxide ions, citrate, acetate, DMSO, DMF, pyridine, ammonia, acetone, acetonitrile, ethers, phosphines, and combinations thereof.
4. The compound of claim 3 , wherein the compound has a core comprising coordination sites, and the coordinating molecules stabilize the compound by binding to the coordination sites.
5. The compound of claim 4 , wherein one or more of the coordinating molecules is substituted by one or more of a pharmaceutical agent, a fluorophore, or a carbohydrate, covalently bonded through a sulfur linkage at a coordination site.
6. The compound of claim 1 , wherein the compound comprises a Ag 32 core and a protecting layer of Ag 2 S 5 capping structures.
7. A silver cluster molecule comprising: a 32-silver-atom dodecahedral core consisting of a 12-silver-atom icosahedron encapsulated by a 20-silver-atom dodecahedron; and 30 coordinating ligands.
8. The silver cluster molecule of claim 7 , wherein the coordinating ligands comprise p-MBA.
9. The silver cluster molecule of claim 7 , wherein the dodecahedral core comprises icosahedral symmetry.
10. The silver cluster molecule of claim 7 , wherein four sulfur atoms connect the mounts to the core.
11. The silver cluster molecule of claim 7 , wherein the silver atoms in the icosahedral core do not contact the coordinating ligands.
12. The silver cluster molecule of claim 7 , wherein each coordinating ligand comprises atoms defining a rhombicuboctahedron capped with six Ag 2 S units.
13. A method of making silver nanoparticles, the method comprising:
preparing a Ag(I)—SR precursor compound;
reducing the Ag(I)—SR precursor compound to grow silver nanoparticles; and
removing by-products to isolate the silver nanoparticles;
wherein SR is a mercaptophenyl ligand.
14. The method of claim 13 , wherein preparing the Ag(I)—SR precursor compound comprises adding a solvent to a mixture of silver nitrate and a mercaptophenyl ligand.
15. The method of claim 14 , further comprising adding a base to the mixture of silver nitrate and a mercaptophenyl ligand.
16. The method of claim 13 , further comprising adjusting the pH to about 9 to solubilize the Ag(I)—SR precursor.
17. The method of claim 13 , further comprising adjusting the pH to about 12 to stabilize the silver nanoparticles.
18. The method of claim 13 , wherein the reducing comprises adding a reducing agent to the Ag(I)—SR precursor compound, wherein the reducing agent is selected from the group consisting of: NaBH 4 , LiBH 4 , KBH 4 , Al(BH 4 ) 3 , and combinations thereof.
19. The method of claim 13 , wherein the by-products are removed by precipitating the silver nanoparticles, and collecting the precipitated silver nanoparticles.
20. The method of claim 19 , wherein the nanoparticles are precipitated by the addition of a non-solvent selected from the group consisting of: methanol, DMF, toluene, and combinations thereof.