Synthesis of substantially monodispersed colloids

Abstract

A method of forming ligated nanoparticles of the formula Y(Z) x where Y is a nanoparticle selected from the group consisting of elemental metals having atomic numbers ranging from 21-34, 39-52, 57-83 and 89-102, all inclusive, the halides, oxides and sulfides of such metals, and the alkali metal and alkaline earth metal halides, and Z represents ligand moieties such as the alkyl thiols. In the method, a first colloidal dispersion is formed made up of nanoparticles solvated in a molar excess of a first solvent (preferably a ketone such as acetone), a second solvent different than the first solvent (preferably an organic aryl solvent such as toluene) and a quantity of ligand moieties; the first solvent is then removed under vacuum and the ligand moieties ligate to the nanoparticles to give a second colloidal dispersion of the ligated nanoparticles solvated in the second solvent. If substantially monodispersed nanoparticles are desired, the second dispersion is subjected to a digestive ripening process. Upon drying, the ligated nanoparticles may form a three-dimensional superlattice structure.

We claim:  
     
         1 . A three-dimensional supperlattice array of ligated nanoparticles produced by a method comprising the steps of: 
 forming a first colloidal dispersion comprising nanoparticles solvated in a molar excess of a first solvent, a second solvent different than the first solvent, and a quantity of ligand moieties;    removing a substantial part of said first solvent and causing said ligand moieties to ligate to said nanoparticles to give a second colloidal dispersion comprising the ligated nanoparticles solvated in said second solvent; and    recovering said ligated nanoparticles.    
     
     
         2 . The superlattice array of  claim 1 , each of said nanoparticles comprising a gold nanoparticle with a plurality of thiol ligand moieties ligated thereto.