Scaffold-organized metal, alloy, semiconductor and/or magnetic clusters and electronic devices made using such clusters

Abstract

A method for forming arrays of metal, alloy, semiconductor or magnetic clusters is described. The method comprises placing a scaffold on a substrate, the scaffold comprising molecules selected from the group consisting of polynucleotides, polypeptides, and perhaps combinations thereof. Polypeptides capable of forming α helices are currently preferred for forming scaffolds. Arrays are then formed by contacting the scaffold with plural, monodispersed ligand-stabilized clusters. Each cluster, prior to contacting the scaffold, includes plural exchangeable ligands bonded thereto. If the clusters are metal clusters, then the metal preferably is selected from the group consisting of Ag, Au, Pt, Pd and mixtures thereof. A currently preferred metal is gold, and a currently preferred metal cluster is Au 55 having a radius of from about 0.7 to about 1 nm. Compositions also are described, one use for which is in the formation of cluster arrays. One embodiment of the composition comprises plural monodispersed, ligand-stabilized clusters coupled to a polypeptide.

We claim:  
     
         1 . A method for forming arrays of metal, alloy, semiconductor and/or magnetic clusters, comprising: 
 placing a scaffold on a substrate; and    contacting the scaffold with monodispersed metal, alloy, semiconductor and/or magnetic clusters having plural exchangeable ligands bonded thereto, thereby forming arrays by bonding the clusters to the scaffold.    
     
     
         2 . The method of  claim 1  wherein forming arrays by bonding clusters to the scaffold comprises ligand exchange of functional groups of the scaffold for at least one of the exchangeable ligands bonded to the cluster prior to contacting the scaffold with the clusters.  
     
     
         3 . The method according to  claim 1  wherein the scaffold comprises molecules selected from the group consisting of polynucleotides, polypeptides, and mixtures thereof.  
     
     
         4 . The method according to  claim 3  wherein the scaffold comprises polypeptides capable of forming α helices.  
     
     
         5 . The method according to  claim 4  wherein the polypeptide is polylysine.  
     
     
         6 . The method according to  claim 1  wherein the clusters comprise metal clusters, and the metal is selected from the group consisting of Au , Ag, Pt, Pd and mixtures thereof.  
     
     
         7 . The method according to  claim 1  wherein the metal cluster is AU 55 .  
     
     
         8 . The method according to  claim 7  wherein the metal clusters comprise Au 55 [P(C 6 H 5 )] 12 Cl 6  or Au 55 (—SR) 25-26 .  
     
     
         9 . The method according to  claim 1  wherein the clusters are semiconductors selected from the group consisting of cadmium selenide, zinc selenide, cadmium sulfide, cadmium tellurite, cadmium-mercury-tellurite, zinc tellurite, gallium arsenide, indium arsenide and lead sulfide.  
     
     
         10 . The method according to  claim 1  wherein placing the scaffold comprises aligning the polypeptides between electrodes on the substrate.  
     
     
         11 . The method according to  claim 1  wherein placing the scaffold on the substrate comprises polymerizing monomers, oligomers or polypeptides into larger polypeptides between electrodes on the substrate.  
     
     
         12 . A method for forming arrays of metal clusters, comprising: 
 placing a scaffold on a substrate, the scaffold comprising molecules selected from the group consisting of polynucleotides, polypeptides, and mixtures thereof; and    forming arrays by contacting the scaffold with plural monodispersed ligand-stabilized metal clusters, the metal being selected from the group consisting of Ag, Au, Pt, Pd and mixtures thereof, the clusters being bonded to the scaffold by ligand exchange of functional groups of the scaffold for at least one of the exchangeable ligands bonded to the cluster prior to contacting the scaffold with the clusters.    
     
     
         13 . The method according to  claim 12  wherein the scaffold comprises polypeptides capable of forming α helices.  
     
     
         14 . The method according to  claim 13  wherein the polypeptide is polylysine.  
     
     
         15 . The method according to  claim 12  wherein the metal cluster is Au 55 .  
     
     
         16 . The method according to  claim 12  wherein the exchangeable ligands are selected from the group consisting of thiols, sulfides, disulfides, amines, carboxylates, alcohols, and mixtures thereof.  
     
     
         17 . The method according to  claim 12  wherein placing the scaffold on the substrate comprises aligning the polypeptides between electrodes on the substrate.  
     
     
         18 . The method according to  claim 12  wherein placing the scaffold on the substrate comprises polymerizing monomers, oligomers or polypeptides into larger polypeptides between electrodes on the substrate.  
     
     
         19 . A composition, comprising: 
 a polypeptide capable of forming α helix; and    plural monodispersed, ligand-stabilized metal and/or semiconductor clusters, each cluster having plural exchangeable ligands bonded thereto, the clusters being bonded to the polypeptide by ligand exchange of functional groups of the polypeptide for at least one of the exchangeable ligands bonded to the cluster prior to contacting the polypeptide with the clusters.    
     
     
         20 . The composition according to  claim 19  wherein the metal clusters have radiuses of from about 0.7 nm to about 1.8 nm.  
     
     
         21 . The composition according to  claim 20  wherein the clusters have radiuses of from about 0.7 to about 1 nm.  
     
     
         22 . The composition according to  claim 19  wherein the clusters comprise metal clusters, and the metal is selected from the group consisting of Au, Ag, Pt, Pd and mixtures thereof.  
     
     
         23 . The composition according to  claim 19  comprising Au 55  metal clusters.  
     
     
         24 . An organized array of metal clusters, comprising: 
 monodispersed, ligand-stabilized metal clusters having metal-cluster radiuses of from about 0.7 nm to about 1.8 nm, the metal being selected from the group consisting of Ag, Au, Pt, Pd and mixtures thereof; and    a scaffold, the metal clusters being bonded to the scaffold to form an organized array.    
     
     
         25 . The array according to  claim 24  wherein the scaffold comprises molecules selected from the group consisting of polynucleotides, polypeptides, and mixtures thereof.  
     
     
         26 . The array according to  claim 25  wherein the scaffold comprises polypeptides capable of forming α helices.  
     
     
         27 . A current control device, comprising: 
 a first metal cluster;    a second metal cluster physically spaced apart from the first metal cluster;    a dielectric coupled between the first and second metal clusters; and    wherein the dielectric has an impedance that is responsive to a first voltage level to electrically couple the first and second metal clusters and that is responsive to a second voltage level to electrically isolate the clusters.    
     
     
         28 . A current control device, comprising: 
 an input terminal formed from a first metal cluster for storing at least one electron;    an output terminal formed from a second metal cluster for storing at least one electron;    a dielectric positioned between the input and output terminals; and    wherein the dielectric is responsive to voltage to pass electrons between the first and second metal clusters.