Synthetic and Postsynthetic Chemistry of M4AuxAg44–x(p-MBA)30 Alloy Nanoparticles

Metal heteroatom substitution in molecular nanoparticles offers a unique opportunity to study alloying with an unprecedented level of detail and control, which may be important for applications in optics, electronics, medicine, and catalysis. Many examples of single- or few-heteroatom substitutions exist in molecular nanoparticles, but true alloys with compositions varying over a wide range of substitutions are rare. Here, we study M4AuxAg44–x(p-MBA)30 alloy nanoparticles as a model system, where M is a countercation and p-MBA is a p-mercaptobenzoic acid ligand, and where 0 ≤ x ≤ 12 represents the full range of possible compositions, all of which are stable in solution. Synthetic reactions produced M4AuxAg44–x(p-MBA)30 alloy nanoparticle products whose compositions were found to be a complex function of the reaction mixture composition. Postsynthetic reactions showed that oxidation of M4AuxAg44–x(p-MBA)30 nanoparticles was slowed in a monotonic fashion by the addition of gold atoms. Density functional the...