SELF-ASSEMBLY OF A 2-DIMENSIONAL SUPERLATTICE OF MOLECULARLY LINKED METAL-CLUSTERS

Close-packed planar arrays of nanometer-diameter metal clusters that a re covalently linked to each other by rigid, double-ended organic mole cules have been self-assembled. Gold nanocrystals, each encapsulated b y a monolayer of alkyl thiol molecules, were cast from a colloidal sol ution onto a flat substrate to form a close-packed cluster monolayer. Organic interconnects (aryl dithiols or aryl di-isonitriles) displaced the alkyl thiol molecules and covalently linked adjacent clusters in the monolayer to form a two-dimensional superlattice of metal quantum dots coupled by uniform tunnel junctions. Electrical conductance throu gh such a superlattice of 3.7-nanometer-diameter gold clusters, deposi ted on a SiO2 substrate in the gap between two gold contacts and linke d by an aryl di-isonitrile [1,4-di(4-isocyanophenylethynyl)-2-ethylben e], exhibited nonlinear Coulomb charging behavior.