Surface Nanochemistry for Combinatorial Fabrication of Molecular Multilayered Films Toward Highly Efficient Molecular Devices

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One of the real challenges for synthetic chemists is to construct a well-defined nanometer-sized structure or space on solid surfaces by self-assembly, starting from simple molecular units. The combination of self-assembly with self organization by metal complexation has the potential to provide novel well-defined nanostructures and functions on surfaces. In this project, we have studied the layer-by-layer fabrication and electrochemical function of dinuclear metal complex modules on surface towards molecular devices. New dinuclear Ru/Os complexes, [M(XP)(BL)M(XP)] (M=Ru and Os), with tetrapod free-standing phosphonate ligand (XP) have been synthesized as a building module. The AFM measurement for the self-assembled monolayer of dinuclear Ru/Os complexes, [M(XP)(BL)M(XP)] (M=Ru and Os) on an ITO electrode provides dear molecular domain images. Electrochemistry of [M(XP)(BL)M(XP)] complex on ITO electrode showed a one-step two-electron process at +0.93 V for M=Ru and +0.66 V for M=Os, r … More espectively. Layer-by-layer growth on the surface was achieved by the help of Zr(IV) coordination to the phosphonate groups in [M(XP)(BL)M(XP)]. By changing the order of the modules with different redox potentials, the different potential sequence towards a molecular rectifier can be constructed. The electron transfer behaviors on the multilayer films strongly depend on the potential gradients within the molecular components.In order to construct a well-defined nanometer-sized 2D structure on solid surfaces, we have studied the DNA-templated nanowiring between Au nanoterminals. Acridine (Acd) group was chosen as an intercalating group in the complex. The complex, [Ru(XP)(L-Acd)] was immobilized on mica surface as molecular dots, which can act as a DNA trapping site. We found that DNA was captured by the molecular dots on the surface. From the AFM measurement. Further, two Au terminals on the micrometer-sized Au/SiO_2 patterned silicon substrate were connected by λ-DNA molecules, which was metallized by the Pd nanoparticles.. Less