Fabrication of Molecular Nano-array Structures at Surface and its Functions

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The bottom-up assembly of functional nanoscale architecture from molecular components at the surface has attracted much interest in the advancement of nanotechnology. Particularly, the chemistry of surface modification by self-assembled monolayers (SAM) and layer-by-layer (LbL) growth of multilayers is highly promising to construct two-dimensional (2D) and three-dimensional (3D) chemical systems on surfaces. To attain this aim, we have undertaken two synthetic approaches based on surface coordination chemistry; i.e., (1) fabrication and functions of multilayers based on redox-active metal complexes on surface, introducing, and (2) DNA nanowiring between two gold terminals on Au/Si02 patterned surface.Novel molecular units with tetrapod or hexapod phosphonate anchoring groups(XP) have been synthesized in order to keep the molecular orientation on the surface. Mono- and dinuclear Ru complexes, [Ru(XP) (btpb)] and 〔[Ru2(XP)2] (btpb)〕, have been immobilized on an ITO electrode. The vertical molecular orientation was supported by AFM measurements. The direction of photocurrent was altered by the direction of applied potential pulse; i.e., the positive potential pulse (0 V -+1 V - 0 V) revealed a cathodic transient photocurrent, however the negative potential pulse (0 V - -1 V - 0 V) gave an anodic current. These responses fulfill a fundamental requirement for molecular memory functionality. Nanowiring of λ-DNA molecules on the micrometer-sized Au/Si02 patterned silicon substrate was also studied.