Molecular architecture of inorganic complex multilayers based on surface coordination chemistry

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The design and fabrication of meso molecular structures on the surface is one of the important and attractive areas in the future material science. In order to construct the meso molecular structures in two dimensions, we employed two methodologies for molecular fabrication on the surface ; one is the self-assembled monolayer (SAM) method on gold, and the other is Langmuir-Blodgett (LB) technique, in both of which coordination bond is used for a chemical "glue" between the molecular module. New anchoring or amphiphilic ligands based on tridentate 2,6-bis(benzimidazol-2-yl)pyridine(L18) and their Ru complexes, [Ru(L18)(X)]^<n+>(X = tridentate or tins monodentate ligand) were synthesized and used as a molecular building block. At the air-water interface, surface pressure-area (pi-A) isotherms showed strong dependence on the subphase condition such as pH or metal ion (Zn^<2+>, Cd^<2+> and Mn^<2+>) for Ru complex containing 2,2' : 6", 2'-terpyridine-4-phosphonate(X= tpy-PO_3H). The surface morphology of the transferred LB films on mica substrates, which was obtained from an AFM image, revealed a relatively regular stripe structure. The surface morphology was also dependent on the auxiliary ligand X.In the case of X = 2,3,5,6-tetrakis(2'-pyridyl)pyrazine, a circular domain structure was observed.Furthermore, the molecular orientation of the Ru complex molecules at the air-water interface was proved by the intensity of MLCT band around 500 nm in in-situ UV spectral measurements. We found that the intensity of MLCT band around 500 nm was changed by pH change or metal coordination from the subphase.