Chromophore shielding on metal oxide surfaces

The work present in this thesis is divided into two parts. The common theme is the development of methods to shield chromophores on heterogeneous metal oxide surfaces; and study the effects of shielding on their surface properties.Part A describes the synthesis of homoleptic ruthenium polypyridine star-shaped complexes with conjugated oligophenylenethylene linkers on each bipyridine ligand to fix the distance between a ruthenium metal center and metal oxide surfaces in all three dimensions. Star complexes did bind covalently to the metal oxide surfaces with bidentate mode. The photophysical properties were influenced by the length of the rigid linkers. On basic TiO2 films, the injection yields decreased as the linker length increased. The injection process was on 100-150 ns time scale. Recombination rate was largely reduced (105 s-1 order) compared to the value of rigid-rods (107 s-1 order) due to well-controlled distance separation. Part B describes the aggregation study of dye@cyclodextrins on metal oxide surface. Cyclodextrins bound to TiO2 surface by –OH group. Suitable-sized cyclodextrins were found to separate pyrene and perylene derivative on ZrO2 surface. Reduced excimer band and enhanced monomer band were observed in fluorescence emission spectra.Ph.D.Includes bibliographical referencesIncludes vitaby Yongyi Zhan