Visible-Light-Induced Hydrophilic Effect in an Ultrathin Hybrid Film of Titania Nanosheet and an Optical Active Ruthenium(II) Complex Cation

Hybrid multilayers of titania nanosheet, amphiphilic alkylammonium cation, and (rac- or Λ-)Ru(II) complex cation have been prepared by a modified Langmuir−Blodgett technique. When a solution of octadecylammonium chloride (CH3(CH2)17NH3+Cl−: ODAH+Cl−) was spread at an interface between the air and an aqueous dispersion of the negatively charged nanosheets, the nanosheets were adsorbed onto the floating monomolecular film of ODAH+ to form a hybrid film at the interface. The surface of the hybrid film deposited on a substrate was immersed in an aqueous [Ru(bpy)3]Cl2 solution. By repeating these procedures, the hybrid multilayer was fabricated. Electronic and infrared spectra of the multilayers indicated layer-by-layer deposition of the hybrid monolayers. X-ray diffraction patterns of the films showed that the layer structure for the film of Λ-[Ru(bpy)3]2+ was perturbed rather than that of rac-[Ru(bpy)3]2+. The second-harmonic generation (SHG) from the hybrid film of Λ-[Ru(bpy)3]2+ was much more intense than ...