TiO₂ thin films doped with various transition metals were systematically fabricated by combinatorial laser MBE technique. Alternating KrF excimer laser ((lambda) equals 248 nm) ablation of TiO₂ and Ti_1-x M_xO₂ (M equals transition metal) was employed to deposit combinatorial library of 18 samples for each dopant with different concentrations. Anatase films with c-axis orientation were grown epitaxially on SrTiO₃(001) substrate while the rutile phase films with a-axis orientation were on Al₂O₃(0001) substrate. Solid solubility of transition metals in both the phases was determined by X-ray diffraction. The anatase phase was found to dissolve the transition metals in higher concentrations than rutile phase. The parallel evaluation of the photocatalytic activity of the doped TiO₂ in combinatorial libraries was performed with respect to photo-decomposition of water in presence of a small amount of oxidizing or reducing agent which induced pH changes on the pixels. The high throughput evaluation of combinatorially deposited photocatalytic thin films was realized by adopting a potentiometric pH field effect transistor for sensing such pH changes.

The adsorption of merocyanine dye onto mesoporous silicas with varied pore sizes (5.5, 9.4 and 2.2 nm) from the toluene solution of 1,3,3-trimethylindolino-6′-nitrobenzopyrylospiran under UV irradiation was investigated quantitatively. The photoinduced adsorption of merocyanine onto SBA-15 with the pore diameter of 9.4 nm followed the pseudo-second order kinetics and the rate constant was larger than that observed for MCM-41 (pore size of 2.2 nm) owing to the efficient diffusion of merocyanine. The maximum adsorbed amounts of the merocyanine dye was 152 mg g⁻¹ of SBA-15, which corresponded to the sufficiently high concentration of merocyanine in the pores (0.376 mol L⁻¹ of pore). The resulting red-colored hybrids (SBA-15 containing merocyanine) showed decoloration in the solid-state by visible light irradiation (negative photochromism). The conversion was high (about 80% at the photostationary state) under visible light irradiation at room temperature using a solar simulator (100 W). The red color was re-generated by storing the photochemically formed colorless samples in the dark at room temperature. The half-lives of the thermal coloration process were 2.6, 1.9 and 1.3 h for the MCM-41, SBA-15s with the BJH pore sizes of 5.5 and 9.4 nm, respectively. Since the coloration was affected by the diffusion of the molecules in the pores, larger pores provided the efficient molecular diffusion, leading to faster reactions.

Pioneered by the success on active transport of ions across membranes in 1980’ using the regulation of the binding properties of crown ethers with covalently linked photoisomerizable units, extensive studies on the movements by using varied interactions between moving objects and environments have been reported. Photoinduced movements of various objects ranging from molecules, polymers to microscopic particles were discussed from the aspects of the driving for the movements, materials design to achieve the movements and systems design to see and to utilize the movements are summarized in this review. Grafical Abstract