Photoinduced electron transfer (PET) was investigated in multicomponent aqueous suspensions composed of tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)_3^<2+>, photocatalyst), methylviologen (1,1'-dimethyl-4,4'-bipyridinium dication, MV^<2+>, electron acceptor), and ethylenediaminetetraacetate (EDTA, sacrificial electron donor) together with particles of smectite-type clays, where Ru(bpy)_3^<2+> and MV^<2+> are present in excess compared with CEC of the clay minerals. Clays with different particle sizes - fluorohectorite (FH) and montmorillonite (Mont) with large particle sizes (>0.1μm), and hectorite (Hect) and saponite (Sapo) with small particle sizes (〜30nm) - were examined, and the PET reaction proceeded in all of the suspensions to yield methylviologen radical cation (MV^<+・>) as the product. However, the difference in the clay particle size gave different product distribution; the large-size clays dominantly gave MV^<+・> dimers whereas the small-size clays mainly produced MV^<+・> monomers similarly to a homogeneous aqueous solution. Also, the large-size clays more stabilized the MV^<+・> species than the small-size ones. These results evidenced contribution of the clay-water interfaces to the reaction.

抄録全体を表示

The adsorption behavior of protonated species of 5,10-diphenyl-15,20-di(4-pyridyl)porphyrin (DPyP) on saponite clay surface was examined under PH=1 in aqueous solution. Beer's plot at Soret band and Q-band indicated that H_4DPyP^<4+> adsorbs on the clay surface without aggregation up to 15% and 100% versus CEC, respectively. The λ_<max> of Soret band slightly shifted to longer wavelength, as porphyrin loading level increased. These indicate that neutral molecule with pyridyl and pyrrole groups can adsorb on the clay surface under acidic conditions, although weak aggregation behavior was observed. The incomplete matching of inter-charge distances in porphyrin molecule and on the clay surface would be a reason for such aggregation behavior.

抄録全体を表示

Highly photoluminescent solids were prepared via hybridization of anionic fluorescein dye (AFD) and 1-alkylsulfonate (C_nS, n: number of carbons in the alkyl chain) salts with layered double hydroxide (LDH). When both C_nS and AFD anions were incorporated in the interlayer nanospace of LDH, it was found that the LDH/AFD/C_nS hybrid solid materials exhibited monomeric photoluminescence (PL) with high quantum yield. It was not possible to obtain high PL from AFD hybridized with LDH alone; without C_nS, the PL of AFD was not completely monomeric even when the concentration of incorporated AFD was extremely low. Notably, the C_4S anion was most effective for inhibiting aggregation of AFD incorporated in the interlayer space of LDH.

抄録全体を表示

We fabricated low-light-scattering hybrid films consisting of synthetic saponite and 1,1'-diethyl-2,2'-cyanine (PIC). J-aggregation of PIC was observed for the hybrid films at high PIC loadings. Two-photon absorption (TPA) and third harmonic generation (THG) properties have been compared between two hybrid films fabricated at 10 and 80% CEC PIC loadings. As a result, the TPA cross-section and THG intensity of PIC in 80% CEC hybrid films were 1.8 and 1.6 times, respectively, larger than those in the film fabricated at 10% CEC. These enhancements were attributed to formation of J-aggregation of PIC in the 80% CEC hybrid film.

抄録全体を表示