Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A heterogeneous catalyst incorporating an inorganic ion cofactor for electrochemical water oxidation was exploited using a CoO(OH) nanoparticle layer-deposited electrode. The significant catalytic current for water oxidation was generated in a Na2B4O7 solution at pH 9.4 when applying 0.94 V versus Ag/AgC1 in contrast to no catalytic current generation in the K2SO4 solution at the same pH. HB4O7 and B4O72- ions were indicated to act as key cofactors for the induced catalytic activity of the CoO(OH) layer. The Na2B4O7 concentration dependence of the catalytic current was analyzed based on a Michaelis-Menten-type kinetics to provide an affinity constant of cofactors to the active sites, K-m = 28 +/- 3.6 mM, and the maximum catalytic current density, I-max = 2.3 +/- 0.13 mA cm(-2). The I-max value of HB4O7- and B4O72- ions was 1.4 times higher than that (1.3 mA cm(-2)) for the previously reported case of CO32- ions. This could be explained by the shorter-range proton transfer from the active site to the proton-accepting cofactor because of the larger size and more flexible conformation of HB4O7 and B(4)O(7)(2-)ions compared with that of CO32- ions.

DOI： 10.1021/acsami.7b13817

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proximal,proximal-(p,p)-[Ru-2(II)(tpy)(2)LXY](n+) (tpy = 2,2';6',2 ''-terpyridine, L = 5-phenyl-2,8-di-2-pyridyl-1,9,10-anthyridine, and X and Y = other coordination sites) yields the structurally and functionally unusual Ru-II(mu-OH)Ru-II core, which is capable of catalyzing water oxidation with key water insertion to the core (Inorg. Chem. 2015, 54, 7627). Herein, we studied a sequence of bridging-ligand substitution among p,p-[Ru-2(tpy)(2)L(mu-Cl)](3+) (RU2(mu-Cl)), p,p-[Ru-2(tpy)(2)L(mu-OH)](3+) (Ru-2(mu-OH)), p,p-[Ru-2(tpy)(2)L-(OH)(OH2)](3+) (Ru-2(OH)(OH2)), and p,p-[Ru-2(tpy)(2)L-(OH)(2)](2+) (Ru-2(OH)(2)) in aqueous solution. Ru-2(mu-Cl) converted slowly (10(-4) s(-1)) to Ru-2(mu-OH), and further Ru-2(mu-OH) converted very slowly (10(-6) s(-1)) to Ru-2(OH)-(OH2) by the insertion of water to reach equilibrium at pH 8.5-12.3. On the basis of density functional theory (DFT) calculations, Ru-2(OH)(OH2) was predicted to be thermodynamically stable by 13.3 kJ mol(-1) in water compared to Ru-2(mu-OH) because of the specially stabilized core structure by multiple hydrogen-bonding interactions involving aquo, hydroxo, and L backbone ligands. The observed rate from Ru-2(mu-OH) to Ru-2(OH)(2) by the insertion of an OH- ion increased linearly with an increase in the OH- concentration from 10 to 100 mM. The water insertion to the core is very slow (similar to 10(-6) s(-1)) in aqueous solution at pH 8.5-12.3, whereas the insertion of OH- ions is accelerated (10(-5)-10(-4) s(-1)) above pH 13.4 by 2 orders of magnitude. The kinetic data including activation parameters suggest that the associative mechanism for the insertion of water to the Ru-II(mu-OH)Ru-II core of Ru-2(mu-OH) at pH 8.5-12.3 alters the interchange mechanism for the insertion of an OH- ion to the core above pH 13.4 because of relatively stronger nucleophilic attack of OH- ions. The hypothesized p,p-[Ru-2(tpy)(2)L(mu-OH2)](4+) and p,p-[Ru-2(tpy)(2)L(OH2)(2)](4+) formed by protonation from Ru-2(mu-OH) and Ru-2(OH)(OH2) were predicted to be unstable by 71.3 and 112.4 kJ mol(-1) compared to Ru-2(mu-OH) and Ru-2(OH)(OH2), respectively. The reverse reactions of Ru-2(mu-OH), Ru-2(OH)(OH2), and Ru-2(OH)(2) to Ru-2(mu-Cl) below pH 5 could be caused by lowering the core charge by protonation of the mu-OH- or OH- ligand.

DOI： 10.1021/acs.inorgchem.7b00978

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Semiconductor nanowires with both nano- and micrometre dimensions have been used as effective materials for artificial photosynthesis; however, a single synthesis approach to provide rational control over the macroscopic morphology, which can allow for the high-throughput screening of photocatalytic performance, and carrier transfer between oxide and sulphide nanostructures has been poorly known. Our recent findings indicate that a single parameter, Nb foil thickness, in a vapor-phase synthesis method can alter the macroscopic morphology of resulting Nb2O5 nanowires. Thick Nb foil results in a free-standing Nb2O5 film, whereas a thinner foil leads to fragmentation to give a powder. During the synthesis process, a Rh dopant was provided through metal-organic chemical vapor deposition to reduce the Nb2O5 energy gap. Upon irradiation with visible light (lambda > 440 nm), the free-standing nanowire film [Nb2O5: Rh-NW(F)] showed photoanodic current with a Faradaic efficiency of 99% for O-2 evolution. Under identical irradiation conditions, the powdered counterpart [Nb2O5: Rh-NW(P)] showed activity for O-2 evolution in the presence of an electron acceptor. The poor water-reduction ability was greatly enhanced by the Au-catalysed vapor-liquid-solid (VLS) growth of H-2-evolving CdS onto the reduction sites of Nb2O5: Rh-NW(P) [Au/CdS/Nb2O5: Rh-NW(P)].

DOI： 10.1038/s41598-017-05292-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Transparent IrOx catalyst films for water oxidation were fabricated on fluorine-doped tin oxide electrodes from Ir precursor complex solutions containing Pluronic P123, Brij 58 or Pluronic F127 as surfactant structure directing agents (SDAs). The thin layers composed of highly dispersed and very small nanoparticles of ca. <= 2 nm were formed for IrOx films derived by Pluronic P123 and Brij 58, both of which act as a 'spacer' between the Ir-building-blocks to inhibit further agglomeration of the nanoparticles. Pluronic F127 with relatively longer hydrophilic poly(ethylene oxide) blocks stabilizes Ir-complexes in the precursor solution due to stronger interaction between its longer ED-units and Ir-complexes, affording the organized mesoporous structures of ca. 8 nm pores templated by micelles formed in the IrOx film derived by Pluronic F127. The cyclic voltammetry revealed the catalytic currents for water oxidation for the SDAs-derived IrOx films were 1.3-1.8 times higher than the IrO, film without SDA. The higher water oxidation activity observed is attributed to the higher intrinsic catalytic activity of Ir-sites on very small nanoparticles in the Pluronic P123 and Brij 58-derived IrOx films, whereas it is attributed to the increased number of active Ir-sites due to the organized mesoporous structures of the Pluronic F127-derived IrOx film. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cattod.2017.03.009

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

N-2-Intercalated crystalline mesoporous tungsten trioxide (WO3) was synthesized by a thermal decomposition technique with dodecylamine (DDA) as a surfactant template with a dual role as an N-atom source for N-2 intercalation, alongside its conventional structure-directing role (by micelle formation) to induce a mesoporous structure. N-2 physisorption analysis showed that the specific surface area (57.3m(2)g(-1)) of WO3 templated with DDA (WO3-DDA) is 2.3 times higher than that of 24.5m(2)g(-1) for WO3 prepared without DDA (WO3-bulk), due to the mesoporous structure of WO3-DDA. The Raman and X-ray photoelectron spectra of WO3-DDA indicated intercalation of N-2 into the WO3 lattice above 450 degrees C. The UV/Vis diffuse-reflectance spectra exhibited a significant shift of the absorption edge by 28nm, from 459nm (2.70eV) to 487nm (2.54eV), due to N-2 intercalation. This could be explained by the bandgap narrowing of WO3-DDA by formation of a new intermediate N 2p orbital between the conduction and valance bands of WO3. A WO3-DDA-coated indium tin oxide (ITO) electrode calcined at 450 degrees C generated a photoanodic current under visible-light irradiation below 490nm due to photoelectrochemical water oxidation, as opposed to below 470nm for ITO/WO3-bulk. The incident photon-to-current conversion efficiency (IPCE=24.5%) at 420nm and 0.5V versus Ag/AgCl was higher than that of 2.5% for ITO/WO3-bulk by one order of magnitude due to N-2 intercalation and the mesoporous structure of WO3-DDA.

DOI： 10.1002/chem.201700088

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A novel type of energy donor-acceptor system on a clay surface has been prepared. The energy transfer between an energy-donating cationic pyrene derivative (An-Py2+) and an energy-accepting tris(bipyridine)ruthenium complex (Ru2+) on the clay surface was investigated using absorption, emission, and lifetime measurements. An obvious energy transfer was observed, and one Ru2+ molecule quenched the emission from five molecules of An-Py2+ with an emission quenching efficiency of 85% on the clay surface. This suggests that the light energies absorbed by five of the An-Py2+ molecules were accumulated in the one Ru2+ molecule. Near-quantitative emission quenching was observed for stoichiometric amounts of An-Py2+ and Ru2+. The apparent quenching rate constant is approximately 10(17) L mol(-1) s(-1), and thus the quenching rate constant is 10(7)-10(8) times higher than the diffusion rate constant in a homogeneous solution.

DOI： 10.1021/acs.langmuir.7b00512

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A novel type of trimethylanilinium-substituted pyrene derivative, 1,6-di(N,N,N-trimethylanilinium-4-y1) pyrene 2I(-)(An-Py2+), was synthesized. An-Py2+ exhibits strong emission with a high-emission quantum yield (approximately 90%) in aqueous solution. An-Py2+ was hybridized on a clay (Sumecton SA (SSA)) surface, and the photochemical behavior of An-Py2+ on the SSA surface was investigated using absorption and emission spectroscopic analyses, emission quantum yield (Phi(f)), and lifetime (tau) measurements. Effective adsorption of An-Py2+ on SSA was observed, and adsorption limit was estimated to be 100% relative to the cation-exchange capacity (CEC) of SSA. The previously reported pyridinium-substituted pyrene derivatives cause a gradual redshift of both absorption and emission on the SSA surface. In contrast, An-Py2+ effectively suppresses such a redshift on SSA due to anilinium substitution of the pyrene unit. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/jjphotochem.2017.01.023

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Synthetic models of oxygen evolving complex (OEC) are used not only to gain better understanding of the mechanism and the roles of cofactors for water oxidation in photosynthesis, but also as water oxidation catalysts to realize artificial photosynthesis, which is anticipated as a promising solar fuel production system. However, although much attention has been paid to the composition and structure of active sites for development of heterogeneous OEC models, the cofactors, which are essential for water oxidation by the photosynthetic OEC, remain little studied. The high activity of CoO(OH) nanoparticles for electrocatalytic water oxidation is shown to be induced by a CO32- cofactor. The possibility of CO32- ions acting as proton acceptors for O-O bond formation based on the proton-concerted oxygen atom transfer mechanism is proposed. The O-O bond formation is supposed to be accelerated due to effective proton acceptance by adjacent CO32- ions coordinated on the CoIV center in the intermediate, which is consistent with Michaelis-Menten-type kinetics and the significant H/D isotope effect observed in electrocatalysis.

DOI： 10.1002/cssc.201601494

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL OF VISUALIZED EXPERIMENTS  

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs within the interlayer space of semiconducting layered titania nanosheet (TNS) films was investigated here. Two types of intermediate films (i.e., TNS films containing methyl viologen (TNS/MV2+) and 2-ammoniumethanethiol (TNS/2-AET(+))) were prepared. The two intermediate films were soaked in an aqueous tetrachloroauric(III) acid (HAuCl4) solution, whereby considerable amounts of Au(III) species were accommodated within the interlayer spaces of the TNS films. The two types of obtained films were then soaked in an aqueous sodium tetrahydroborate (NaBH4) solution, whereupon the color of the films immediately changed from colorless to purple, suggesting the formation of AuNPs within the TNS interlayer. When only TNS/MV2+ was used as the intermediate film, the color of the film gradually changed from metallic purple to dusty purple within 30 min, suggesting that aggregation of AuNPs had occurred. In contrast, this color change was suppressed by using the TNS/2-AET(+) intermediate film, and the AuNPs were stabilized for over 4 months, as evidenced by the characteristic extinction (absorption and scattering) band from the AuNPs.

DOI： 10.3791/55169

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Polychromium-oxo-deposited TiO2 ((CrxOy)-O-III/TiO2) electrodes were fabricated by a simple electrochemical technique by using different TiO2 basal electrodes (anatase, rutile, and mixed polymorphic phases P25) as earth-abundant photoanodes for visible-light-driven water oxidation. The high-resolution transmission electron microscopy (HR-TEM) observation illustrated that an (CrxOy)-O-III layer with approximately 2-3nm thickness was formed on the surface of the crystalline TiO2 particles. Upon visible-light irradiation of the electrodes, the photoanodic current based on water oxidation was generated at the (CrxOy)-O-III/TiO2 electrodes. However, the wavelength (below 620nm) for photocurrent generation at (CrxOy)-O-III/TiO2-rutile was longer than that (below 560nm) at (CrxOy)-O-III/TiO2-P25 by 60nm, which is in agreement with the difference (0.2eV) in the conduction band (CB) edge energy between rutile and anatase TiO2. This gives a quantitative account for the photocurrent generation based on interfacial charge transfer (IFCT) from Cr3d of the deposited (CrxOy)-O-III layer to the TiO2 CB. The photocurrent generated for (CrxOy)-O-III/TiO2-rutile was higher than that for (CrxOy)-O-III/TiO2-anatase, which is ascribed to 1)more effective (CrxOy)-O-III deposition on the rutile particles, 2)a larger electrolyte/(CrxOy)-O-III interface for water oxidation as a result of smaller rutile particles (ca. 30-40nm) compared with larger P25 particles (ca. 40-80nm), and 3)more effective use of visible light owing to the low energy IFCT transition of rutile.

DOI： 10.1002/cplu.201600288

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A new transparent iridium oxide (IrOx) film on fluorine-doped tin oxide (FTO) electrodes were achieved from a homogeneous precursor complex solution by employing a facile spin-coating technique. The composition of the nanostructure and crystallinity of the IrOx film is tunable by a simple annealing treatment of a compact complex layer, which is responsible for their significantly different electrocatalytic performances for water oxidation. Transmission electron microscopy (TEM) observations showed uniformly dispersed small IrOx nanoparticles of dimensions ca. 2-5 nm for the film annealed at 300 degrees C, and the nanoparticles gradually agglomerated to form relatively large particles at higher temperatures (400 and 500 degrees C). The IrOx films prepared at different annealing temperatures are characterized by Raman spectroscopic data to reveal intermediate IrOx(OH)(y) nanoparticles with two oxygen binding motifs: terminal hydroxo and bridging oxo at 300 and 350 degrees C annealing, via amorphous IrOx at 400 degrees C, transforming ultimately to crystalline IrO2 nanoparticles at 500 degrees C. Cyclic voltammetry suggests that the intrinsic activity of catalytic Ir sites in intermediate IrOx(OH)(y) nanoparticles formed at 300 degrees C annealing is higher in comparison with amorphous and crystalline IrOx nanoparticles. Electrochemical impedance data showed that the charge transfer resistance (R-ct = 232 Omega) for the IrOx(OH)(y) film annealed at 300 degrees C is lower relative to that of films annealed at higher temperatures. This is ascribable to the facilitated electron transfer in grain boundaries between smaller IrOx particles to lead the efficient electron transport in the film. The high intrinsic activity of catalytic Ir sites and efficient electron transport are responsible for the high electrocatalytic performance observed for the intermediate IrOx(OH)(y) film annealed at 300 degrees C; it provides the lowest overpotential (eta) of 0.24 V and Tafel slope of 42 mV dec(-1) for water oxidation at neutral pH, which are comparable with values for amorphous IrOx center dot nH(2)O nanoparticle films (40-50 mV dec(-1)) reported as some of the most efficient electrocatalysts so far.

DOI： 10.1021/acscatal.6b00621

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

We report the first in situ synthesis of copper nanoparticles (CuNPs) within the interlayer space of inorganic layered semiconductors (titania nanosheet films) through the following steps. A sintered titania nanosheet (s-TNS) film was synthesised, forming a transparent, layered semiconductor film (similar to 2 mu m thick). A considerable amount of copper ions (ca. 68% relative to the cation exchange capacity of TNSs) was intercalated in the s-TNSs using the methyl viologen-containing s-TNSs as the intermediate. The resultant copper-containing s-TNS (TNS/Cu2+) film was treated with an aqueous solution of NaBH4, resulting in a colour change. Extinction spectra of NaBH4-treated films exhibited a wide extinction band at lambda(max) (the extinction band maximum) = 683 nm. The spectral shapes and lambda(max) were similar to those for copper nanoparticles on TiO2 surfaces. Transmission electron microscopy analysis demonstrated the wide distribution of electron dense particles on the titania sheet of NaBH4-treated TNS/Cu2+. XRD analysis and absorption/extinction analysis with different amounts of TNSs suggest that CuNPs were formed within the interlayer space rather than the surface of TNSs through NaBH4 treatment. Repeatable oxidation and reduction behaviour, i.e. colouration and decolouration cycles of the copper species within TNS films, was investigated.

DOI： 10.1039/c5tc03152d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Tetracationic pyrene derivatives (Py4+) and dicationic tris(bipyridine)ruthenium(II) (Ru2+) were hybridized on a synthetic clay (SSA) surface; the hybrid is denoted as Py4+/Ru2+/SSA. The photochemical properties of the Py4+/Ru2+/SSA system, especially the energy transfers from Py4+ to Ru2+, were investigated. Absorption analysis revealed fading of Ru2+; this hypochromic effect suggests that the Ru2+ and Py4+ weakly interacted on the SSA surface. The remarkable quenching of the emission from Py4+ by the coadsorbed Ru2+ was probably stimulated by energy transfer from Py4+ to Ru2+. Emission of Ru2+ was amplified 4-5 times within the Py4+/Ru2+/SSA system; the maximum emission quantum yield of Ru2+ was 30.4 +/- 3.8%. Very interestingly, the three independent photochemical behaviors of By(4+)/Ru2+/SSA, namely fading of Ru2+, stimulation of emission quenching of Py4+, and emission amplification of Ru2+, occurred at almost identical critical amounts of adsorbed Ru2+ (11-13% cation exchange capacity (CEC)). Molecular distribution modeling of the SSA surface suggests that Py4+ and Ru2+ adjoined on the SSA surface when the amount of adsorbed Ru2+ exceeded ca. 11% CEC. On the other hand, the unique photochemical and photophysical properties might arise from the adjoined geometrical arrangement of Py4+ and Ru2+ coadsorbed on the SSA surface. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jphotochem.2015.05.015

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Electrochemical water oxidation by [Ru(EtOtpy)(bpy)OH2](2+) (1) (EtOtpy =4'-ethoxy-2,2':6'2 ''-terpyridine, bpy = 2,2'-bipydidine) was investigated in a homogeneous solution under weakly acidic conditions (pH 5.3). The cyclic voltammogram of a 1 aqueous solution showed that successive proton-coupled electron transfer reactions of Ru-II-OH2 Ru-III-OH and Ru-III-OH/Ru-IV=O redox pairs and high anodic current above 1.1 V vs SCE. Electrocatalytic water oxidation was corroborated by the bulk electrolysis at 1.5 V; the significant amount of O-2 was evolved compared with the blank during the electrolysis. Potential-step chronocoulospectrometry (PSCCS) from 0.0 V to 1.52 V vs SCE was conducted to observe the change of 1 in solution during the electrocatalysis. The in situ UV visible spectral change showed oxidation of I (Ru-II-OH2) to Ru-III-OH and to further oxidation of Ru-III-OH to Ru-IV=O, and that the Ru-IV=O species mainly exists in a steady state after 200 s in the electrocatalysis. The in situ UV-vis spectral change in a reverse potential step from 1.52V to 0.22V vs SCE exhibited that Ru-II-OH2 completely recovers by two electron re-reduction process from the steady state in the electrocatalysis. The observation of Ru-IV=O in a steady state suggests that a rate determining step in the catalytic cycle is oxidation of Ru-IV=O to Ru-V=O rather than the O-O bonding formation by nucleophilic attack of water to Ru-V=O in the electrocatalysis in a homogeneous solution. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jphotochem.2015.06.010

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distal-[Ru(Cl-tpy)(pynp)Cl](+) (d-2Cl) (Cl-tpy = 4'-chloro-2,2';6',2"-terpyridine, pynp =2-(2-pyridy1)-1,8-naphthyridine), and distal- and proximal-[Ru(Cl-tpy)(pynp)OH2](2+) (d- and p-2H(2)O) complexes are newly synthesized and characterized to compare structures and physicochemical properties with a 2,2';6',2 ''-terpyridine (tpy) ligand derivatives of distal-[Ru(tpy)(pynp)Cl](+) (d-1Cl), distal- and proximal-[Ru(tpy) (PYnP)OH2](2+) (d- and p-1H(2)O). The equilibrium turned out to be involved in the aquation reaction of d-2Cl to d-2H(2)O in contrast to observed irreversible aquation reaction of d-1Cl under the same conditions. The kinetic analysis showed that the aquation reaction of d-2Cl is slightly slower than that of d-1Cl. The stoichiometric photoisomerization of d-2H(2)O to p-2H(2)O occurs by visible light irradiation as it is for d-1H(2)O, and (2.1%) at 520 nm for photoisomerization of d-2H(2)O was higher than that (1.5%) observed for d-1H(2)O. d-2H(2)O undergoes the two-step reaction involving the successive one-proton-coupled oneelectron reactions of the Ru-II-OH2/Ru-III-OH and Ru-III-OH/Ru-IV=O redox couples, whereas p-2H(2)O undergoes the one-step reaction involving the two-proton-coupled two-electron reaction of the RuII-OH2/Ru-IV=O redox couple. These redox potentials of d- and p-2H(2)O are higher than those for d- and p-1H(2)O at pH 7.0 by 10 similar to 50 my due to the electron-withdrawing chloro substitution. The turnover frequency (k(o2) = 6.3 x 10(-3) s(-1)) of d-2H(2)O for water oxidation was higher than that (3.9 x 10(-4) s(-1)) of p-2H(2)O by a factor of 16. k(o2) for d-2H(2)O was also 1.6 times higher than that (3.8 x 10(-3) s(-1)) for d-1H(2)O, whereas k(o2) for p-2H(2)O was 1.2 times lower than that (4.8 x 10(-4) s(-1)) for p-1H(2)O. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jphotochem.2015.05.029

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Nanowire of nickel molybdate hydrate, being recognized as an emerging supercapacitor material, was synthesized from the intercrystal self-assembly process (commonly referred to as oriented aggregation or attachment). The detailed lattice image of a NiMoO4 center dot 0.75H(2)O nanowire and the intermediate nanostructure before reaching the interplanar binding were successfully captured by means of high-resolution transmission and scanning electron microscopies. NiMoO4 center dot 0.75H(2)O possessed highly crystalline surface and internal nanostructures.

DOI： 10.1021/acs.inorgchem.5b00625

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A new series of proximal proximal-[Ru-2(tpy)(2)(L)XY](n+) (p,p-Ru2XY, tpy = 2,2':6',2 ''-terpyridine, L = 5-phenyl-2,8-di(2-pyridyl)-1,9,10-anthyridine, X and Y = other coordination sites) were synthesized using, photoisomerization of a mononuclear complex. The p,p-Ru2XY complexes undergo unusual reversible bridge-exchange reactions to generate p,p-Ru-2(mu-Cl), p,p-Ru-2(mu-OH), and p,p-Ru-2(OH)(OH2) with mu-Cl, mu-OH, as well as hydroxo and aquo ligands at X and Y sites of p,p-Ru2XY, respectively. The geometric and electronic structures of these complexes were characterized based on UV vis and H-1 NMR spectra, X-ray crystallography, and density functional theory (DFT) calculations. H-1 NMR data showed C-2 symmetry of p,p-Ru-2(OH)(OH2) with the distorted L chelate and nonequivalence of two tpy ligands, in contrast to the C-2 symmetry of p,p-Ru-2(mu-Cl) and p,p-Ru-2(mu-OH). However, irrespective of the lower symmetry, p,p-Ru-2(OH)(OH2) is predominantly formed in neutral and weakly basic conditions due to the specially stabilized core structure by multiple hydrogen-bond interactions among aquo, hydroxo, and backbone L ligands. The electrochemical data suggested that p,p-Ru-2(OH)(OH2) (Ru-II-OH:Ru-II-OH2) is oxidized to the Ru-III-OH:Ru-III-OH state at 0.64 V vs saturated calomel electrode (SCE) and further to Ru-IV=O:Ru-IV-OH at 0.79 V by successive 1-proton-coupled 2-electron processes at pH 7.0. The cyclic voltammogram data exhibited that the p,p-Ru-2(OH)(OH2) complex works more efficiently for electrocatalytic water oxidation, compared with a similar mononuclear complex distal-[Ru(tpy)(L)OH2](2+) (d-RuOH2) and p,p-Ru-2(mu-Cl) and p,p-Ru-2(mu-OH), showing that the p,p-Ru-2 core structure with aquo and hydroxo ligands is important for efficient electrocatalytic water oxidation. Bulk electrolysis of the p,p-Ru-2(OH)(OH2) solution corroborated the electrocatalytic cycle involving the Ru-III-OH:Ru-III-OH state species as a resting state. The mechanistic insight into O-O bond formation for O-2 production was provided by the isotope effect on electrocatalytic water oxidation by p,p-Ru-2(OH)(OH2) and d-RuOH2 in H2O and D2O media.

DOI： 10.1021/acs.inorgchem.5b01264

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The photoisomerization equilibrium between distal- and proximal-[Ru(tpy)(pyqu)OH2](2+) [d- and p-RuH2O, tpy = 2,2;6,2-terpyridine, pyqu = 2-(2-pyridyl)quinoline] is characterized. The kinetic analysis of the pD-dependent photoisomerization reactions (monitored by H-1 NMR) of d-RuH2O and p-RuH2O shows (1) that both hydroxo isomers, distal- and proximal-[Ru(tpy)(pyqu)OH](+), are inert to photoisomerization, and (2) that the back reaction (distal to proximal) is 3.0 times faster than the forward reaction (proximal to distal). Isolation of distal- and proximal-[Ru(tpy)(pyqu)Cl](+) (d- and p-RuCl) as well as d- and p-RuH2O isomers enabled comprehensive studies on geometric structures, ligand exchange and redox reactions, and water oxidation catalysis for these isomers. The observed aquation rate constant (9.2x10(-2)s(-1) at 40 M) of p-RuCl to form p-RuH2O is 1700 times higher than that (5.4x10(-5)s(-1) at 63 M) of d-RuCl at 298 K owing to the steric repulsion between a chloro ligand and the 8-proton of the quinoline moiety. The turnover frequency (TOF = 1.7x10(-3)s(-1)) of p-RuH2O for catalytic water oxidation is 1.7 times greater than that (1.0x10(-3)s(-1)) for d-RuH2O, in contrast to the [Ru(tpy)(pynp)OH2](2+) isomer system, in which the TOF of the distal isomer is higher than that of the proximal one by one order of magnitude. The mechanisms and factors controlling the photoisomerization equilibria and water oxidation catalysis of the d- and p-RuH2O isomers are discussed on the basis of experimental and theoretical investigations.

DOI： 10.1002/ejic.201500642

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The current approaches to electrochemically synthesizing valve metal derived nanochannel films with longitudinal nanospaces aligned at a right angle to planar substrates rely on highly toxic fluoride compounds and require severe reaction conditions. Herein, we report on a fluoride-free, room-temperature, electrochemical synthesis Of a genuine mesoporous niobia thin filth from the parent metal. The electrochemical reaction is driven by only a 1 V bias with respect to a Pt counter electrode in at aqueous solution. The solution contained an inexpensive, less toxic potassium hydroxide, and the reaction produced favorable byproducts, namely, recyclable K8Nb6O19 and H-2.

DOI： 10.1021/ic502580e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

We report the first accessible channel-like open pore architecture of ordered 2D hexagonal mesoporous IrO2 films and its utilization as an efficient anode for electrocatalytic water oxidation. A well-ordered mesostructure of circa 7nm pores were obtained by a facile one-pot soft-templating strategy, employing a [Ir(OH)(6)](2-) precursor stabilized by a triblock copolymer PluronicF127 as a pore-directing template. A mesoporous IrO2 film calcined at 400 degrees C (approximate to 70nm thick) affords a high surface area of 512m(2)cm(-3) and 2times higher O-2 evolution during the electrocatalytic water oxidation relative to an untemplated IrO2 coating film.

DOI： 10.1002/cssc.201402911

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

A photocatalytic system for CO2 reduction exhibiting visible-light harvesting was developed by preparing a hybrid consisting of a supramolecular metal complex as photocatalyst and periodic mesoporous organosilica (PMO) as light harvester. A (RuReI)-Re-II binuclear complex (RuRe) with methylphosphonic acid anchor groups was adsorbed on acridone or methylacridone embedded in the walls of PMO mesochannels to yield the hybrid structure. The embedded organic groups absorbed visible light, and the excitation energy was funneled to the Ru units. The energy accumulation was followed by electron transfer and catalytic reduction of CO2 to CO on the Re unit. The light harvesting of these hybrids enhanced the photocatalytic CO evolution rate by a factor of up to ten compared with that of RuRe adsorbed on mesoporous silica without a light harvester.

DOI： 10.1002/cssc.201403194

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Tetra-cationic pyrene derivative (Py4+) and tris(bipyridine)ruthenium(II) (Ru2+) were hybridized onto the surface of a synthesized clay. We observed the remarkable stimulation of excited Py4+ emission quenching on the clay surface, with a very large apparent quenching rate constant (k(q) = 7.4 +/- 0.7 x10 (15) L mol(-1) s(-1)).

DOI： 10.1021/la504597t

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Tungsten trioxide (WO3) films with nanoporous morphology were prepared by a facile and simple method utilizing commercially available WO3 nanopowder with polyethylene glycol to guide porosity of a nanostructure, and the resulted photoanode was working efficiently for visible-light-driven water oxidation. The SEM observation and XRD measurement revealed formation of interparticulate nanopores between the well-connected WO3 crystaline particles of dimension ca. 100-200 nm. The nanoporous WO3 electrode generated a significant photoanodic current density of 1.8 mA cm(-2) due to water oxidation at 1.0 V versus Ag/AgCl on visible light irradiation (lambda>390 nm, 100 mW cm(-2)). The onset potential of the WO3 electrode was 0.67 V versus a reversible hydrogen electrode (RHE), being lower by 0.56 V than the theoretical potential for water oxidation (1.23 V versus RHE). The incident photon to current conversion efficiency (IPCE) reached 45% at 400 nm of light wavelength and 1.04 V versus Ag/AgCl of an applied potential. The photoanodic current and photostability of the WO3 electrode were improved by addition of Co2+ ions in the electrolyte solution during photoelectrocatalysis. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2014.06.062

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Mesoporous tungsten trioxide (WO3) was prepared from tungstic acid (H2WO4) as a tungsten precursor with dodecylamine (DDA) as a template to guide porosity of the nanostructure by a solvothermal technique. The WO3 sample (denoted as WO3-DDA) prepared with DDA was moulded on an electrode to yield efficient performance for visible-light-driven photoelectrochemical (PEC) water oxidation. Powder X-ray diffraction (XRD) data of the WO3-DDA sample calcined at 400 degrees C indicate a crystalline framework of the mesoporous structure with disordered arrangement of pores. N-2 physisorption studies show a Brunauer-Emmett-Teller (BET) surface area up to 57 m(2) g(-1) together with type IV isotherms and uniform distribution of a nanoscale pore size in the mesopore region. Scanning electron microscopy (SEM) images exhibit well-connected tiny spherical WO3 particles with a diameter of ca. 5 to 20 nm composing the mesoporous network. The WO3-DDA electrode generated photoanodic current density of 1.1 mA cm(-2) at 1.0 V versus Ag/AgCl under visible light irradiation, which is about three times higher than that of the untemplated WO3. O-2 (1.49 mu mol; Faraday efficiency, 65.2%) was evolved during the 1-h photoelectrolysis for the WO3-DDA electrode under the conditions employed. The mesoporous electrode turned out to work more efficiently for visible-light-driven water oxidation relative to the untemplated WO3 electrode.

DOI： 10.1186/1556-276X-9-542

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Fluorescent poly(boron enaminoketonate)s (PBEKs) were synthesized via the polycycloaddition of a homoditopic nitrile N-oxide to diynes followed by other polymer reactions. Click polycycloaddition of the nitrile N-oxide to various diynes effectively produced polyisoxazoles in high yields. The polyisoxazoles were transformed into the corresponding fluorescent PBEKs by forming the poly(beta-aminoenone) intermediates and reacting these intermediates with (C6F5)(2)BF center dot OEt2. The solution and solid-state optical properties of the PBEKs were evaluated by ultraviolet-visible (UV-vis) and fluorescence spectroscopy.

DOI： 10.1038/pj.2014.31

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A new method for the hybridization of a ruthenium(11) polypyridyl complex ([Ru-(bpy)(2)((CH2PO3H2)(2)-bpy)](2+) (RuP22+: bpy =2,2'-bipyridine; (CH2PO3H2)(2)-bpy =2,2'-bipyridine-4,4'di(metylphosphonic acid)) with biphenylene-bearing periodic mesoporous organosilica (Bp-PMO made from 4,4'bis(triethoxysilyl)biphenyl [(C2H5O)(3)Si-(C6H4)(2)-Si(OC2H5)(3)]) was developed. Efficient and secure fixation of the ruthenium(II) complex with methylphosphonic acid groups (RuP22+) in the mesopores of Bp-PMO occurred. This method introduced up to 660 mu mol of RuP22+. in 1 g of Bp-PMO. Two modes of adsorption of RuP22+ in the mesopores of Bp-PMO were observed: one is caused by the chemical interaction between the methylphosphonic acid groups of RuP22+ and the silicate moieties of Bp-PMO and the other is attributed to aggregation of the RuP22+ complexes. In the case of the former mode, adsorbed RuP22+ (up to 80-100 mu mol g(-1)) did not detach from Bp-PMO after washing with acetonitrile, dimethylformamide, or even water. Emission from the excited biphenylene (Bp) units was quantitatively quenched by the adsorbed RuP22+ molecules in cases where more than 60 mu mol g(-1) of RuP22+ was adsorbed, and emission from RuP22+ was observed. Quantitative emission measurements indicated that emission from approximately 100 Bp units can be completely quenched by only one RuP22+ molecule in the mesopore, and photons absorbed by approximately 400 Bp units are potentially accumulated in one RuP22+ molecule.

DOI： 10.1021/am405065a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A polychromium-oxo-deposited TiO2 electrode was fabricated as an earth-abundant photoanode for visible-light-driven water oxidation by a simple electrochemical technique. The photoelectrocatalytic water oxidation could occur based on a specific interfacial charge transfer (IFCT) from a Cr-III to the TiO2 conduction band.

DOI： 10.1039/c3cc47764a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

An efficient artificial light harvesting (LH) system was developed via sequential two-step energy accumulation. A periodic mesoporous organosilica with bridging biphenyl groups in the framework (Bp-PMO) was used as an LH antenna. The center of a linear-shaped Re(I) pentanuclear complex was connected to a Ru(II) trisdiimine complex through a covalent bond, these served as the first and second energy acceptors, respectively, (Ru-Re-5). Hybridization was achieved with the non-ionic surfactant C12H25(OCH2CH2)(4)OH in an acetonitrile solution, and in the hybrid (Ru-Re-5-Bp-PMO), the Ru-Re-5 molecules were adsorbed in an orderly fashion in the mesopores of the Bp-PMO. Photons absorbed by 437 +/- 43 of the Bp units were first accumulated in the five Re units in Ru-Re-5 and then transferred to only one Ru unit, which emitted the light strongly.

DOI： 10.1039/c3sc51959g

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DOI： 10.1002/anie.201306004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The effect of rotaxane shuttling on the fluorescence properties of a fluorophore was investigated by exploiting fluorophore-tethered [2]rotaxanes. A fluorescent boron enaminoketonate (BEK) moiety was introduced in a rotaxane via transformation of an isoxazole unit generated as a result of an end-capping reaction using a nitrile N-oxide. The rotaxane exhibited a red shift of the fluorescence maximum along with a remarkable enhancement of the fluorescence quantum yield through wheel translation to the fluorophore.

DOI： 10.1021/ol401984j

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Eight novel polyfluorinated surfactants (CnF 2n+1CONH(CH2)2 N+(CH 3)2C16H33 Br-
abbreviated as CnF-S, where n = 1, 2, 3, 4, 5, 6, 8, 10) were synthesized and their intercalation into cation-exchangeable clay was investigated. All of the polyfluorinated surfactants intercalated in amounts exceeding the cation exchange capacity (CEC) of the clay. The C4F-S and C5F-S surfactants exhibited intercalation up to 480% of the CEC as a saturated adsorption limit. On the basis of X-ray analysis, CnF-S surfactants intercalated between clay nanosheets to form a bilayer structure in which the surfactant molecules tilt at an angle of ∼60 with respect to the clay surface. The saturated adsorption limits and layer distances differed between surfactants with short (n = 1, 2) and long (n = 3-10) perfluoroalkyl chains. For long-chain surfactants, their saturated adsorption limits were independent of the perfluoroalkyl chain length and the layer distances systematically increased with increasing perfluoroalkyl chain length. These results suggest that the microscopic orientation differed between the short and long chains. X-ray analysis showed that the long-chain surfactants orient the perfluoroalkyl chains at a tilt of 41 ± 5 with respect to the clay layer. This value was in good agreement with polarized IR measurements of 42 ± 2 for this angle. © 2013 American Chemical Society.

DOI： 10.1021/la4019212

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We report a template-free facile technique that allows for the first ever synthesis of a monoclinic Ag2Mo2O7 nanowire (m-Ag2Mo2O7-NW), using a commercially available MoO3 particle. The nanowire possessed high crystallinity and structural homogeneity and strongly suggested that the nanowire was grown through an oriented aggregation mechanism in contrast to the case of a typical solution-phase method. The corresponding bulky counterpart showed no photoresponse; however, a complete structural transformation toward a nanowire triggered activity for O-2 evolution in the presence of Ag+ as an electron acceptor under visible-light irradiation.

DOI： 10.1021/ic401236b

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A photosynthetic photosystem II (PS II) model was developed by adsorbing [(OH2)(terpy)MnIII(μ-O)2Mn IV(terpy)(OH2)]3+ (1, terpy = 2,2′:6′,2″-terpyridine) as an oxygen evolving center and Ru(bpy)32+ (bpy = 2,2′-bipyridine) as a photoexcitation center onto mica. The mica adsorbates were prepared by three different methods
Adsorbate A was prepared by adsorption of 1 followed by Ru(bpy)32+ on mica, and Adsorbates B and C were prepared by the opposite adsorption order and co-adsorption of 1 and Ru(bpy) 32+, respectively. The UV-visible diffuse reflectance (DR) spectroscopic data and emission decay measurements of the photoexcited Ru(bpy)32+ suggested the different arrangements of 1 and Ru(bpy)32+ among the three adsorbates in a mica interlayer. For Adsorbate A, Ru(bpy)32+ could be adsorbed near the mica surface, being shallowly intercalated relative to 1. For Adsorbate B, 1 is adsorbed near the mica surface, Ru(bpy)32+ being deeply intercalated relative to 1. For Adsorbate C, either 1 or Ru(bpy) 32+ could be randomly intercalated relative to the other adsorbates. In photochemical water oxidation experiments, a significant amount of O2 was evolved when visible light was used to irradiate an aqueous suspension of Adsorbate A containing a S2O82- electron acceptor in a liquid phase, whereas O2 was not evolved under the same conditions when using Adsorbates B and C. 1 is considered to work for photochemical water oxidation in Adsorbate A due to an efficient electron transport from deeply intercalated 1 to S2O82- ions in a liquid phase via Ru(bpy)32+ photoexcitation near the mica adsorbate surface. © 2013 The Royal Society of Chemistry.

DOI： 10.1039/c3cy00010a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Reduction of CO2 using semiconductors as photocatalysts has recently attracted a great deal of attention again. The effects of organic adsorbates on semiconductors on the photocatalytic products are noteworthy. On untreated TiO2 (P-25) particles a considerable number of organic molecules such as acetic acid were adsorbed. Although irradiation of an aqueous suspension of this TiO2 resulted in the formation of a significant amount of CH4 as a major product, it was strongly suggested that its formation mainly proceeded via the photo-Kolbe reaction of acetic acid. Using TiO2 treated by calcination and washing procedures for removal of the organic adsorbates, CO was photocatalytically generated as a major product, along with a very small amount of CH4, from an aqueous suspension under a CO2 atmosphere. In contrast, by using Pd (>0.5 wt %) deposited on TiO2 (Pd-TiO2) on which organic adsorbates were not detected, CH4 was the main product, but CO formation was drastically reduced compared with that on the pretreated TiO2. Experimental data, including isotope labeling, indicated that CO2 and CO32- are the main carbon sources of the CH4 formation, which proceeds on the Pd site of Pd-TiO2. Prolonged irradiation caused deactivation of the photocatalysis of Pd-TiO2 because of the partial oxidation of the deposited Pd to PdO.

DOI： 10.1021/am200425y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Photoinduced electron transfer between an anionic porphyrin derivative (tetrakis(p-carboxyphenyl)porphyrin; H2TCPP4-) and an electron accepting methyl viologen (MV2+) was investigated in two different nanoscale configurations, i.e., layered titania nanosheet (TNS) photocatalysts and ammonium-functionalized monodisperse mesoporous silica (AMMSS) particles. Cationic MV2+ intercalated within the TNS interlayers while anionic H2TCPP4- was accommodated within AMMSS nanocavities to form (MV2+-TNS)/(H2TCPP4--AMMSS) hybrid films. Upon irradiation with UV light and excitation of the TNS in the (MV2+-TNS)/(H2TCPP4--AMMSS) hybrid films, the consumption of H2TCPP4- and the formation of a one-electron reduced MV2+ (MV+center dot) were simultaneously observed. No consumption of H2TCPP4- was observed when an electrically insulating poly(styrene) (PS) was also introduced at the interface. These results suggest that photoinduced electron transfer occurred at the interface between the TNS and the AMMSS.

DOI： 10.1021/am101281n

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Language：English   Publishing type：Part of collection (book)   Publisher：SPRINGER-VERLAG BERLIN  

We are facing three serious problems related to fossil resources, i.e., shortage of energy, shortage of carbon resources, and the global worming problem. Development of practical systems for converting CO2 to useful chemicals using solar light, i.e., photocatalytic CO2 reduction systems, should be one of the best solutions for these problems. In this article, we review photocatalytic CO2 reduction systems, which are classified in two categories: (1) homogeneous reaction systems mainly using transition metal complexes, and (2) heterogeneous systems mainly using inorganic semiconductor as a light absorber.

DOI： 10.1007/128_2011_139

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A novel type of light-harvesting complexes was synthesized with a linear-shaped Re(I) oligomer as a photon absorber and a Ru(II) polypyridyl complex as an energy acceptor. The Re(I) oligomer and the Ru(II) complex are connected to each other with a bisdiimine ligand, that is, 1,2-bis[4-(4'-methyl-2,2'-bipyridinyl)]ethane (C2dmb). These Ru(II)-Re(I) multinuclear complexes, [Ru(dmb)(2)(C2dmb)Re(CO)(2)-{-PP-Re(dmb)(CO)(2)-PP-Re(dmb)(CO)(3)}(2)](PF(6))(7), [Ru(dmb)(2)(C2dmb)Re(CO)(2){-PP-Re(dmb)(CO)(3)}(2)](PF(6))(5), and [Ru(dmb)(2)(C2dmb)Re(CO)(3)-PP-Re(dmb)(CO)(2)-PP-Re(dmb)(CO)(3)](PF(6))(5) (dmb = 4,4'-dimethyl-2,2'-bipyridine; PP = bis(diphenylphosphino)acetylene), can strongly absorb a wide range of UV-vis light and emit mostly from the (3)MLCT excited state of the Ru(II) unit at room temperature in solution even when the Re chain absorbs the light. Comparison of their photophysical properties with those of the corresponding model complexes shows that a highly efficient energy transfer from the Re chain to the Ru(II) unit occurs, and the energy transfer rate constants from each Re(I) unit were determined.

DOI： 10.1021/ja104601b

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Language：English   Publisher：ELSEVIER SCIENCE SA  

UV-light induced redox reactions between cationic porphyrins (H2TMPyP) and methyl viologen (MV2+) separately incorporated in titania nanosheets (TNS) and cubic-mesoporous silica (MPS) integrated films, respectively, were investigated. In this system. the following two modified hybrids, i.e., the normally stacked (MV2+-TNS)/(H2TMPyP-MPS) on a FTO electrode and the inversely stacked (H2TMPyP-MPS)/(TNS) films on a FTO electrode were examined. In accordance with the expected electron flow from H2TMPyP to MV2+, cathodic photocurrents were observed for the normally stacked film in acetonitrile (CH3CN) under a negative bias voltage of -0.4V. However, under the influence of a positive bias voltage of +0.3 V, anodic photocurrents were observed even in CH3CN. On the other hand, anodic photocurrents were also observed in water for the normally stacked films at both bias voltages of +0.3 and -0.4V due to photoreduction followed by proton abstraction of the H2TMPyP molecules from H2O within the MPS nano-cavities. In addition, ca. 0.98 mC of the photocurrents were determined in water for the inversely stacked (H2TMPyP-MPS)/(TNS) films without MV2+, of which ca. 50% resulted in the oxidative consumption of H2TMPyP in the MPS cavities. (C) 2009 Elsevier BY. All rights reserved.

DOI： 10.1016/j.jphotochem.2008.12.018

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A remarkably stable and continuous photoinduced charge separation with a half lifetime longer than 2.5 h in ambient atmosphere was observed at the interface of mesoporous silica and titania nanosheets involving porphyrins and viologen in their nanospaces, respectively.

DOI： 10.1246/bcsj.82.914

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SCIENTIFIC PUBLISHERS  

Photo-induced redox reactions in a hybrid film of a cationic porphyrin dye (H2TMPyP) accommodated within a transparent mesoporous silica (MPS) film spin-coated on an FTO electrode have been investigated for such applications as the construction of efficient solar energy storage devices and novel light-stimulated sensors. In this system, anodic and cathodic photocurrents were observed under bias voltages of +0.3 V and -0.4 V, respectively. The action spectrum of the photocurrents corresponded well with the absorbance of the H2TMPyP molecules in the visible light region. Control experiments showed no photocurrents for the mesoporous silica without H2TMPyP. Our investigations showed that the H2TMPyP molecules function not only as a sensitizer but also as a mediator for electron migrations within mesoporous nano-cavities.

DOI： 10.1166/jnn.2009.J007

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

2,7-Dialkyl[1]benzothieno[3,2-b]benzothiophenes were tested as solution-processible molecular semiconductors. Thin films of the organic semiconductors deposited on Si/SiO2 substrates by spin coating have well-ordered structures as confirmed by XRD analysis. Evaluations of the devices under ambient conditions showed typical p-channel FET responses with the field-effect mobility higher than 1.0 cm(2) V-1 S-1 and /(n)//(off) of -10(7).

DOI： 10.1021/ja074841i

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Language：English   Publisher：AMER CHEMICAL SOC  

The synthesis of polyaniline (PANI) with semiconducting layered niobate (NbO) to form PANI/NbO hybrid materials and their reversible color change under a unique redox process under the influence of UV and/or visible light have been investigated. The in-situ polymerization of anilinium chlorides (ANI) packed in a regular orientation in a bilayer structure within the NbO interlayers led to PANI/NbO hybrid powders by heat treatment using (NH4)(2)S2O8 as the catalyst. The resulting PANI of these hybrids showed the characteristics of a fully oxidized quinoid form, i.e., pernigranine (PG). The PANI/NbO suspension in H(2)0 was cast on a glass substrate to form a PANI/NbO film after evaporation of the water with a good parallel orientation of the NbO layers against the glass substrate. Upon UV light irradiation in the presence of a reductant such as MeOH, the violet-colored PANI (PG) polymers within the NbO interlayers were reduced by the NbO-induced photocatalytic reactions and led to a colorless PANI, i.e., leucoemeraldine (LE). Moreover, the resulting colorless PANI/NbO films reverted back to a blue-colored PANI, i.e., erneraldine (EM), due to oxidation by the surrounding 02 gas. The PANI/NbO hybrid films were able to retain repetitive and reversible photoinduced patterning for over 50 cycles under such alternate UV and visible light irradiation.

DOI： 10.1021/jp0747048

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Diarylethene derivatives (DE) covalently bonded to silanol oxygens of layered silicate surfaces. i.e., magadiite (Mag), were synthesized and investigated for their photochromic behavior. The DE-Mag layered hybrids were found to undergo reversible color change by alternating UV and visible light irradiation. A more highly efficient, reproducible photochromic behavior was realized with DE-Mag than with a corresponding DE-Si possessing silyl substituents on DE in place of the Mag surface. Moreover, the present covalently bonded DE exhibited an improvement over DE hybrids incorporated in layered double hydroxide (LDH) clays, in which the repetitive photochromic behavior decreased during alternating irradiation, due to the accumulation of the photochemically inert parallel isomers of DE.

DOI： 10.1163/156856707779160870

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCI PUBL CO INC  

Nano-ordered hybrid films of layered double hydroxide (LDH) nanosheets and two types of anionic dye molecules, i.e. tetrakis(4-carboxyphenyl)porphyrin (TCPP) and 1,3,6,8-pyre-netetrasulfonic acid (PTSA), were prepared by a layer by-layer deposition (LBL) method. Photo-induced energy transfers (PET) between the PTSA and TCPP layers were investigated for two differently stacked structures of the TCPP/LDH/PTSA hybrid films, Le; (a) PTSA/LDH multilayers independently stacked on the TCPP/LDH multilayers to form (TCPP/LDH)(n)/(PTSA/LDH)(n) and (b) TCPP/ LDH and PTSA/LDH monolayers deposited alternately to form [(TCPP/LDH)/(PTSA/LDH)](n) hybrid films, which were both prepared by varying the successivie-and alternate stacking of-the (TCPP/LDH) and (PTSA/LDH) unit layers. A Foerster type resonance energy transfer is observed in the present hybrid films, where the efficiency of PET was strongly affected by changing the distance between the TCPP and PTSA molecules in the (TCPP/LDH)(3)/(PSS/LDH)(m)/(PTSA/LDH)(3) hybrid films (m = 1-10) obtained by the insertion of the photochemically inert poly (styrenesulfonic acid) (PSS) and LDH hybrid layers, i.e. the insertion of (PSS/LDH). between the (TCPP/LDH), and (PTSA/LDH), layers. Copyright (C) 2007 Society of Porphyrins & Phthalocyanines.

DOI： 10.1142/S1088424607000485

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The hexaniobate potassium K4Nb6O17, that kind of layered metal oxide semiconductor, can be accommodates various molecules in that interlayers by intarcaration, and thus, hybridization with functional organic molecules were well studied. In this research, we show the syntheses poly(aniline)/niobate hybrid(PANI/niobate). The poly(aniline) changes electroconductivity and the color by the oxidation state. PANI/niobate hybrid changed its coloring from purple red to blue through the UV-light irradiation (excitation of Niobate). And, in the presence of ethanol as a hole scavenger, the color change by irradiating light reached from blue to white. These results suggest that the transformation from starting pernigraniline base to leucoemeraldine base through emeraldine base of PANI and photo-generated conduction band electron of Niobate reduces pernigranilne-type PANI. Moreover, the niobate layers of the PANI/niobate cast film were parallel to the substrate from wide angle X-ray diffraction measurement.

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Language：English   Publisher：AMER CHEMICAL SOC  

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Two spatially different nano-structured inorganic materials, titania nanosheets (TNS) and mesoporous silica (MPS), were integrated onto a glass substrate to form stacked composite thin films. Investigations were then carried out on photoinduced electron transfers between the tetrakis(1-methylpyridinium-4-yl)porphyrinatometal(4+) ion ([M(tmpyp)](4+)); M = H-2, Zn, and Co) and 1,1'-dimethyl-4,4'-bipyridinium (methyl viologen; MV2+) within the hybrid films. The [M(tmpyp)](4+) molecules were found to be adsorbed only in the MPS nano-cavities, while MV2+ was intercalated only in the TNS layer, i.e., the [M(tmpyp)](4+) and MV2+ molecules could be separately and selectively accommodated into the NIPS nano-cavities and TNS layers of the hybrid films, respectively. Upon UV light irradiation (TNS excitation) of the films containing [H-2)(tmpyp)](4+), the decomposition of [H-2 (tmpyp)](4+) and the formation of a one-electron reduced MV2+ (MV+.) were observed, clearly indicating photoinduced electron transfers in the MPS/TNS films. Moreover, when the metal-complex [Zn(tmpyp)](4+) or CO(tmpyp)](4+) was used in place of [H-2(tmpyp)(4+), visible light-induced electron transfers could be observed in the present MPS/TNS hybrid films, the first report of such charge separation in consecutively stacked thin films by visible light.

DOI： 10.1246/bcsj.79.386

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Photochemical Electron Transfer (ET) between an organic dye, the porphyrin derivative TMPyP, and an electron acceptor, methyl viologen MV2+, have been investigated at the interface of two different inorganic films, i.e., layered titania nano-sheets (TNS) and a monolayer film of spherical and mono-dispersed mesoporous silica (sMPS) particles (ca. 0.5 mm). TMPyP ions were intercalated within the sMPS nano-cavities to form (TMPyP-sMPS) while MV2+ ions were intercalated into the TNS interlayers to form (MV2+-TNS). The (TMPyP-sMPS) and (MV2+-TNS) films were then stacked on a silica substrate in this order to form a (MV2+-TNS)/(TMPyP-sMPS) film and, upon UV light irradiation, ET could be induced. However, when this film was stacked inversely, i.e., for the (TMPyP-sMPS)/(MV2+-TNS) films on a silica substrate, no photoinduced ET were observed. Interestingly, however, even for this photo-inactive inversely stacked film, ET could be generated by inserting a gold vapor-deposited layer between the (MV2+-TNS) and (TMPyP-sMPS)films. The conjugation conditions at the interface of the inversely stacked (TMPyP-sMPS)/(MV2+-TNS) hybrid film were, thus, confirmed to strongly affect the photoinduced electron transfers and their efficiencies.

DOI： 10.1039/b609779k

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Language：English   Publisher：SPRINGER  

The hybridization of two different types of organic polycations, 1,1'-dimethyl-4,4'-bipyridinium dications (methyl viologen, MV2+) and 5,10,15,20-tetrakis(N-methyl-pyridinium-4-yl)21H,23H-porphine tetracations (TMPyP4+), into layered mobates was investigated to construct an efficient dye-modified semiconductor for solar conversion and storage. Two different methods were employed for the direct intercalation of the cationic species, i.e., conventional ion-exchange with K4Nb6O17 center dot 3H(2)O as the starting host and a novel acid-base neutralization method with H4Nb6O17 as the starting host. These two methods showed totally different behavior and the characteristic features of both will be discussed in relation to the structure of the hybrid formed, the amount of absorption observed for the guest molecules and the intercalation rates. An analysis of the photoinduced electron-transfer reactions will also be discussed to show how control of the intercalation of guest molecules affects the photofunctionality of these unique hybrids.

DOI： 10.1163/156856706778400307

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Language：English   Publisher：ROYAL SOC CHEMISTRY  

DOI： 10.1039/b609779k

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Language：English   Publisher：The Clay Science Society of Japan  

Photochemical electron transfer reactions of cationic porphyrins on an anionic-type clay (Smecton SA) surface were investigated. Two types of complexes were formed between the cationic porphyrin and the anionic-type clay depending on the conditions. In the first type, the porphyrin molecules are adsorbed on surfaces of the individual dispersed clay sheets or layers (exfoliated complex). In the second type, the porphyrin molecules are intercalated between the stacked clay sheets (intercalated complex). For the exfoliated complex, we have found recently that the porphyrin molecules adsorb in a flat orientation on the clay sheets as monolayers, without discernible aggregation. The high packing density is determined by the fact that the positive charges on the porphyrin precisely neutralize the negative charges on the clay surface. Fluorescence quenching experiments of porphyrins in exfoliated and intercalated complexes by hydroquinone and ascorbate as electron donors were carried out. The quenching rate constant was affected by the charges of the electron donor in solution. When hydroquinone was used as a neutral electron donor, an efficient electron transfer was observed both in exfoliated and intercalated complexes. The fluorescence quenching experiment for the intercalated complex indicated that the diffusion of hydroquinone is restricted in the interlayer space.

DOI： 10.11362/jcssjclayscience1960.12.Supplement2_82

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The electron-transfer reaction in the composite films of a meso-(tetramethylpyridinium)porphyrin (TMPyP)-mesoporous silica (MPS) (TMPyP-MPS) and a methyl viologen (MV2+)- titania nanosheet (TN) (MV2+-TN) was studied by nanosecond transient absorption measurements. The effects of the (TMPyP-MPS) layer on the one-electron reduction process of MV2+ were examined.

DOI： 10.1246/cl.2005.1522

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Dicetyl phosphate (DCP) ions incorporated into layered double hydroxide (LDH) clays to form a DCP/LDH hybrid were prepared and structurally characterized by X-ray diffraction analysis, scanning electron microscopy, thermogravimetry, and differential thermal analyses. DCP was concluded not only to form well-aligned bilayer structures along the vertical axis of the LDH layers but also to be arranged in a distorted hexagonal packing orientation in the lateral planes within the DCP/LDH hybrid interlayers. (c) 2005 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.jcis.2005.04.102

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The hybridization of 1,1'-dimethyl-4,4'-bipyridinium dihydroxide [MV2+(OH-)(2)] into H4Nb6O17 was successfully carried out by a novel neutralization method. X-ray diffraction analysis showed the direct intercalation of the MV2+ ions into both of the two chemically different niobate layers in place of the alkylammonium-niobate composite as the precursor.

DOI： 10.1246/cl.2005.1074

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The LDH clay template polymerization of 12-methacryloyloxydodecanoate (MADA) ions under UV light irradiation resulted in the formation of preferential meso polymer ions through radical propagation in a parallel-oriented MADA hybrid assembly.

DOI： 10.1246/cl.2005.990

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Arenecarboxylate counterions, i.e.. benzoate (BA) and p-t-butylbenzoate (p-t-BBA), were observed to be effective in facilitating E-to-Z photoisomerizations in cast films of 1:1 ion-pair salts of cationic surfactant azobenzene (C8AzoC10N(+)). Such an effect of the arenecarboxylate ions in C8AzoC10N(+) salts showed a contrast to untreated, as-prepared bromide salts, which exhibited no such activity. A remarkable E-to-Z photoisomerization was observed to take place with the cast films of C8AzoC10N(+) salts involving bulky anions,BA (or p-t-BBA); their photochromic behavior corresponded well with the aggregated structures of the 1: 1 ion-pair salts. Analyses of the pi-A isothermal profiles, XRD, and UV-vis spectroscopic investigations showed that C8AzoC10N(+) -Br stacked films form densely packed interdigitated monolayers, whereas films of the C8AzoC10(+) -salt with BA (or p-t-BBA) were found to form loosely packed monolayers.

DOI： 10.1246/bcsj.78.698

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The present investigation reports on the significant differences observed in the efficiency of the polymerization depending on the odd- or even-numbered methylene chains of diacetylenecarboxylates, CH3(CH2)(m-1)C C-C C(CH2)(n-1)CO2- (mono-[m,n]), incorporated in layered double hydroxide (LDH)clay. Upon gamma-ray irradiation of the diacetylenecarboxylates, or mono-[m,n], in LDH clay, polymer hybrids or poly-[m,n]/LDH, which exhibited coloring from light orange to violet, were obtained. The color of the poly-[m,n]/LDH hybrids was strongly dependent on the extent of the polymerization degrees. Moreover, the polymerization degrees were controlled by the number of methylene spacers n between the carboxyl and diacetylene groups. An odd-numbered n for the methylene chain of mono-[m,n] was found to be the determining factor in the efficient polymerization of these self-assembling aggregates within the interlayers of LDH clay.

DOI： 10.1021/la047052c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Composite films of a meso-(tetramethylpyridinium)porphyrin (TMPyP) hybrid incorporated in mesoporous silica (MPS) and cast on a methyl viologen (MV2+)/titania nanosheet hybrid were synthesized and a light-induced charge separation between the two could be observed. These composite thin films were able to initiate a one-electron reduction of the MV2+ ions accompanied by the simultaneous decomposition of the TMPyP organic dye within the mesoporous silica channels.

DOI： 10.1021/la047385+

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The present study is an investigation of a reversible thermal color change induced in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide (LDH) nanosheets. These poly-[m,n]/ LDH hybrids prepared by the photo- or gamma-ray-induced polymerization of diacetylenecarboxylates, i.e., CH3-(CH2)(m-1) CdropC-CdropC(CH2)(n-1)CO2- (mono-[m,n]), and intercalated in LDH lamella sheets, were observed to develop colors ranging from yellow to blue. The change in color was found to depend greatly on the alkyl carbon numbers of the mono-[m,n] (m,n = 10, 11; 5,11; 10,5; 16, 1) values. Moreover, the conformational alignment of the mono-[m,n] within the LDH was observed to be a crucial factor in color development, which was greatly affected by the intercalation degrees and extent of poly(ene-yne) linkage elongation of the polymers. For the poly-[m,n]/LDH hybrids investigated, a reversible color change was found to occur repeatedly and remarkably for the poly- [10,11]/LDH hybrid. This color change occurred at temperatures between ca. 20 and 80 degreesC back and forth from purple red to bright orange, in stark contrast to the irreversible color change for poly-[10,11] without LDH. Moreover, DSC and Raman spectroscopic studies of the LDH hybrids showed that the thermochromic temperature corresponded to the phase transition temperature of 80 degreesC. XRD analysis also indicated that the poly-[m,n]/LDH hybrid could retain its lamella structure during such thermochromic color changes, enabling conformational recovery in the polymer chains by a cooling down of the hybrids to temperatures lower than the transition temperature, while the nonhybrid poly-[10,11] powders exhibited an irreversible color change at 60 degreesC, above which the polymer powder turned amorphous.

DOI： 10.1021/jp045410e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

This work presents the first investigation of an effective methodology for the synthesis of transparent and durable thin films with a high regularity along the c-axis using titania nanosheets (TN) on electrodes. This technique, an electrophoretic deposition method (EPD), was found to be applicable for the preparation of TN thin films deposited on ITO electrodes, a promising nanomaterial for the design of UV-visible light-sensitive energy conversion systems. The deposition of TN was found to be significantly affected by the concentrations, viscosity, and pH values of the aqueous TN solutions. Using quartz crystal analysis (QCA), the optimal deposition conditions for the most adhesive amounts of TN were established, and the delicate balance between the TN solution viscosity and surface charges of the TN layers that govern the amount of TN deposited on the substrate was discerned. Moreover, the deposited thin films were greatly improved by the addition of poly(vinyl alcohol) (PVA) into the solutions, initiating an increase in the deposition weight and optical transmittance, thus leading to firm adhesion onto the substrate. Methyl viologen (MV2+) was intercalated into the TN layers and irradiated with UV light shorter than the end absorption of TN, leading to a blue coloring for the TN/MV2+ thin films attributed to the formation of reduction products from MV2+ and clearly indicating photocatalytic reactivity.

DOI： 10.1021/cm0491882

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

The intercalation of the colorless open (10) and the blue-colored closed forms (1C) of monocationic diarylethene into cation exchange clays and the photochromic reversibility of these hybrid materials was investigated. Both the 10/clay and 1C/clay hybrid powders exhibited reversible color changes upon alternative irradiation of UV and visible light, however, the photochromic durability was found to be strongly influenced by the form upon intercalation, i.e., open or closed, as well as by the coverage degrees. The blue-colored, closed 1C/clay was found to exhibit higher photochromic durability than the 10/clay.

DOI： 10.1080/15421400590946686

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Variation in the coloration of LDH clay-intercalated poly(diacetylenecarboxylates), i.e., poly-[m,n]/LDH, was found to be dependent on the conformations of the carboxylates within the hybrid which were quite sensitive to the carbon numbers, m and n, in the alkyl chains.

DOI： 10.1246/cl.2004.1268

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Diarylethene covalently bonded to the silanol oxygen of the layered surfaces of magadiite was seen to undergo a more improved photochromic reversibility than a corresponding silylated analog in ethanol without fixation to the magadiite.

DOI： 10.1246/cl.2004.1116

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Alternate light illumination of ion-pairs of (3-perfluorooctanecarboxamido) propyltrimethylammonium azobenzene-4-carboxylate (FOAM-AzoB) at 340 and >440 nm was found to initiate a reversible photoisomerization between the E- and Z-azobenzene chromophores in multi-lamella films. This was in sharp contrast to the case of films involving the corresponding unfluorinated ion-pair, 3-(octanecarboxamidopropyl) trimethylammonium azobenzene-4-carboxylate (HOAM-AzoB) in which no substantial isomerization could take place. These photochemical characteristics are discussed here in terms of the free space surrounding the azobenenzene units of the ion-pairs molecularly packed within the films. Characterization studies using XRD and polarized spectroscopy revealed that the FOAM - AzoB stacked films consist of loosely packed interdigitated monolayers whereas HOAM - AzoB was found to form compactly packed bilayer stacked films.

DOI： 10.1039/b302869k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

The preparation of hybrid materials of poly(ethylene terephthalate) (PET) with montmorillonite (Mont) clay was investigated using anchor monomers, i.e. hydroxyethyl isonicotinamide (HENA) or hydroxypentyltrimethylammonium iodide (HPTA), which both have cationic substituents to adsorb onto clay surfaces and a hydroxyethyl moiety (-CH2CH2OH) to react with the polymer chain terminal of PET. The condensation of the mixtures of the intercalation compounds, bis (2-hydroxyethyl) terephthalate (BHET) and HENA/Mont or HPTA/Mont, led to a homogenous and transparent PET hybrid in which the Mont clay particles were scattered homogenously. The HPTA/Mont hybrid films copolymerized with BHET exhibited a dramatic improvement in such characteristics as tensile strength and optical transparency.

DOI： 10.1163/1568554041738184

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The present investigation deals with the light-driven morphological changes in multilamella films of N-methyl-4-octadecyloxystilbazolium arylcarboxylates (C(18)OStZ(+)X(-)) cast on glass slides. The results of XRD analysis show a photostimulated layer expansion and shrinkage of the stacked thin films along the c-axis under alternative illumination at >350 and 254 nm, respectively. It was revealed that such lamellar changes could be switched either way by a reversible transformation between the mono- and bilayer units in these stacked multilamella films. Moreover, such controlled structural adjustments in the alignment could be initiated by the photocyclodimerization of the stilbazolium moieties of the arylcarboxylate salts; i.e., a monolayer-to-bilayer transformation could be induced at a stage of only 10% cyclodimer formation. The photoinduced patterning on the surface of the films was also analyzed by SEM and fluorescence microscopic investigations.

DOI： 10.1021/ja030310s

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A structural investigation of composite films of self-assembling stearate ions (C18) in layered double hydrotalcite clay (LDH) was carried out by means of X-ray diffraction (XRD) analysis, gas chromatography (GC), elemental analysis, thermogravimetry (TG), differential thermal analysis (DTA), and inductive coupled plasma emission spectrometric analysis (ICP-AES). From these detailed characterization studies, it was found that C18 forms a well-aligned bilayer structure within the inorganic LDH layers absorbed by the H2O monolayers with a tilt angle of approximately 29 from the right angle of the layers. Moreover, two-dimensional XRD analysis shows the guest anions to be arranged in a distorted hexagonal packing orientation along the lateral axis.

DOI： 10.1021/la0302448

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Polyfluorinated surfactant (CnF2n+1CONH(CH2)(2)N+(CH3)(2)C16H33Br-; designated as CnF-S, where n = 1-3)/clay hybrid compounds have been shown to provide polyfluorinated microcavities in the clay interlayers with molecular dimensions. The aggregation behavior of a water-soluble porphyrin (tetra(4-sulfonatophenyl)porphyrinatoantimony(V); Sb(V)TSPP) that cointercalates with the surfactant in the polyfluorinated microcavity was investigated. One of the key findings in this study was that the absorption spectra of Sb(V)TSPP molecules that intercalate in the C3F-S polyfluorinated surfactant/clay hybrid microstructures are drastically changed upon dispersion in benzene. The monomer Soret absorption band of Sb(V)TSPP (422 nm) was observed to split into both a longer (438 nm) and a shorter (388 nm) wavelength component. These spectral changes are dependent on the adsorbed amount of Sb(V)TSPP and can be accounted for on the basis of dimer formation. The absorption and emission measurements suggest that two types of dimers (J and H dimers) are formed in the polyfluorinated surfactant/clay hybrid interlayers. It was also found that when the adsorbed amount of surfactant molecules decreased, i.e., when the volume of the polyfluorinated microcavity in the interlayer increased, then the dimerization of Sb(V)TSPP was enhanced. In the case of C2F-S and CIF-S polyfluorinated/clay hybrid compounds, similar spectral behavior arising from dimerization was observed. In contrast, in the case of the hydrocarbon analogues (C3H-S) and cetyltrimethylammonium bromide (CTAB)/clay hybrid compounds, the absorption and emission arising from Sb(V)TSPP indicates that it essentially retains its monomer character. Small-angle X-ray scattering experiments revealed that the clearance space (distance between the layers) for the hybrid compounds in benzene increases compared to that of the solid hybrid compounds. This result indicates a penetration of the benzene molecules into the hybrid layers. It is proposed that the aggregation mechanism of Sb(V)TSPP in polyfluorinated surfactant/clay hybrid compounds obeys the following sequence: (1) formation of a polyfluorinated environment of interlayers that have very weak intermolecular interactions among the surfactant molecules; (2) upon penetration of the benzene solvent molecules, swelling of the hybrid compounds and solvation of Sb(V)TSPP in the interlayers; (3) expulsion of Sb(V)TSPP molecules from the polyfluorinated assemblies into the interlayer space; and (4) migration of Sb(V)TSPP molecules to the microcavities, with concomitant dimer (H and J) formation.

DOI： 10.1021/jp026648a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The microenvironments of a series of polyfluorinated surfactants [CnF2n+1CONH(CH2)(2)N+(CH3)(2)C16H33 Br-; designated as CnF-S, where n = 1-3]/day (saponite) hybrid compounds dispersed in water-saturated benzene were investigated based on the photochemical behavior of Rose Bengal (RB) as a probe molecule. A small-angle X-ray scattering study showed that the interlayer distance (clearance space) of the C3F-S/clay hybrid compounds was expanded up to 3.8 nm by the dispersion in water-saturated benzene from the original distance of 3.0 nm for the dried hybrid compound, indicating expansion of the hybrid compound upon swelling with the solvent benzene. The RB molecules are proposed to form ion-association complexes with the CnF-S surfactant, most likely existing in the vicinity of the ammonium group of the surfactant intercalated in the cation-exchangeable clay saponite. The absorption and fluorescence maxima of RB intercalated in the hybrid compounds were significantly red-shifted from those in aqueous solution. The hybrid compounds provide an environment with polarity between that of ethyl acetate and 1-butanol. The microscopic polarity of the hybrid compounds depends on the fluorocarbon chain length (n) of the surfactant, and the polarities increase with increasing fluorocarbon chain length. On the basis of the observed photochemical behavior of RB, including the relative decomposition rates, excited triplet lifetimes, and relative excited triplet quantum yields, the microscopic concentration of water in the hybrid layer was estimated to decrease in the order C3F-S > C2F-S > C1F-S. These differences are discussed in relation to differences in the microscopic orientational structure of the polyfluorinated surfactant within the clay layer.

DOI： 10.1021/la011697k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Several inorganic-organic hybrid complexes were synthesized from a synthetic clay (Sumecton SA) and cationic porphyrins (+4 charge). In the clay-porphyrin complexes, the lambda(max) values of the Soret bands of the porphyrins were shifted to longer wavelengths compared to those in water. Two types of complexes were formed depending on the preparation method. One is assigned to a complex in which the porphyrin molecules are adsorbed on the external surfaces of the dispersed clay layers (type b complexes). The other is assigned to a complex in which the porphyrin molecules are intercalated within the stacked clay layers (type c complexes). The aqueous solutions of both types of complexes do not scatter light in the UV-visible wavelength region. Surprisingly, the porphyrin molecules were found to adsorb on the clay sheets as densely packed monolayers with controlled intermolecular gap distance. In type b, the porphyrins are adsorbed as flat monolayers, without discernible aggregation, that precisely neutralize the negative charges of the clay surface. According to fluorescence lifetime measurements, the adsorbed porphyrin molecules have sufficiently long lifetimes to be used as sensitizers. The fluorescence lifetimes of tetrakis (AT, N N-trimethyl-anilinium-4-yl) porphyrin were found to be 4.1 ns in type b complexes and 3.2 ns in type c, while that in water is 9.3 ns. We report here a novel method in which highly dense yet controllable structures without aggregation can be produced as adsorbed layers on clay surfaces for the first time. We propose that the mechanism for this extraordinary monolayer adsorption could be a precise matching of distances between the negatively charged sites on the clay sheets and that between the positively charged sites in the porphyrin molecule. We have termed this the "size-matching effect.".

DOI： 10.1021/la011524v

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Intercalation of seven types of cationic surfactants, including polyfluorinated surfactants, into a cation-exchangeable clay mineral, saponite, was investigated. All of the surfactants were found to intercalate in amounts exceeding the cation exchange capacity (CEC). This tendency was more evident in the cases of the polyfluorinated surfactants, ((((perfluoroalkanoyl)amino)ethyl)hexadecyl)dimethylammonium bromide (CnF-S, where n indicates the number of carbons in the perfluoroalkyl group, F denotes a fluorinated surfactant, and S denotes a surfactant having a single, long alkyl chain); C3F-S exhibited intercalation up to 4.4 times CEC as a saturated adsorption limit. The saponite interlayer distance increased upon surfactant intercalation and reached a constant value at intercalation levels exceeding CEC. The occupied areas for each surfactant molecule decreased in the order C1F-S > C2F-S > C3F-S among the polyfluorinated surfactants. All of the experimental results, including the saturated intercalation levels, the occupied areas, the interlayer distances, and the DSC measurements, suggest that CnF-S intercalated in saponite forms a rigidly packed bilayer structure in which the long alkyl chains tilt at an angle of ca. 35degrees with respect to the clay surface. The microscopic structure of the hybrid compounds is discussed.

DOI： 10.1021/la011297x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

An anionic metalloporphyrin (Zn(II)TCPP4-) was successfully co-intercalated into the layered oxide K4Nb6O17 with cationic surfactant (CTAB). Photochemical injection of electrons into the niobate layer was observed.

DOI： 10.1246/cl.2001.644

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Adsorption of the +4 charged cationic porphyrins onto an artificially synthesized smectite was studied. Porphyrin molecules adsorb on the clay sheet with high density to neutralize all the minus charges of the clay surface without aggregation by a novel method of a size-matching of distances between the charge sites. An efficient energy transfer between different porphyrins was induced on the clay surface, while there was no interaction in the ground state.

DOI： 10.1246/cl.2001.128

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GORDON BREACH SCI PUBL LTD  

Tetra-(4-sulfonatophenyl)porphyrinatotin(IV) aggregated efficiently in a clay (saponite) layer intercalated with a polyfluorinated surfactant, but no aggregation was observed in a hydrocarbon type surfactant-clay hybrid environment. Germanium(IV) porphyrins remained as monomers even in the polyfluorinated environment.

DOI： 10.1080/10587250008026162

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Three novel polyfluorinated cationic surfactants having a short perfluoroacyl group and double long alkyl chains, and three corresponding hydrocarbon analogues were synthesized. All of the surfactants formed small unilamellar vesicles in water upon sonication. The temperature conditions for the sonication were carefully determined by confirming that the DSC curve had a reproducible single phase transition peak. The TEM images indicated that the size of the polyfluorinated vesicles was in the range of 56-89 nm. The NMR relaxation study upon the addition of paramagnetic Mn2+ ions to the bulk water phase showed that the terminal trifluoromethyl group of the short acylamide chain in the surfactants faced directly to the bulk water phase; the vesicle had a unique micro-structure with the perfluoroalkyl group extending its arm straightforwardly to the water phase. The vesicles were named "surface polyfluorinated vesicles''. The local oxygen concentrations surrounding each fluorine nucleus and proton of the surfactants within the vesicles were estimated by observing the longitudinal relaxation time under nitrogen and oxygen atmospheres. Oxygen was enriched in the microenvironment surrounding the long alkyl chain and perfluoralkyl group, while the N-methyl group had a low oxygen concentration around it. The micro-distribution of water within the vesicle was discussed by the estimated local concentration of oxygen. The vesicles were thought to be stabilized by the channel-like water connecting the bulk water phase with the hydrated water of the N-methyl groups inside the vesicles. The surface polyfluorinated layer exhibited a substantial protective effect against the oxidative attack of hydroxyl radical generated in the bulk phase water.

DOI： 10.1039/a901833f

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DOI： 10.11454/photogrst1964.66.326

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Applicant：日本化薬株式会社

Application no：特願2009-533172  Date applied：2008.9

Patent/Registration no：特許第5428113号  Date issued：2013.12

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Applicant：国立大学法人広島大学, 日本化薬株式会社

Application no：特願2008-160377  Date applied：2008.6

Announcement no：特開2010-001236  Date announced：2010.1

J-GLOBAL

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Applicant：国立大学法人広島大学, 日本化薬株式会社

Application no：特願2008-160377  Date applied：2008.6

Announcement no：特開2010-001236  Date announced：2010.1

Patent/Registration no：特許第5288372号  Date issued：2013.6

J-GLOBAL

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Applicant：国立大学法人広島大学, 日本化薬株式会社

Application no：特願2008-135951  Date applied：2008.5

Announcement no：特開2009-283786  Date announced：2009.12

J-GLOBAL

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Applicant：日本化薬株式会社

Application no：特願2008-135951  Date applied：2008.5

Announcement no：特開2009-283786  Date announced：2009.12

Patent/Registration no：特許第5428104号  Date issued：2013.12

J-GLOBAL

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Application no：特願04527000 

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Application no：特願2008-12860 

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Application no：特願2007-051403 

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Application no：特願2007-003276 

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