Energy transfer reaction of cationic porphyrin complexes on the clay surface: effect of sample preparation method

Takagi, Shinsuke; Eguchi, Miharu; Shimada, Takahiro; Hamatani, Satoshi; Inoue, Haruo

doi:10.1163/156856707779160889

Cited by 22 publications

(38 citation statements)

References 24 publications

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“…This can be explained by the ease with which the porphyrin 4-pyridyl group approaches the TiO 2 due to the interaction between incompletely coordinated titanium atoms on the surface of TiO 2 , and the lone electron pair of the nitrogen atom, favoring electron transfer from a photosensitizer to the TiO 2 surface. On the other hand, the steric effect of the methyl (−CH 3 ) group prevents the SnTMPyP from approaching the surface of TiO 2 or Pt, thus inhibiting the electron transfer. Additionally, it can be seen (see also Figure ) that the energy of the electron in the π-radical anion of SnTMPyP (estimated by the first reduction potential of the respective porphyrin) and its further reduction products is the lowest among the porphyrins studied and approaches the energy required for the proton reduction, which could make this porphyrin less efficient, if any overpotential is present.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, according to the redox potential sequence they have a lower oxidizing strength in the excited state for reductive quenching with EDTA as discussed in section . , On the other hand, N -methyl-4-pyridyl is the most electron-withdrawing substituent with a longer lifetime of its π-radical anion and a higher tendency to form phlorin rather than chlorin. However, it cannot be adsorbed on the semiconductor due to the steric effect of the methyl group hindering its approach to the TiO 2 or to the catalyst surfaces. The 4-pyridyl group has desirable characteristics, namely, electron-withdrawing ability and no steric hindrance preventing it from approaching the TiO 2 surface.…”

Section: Resultsmentioning

confidence: 99%

“…For a photodriven system, where solar energy is stored as H 2 , it is necessary to use effective and stable porphyrin because chlorophylls extracted from natural systems are not stable . A series of works have been devoted to the characterization of the structural and photochemical properties of organized systems of porphyrins in inorganic micro- and nanostructured host materials for photochemical reactions, the intermediate structures of metal porphyrins in their photocatalytic reactions as well as Sb(V) and Sn(IV) porphyrins having strong oxidizing power as photosensitizers in photochemical systems. ,− …”

Section: Introductionmentioning

confidence: 99%

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Influence of Meso-Substitution of the Porphyrin Ring on Enhanced Hydrogen Evolution in a Photochemical System

et al. 2016

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This study establishes the relationships between the structure of a series of meso-substituted tin(IV) porphyrins and their efficiency as photosensitizers for hydrogen generation in the Sn(IV)P/Pt–TiO2 nanocomposite system. The electrochemical properties of a series of SnPs, the catalytic performance of Pt nanomodifications, and the morphology of the Pt/TiO2 nanocomposites were characterized by electrochemical and electron microscopy methods. The dependence of photocatalytic performance on the structure for a series of Sn(IV) meso-substituted phenyl porphyrins was studied, and possible mechanisms are discussed employing the results of the electrochemical studies. It was found that the time course and type of the photochemically reduced species of Sn(IV)Ps, which are essential intermediates, are important factors and depend on the electronegativity of the metal center, the character of meso-substituents of the porphyrin ring, and pH and are correlated with the redox potential sequence of the respective Sn(IV)Ps: SnTMPyP > SnTPyP > SnTPPS > SnTPPC. Optimization of the experimental parameters was performed with regard to the SnPs with different functional groups, pH values, concentrations of Pt/TiO2, light intensity, and Pt nanoparticles with different surface stabilizers. Finally, the maximum hydrogen yield under visible light was obtained from the system of Sn(IV) meso-tetra(4-pyridyl)porphyrin dichloride (SnTPyP) sensitized TiO2/Pt prepared by the citrate method/EDTA at pH 9.0. This demonstrates that the photochemically reduced species of SnTPyP are relatively long lived, so they have enough time to complete electron transfer to TiO2 and/or Pt. The adsorption of SnTPyP on the TiO2/Pt surface is therefore not essential for hydrogen generation. Moreover, this study demonstrates for the first time the synergic effect of the excitation of TiO2 and mostly Q-bands of Sn(IV)P (wavelength range 390–650 nm), which enhances the efficiency of photocatalytic hydrogen generation in the system. The Soret band of Sn(IV)TPyP was found to produce a minor (about 23%) contribution to the photocatalytic activity of the porphyrin sensitizer in this system. Possible processes involved are discussed, and mechanisms are proposed explaining different aspects of a series of photocatalytic systems with SnPs and Pt catalysts for hydrogen production under visible light. These structure–function relationships are essential to effectively harness solar energy for hydrogen production as well as for a wide range of energy and environmentally related problems.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Meso-Substitution of the Porphyrin Ring on Enhanced Hydrogen Evolution in a Photochemical System

et al. 2016

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“…The concentration of the dyes, which are adsorbed on the surface of colloidal particles or are intercalated in solid matrix, is mostly sufficiently high. The close intermolecular distances between ED and EA molecules support an efficient FRET (Takagi et al, 2007). Multistep FRET has been observed in ternary or more complex systems based on clay minerals and three types of interacting dyes (Bujdák et al, 2011;Belušáková et al, 2015).…”

Section: Resonance Energy Transfer In Hybrid Materialsmentioning

confidence: 88%

Hybrid systems based on organic dyes and clay minerals: Fundamentals and potential applications

Bujdák

2015

Clay miner.

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This review summarizes several aspects of the interactions between organic dyes and clay minerals, and presents some interesting properties of hybrid materials based on these components. It explains the basic phenomena and photophysical properties of dye/clay mineral hybrid systems (DCHS) while examining the role of clay minerals in them. A brief history of using dyes as tools for clay research and on traditional materials based on DCHS is presented. Metachromasy, the phenomenon of colour change related to the formation of dye molecular aggregates is described in detail and analysed from various perspectives. The properties of DCHS, including photoactivity, luminescence, photocatalytic properties, optical anisotropy and non-linear optical properties are analysed in detail. Clay minerals often play a significant role in the occurrence of specific photophysical phenomena such as resonance energy transfer and luminescence quenching and may influence various reactions, such as conformational changes in dye molecules, photochromism, photoisomerization, photosensitization and other photochemical processes. Routes to synthesize various types of hybrid materials are also described here. The relevance of DCHS for clay research, chemistry and materials science is summarized briefly.

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“…The mixing was aimed at reducing the void size in the films which causes the reduced light scattering. 10) and Rockwood Additives, 11) respectively. The cation exchange capacity (CEC) of these smectites were determined as 76 and 80 meq/100 g, respectively, by quantitative elemental analysis of sodium using inductively-coupled plasma atomic emission spectrometry (ICP-AES).…”

Section: Introductionmentioning

confidence: 99%

Heat Resistant Transparent Flexible Film Obtained from Two Tetraphenylphosphonium Modified Smectites with Different Particle Size

Kawasaki

Ebina

Hanaoka

et al. 2011

Jpn. J. Appl. Phys.

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Transparent clay films were prepared using tetraphenyl phosphonium (TPP) modified smectites (TPP-SA, TPP-HE, and TPP-SA-HE), which were prepared by ion exchange of either synthetic saponite (SA) or synthetic hectorite (HE) as well as a mixture of these two kinds of smectites (SA-HE) with TPP-bromide (TPP-Br). Uniform liquid dispersions of these TPP-smectites were successfully prepared by adding N,N-dimethylformamide (DMF) to hydrous gels of TPP-smectites. Finally, transparent self-supported films of about 30 m thickness were prepared by casting these dispersions. From the optical studies, it was confirmed that the transparent clay films maintained their optical transparency in the visible range even after annealing at 350 C for an hour. Particularly, haze value of the TPP-SA-HE film decreased by one-third compared to TPP-SA, and it was also confirmed that the flexibility of TPP-SA-HE film was better than that of TPP-HE. From the cross-sectional scanning electron microscope (SEM) images, it was confirmed that TPP-SA film has large voids, which causes scattering of light compared to TPP-HE. Finally, the average void size was reduced by mixing these two TPP-smectites with different particle size. #

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Energy transfer reaction of cationic porphyrin complexes on the clay surface: effect of sample preparation method

Cited by 22 publications

References 24 publications

Influence of Meso-Substitution of the Porphyrin Ring on Enhanced Hydrogen Evolution in a Photochemical System

Influence of Meso-Substitution of the Porphyrin Ring on Enhanced Hydrogen Evolution in a Photochemical System

Hybrid systems based on organic dyes and clay minerals: Fundamentals and potential applications

Heat Resistant Transparent Flexible Film Obtained from Two Tetraphenylphosphonium Modified Smectites with Different Particle Size

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