Synthesis and Photodynamics of 9-Mesitylacridinium Ion-Modified Gold Nanoclusters

Fukuzumi, Shunichi; Hanazaki, Ryo; Kotani, Hiroaki; Ohkubo, Kei

doi:10.1021/ja105314x

Cited by 27 publications

(49 citation statements)

References 33 publications

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“…[15] The ET state is capable of oxidizing NADH (E ox = 0.76 V vs. SCE) [33,34] by the MesC + moiety in AcrCMesC + (E red = 1.88 V vs. SCE) [15] to produce NADHC + and AcrC-Mes (Scheme 1). [17] The resulting NADHC + undergoes facile deprotonation to produce NADC that can reduce Acr + -Mes by ET from NADC to produce additional AcrC-Mes.…”

Section: Resultsmentioning

confidence: 99%

“…[17] Two equivalents of AcrC-Mes were produced by ET from NADH to the ET state of Acr + -Mes (AcrC-MesC + ) and also ET from the resulting deprotonated NADHC + (NADC) to Acr + -Mes, as shown in Scheme 3. [17] The rate constant of the ET reduction of Acr + -Mes (E red = À0.66 V vs. SCE) with NADC (E ox = À1.1 V) [34] to Acr + -Mes (E red = À0.66 V vs. SCE) [15] was re- ported to be 3.7 10 9 m À1 s…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

“…[5b] In this context, we have reported an efficient photocatalytic hydrogen-evolution system without MV 2 + , composed of a simple electron donor-acceptor dyad, 9-mesityl-10-methylacridinium ion (Acr + -Mes), [15] dihydronicotinamide adenine dinucleotide (NADH), [16] and water-soluble Pt nanoparticles (PtNPs). [17] PtNPs have been widely employed as a hydrogen-evolution catalyst in various hydrogen-evolution systems, whereas the catalytic mechanism of hydrogen evolution has yet to be clarified.…”

Section: Introductionmentioning

confidence: 99%

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Size‐ and Shape‐Dependent Activity of Metal Nanoparticles as Hydrogen‐Evolution Catalysts: Mechanistic Insights into Photocatalytic Hydrogen Evolution

Kotani

Hanazaki

Ohkubo

et al. 2011

Chemistry A European J

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103

126

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The catalytic activity of Pt nanoparticles (PtNPs) with different sizes and shapes was investigated in a photocatalytic hydrogen-evolution system composed of the 9-mesityl-10-methylacridinium ion (Acr(+)-Mes: photocatalyst) and dihydronicotinamide adenine dinucleotide (NADH: electron donor), based on rates of hydrogen evolution and electron transfer from one-electron-reduced species of Acr(+)-Mes (Acr·-Mes) to PtNPs. Cubic PtNPs with a diameter of (6.3±0.6) nm exhibited the maximum catalytic activity. The observed hydrogen-evolution rate was virtually the same as the rate of electron transfer from Acr·-Mes to PtNPs. The rate constant of electron transfer (k(et)) increased linearly with increasing proton concentration. When H(+) was replaced by D(+), the inverse kinetic isotope effect was observed for the electron-transfer rate constant (k(et)(H)/k(et)(D)=0.47). The linear dependence of k(et) on proton concentration together with the observed inverse kinetic isotope effect suggests that proton-coupled electron transfer from Acr·-Mes to PtNPs to form the Pt-H bond is the rate-determining step for catalytic hydrogen evolution. When FeNPs were used instead of PtNPs, hydrogen evolution was also observed, although the hydrogen-evolution efficiency was significantly lower than that of PtNPs because of the much slower electron transfer from Acr·-Mes to FeNPs.

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Section: Resultsmentioning

confidence: 99%

Section: Wwwchemeurjorgmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Size‐ and Shape‐Dependent Activity of Metal Nanoparticles as Hydrogen‐Evolution Catalysts: Mechanistic Insights into Photocatalytic Hydrogen Evolution

Kotani

Hanazaki

Ohkubo

et al. 2011

Chemistry A European J

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103

126

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“…69 However, the formation of the electron-transfer state (Acr • -Mes •+ ) has been clearly demonstrated by observation of the near-IR absorption band due to the π-dimer radical cation formed between Acr • -Mes •+ and Acr + -Mes. [70][71][72] The long lifetime of the electron transfer state (Acr • -Mes •+ ) has enabled to clarify the structural changes in which the N-methyl group in Acr • was bent, and a weak electrostatic interaction between Mes •+ and a counteranion in the crystal (ClO 4 -) was observed upon photoinduced electron transfer by laser pump and X-ray probe crystallographic analysis. 73 The high energy and long lifetime of Acr • -Mes •+ has also enabled to use Acr + -Mes as an efficient electron-transfer photocatalyst for highly selective oxygenation of various substrates with O 2 via selective radical coupling of the donor radical cation and O 2…”

Section: Photocatalytic Oxygenation Using 9-mesityl-10methylacridiniumentioning

confidence: 99%

Selective photocatalytic reactions with organic photocatalysts

2013

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Selective photocatalytic oxygenation of various substrates has been achieved using organic photocatalysts via photoinduced electron-transfer reactions of photocatalysts with substrates and dioxygen under visible light irradiation. Photoinduced electron transfer from benzene to the singlet-excited state of the 3-cyano-1-methylquinolinium ion has enabled the oxidation of benzene by dioxygen with water to yield phenol selectively. Alkoxybenzenes were obtained when water was replaced by alcohols under otherwise the same experimental conditions. Photocatalytic selective oxygenation reactions of aromatic compounds have also been achieved using an electron donor-acceptor linked dyad, 9-mesityl-10-methylacridinium ion (Acr + -Mes) acting as a photocatalyst and dioxygen as an oxidant under visible light irradiation. The oxygenation reaction is initiated by intramolecular photoinduced electron transfer from the mesitylene moiety to the singlet-excited state of the acridinium moiety of Acr + -Mes to afford an extremely longlived electron-transfer state. The electron-transfer state can oxidize and reduce substrates and dioxygen, respectively, leading to selective oxygenation and halogenation of substrates. C-C bond formation of substrates has also been made possible by using Acr + -Mes as a photocatalyst.

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“…[47] At room temperature in solution, however, AcrC-MesC + forms a p dimer radical cation with Acr + -Mes, which decays by diffusion-limited bimolecular back electron transfer. [48,49] To avoid such bimolecular back electron transfer, electron donor-acceptor organic molecules must be isolated from each other, as in natural photosynthetic centers in which they are separated in chloroplast thylakoid membrane protein environments. This was achieved by incorporating Acr + -Mes into nanosized mesoporous silica-alumina (AlMCM-41) with the use of cation exchange to obtain the nanocomposite (i.e., Acr + -Mes@AlMCM-41), [50] because silica-alumina has cation exchange sites.…”

Section: Nanomaterials For Light Harvesting and Charge Separationmentioning

confidence: 99%

Shape‐ and Size‐Controlled Nanomaterials for Artificial Photosynthesis

Fukuzumi

Yamada

2013

ChemSusChem

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Nanomaterials with various shapes and sizes have been developed to mimic functions of photosynthesis in which solar energy conversion is achieved by using nanosized proteins with controlled shapes and sizes. Artificial photosynthesis consists of light-harvesting and charge-separation processes together with catalytic units of water oxidation and reduction. Nanosized mesoporous silica-alumina was utilized to encapsulate organic charge-separation molecules inside the nanospace to elongate the lifetimes of the charge-separated states, as observed in the photosynthetic reaction centers. Metal nanoparticles with controlled shapes and sizes have also been utilized as efficient catalysts for photocatalytic hydrogen evolution from water with reductants by using electron donor-acceptor organic molecules as photocatalysts. The control of the shape and size of metal nanoparticles plays a very important role in achieving high catalytic performance in catalytic hydrogen evolution in water reduction and also in catalytic oxygen evolution in water oxidation.

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Synthesis and Photodynamics of 9-Mesitylacridinium Ion-Modified Gold Nanoclusters

Cited by 27 publications

References 33 publications

Size‐ and Shape‐Dependent Activity of Metal Nanoparticles as Hydrogen‐Evolution Catalysts: Mechanistic Insights into Photocatalytic Hydrogen Evolution

Size‐ and Shape‐Dependent Activity of Metal Nanoparticles as Hydrogen‐Evolution Catalysts: Mechanistic Insights into Photocatalytic Hydrogen Evolution

Selective photocatalytic reactions with organic photocatalysts

Shape‐ and Size‐Controlled Nanomaterials for Artificial Photosynthesis

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