ESR, XPS, UV-VIS and FT-IR investigations on the interaction of no and O2 with highly dispersed C60 supported on silica, titania and alkali cation-exchanged Y-zeolites

Anpo, M.; Zhang, S. G.; Okamoto, Seiji; Yamashita, Hideki; Gu, Zhennan

doi:10.1163/156856795x00477

Cited by 7 publications

(11 citation statements)

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“…Spectral changes similar to those in Figure were also observed during UV oxidation of fullerenes in oxygenated benzene or toluene solutions with UV light irradiation. − These photochemical changes were considered by these researchers to arise from epoxide formation. We attribute the spectral changes in the present experiments (Figure ) to the formation of epoxide type chemical species on the TiO 2 surface since these are similar to those observed with UV irradiation experiments. − Our assignment is further supported from the work of Anpo and co-workers, who characterized C 60 O formation on oxide surfaces using EPR and XPS techniques. Please note that bulk C 60 is chemically stable to visible light irradiation.…”

Section: Resultssupporting

confidence: 84%

“…However, recent reports suggest the oxidation of fullerenes to their epoxides with UV irradiation. − For example, photooxidation of C 60 in benzene solution has been carried out by irradiating oxygenated solutions to UV light, and the photoproduct, fullerene epoxide (C 60 O), has been isolated. Recently, Anpo and co-workers have shown that oxide surfaces such as TiO 2 can facilitate production of EPR-active species of C 60 in air and under ambient conditions or UV irradiation. EPR signals corresponding to C 60 −O n system have also been observed by Pace and his co-workers …”

Section: Introductionmentioning

confidence: 99%

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Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C₆₀ on TiO₂ Nanoparticles

1997

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The photochemical behavior of C60 adsorbed on TiO2 particles has been investigated using diffuse reflectance laser flash photolysis. At submonolayer coverages, irreversible oxidation of C60 is observed on titanium dioxide particles. A photochemical transient with a difference absorption maxima at ∼390 nm and at wavelengths greater than 700 is observed following the 532 nm laser pulse excitation of the C60-coated TiO2 particles. This transient is not sensitive to the presence of oxygen. The bleaching in the 600 nm region confirms the depletion of C60 during the surface photochemical oxidation of C60. Formation of both triplet excited state and the oxidation product are observed at higher coverages. This suggests that direct interaction with the oxide surface is crucial for observing the photochemical oxidation of C60. A biphotonic electron ejection from excited C60 is followed by the formation of fullerene epoxide on the TiO2 surface. The diffuse reflectance laser flash photolysis experiments which highlight the surface photochemistry process of C60 are presented.

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Section: Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C₆₀ on TiO₂ Nanoparticles

1997

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“…Recent reports have described the adsorption of C 60 in faujasite-type zeolites assuming the internal location of fullerene molecules without providing direct experimental evidence supporting the incorporation inside the pores. − These reports appear to be contradictory with the need of employing extra large pore zeotypes claimed by different authors. , …”

Section: Resultsmentioning

confidence: 99%

“…In order to gain control on the superconducting, , optical, − and other molecular properties − of buckminsterfullerene C 60 , an intensive effort is being devoted to develop systems with a reduced dimensionality from tridimensional bulk material to supramolecular entities with zero-dimensionality with respect to the fullerene guest. − The last type of organized assemblies, commonly termed as quantum dots, − express the concept that in a particular situation each fullerene molecule would be isolated from the rest. In this way, intermolecular interactions could be simply avoided.…”

Section: Introductionmentioning

confidence: 99%

On the Incorporation of Buckminsterfullerene C₆₀ in the Supercages of Zeolite Y

et al. 1997

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A series of vapor-phase adsorptions of C60 on NaY zeolite have been carried out under reduced pressure (1 Torr) in the range of temperatures between 400 and 700 °C to determine whether C60-fullerene (0.79 nm diameter) can be incorporated within the internal voids of faujasites (tridirectional large-pore zeolite containing supercavities of 1.3 nm diameter tetrahedrally connected through 0.74 nm windows). After the incorporation procedure, the samples were submitted to exhaustive solid−liquid extraction using toluene as solvent. The optimum adsorption temperature was found to be around 650 °C. Analogous treatment using silica−alumina instead of NaY did not lead to significant retention of C60. The samples were characterized by X-ray powder diffraction, combustion chemical analysis, and thermogravimetry-differential scanning calorimetry as well as by diffuse reflectance, Fourier transform infrared, and magic angle spinning 13C NMR spectroscopies. None of these techniques provides direct evidence of the location of C60 in the zeolite matrix. Molecular dynamics simulations of the faujasite cavity window vibrations at different temperatures (100−800 °C) show that although there are remarkable instantaneous variations in the pore diameter (some of them allowing the entrance of fullerene molecules), the vibrations are too rapid (in the ps time scale) to allow the complete passage of fullerene. Interestingly, the average pore diameter of the faujasite cavity windows are predicted to be rather insensitive to increasing temperatures. Finally, high-resolution electron microscopy has experimentally revealed that fullerene molecules are highly dispersed through the zeolite particles, and in certain regions there are some preferential spatial arrangements of C60. In addition, the presence of weak new reflections in the electron diffractogram pattern of C60-doped NaY (forbidden for a Fd3̄m symmetry such as Y zeolite) was observed. This has been taken as an experimental evidence that a small fraction of C60 molecules has penetrated inside the supercages, showing a spatial order and changing the zeolite symmetry. Meanwhile, most of the C60 molecules are located in the open cavities at the external surface.

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“…Oxidizing superacid media, 105,112,[208][209][210][211][212] chlorine dioxide, 213 and zeolites [214][215][216] have been employed in attempts to prepare stable cations of fullerenes, but even in the best of cases, success has been limited to the unquantified detection of C 60 + by NIR and/or EPR spectroscopies (see sections IV.D and IX.G). The problem seems to be that cations of C 60 The first successful synthesis of a fullerenium radical cation required the development of a new oxidant, one that was strong enough for the task but which did not bring along a reacting nucleophile.…”

Section: Chemical Oxidation Of Fullerenes To Fullerenium Cationsmentioning

confidence: 99%

Discrete Fulleride Anions and Fullerenium Cations

2000

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His research interests include reactive cation and superacid chemistry with inert carborane counterions, ionic liquids, bioinorganic chemistry, spin-coupling phenomena, fullerene chemistry, and new carbon-or porphyrin-based materials. He is a Sloan Fellow, a Dreyfus Teacher−Scholar Awardee, and a Guggenheim Fellow. Robert Bolskar received his B.S. degree in Chemistry from Carroll College in Waukesha, WI, in 1992. He earned his Ph.D. degree at the University of Southern California in Los Angeles under the direction of Christopher Reed in 1997, investigating the synthetic redox chemistry of fullerene anions and cations. In 1998 he moved to the University of California, Riverside, as Managing Research Associate. He is currently Senior Chemist at TDA Research in Wheat Ridge, CO. His research interests include the chemistry and physics of fullerene compounds, supramolecular chemistry, strongly oxidizing systems, and electrophilic cations.

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ESR, XPS, UV-VIS and FT-IR investigations on the interaction of no and O2 with highly dispersed C60 supported on silica, titania and alkali cation-exchanged Y-zeolites

Cited by 7 publications

References 20 publications

Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C₆₀ on TiO₂ Nanoparticles

Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C₆₀ on TiO₂ Nanoparticles

On the Incorporation of Buckminsterfullerene C₆₀ in the Supercages of Zeolite Y

Discrete Fulleride Anions and Fullerenium Cations

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ESR, XPS, UV-VIS and FT-IR investigations on the interaction of no and O2 with highly dispersed C60 supported on silica, titania and alkali cation-exchanged Y-zeolites

Cited by 7 publications

References 20 publications

Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C60 on TiO2 Nanoparticles

Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C60 on TiO2 Nanoparticles

On the Incorporation of Buckminsterfullerene C60 in the Supercages of Zeolite Y

Discrete Fulleride Anions and Fullerenium Cations

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Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C₆₀ on TiO₂ Nanoparticles

Photochemistry on Semiconductor Surfaces. Visible Light Induced Oxidation of C₆₀ on TiO₂ Nanoparticles

On the Incorporation of Buckminsterfullerene C₆₀ in the Supercages of Zeolite Y