Isolation and characterization of the metallofullerene LaC82

Kikuchi, Kôichi; Suzuki, Satoshi; Nakao, Yasuhiko; Nakahara, N.; Wakabayashi, Tomonari; Shiromaru, H.; Saito, Kazuya; Ikemoto, Isao; Achiba, Yohji

doi:10.1016/0009-2614(93)e1269-m

Cited by 227 publications

(99 citation statements)

References 18 publications

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“…It is envisioned, therefore, that metallofullerenes could provide a unique alternative to chelating compounds because of their resistance to metabolism and their high kinetic stability. Additionally, the large carbon-based surface area of fullerenes and metallofullerenes (Ϸ200 Å 2 ) facilitates the development of tissue-targeting compounds by using established metallofullerene derivative chemistry (10)(11)(12)(13)(14)(15). Thus, the metallofullerenes may be useful as a new, more stable alternative for transporting radiometals in vivo.…”

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confidence: 99%

“…4), but comparatively little is known about endohedral metallofullerenes because of their low production yields, low solution solubilities, difficult purification, and air sensitivity (5)(6)(7)(8)(9). However, advances in HPLC purification procedures (5)(6)(7)(8)(9) and chemical derivatization (10)(11)(12)(13)(14)(15) of fullerenes have recently expanded research possibilities into applications for metallofullerenes when relatively small amounts of material are required.…”

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confidence: 99%

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In vivo studies of fullerene-based materials using endohedral metallofullerene radiotracers

Cagle

Kennel²,

Mirzadeh³

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

287

156

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Biodistribution studies of a water-soluble radioactive metallofullerene compound have been conducted using BALB͞c mice. To this end, a sample containing Ho x @C 82 (x ‫؍‬ 1, 2) was purified and derivatized to prepare the watersoluble metallofullerol, Ho x @C 82 Since the discovery of fullerenes in 1985 (1) and the subsequent incorporation of metal atoms within their carbon cage (2), intense interest has focused on these unique molecules. Research efforts have greatly extended our knowledge of the chemical and biological properties of empty fullerenes (3; for review, see ref. 4), but comparatively little is known about endohedral metallofullerenes because of their low production yields, low solution solubilities, difficult purification, and air sensitivity (5-9). However, advances in HPLC purification procedures (5-9) and chemical derivatization (10-15) of fullerenes have recently expanded research possibilities into applications for metallofullerenes when relatively small amounts of material are required.One potential application for metallofullerenes is in the field of nuclear medicine. Current radiopharmaceuticals employ small quantities (nanograms to milligrams) of drugs containing specially chelated radioisotopes of metals for imaging or therapeutic applications. The chelating ligands prevent direct binding of the toxic metal ions with serum components and tissue by providing a thermodynamically stable molecular environment. A major concern with these drugs, however, is their in vivo kinetic instability, which can allow the release of small amounts of toxic radiometals (16). It is envisioned, therefore, that metallofullerenes could provide a unique alternative to chelating compounds because of their resistance to metabolism and their high kinetic stability. Additionally, the large carbon-based surface area of fullerenes and metallofullerenes (Ϸ200 Å 2 ) facilitates the development of tissue-targeting compounds by using established metallofullerene derivative chemistry (10-15). Thus, the metallofullerenes may be useful as a new, more stable alternative for transporting radiometals in vivo.Empty fullerenes have low cytotoxicity both in vitro (17-22) and in vivo (17,(23)(24)(25)(26), despite one report of a photosensitizing C 60 derivative (24). In addition, empty fullerenes and their derivatives have been tested for their biodistribution, and some C 60 derivatives have shown promise as anti-HIV (27-34) and anticancer (35-37) agents and as an agent to reduce reactive oxygen species (20,21). Dugan et al. (17,38) have also demonstrated the usefulness of fullerene derivatives as biological freeradical scavengers in vivo. Research involving the biodistribution of fullerenes in vivo is limited to studies on C 60 and La@C 82 suspensions (23, 25), and to three water-soluble C 60 derivatives (26,30,39). All of these studies indicate rapid localization and long-term residency in the liver (Ͻ1% clearance), and one of the studies demonstrated that fullerenes are not metabolized rapidly in vivo (39). To help opti...

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confidence: 99%

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confidence: 99%

In vivo studies of fullerene-based materials using endohedral metallofullerene radiotracers

Cagle

Kennel²,

Mirzadeh³

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

287

156

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“…All of these metal atoms are known to be included in fullerene carbon cage , Kikuchi et al (1993), Takata et al (1995)]. Even though the metalcontaining fullerene is expected to have very interesting physical and chemical properties, the macroscopic generation of such fullerene is extremely difficult.…”

Section: Metal-carbon Binary Clustersmentioning

confidence: 99%

“…Then, in 1990 the macroscopic generation by arcdischarge technique [Krätschmer et al (1990), Haufler et al (1991)] was introduced. Furthermore, higher fullerene [Kikuchi et al (1992)], metal-containing fullerene , Kikuchi et al (1993), Takata et al (1995] and nanotube [Iijima (1991), Thess et al (1996)] were also generated by the similar technique. Even though the generation of fullerene is now possible by the arc-discharge technique or laser-oven technique ), Wakabayashi et al (1997], the formation mechanism of such spherical molecules is not clarified yet.…”

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FT-ICR Studies of Laser Desorbed Carbon Clusters.

Maruyama

Yoshida²,

Kohno³

1999

Trans.JSME, Ser.B

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Atomic and molecular clusters are being recognized as playing an important role in the thin-film deposition process and phase-change phenomena. Furthermore, small clusters are the most adequate system for the verification of quantum molecular dynamics calculations such as the interference of light and matter. Hence, experimental treatments of such atomic and molecular clusters are now desired. In order to examine such clusters, we have implemented a Fourier transform ion cyclotron resonance (FT-ICR) spectrometer directly connected to a laser-vaporization supersonicexpansion cluster beam source.The heart of the FT-ICR spectrometer was made of ICR cell cylinder centered in a strong homogeneous magnetic field of a 6 Tesla superconducting magnet. The atomic cluster beam was generated outside of magnetic field by the laser vaporization of a solid sample disk, followed by cooling with supersonic expansion of pulsed helium gas. The ionized cluster was carried by helium gas and directly injected to the magnetic field. By measuring the ion-cyclotron frequency, which was inversely proportional to the ion mass, a very highresolution mass spectrum can be obtained.The high mass-resolution was demonstrated for positive mass spectra of silicon, carbon, and metal-carbon binary clusters and negative mass spectra of metal-carbon binary clusters. For bare carbon positive clusters, we found the special condition where the odd-numbered clusters were observed in the range of C 30 to C 50 and the continuous change to C 60 -dominant condition and 'normal' even-numbered distribution.An example of mass spectrum measured by the directinjection FT-ICR apparatus is shown in Figure A Copyright © 1999 by ASME 2Magnetic field f :Ion cyclotron resonance frequency m :Mass of cluster ion q :Charge of cluster ion r :Radius of cyclotron motion v : Velocity INTRODUCTIONAtomic and molecular clusters are being recognized as playing an important role in the thin-film deposition process and phase-change phenomena. Furthermore, small clusters are the most adequate system for the verification of quantum molecular dynamics calculations such as the interference of light and matter, since a cluster is the unique small atomic system with a physically clear boundary condition. Hence, experimental treatments of such atomic and molecular clusters are now desired.Studies of clusters have another possibility leading to the discovery of new materials such as fullerene. Fullerene was first discovered in the mass-spectroscopic study by Kroto et al. (1985). Then, in 1990 the macroscopic generation by arcdischarge technique [Krätschmer et al. (1990), Haufler et al. (1991)] was introduced. Furthermore, higher fullerene [Kikuchi et al. (1992)], metal-containing fullerene , Kikuchi et al. (1993), Takata et al. (1995] and nanotube [Iijima (1991), Thess et al. (1996)] were also generated by the similar technique. Even though the generation of fullerene is now possible by the arc-discharge technique or laser-oven technique ), Wakabayashi et al. (1997], the formation ...

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“…It was among the first metallofullerenes to be isolated [13]; since then it has been characterized by a variety of physical methods (see [2][3][4][5]14] and references therein). It has also been subject of several investigations in the gas phase [15][16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%