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Sample records for gadolinium-containing endoedral metallofullerenes

  1. Endohedral metallofullerenes

    NASA Astrophysics Data System (ADS)

    Shinohara, H.

    2000-06-01

    Endohedral metallofullerenes (fullerenes with metal atom(s) encapsulated) are novel forms of fullerene-based materials which have attracted wide interest during the past eight years, not only in physics and chemistry but also in such interdisciplinary areas as materials and biological sciences. In this paper, advances in the production, separation (isolation) and various spectroscopic characterizations of endohedral metallofullerenes are presented in an attempt to clarify their structural, electronic and solid state properties. Endohedral metallofullerenes are normally produced by DC electric arc discharge of metal/graphite composite rods used as positive electrodes. The metallofullerenes can also be produced by the so-called laser furnace method which incorporates laser vaporization of the composite rods under high temperature (ca 1000 °C). The endohedral metallofullerenes so far produced are centred on group 2 and 3 metallofullerenes such as Sc, Y, La, Ca, Sr and Ba as well as lanthanide metallofullerenes (Ce-Lu). These metal atoms have been encapsulated in higher fullerenes, especially in C82. These metallofullerenes have easily been extracted by solvents from primary soot. By using an elaborate high-performance liquid chromatography technique, the metallofullerenes are completely purified and isolated like C60 and C70. Synchrotron x-ray diffraction, 13C NMR and ultra-high vacuum scanning tunnelling microscopy (UHV-STM) studies have revealed that metal atoms are indeed encapsulated by the carbon cage and that the metal atoms are not in the centre of the fullerene cage but very close to the carbon cage, indicating the presence of a strong metal-cage interaction. It has been revealed by electron spin resonance and also by theoretical calculations that substantial electron transfers take place from the encaged metal atom to the carbon cage: intrafullerene electron transfers. Good examples are lanthanum and yttrium metallofullerenes which have the charge states of

  2. Cerium metallofullerenes

    NASA Astrophysics Data System (ADS)

    Georgi, Petra; Kuran, Pavel; Dunsch, Lothar

    1999-09-01

    With respect to its redox state cerium is of high interest in metallofullerene research as its preferable redox states are 3+ and 4+. As representative structures of the cerium fullerene family both Ce2@C72 and Ce@C82 were prepared by the Krätschmer arc burning method. The metallofullerene Ce2@C72 was isolated for the first time using a two stage HPLC separation technique. The UV-Vis-NIR, IR and ESR spectra were compared with those of other C72 cage metallofullerenes. The existence and stability of the Ce2@C72 structure supports the assumption that the C72 carbon cage can be stabilised by metal ions. The endohedral fullerene Ce@C82 was also isolated by two stage HPLC and characterized by UV-Vis-NIR, IR and ESR spectroscopy for comparison with other endohedral C82 fullerenes. The redox properties of this metallofullerene structure were studied by cyclic voltammetry.

  3. Characterization of actinide metallofullerenes

    NASA Astrophysics Data System (ADS)

    Akiyama, K.; Sueki, K.; Zhao, Y.-L.; Haba, H.; Tsukada, K.; Kodama, T.; Kikuchi, K.; Ohtsuki, T.; Nagame, Y.; Nakahara, H.; Katada, M.

    2001-10-01

    In this paper, the characterization of a number of actinoid metallofullerenes is reported. From the similarity of the HPLC elution behavior and identification by mass spectroscopy we observe that the electronic structures of U, Np, and Am metallofullerenes are extremely similar to that of Ce@C82 and that the oxidation states of encapsulated Th and Pa have the value +3 or 4.

  4. Spectroscopic Characterization of Metallofullerenes

    NASA Astrophysics Data System (ADS)

    Bethune, D. S.; de Vries, M. S.; Macfarlane, R.; Wittman, G.; Grannan, S.; Birmingham, J.; Richards, P.; Stevenson, S.; Glass, T.; Burbank, P.; Sun, Z.; Dorn, H. C.

    1996-03-01

    Scandium and Erbium metallofullerenes have been isolated using HPLC techniques and characterized by NMR, optical and far IR spectroscopy. In particular, Sc NMR spectra of Sc_2@C_2n species for several n have been obtained, and far infrared spectra of both discandium and and dierbium metallofullerenes have been measured. These show structure in the 20-200 cm-2 where vibrations of the encapsulated metal atoms are expected. Fluorescence spectra from dierbium metallofullerenes in the 1.5 μm region have been obtained at He and room temperatures.

  5. Endohedral Metallofullerene Derivatives

    NASA Technical Reports Server (NTRS)

    Dorn, Harry C. (Inventor); Iezzi, Erick B. (Inventor); Duchamp, James (Inventor)

    2008-01-01

    Trimetallic nitride endohedral metallofullerene derivatives and their preparation are described. The trimetallic nitride endohedral metallofullerene derivatives have the general formula A(sub 3-n)X(sub n)@C(sub m)(R) where n ranges from 0 to 3, A and X may be trivalent metals and may be either rare earth metal or group IIIB metals, m is between about 60 and about 200, and R is preferably an organic group. Derivatives where the R group forms cyclized derivatives with the fullerene cage are also described.

  6. Another big discovery-metallofullerenes.

    PubMed

    Shinohara, Hisanori

    2016-09-13

    Several days after the first experimental observation of the 'magic number' soccerball-shaped C60 in a laser-vaporized cluster beam mass spectrum by Kroto and co-workers (Heath et al 1985 J. Am. Chem. Soc. 107, 7779-7780. (doi:10.1021/ja00311a102)) they also found a magic number feature owing to La@C60 in a mass spectrum prepared by laser vaporization of a LaCl3-impregnated graphite rod. With the advent of macroscopic synthesis and the following successful separation and purification of metallofullerenes, both experimental and theoretical studies of metallofullerenes have developed quite rapidly to date so as to elucidate their structural, electronic, magnetic and transport properties. Furthermore, a bottom-up closed network growth mechanism has experimentally been shown to play a crucial role in generating various types of metallofullerenes.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'. PMID:27501973

  7. Production and characterization of metallofullerene superatoms

    SciTech Connect

    Ying, Z.C.; Hettich, R.L.; Puretzky, A.A.; Haufler, R.E.; Compton, R.N.

    1994-09-01

    Lanthanum metallofullerenes, with the La atoms presumably located inside the carbon cages, were produced using the laser vaporization method with optimum parameters, and concentrated using vacuum sublimation. The obtained material was analyzed using Fourier transform mass spectrometry. The electron affinities of LaC{sub n} (n = 60, 70 {minus} 84) were determined, using the charge-transfer bracketing technique, to be in a range between 2.7 {plus_minus} 0.2 and 3.3 {plus_minus} 0.3 eV. The ionization potentials of these metallofullerenes were measured to be less than 6.2 eV.

  8. Synthesis, characterization, and neutron activation of holmium metallofullerenes

    SciTech Connect

    Cagle, D.W.; Thrash, T.P.; Wilson, L.J.; Alford, M.; Chibante, L.P.F.; Ehrhardt, G.J.

    1996-08-28

    Isolation of the first macroscopic quantities of endohedral holmium metallofullerenes (principally Ho@C{sub 82}, Ho{sub 2}@C{sub 82}, and Ho{sub 3}@C{sub 82} by LD-TOF mass spectrometry) has been accomplished by carbon-arc and preparative HPLC methodologies. The detailed procedure for production and isolation of the metallofullerenes includes a new technique whereby holmium-impregnated electrodes are prepared simply by soaking porous graphite rods in an ethanolic solution of Ho(NO{sub 3}){sub 3}.xH{sub 2}O. Monoisotopic {sup 165}Ho offers a unique combination of advantages for neutron-activation studies of metallofullerenes, and purified samples containing {sup 165}Ho@C{sub 82}, {sup 165}Ho{sub 2}@C{sub 82}, and {sup 165}Ho{sub 3}@C{sub 82} have been activated by high-flux neutron irradiation ({Phi} = 4 x 10{sup 13}n cm{sup -2} s{sup -1}) to generate {sup 166}Ho metallofullerenes, which undergo {beta}{sup -} decay to produce stable {sup 166}Er. Chemical workup of the irradiated samples, followed by re-irradiation, has been used to demonstrate that observed decomposition of holmium metallofullerenes is due mainly to `fast` neutron damage rather than to holmium atom nuclear recoil (E{sub max} = 200 eV). This implies that metallofullerene damage can be minimized by using neutron fluxes with the highest possible thermal component. 60 refs., 4 figs.

  9. Structures and Dynamics of Endohedral Scandium Metallofullerenes

    NASA Astrophysics Data System (ADS)

    Shinohara, H.; Tansho, M.; Inakuma, M.; Saito, Y.; Sato, H.; Hayashi, N.; Kato, T.; Hashizume, T.; Sakurai, T.

    The endohedral metallofullerenes, such as Sc@C82, Sc2@C84, and Sc3@C82, have been purified and isolated by using two-stage high-performance liquid chromatography (HPLC). The ESR spectrum of the isolated Sc3@C82 exhibits a perfectly symmetric 22 hyperfined splittings with an inherent linewidth of 0.77 Gauss at 220 K, which is consistent with a unique structure that three scandium atoms are encaged triangularly within the C3v isomer of C82. In addition, we report the direct imaging of the isolated discandium fullerene (Sc2@C84) on silicon clean surfaces in an ultrahigh-vacuum environment by utilizing scanning tunneling microscopy (STM). The STM images reveal spherical Sc2@C84 fullerenes, spaced 11.7 Å apart, stacked in close-packed arrays.

  10. Investigation of the neutron activation of endohedral rare earth metallofullerenes

    SciTech Connect

    Shilin, V. A. Lebedev, V. T.; Kolesnik, S. G.; Kozlov, V. S.; Grushko, Yu. S.; Sedov, V. P.; Kukorenko, V. V.

    2011-12-15

    Endohedral lanthanide metallofullerenes and their water-soluble biocompatible derivatives have been synthesized. The effect that fast-neutron irradiation has on the stability and nuclear physical properties of endohedral metallofullerenes that are used as magnetocontrast materials ({sup 46}Sc, {sup 140}La, {sup 141}Nd, {sup 153}Sm, {sup 152}Eu, {sup 154}Eu, {sup 153}Sm, {sup 160}Tb, {sup 169}Yb, {sup 170}Tm (isomers I and III), and {sup 177}Lu) is studied. Our hypothesis, according to which carbon-shell relaxation is based on the fast nonradiative processes of an electron shake-off type, is confirmed.

  11. Non-HPLC rapid separation of metallofullerenes and empty cages with TiCl4 Lewis acid.

    PubMed

    Akiyama, Kazuhiko; Hamano, Tatsuyuki; Nakanishi, Yusuke; Takeuchi, Erina; Noda, Shoko; Wang, Zhiyong; Kubuki, Shiro; Shinohara, Hisanori

    2012-06-13

    Rapid and efficient separation/purification of pure metallofullerenes M(x)@C(n) (M = metal; x = 1, 2; n > 70) and carbide metallofullerenes of the type M(y)C(2)@C(n-2) (y = 2, 3, 4; n - 2 > 68) has been reported. The present method utilizes rapid and almost perfect preferential formation of TiCl(4) (generally known as a Lewis acid)-metallofullerene complexes, which easily decompose to provide pure metallofullerene powders by a simple water treatment. The present method enables one to separate the metallofullerenes up to >99% purity within 10 min without using any type of high-performance liquid chromatography (HPLC). It is found that the oxidation potentials of the metallofullerenes are crucial factors for efficient purification. The current separation/purification technique may open a brand-new era for inducing further applications and commercialization of endohedral metallofullerenes. PMID:22591414

  12. Bottom-up formation of endohedral mono-metallofullerenes is directed by charge transfer.

    PubMed

    Dunk, Paul W; Mulet-Gas, Marc; Nakanishi, Yusuke; Kaiser, Nathan K; Rodríguez-Fortea, Antonio; Shinohara, Hisanori; Poblet, Josep M; Marshall, Alan G; Kroto, Harold W

    2014-01-01

    An understanding of chemical formation mechanisms is essential to achieve effective yields and targeted products. One of the most challenging endeavors is synthesis of molecular nanocarbon. Endohedral metallofullerenes are of particular interest because of their unique properties that offer promise in a variety of applications. Nevertheless, the mechanism of formation from metal-doped graphite has largely eluded experimental study, because harsh synthetic methods are required to obtain them. Here we report bottom-up formation of mono-metallofullerenes under core synthesis conditions. Charge transfer is a principal factor that guides formation, discovered by study of metallofullerene formation with virtually all available elements of the periodic table. These results could enable production strategies that overcome long-standing problems that hinder current and future applications of metallofullerenes. PMID:25524825

  13. Bottom-up formation of endohedral mono-metallofullerenes is directed by charge transfer

    NASA Astrophysics Data System (ADS)

    Dunk, Paul W.; Mulet-Gas, Marc; Nakanishi, Yusuke; Kaiser, Nathan K.; Rodríguez-Fortea, Antonio; Shinohara, Hisanori; Poblet, Josep M.; Marshall, Alan G.; Kroto, Harold W.

    2014-12-01

    An understanding of chemical formation mechanisms is essential to achieve effective yields and targeted products. One of the most challenging endeavors is synthesis of molecular nanocarbon. Endohedral metallofullerenes are of particular interest because of their unique properties that offer promise in a variety of applications. Nevertheless, the mechanism of formation from metal-doped graphite has largely eluded experimental study, because harsh synthetic methods are required to obtain them. Here we report bottom-up formation of mono-metallofullerenes under core synthesis conditions. Charge transfer is a principal factor that guides formation, discovered by study of metallofullerene formation with virtually all available elements of the periodic table. These results could enable production strategies that overcome long-standing problems that hinder current and future applications of metallofullerenes.

  14. Synthesis and EPR Characterization of Exohedrally Perfluoroalkylated Paramagnetic Lanthanum Metallofullerenes: A Fluorous Phase Approach

    NASA Astrophysics Data System (ADS)

    Tagmatarchis, Nikos; Taninaka, Atsushi; Shinohara, Hisanori; Prato, Maurizio

    2002-10-01

    A strategy to chemically derivatize the outer sphere of endohedral metallofullerenes by using a modern organic technique that utilizes a fluorous synthesis-partitioning approach has been developed. The newly synthesized materials were found to be paramagnetic species and were characterized by electron paramagnetic resonance spectroscopy (EPR), laser desorption time-of-flight spectrometry (LD-TOF) and electronic absorption spectroscopy (UV-VIS-NIR). The systematic study of exohedrally derivatized endohedral metallofullerenes should ultimately provide technologically intriguing novel nano-materials.

  15. Regioselective synthesis and molecular structure of the first derivative of praseodymium-containing metallofullerenes.

    PubMed

    Zhou, Qin; Li, Hui; Lian, Yongfu; Suzuki, Mitsuaki; Bao, Lipiao; Cai, Wenting; Wang, Weiwei; Nagase, Shigeru; Lu, Xing; Akasaka, Takeshi

    2014-09-01

    Regioselective cycloaddition of adamantylidene carbene to Pr@C(2v)(9)-C82 affords the first derivative of praseodymium-containing metallofullerenes. Single-crystal X-ray crystallographic data in combination with theoretical studies demonstrate that the addition is dictated by the single metal ion encapsulated inside the fullerene cage. PMID:25026192

  16. Chemical oxidation of endohedral metallofullerenes: identification and separation of distinct classes.

    PubMed

    Bolskar, Robert D; Alford, J Michael

    2003-06-01

    Chemical oxidation is useful for solubilizing and separating endohedral metallofullerenes, as demonstrated here by a separation of three categories of Gd@C2n species and by the solubilization of Tm@C60+ and Tm@C70+ for the first time. PMID:12809236

  17. Recent progress in the chemistry of endohedral metallofullerenes.

    PubMed

    Lu, Xing; Bao, Lipiao; Akasaka, Takeshi; Nagase, Shigeru

    2014-12-01

    Putting metal atoms or metallic clusters into fullerenes has generated a new class of hybrid molecules, defined as endohedral metallofullerenes (EMFs), possessing novel structures and fascinating properties which are different from those of empty fullerenes. In particular, it has been revealed that the chemical properties of the cage carbons of EMFs depend strongly on the nature of the internal metallic species, such as their electronic configuration, location and even motion. Since the first report describing the successful derivatization of La@C82 in 1995, great efforts have been devoted to the chemical modification of EMFs during the last two decades. Although earlier studies mainly focused on readily available species such as M@C82, M2@C80 and M3N@C80 and the related results have been systematically summarized in our previous review paper (Chem. Commun., 2011, 47, 5942-5957), recent concerns about some relatively rare EMFs have developed rapidly. Moreover, taking advantage of single crystal X-ray crystallography, we can now clearly demonstrate the mutual influences between the internal metallic species and the chemical behaviours of the surrounding cage carbons, and the addends as well. In this article, we present recent achievements in the chemical functionalization of EMFs, which were mainly published during the last four years. For consistency, we will still pay special attention to the role that the metals play in controlling the properties of the whole EMF molecules. In this review, however, we will not only focus on concrete experimental results such as X-ray crystallographic and NMR spectroscopic data but will also include computational studies which have indeed enhanced our understanding of the chemical properties of EMFs. Applicable materials based on EMFs are also mentioned but are not discussed in detail. PMID:25126657

  18. Tuning the selectivity of Gd3N cluster endohedral metallofullerene reactions with Lewis acids.

    PubMed

    Stevenson, Steven; Rottinger, Khristina A; Fahim, Muska; Field, Jessica S; Martin, Benjamin R; Arvola, Kristine D

    2014-12-15

    We demonstrate the manipulation of the Lewis acid strength to selectively fractionate different types of Gd3N metallofullerenes that are present in complex mixtures. Carbon disulfide is used for all Lewis acid studies. CaCl2 exhibits the lowest reactivity but the highest selectivity by precipitating only those gadolinium metallofullerenes with the lowest first oxidation potentials. ZnCl2 selectively complexes Gd3N@C88 during the first 4 h of reaction. Reaction with ZnCl2 for an additional 7 days permits a selective precipitation of Gd3N@C84 as the dominant endohedral isolated. A third fraction is the filtrate, which possesses Gd3N@C86 and Gd3N@C80 as the two dominant metallofullerenes. The order of increasing reactivity and decreasing selectivity (left to right) is as follows: CaCl2 < ZnCl2 < NiCl2 < MgCl2 < MnCl2 < CuCl2 < WCl4 ≪ WCl6 < ZrCl4 < AlCl3 < FeCl3. As a group, CaCl2, ZnCl2, and NiCl2 are the weakest Lewis acids and have the highest selectivity because of their very low precipitation onsets, which are below +0.19 V (i.e., endohedrals with first oxidation potentials below +0.19 V are precipitated). For CaCl2, the precipitation threshold is estimated at a remarkably low value of +0.06 V. Because most endohedrals possess first oxidation potentials significantly higher than +0.06 V, CaCl2 is especially useful in its ability to precipitate only a select group of gadolinium metallofullerenes. The Lewis acids of intermediate reactivity (i.e., precipitation onsets estimated between +0.19 and +0.4 V) are MgCl2, MnCl2, CuCl2, and WCl4. The strongest Lewis acids (WCl6, ZrCl4, AlCl3, and FeCl3) are the least selective and tend to precipitate the entire family of gadolinium metallofullerenes. Tuning the Lewis acid for a specific type of endohedral should be useful in a nonchromatographic purification method. The ability to control which metallofullerenes are permitted to precipitate and which endohedrals would remain in solution is a key outcome of this work. PMID

  19. Enhanced nonlinear optical response of an endohedral metallofullerene through metal-to-cage charge transfer

    NASA Astrophysics Data System (ADS)

    Heflin, J. R.; Marciu, D.; Figura, C.; Wang, S.; Burbank, P.; Stevenson, S.; Dorn, H. C.

    1998-06-01

    A new mechanism for increasing the third-order nonlinear optical susceptibility, χ(3), is described for endohedral metallofullerenes. A two to three orders of magnitude increase in the nonlinear response is reported for degenerate four-wave mixing experiments conducted with solutions of Er2@C82 (isomer III) relative to empty-cage fullerenes. A value of -8.7×10-32esu is found for the molecular susceptibility, γxyyx, of Er2@C82 compared to previously reported values of γxxxx=3×10-34 esu and γxyyx=4×10-35 esu for C60. The results confirm the importance of the metal-to-cage charge-transfer mechanism for enhancing the nonlinear optical response in endohedral metallofullerenes.

  20. The Regioselectivity of Bingel-Hirsch Cycloadditions on Isolated Pentagon Rule Endohedral Metallofullerenes.

    PubMed

    Garcia-Borràs, Marc; Cerón, Maira R; Osuna, Sílvia; Izquierdo, Marta; Luis, Josep M; Echegoyen, Luis; Solà, Miquel

    2016-02-12

    In this work, the Bingel-Hirsch addition of diethylbromomalonate to all non-equivalent bonds of Sc3N@D3h -C78 was studied using density functional theory calculations. The regioselectivities observed computationally allowed the proposal of a set of rules, the predictive aromaticity criteria (PAC), to identify the most reactive bonds of a given endohedral metallofullerene based on a simple evaluation of the cage structure. The predictions based on the PAC are fully confirmed by both the computational and experimental exploration of the Bingel-Hirsch reaction of Sc3N@D5h -C80, thus indicating that these rules are rather general and applicable to other isolated pentagon rule endohedral metallofullerenes. PMID:26765333

  1. Near-Infrared Photoluminescence Properties of Endohedral Mono- and Dithulium Metallofullerenes.

    PubMed

    Wang, Zhiyong; Izumi, Noriko; Nakanishi, Yusuke; Koyama, Takeshi; Sugai, Toshiki; Tange, Masayoshi; Okazaki, Toshiya; Shinohara, Hisanori

    2016-04-26

    The optical properties of endohedral metallofullerene molecules can be tuned by changing the fullerene size as well as the number of metal atoms inside the fullerene cages. In this work we have synthesized and isolated a series of mono- and dithulium metallofullerenes, including Tm@C82 (isomers I, II, III, IV), Tm@C88 (I-IV), Tm2@C82 (I-III), and (Tm2C2)@C82 (I-III). Near-infrared photoluminescence is observed from the thulium metallofullerenes. By changing the number of Tm ion in the fullerene cage, we have found that one can vary and tune the photoluminescence from 1200 to 1300-2000 nm observed for Tm(2+) (4f(13)) in Tm@C88 and Tm(3+) (4f(12)) in (Tm2C2)@C82, respectively. The photoluminescence intensity depends sensitively on the fullerene cages. (Tm2C2)@C82 (III) exhibits the highest photoluminescence intensity among the three structural isomers because of its large HOMO-LUMO energy gap. PMID:27057619

  2. Thermodynamically stable [4 + 2] cycloadducts of lanthanum-encapsulated endohedral metallofullerenes.

    PubMed

    Takano, Yuta; Nagashima, Yuki; Herranz, M Ángeles; Martín, Nazario; Akasaka, Takeshi

    2014-01-01

    The [4 + 2] cycloaddition of o-quinodimethanes, generated in situ from the sultine 4,5-benzo-3,6-dihydro-1,2-oxathiin 2-oxide and its derivative, to La metal-encapsulated fullerenes, La2@C80 or La@C82, afforded the novel derivatives of endohedral metallofullerenes (3a,b, 4a,b and 5b). Molecular structures of the resulting compounds were elucidated using spectroscopic methods such as MALDI-TOF mass, optical absorption, and NMR spectroscopy. The [4 + 2] adducts of La2@C80 (3a,b, and 4a,b) and La@C82 (5b), respectively, retain diamagnetic and paramagnetic properties, as confirmed by EPR spectroscopy. Dynamic NMR measurements of 4a at various temperatures demonstrated the boat-to-boat inversions of the addend. In addition, 5b revealed remarkable thermal stability in comparison with the reported [4 + 2] cycloadduct of pentamethylcyclopentadiene and La@C82 (6). These findings demonstrate the utility of sultines to afford thermodynamically stable endohedral metallofullerene derivatives for the use in material science. PMID:24778724

  3. A multicomponent molecular approach to artificial photosynthesis - the role of fullerenes and endohedral metallofullerenes.

    PubMed

    Rudolf, M; Kirner, S V; Guldi, D M

    2016-02-01

    In this review article, we highlight recent advances in the field of solar energy conversion at a molecular level. We focus mainly on investigations regarding fullerenes as well as endohedral metallofullerenes in energy and/or electron donor-acceptor conjugates, hybrids, and arrays, but will also discuss several more advanced systems. Hereby, the mimicry of the fundamental processes occurring in natural photosynthesis, namely light harvesting (LH), energy transfer (EnT), reductive/oxidative electron transfer (ET), and catalysis (CAT), which serve as a blue print for the rational design of artificial photosynthetic systems, stand at the focalpoint. Importantly, the key processes in photosynthesis, that is, LH, EnT, ET, and CAT, define the structure of this review with the only further differentiation in terms of covalent and non-covalent systems. Fullerenes as well as endohedral metallofullerenes are chosen by virtue of their small reorganization energies in electron transfer processes, on the one hand, and their exceptional redox behaviour, on the other hand. PMID:26744992

  4. A piggyback ride for transition metals: encapsulation of exohedral metallofullerenes in carbon nanotubes.

    PubMed

    Chamberlain, Thomas W; Champness, Neil R; Schröder, Martin; Khlobystov, Andrei N

    2011-01-10

    We have developed a method that enables the efficient insertion of transition-metal atoms and their small clusters into carbon nanotubes. As a model system, Os complexes attached to the exterior of fullerene C60 (exohedral metallofullerenes) were shown to be dragged into the nanotube spontaneously and irreversibly due to strong van der Waals interactions, specific to fullerenes and carbon nanotubes. The size of the metal-containing groups attached to C60 was shown to be critical for successful insertion, as functional groups too bulky to enter the nanotube were stripped off the fullerene during the encapsulation process. Once inside the nanotube, Os atoms catalyse polymerisation and decomposition of fullerene cages, which is related to a much higher catalytic activity of metal atoms situated on the surface of the fullerene cage, as compared to metal atoms in endohedral fullerenes, such as M@C82. Thus, exohedral metallofullerenes show promise for applications in catalysis in carbon “nano” test tubes. PMID:21207588

  5. Exchange interactions of spin-active metallofullerenes in solid-state carbon networks

    NASA Astrophysics Data System (ADS)

    Zaka, Mujtaba; Warner, Jamie H.; Ito, Yasuhiro; Morton, John J. L.; Rümmeli, Mark H.; Pichler, Thomas; Ardavan, Arzhang; Shinohara, Hisanori; Briggs, G. Andrew D.

    2010-02-01

    The electron paramagnetic resonance (EPR) of spin-active metallofullerenes (MFs) La@C82 and Sc@C82 diluted in solid-state C60 crystalline matrices with molar concentrations varying from 0.4% to 100% are investigated. For dilute concentrations, the hyperfine structure of the MFs is resolved, and as the concentration increases exchange narrowing is observed leading to a single peak in the EPR. Sc@C82 MFs are inserted into single-walled carbon nanotubes to form peapods with concentrations of 10% and 0.1%, diluted with C60 . For the case of peapods containing 10% Sc@C82 a strong narrow peak is observed in X -band CW EPR, but not pulsed measurements. Peapods containing Ce@C82 MFs are prepared and these also show similar CW EPR to the Sc@C82 , indicating the peak arises from charge transfer with the SWNT.

  6. Metallofullerene-Nanoplatform-Delivered Interstitial Brachytherapy Improved Survival in a Murine Model of Glioblastoma Multiforme

    PubMed Central

    Wilson, John D.; Broaddus, William C.; Dorn, Harry C.; Fatouros, Panos P.; Chalfant, Charles E.; Shultz, Michael D.

    2012-01-01

    Fullerenes are used across scientific disciplines because of their diverse properties gained by altering encapsulated or surface bound components. In this study, the recently developed theranostic agent based on a radiolabeled functionalized metallofullerene (177Lu-DOTA-f-Gd3N@C80) was synthesized with high radiochemical yield and purity. The efficacy of this agent was demonstrated in two orthotopic xenograft brain tumor models of glioblastoma multiforme (GBM). A dose-dependent improvement in survival was also shown. The in vivo stability of the agent was verified through dual label measurements of biological elimination from the tumor. Overall, these results provide evidence that nanomaterial platforms can be used to deliver effective interstitial brachytherapy. PMID:22881865

  7. Development of Electron Cyclotron Resonance Ion Source for Synthesis of Endohedral Metallofullerenes

    SciTech Connect

    Tanaka, K.; Muramatsu, M.; Uchida, T.; Hanajiri, T.; Yoshida, Y.; Biri, S.; Kitagawa, A.; Kato, Y.

    2008-11-03

    A new electron cyclotron resonance ion source (ECRIS) has been constructed for synthesis of endohedral metallofullerenes. The main purpose of the ion source is to produce new biological and medical materials. The design is based on ECRIS for production of multicharged ion beams with a traditional minimum-B magnetic field. An 8-10 GHz traveling wave tube (TWT) amplifier and a 2.45 GHz magnetron have been applied as microwave sources. Fullerene and metal vapor are introduced with a filament heating micro-oven and an induction heating oven, respectively. In preliminary ion-extraction test, Ar{sup +} is 54 {mu}A. Many broken fullerenes such as C{sub 58} and C{sub 56} are observed in fullerene ion beams.

  8. C₇₄ endohedral metallofullerenes violating the isolated pentagon rule: a density functional theory study.

    PubMed

    Zheng, Hong; Zhao, Xiang; Ren, Ting; Wang, Wei-Wei

    2012-08-01

    Precise studies on M(2)@C(74) (M = Sc, La) series by means of DFT methods have disclosed that certain non-IPR isomers are more stable than the IPR structure. M(2)@C(2)(13295)-C(74) and M(2)@C(2)(13333)-C(74), both of which have two pentagon adjacencies (PA), present excellent thermodynamic stability with very small energy differences. Statistical mechanics calculations on the M(2)@C(74) series reveal that M(2)@C(2)(13295)-C(74) and M(2)@C(2)(13333)-C(74) are quite favoured by entropy effects below 3000 K. Sc(2)@C(74) and La(2)@C(74) series are found to have similar electronic transfer but different electronic structures due to the distinct properties of scandium and lanthanum elements according to Natural Bond Orbital (NBO) analysis in conjunction with orbital interaction diagrams. Investigations of bonding energies reflect quite different influences of the two types of metal atoms to C(74) metallo-fullerenes. Further examinations on C(74) metallo-fullerenes uncover significant stabilization effects of metal atoms acting on PA fragments. Geometrical structures of certain non-IPR cages (from C(72) to C(76)), which exhibit splendid stabilities when encapsulating metallo-clusters, are found to be related by Stone-Wales transformation and C(2) addition. Furthermore, IR spectra and (13)C NMR spectra of M(2)@C(2)(13295)-C(74) and M(2)@C(2)(13333)-C(74) have been simulated to assist further experimental characterization. PMID:22695730

  9. Molecular Location Sensing Approach by Anisotropic Magnetism of an Endohedral Metallofullerene.

    PubMed

    Takano, Yuta; Tashita, Ryo; Suzuki, Mitsuaki; Nagase, Shigeru; Imahori, Hiroshi; Akasaka, Takeshi

    2016-06-29

    Location recognition at the molecular scale provides valuable information about the nature of functional molecular materials. This study presents a novel location sensing approach based on an endohedral metallofullerene, Ce@C82, using its anisotropic magnetic properties, which lead to temperature-dependent paramagnetic shifts in (1)H NMR spectra. Five site-isomers of Ce@C82CH2-3,5-C6H3Me2 were synthesized to demonstrate the spatial sensing ability of Ce@C82. Single-crystal structures, absorption spectra, and density functional theory calculations were used to select the plausible addition positions in the radical coupling reaction, which preferentially happens on the carbon atoms with high electron density of the singly occupied molecular orbital (SOMO) and positive charge. Temperature-dependent NMR measurements demonstrated unique paramagnetic shifts of the (1)H peaks, which were derived from the anisotropic magnetism of the f-electron in the Ce atom of the isomers. It was found that the magnetic anisotropy axes can be easily predicted by theoretical calculations using the Gaussian 09 package. Further analysis revealed that the temperature-dependent trend in the shifts is clearly predictable from the distance and relative position of the proton from the Ce atom. Hence, the Ce-encapsulated metallofullerene Ce@C82 can provide spatial location information about nearby atoms through the temperature-dependent paramagnetic shifts of its NMR signals. It can act as a molecular probe for location sensing by utilizing the anisotropic magnetism of the encapsulated Ce atom. The potentially low toxicity and stability of the endohedral fullerene would make Ce@C82 suitable for applications in biology and material science. PMID:27314267

  10. A New Interleukin-13 Amino-Coated Gadolinium Metallofullerene Nanoparticle for Targeted MRI Detection of Glioblastoma Tumor Cells.

    PubMed

    Li, Tinghui; Murphy, Susan; Kiselev, Boris; Bakshi, Kanwarpal S; Zhang, Jianyuan; Eltahir, Amnah; Zhang, Yafen; Chen, Ying; Zhu, Jie; Davis, Richey M; Madsen, Louis A; Morris, John R; Karolyi, Daniel R; LaConte, Stephen M; Sheng, Zhi; Dorn, Harry C

    2015-06-24

    The development of new nanoparticles as next-generation diagnostic and therapeutic ("theranostic") drug platforms is an active area of both chemistry and cancer research. Although numerous gadolinium (Gd) containing metallofullerenes as diagnostic magnetic resonance imaging (MRI) contrast agents have been reported, the metallofullerene cage surface, in most cases, consists of negatively charged carboxyl or hydroxyl groups that limit attractive forces with the cellular surface. It has been reported that nanoparticles with a positive charge will bind more efficiently to negatively charged phospholipid bilayer cellular surfaces, and will more readily undergo endocytosis. In this paper, we report the preparation of a new functionalized trimetallic nitride template endohedral metallofullerene (TNT EMF), Gd3N@C80(OH)x(NH2)y, with a cage surface bearing positively charged amino groups (-NH3(+)) and directly compare it with a similar carboxyl and hydroxyl functionalized derivative. This new nanoparticle was characterized by X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and infrared spectroscopy. It exhibits excellent (1)H MR relaxivity. Previous studies have clearly demonstrated that the cytokine interleukin-13 (IL-13) effectively targets glioblastoma multiforme (GBM) cells, which are known to overexpress IL-13Rα2. We also report that this amino-coated Gd-nanoplatform, when subsequently conjugated with interleukin-13 peptide IL-13-Gd3N@C80(OH)x(NH2)y, exhibits enhanced targeting of U-251 GBM cell lines and can be effectively delivered intravenously in an orthotopic GBM mouse model. PMID:26022213

  11. Photoionization of Au+ ions and developments in the synthesis of the metallofullerene Au@C60

    NASA Astrophysics Data System (ADS)

    Bogolub, Kyren; Macaluso, David; Mueller, Allison; Johnson, Andrea; Müller, Alfred; Schippers, Stefan; Hellhund, Jonas; Borovik, Alexander; Anders, Andre; Aguilar, Alex; Kilcoyne, A. L. David

    2014-05-01

    Single photoionization of Au+ ions was investigated via the merged-beams technique at AMO Beamline 10.0.1.2 of the Advanced Light Source at Lawrence Berkeley National Laboratory. The relative single photoionization yield was measured as a function of photon energy in the 45 eV to 120 eV energy range. These measurements were made in preparation for future photoionization studies of the endohedral metallofullerene Au@C60, the production of which was also investigated. In proof-of-principle measurements a mass-resolved beam of Au@C60+was produced with a primary ion beam current in the single picoamp range without optimization of the ion source or synthesis parameters. Plans are presented for improved metallofullere production yield to be used in photoionization measurements of the endohedral fullerene ions in conjunction with the continuing study of pure Au. We would like to acknowledge the generous sharing of equipment vital to this work by Andre Anders, the Plasma Applications group leader at the Advanced Light Source, LBNL.

  12. Metabolizer in vivo of fullerenes and metallofullerenes by positron emission tomography

    NASA Astrophysics Data System (ADS)

    Li, Juan; Yang, Wenjiang; Cui, Rongli; Wang, Dongliang; Chang, Yanan; Gu, Weihong; Yin, Wenyan; Bai, Xue; Chen, Kui; Xia, Lin; Geng, Huan; Xing, Gengmei

    2016-04-01

    Fullerenes (C60) and metallofullerenes (Gd@C82) have similar chemical structure, but the bio-effects of both fullerene-based materials are distinct in vivo. Tracking organic carbon-based materials such as C60 and Gd@C82 is difficult in vivo due to the high content of carbon element in the living tissues themselves. In this study, the biodistribution and metabolism of fullerenes (C60 and Gd@C82) radiolabeled with 64Cu were observed by positron emission tomography (PET). 64Cu-C60 and 64Cu-Gd@C82 were prepared using 1, 4, 7, 10-tetrakis (carbamoylmethyl)-1, 4, 7, 10-tetra-azacyclodo-decanes grafted on carbon cages as a chelator for 64Cu, and were obtained rapidly with high radiochemical yield (≥90%). The new radio-conjugates were evaluated in vivo in the normal mouse model and tissue distribution by small animal PET/CT imaging and histology was carried out. The PET imaging, the biodistribution and the excretion of C60 and Gd@C82 indicated that C60 samples have higher blood retention and lower renal clearance than the Gd@C82 samples in vivo and suggested that the differences in metabolism and distribution in vivo were caused by the structural differences of the groups on the fullerene cages though there is chemical similarity between C60 and Gd@C82.

  13. Electron transport in endohedral metallofullerene Ce@C{sub 82} single-molecule transistors

    SciTech Connect

    Okamura, Naoya; Yoshida, Kenji; Sakata, Shuichi; Hirakawa, Kazuhiko

    2015-01-26

    We have investigated the electron transport in endohedral metallofullerene Ce@C{sub 82} single-molecule transistors (SMTs) together with that in reference C{sub 84} SMTs. The vibrational modes (bending and stretching) of the encapsulated single Ce atom in the C{sub 82} cage appear in Coulomb stability diagrams for the single-electron tunneling through Ce@C{sub 82} molecules, demonstrating the single-atom sensitivity of the transport measurements. When a bias voltage larger than 100 mV is applied across the source/drain electrodes, large hysteretic behavior is observed in the current-voltage (I-V) characteristics. At the same time, the pattern in the Coulomb stability diagram is changed. No such hysteretic behavior is observed in the I-V curves of hollow-cage C{sub 84} SMTs, even when the bias voltage exceeds 500 mV. This hysteretic change in the I-V characteristics is induced by a nanomechanical change in the configuration of the Ce@C{sub 82} molecule in the nanogap electrode due to the electric dipole that exists in Ce@C{sub 82}.

  14. Key Structural Motifs To Predict the Cage Topology in Endohedral Metallofullerenes.

    PubMed

    Wang, Yang; Díaz-Tendero, Sergio; Martín, Fernando; Alcamí, Manuel

    2016-02-10

    We show that the relative isomer stability of fullerene anions is essentially governed by a few simple structural motifs, requiring only the connectivity information between atoms. Relative energies of a large number of isomers of fullerene anions, C(2n)(q) (2n = 68-104; q = -2, -4, -6), can be satisfactorily reproduced by merely counting the numbers of seven kinds of hexagon-based motifs. The dependence of stability on these motifs varies with the charge state, which reflects the fact that the isomeric form of the carbon cage in endohedral metallofullerenes (EMFs) often differs from that in neutral empty fullerenes. The chemical origin of the stabilization differences between motifs is discussed on the basis of electronic and strain effects as well as aromaticity. On the basis of this simple model, the extraordinary abundance of the icosahedral C80 cage in EMFs can be easily understood. We also provide an explanation for why the well-known isolated pentagon rule is often violated in smaller EMFs. Finally, simple topological indices are proposed for quantitatively predicting the relative stability of fullerene anions, allowing a rapid determination of suitable hosting cages in EMFs by just counting three simple structural motifs. PMID:26762322

  15. Use of trimetasphere metallofullerene MRI contrast agent for the non-invasive longitudinal tracking of stem cells in the lung.

    PubMed

    Murphy, Sean V; Hale, Austin; Reid, Tanya; Olson, John; Kidiyoor, Amritha; Tan, Josh; Zhou, Zhiguo; Jackson, John; Atala, Anthony

    2016-04-15

    Magnetic Resonance Imaging (MRI) is a commonly used, non-invasive imaging technique that provides visualization of soft tissues with high spatial resolution. In both a research and clinical setting, the major challenge has been identifying a non-invasive and safe method for longitudinal tracking of delivered cells in vivo. The labeling and tracking of contrast agent labeled cells using MRI has the potential to fulfill this need. Contrast agents are often used to enhance the image contrast between the tissue of interest and surrounding tissues with MRI. The most commonly used MRI contrast agents contain Gd(III) ions. However, Gd(III) ions are highly toxic in their ionic form, as they tend to accumulate in the liver, spleen, kidney and bones and block calcium channels. Endohedral metallofullerenes such as trimetallic nitride endohedral metallofullerenes (Trimetasphere®) are one unique class of fullerene molecules where a Gd3N cluster is encapsulated inside a C80 carbon cage referred to as Gd3N@C80. These endohedral metallofullerenes have several advantages over small chelated Gd(III) complexes such as increased stability of the Gd(III) ion, minimal toxic effects, high solubility in water and high proton relativity. In this study, we describe the evaluation of gadolinium-based Trimetasphere® positive contrast agent for the ​in vitro labeling and in vivo tracking of human amniotic fluid-derived stem cells within lung tissue. In addition, we conducted a 'proof-of-concept' experiment demonstrating that this methodology can be used to track the homing of stem cells to injured lung tissue and provide longitudinal analysis of cell localization over an extended time course. PMID:26546729

  16. Use of trimetasphere metallofullerene MRI contrast agent for the non-invasive longitudinal tracking of stem cells in the lung

    PubMed Central

    Murphy, Sean V.; Hale, Austin; Reid, Tanya; Olson, John; Kidiyoor, Amritha; Tan, Josh; Zhou, Zhiguo; Jackson, John; Atala, Anthony

    2016-01-01

    Magnetic Resonance Imaging (MRI) is a commonly used, non-invasive imaging technique that provides visualization of soft tissues with high spatial resolution. In both a research and clinical setting, the major challenge has been identifying a non-invasive and safe method for longitudinal tracking of delivered cells in vivo. The labeling and tracking of contrast agent labeled cells using MRI has the potential to fulfill this need. Contrast agents are often used to enhance the image contrast between the tissue of interest and surrounding tissues with MRI. The most commonly used MRI contrast agents contain Gd(III) ions. However, Gd(III) ions are highly toxic in their ionic form, as they tend to accumulate in the liver, spleen, kidney and bones and block calcium channels. Endohedral metallofullerenes such as trimetallic nitride endohedral metallofullerenes (Trimetasphere®) are one unique class of fullerene molecules where a Gd3N cluster is encapsulated inside a C80 carbon cage referred to as Gd3N@C80. These endohedral metallofullerenes have several advantages over small chelated Gd(III) complexes such as increased stability of the Gd(III) ion, minimal toxic effects, high solubility in water and high proton relativity. In this study, we describe the evaluation of gadolinium-based Trimetasphere® positive contrast agent for the in vitro labeling and in vivo tracking of human amniotic fluid-derived stem cells within lung tissue. In addition, we conducted a ‘proof-of-concept’ experiment demonstrating that this methodology can be used to track the homing of stem cells to injured lung tissue and provide longitudinal analysis of cell localization over an extended time course. PMID:26546729

  17. The metallofullerene field-induced single-ion magnet HoSc2 N@C80.

    PubMed

    Dreiser, Jan; Westerström, Rasmus; Zhang, Yang; Popov, Alexey A; Dunsch, Lothar; Krämer, Karl; Liu, Shi-Xia; Decurtins, Silvio; Greber, Thomas

    2014-10-13

    The low-temperature magnetic properties of the endohedral metallofullerene HoSc2 N@C80 have been studied by superconducting quantum interference device (SQUID) magnetometry. Alternating current (ac) susceptibility measurements reveal that this molecule exhibits slow relaxation of magnetization in a small applied field with timescales in the order of milliseconds. The equilibrium magnetic properties of HoSc2 N@C80 indicate strong magnetic anisotropy. The large differences in magnetization relaxation times between the present compound and the previously investigated DySc2 N@C80 are discussed. PMID:25164532

  18. In Vitro and In Vivo Studies of Single-Walled Carbon Nanohorns with Encapsulated Metallofullerenes and Exohedrally Functionalized Quantum Dots

    SciTech Connect

    Zhang, Jianfei; Ge, Jiechao; Shultz, M.D.; Chung, Eunna; Singh, Gurpreet; Shu, Chunying; Deck, Paul; Fatouros, Panos; Henderson, Scott; Corwin, Frank; Geohegan, David B; Rouleau, Christopher M; More, Karren Leslie; Rylander, Nichole M; Rylander, Christopher; Gibson, Harry W; Dorn, Harry C

    2010-07-01

    Single-walled carbon nanohorns (SWNHs) are new carbonaceous materials. In this paper, we report the first successful preparation of SWNHs encapsulating trimetallic nitride template endohedral metallofullerenes (TNT-EMFs). The resultant materials were functionalized by a high-speed vibration milling method and conjugated with CdSe/ZnS quantum dots (QDs). The successful encapsulation of TNT-EMFs and external functionalization with QDs provide a dual diagnostic platform for in vitro and in vivo biomedical applications of these new carbonaceous materials.

  19. Metabolizer in vivo of fullerenes and metallofullerenes by positron emission tomography.

    PubMed

    Li, Juan; Yang, Wenjiang; Cui, Rongli; Wang, Dongliang; Chang, Yanan; Gu, Weihong; Yin, Wenyan; Bai, Xue; Chen, Kui; Xia, Lin; Geng, Huan; Xing, Gengmei

    2016-04-15

    Fullerenes (C60) and metallofullerenes (Gd@C82) have similar chemical structure, but the bio-effects of both fullerene-based materials are distinct in vivo. Tracking organic carbon-based materials such as C60 and Gd@C82 is difficult in vivo due to the high content of carbon element in the living tissues themselves. In this study, the biodistribution and metabolism of fullerenes (C60 and Gd@C82) radiolabeled with (64)Cu were observed by positron emission tomography (PET). (64)Cu-C60 and (64)Cu-Gd@C82 were prepared using 1, 4, 7, 10-tetrakis (carbamoylmethyl)-1, 4, 7, 10-tetra-azacyclodo-decanes grafted on carbon cages as a chelator for (64)Cu, and were obtained rapidly with high radiochemical yield (≥90%). The new radio-conjugates were evaluated in vivo in the normal mouse model and tissue distribution by small animal PET/CT imaging and histology was carried out. The PET imaging, the biodistribution and the excretion of C60 and Gd@C82 indicated that C60 samples have higher blood retention and lower renal clearance than the Gd@C82 samples in vivo and suggested that the differences in metabolism and distribution in vivo were caused by the structural differences of the groups on the fullerene cages though there is chemical similarity between C60 and Gd@C82. PMID:26926042

  20. Metallofullerene and fullerene formation from condensing carbon gas under conditions of stellar outflows and implication to stardust

    PubMed Central

    Dunk, Paul W.; Adjizian, Jean-Joseph; Kaiser, Nathan K.; Quinn, John P.; Blakney, Gregory T.; Ewels, Christopher P.; Marshall, Alan G.; Kroto, Harold W.

    2013-01-01

    Carbonaceous presolar grains of supernovae origin have long been isolated and are determined to be the carrier of anomalous 22Ne in ancient meteorites. That exotic 22Ne is, in fact, the decay isotope of relatively short-lived 22Na formed by explosive nucleosynthesis, and therefore, a selective and rapid Na physical trapping mechanism must take place during carbon condensation in supernova ejecta. Elucidation of the processes that trap Na and produce large carbon molecules should yield insight into carbon stardust enrichment and formation. Herein, we demonstrate that Na effectively nucleates formation of Na@C60 and other metallofullerenes during carbon condensation under highly energetic conditions in oxygen- and hydrogen-rich environments. Thus, fundamental carbon chemistry that leads to trapping of Na is revealed, and should be directly applicable to gas-phase chemistry involving stellar environments, such as supernova ejecta. The results indicate that, in addition to empty fullerenes, metallofullerenes should be constituents of stellar/circumstellar and interstellar space. In addition, gas-phase reactions of fullerenes with polycyclic aromatic hydrocarbons are investigated to probe “build-up” and formation of carbon stardust, and provide insight into fullerene astrochemistry. PMID:24145444

  1. A missing link in the transformation from asymmetric to symmetric metallofullerene cages implies a top-down fullerene formation mechanism

    NASA Astrophysics Data System (ADS)

    Zhang, Jianyuan; Bowles, Faye L.; Bearden, Daniel W.; Ray, W. Keith; Fuhrer, Tim; Ye, Youqing; Dixon, Caitlyn; Harich, Kim; Helm, Richard F.; Olmstead, Marilyn M.; Balch, Alan L.; Dorn, Harry C.

    2013-10-01

    Although fullerenes were discovered nearly three decades ago, the mechanism of their formation remains a mystery. Many versions of the classic ‘bottom-up’ formation mechanism have been advanced, starting with C2 units that build up to form chains and rings of carbon atoms and ultimately form those well-known isolated fullerenes (for example, Ih-C60). In recent years, evidence from laboratory and interstellar observations has emerged to suggest a ‘top-down’ mechanism, whereby small isolated fullerenes are formed via shrinkage of giant fullerenes generated from graphene sheets. Here, we present molecular structural evidence for this top-down mechanism based on metal carbide metallofullerenes M2C2@C1(51383)-C84 (M = Y, Gd). We propose that the unique asymmetric C1(51383)-C84 cage with destabilizing fused pentagons is a preserved ‘missing link’ in the top-down mechanism, and in well-established rearrangement steps can form many well-known, high-symmetry fullerene structures that account for the majority of solvent-extractable metallofullerenes.

  2. Metallofullerene and fullerene formation from condensing carbon gas under conditions of stellar outflows and implication to stardust.

    PubMed

    Dunk, Paul W; Adjizian, Jean-Joseph; Kaiser, Nathan K; Quinn, John P; Blakney, Gregory T; Ewels, Christopher P; Marshall, Alan G; Kroto, Harold W

    2013-11-01

    Carbonaceous presolar grains of supernovae origin have long been isolated and are determined to be the carrier of anomalous (22)Ne in ancient meteorites. That exotic (22)Ne is, in fact, the decay isotope of relatively short-lived (22)Na formed by explosive nucleosynthesis, and therefore, a selective and rapid Na physical trapping mechanism must take place during carbon condensation in supernova ejecta. Elucidation of the processes that trap Na and produce large carbon molecules should yield insight into carbon stardust enrichment and formation. Herein, we demonstrate that Na effectively nucleates formation of Na@C60 and other metallofullerenes during carbon condensation under highly energetic conditions in oxygen- and hydrogen-rich environments. Thus, fundamental carbon chemistry that leads to trapping of Na is revealed, and should be directly applicable to gas-phase chemistry involving stellar environments, such as supernova ejecta. The results indicate that, in addition to empty fullerenes, metallofullerenes should be constituents of stellar/circumstellar and interstellar space. In addition, gas-phase reactions of fullerenes with polycyclic aromatic hydrocarbons are investigated to probe "build-up" and formation of carbon stardust, and provide insight into fullerene astrochemistry. PMID:24145444

  3. Trimetallic nitride template endohedral metallofullerenes: discovery, structural characterization, reactivity, and applications.

    PubMed

    Zhang, Jianyuan; Stevenson, Steven; Dorn, Harry C

    2013-07-16

    Shortly after the discovery of the carbon fullerene allotrope, C₆₀, researchers recognized that the hollow spheroidal shape could accommodate metal atoms, or clusters, which quickly led to the discovery of endohedral metallofullerenes (EMFs). In the past 2 decades, the unique features of EMFs have attracted broad interest in many fields, including inorganic chemistry, organic chemistry, materials chemistry, and biomedical chemistry. Some EMFs produce new metallic clusters that do not exist outside of a fullerene cage, and some other EMFs can boost the efficiency of magnetic resonance (MR) imaging 10-50-fold, in comparison with commercial contrast agents. In 1999, the Dorn laboratory discovered the trimetallic nitride template (TNT) EMFs, which consist of a trimetallic nitride cluster and a host fullerene cage. The TNT-EMFs (A₃N@C2n, n = 34-55, A = Sc, Y, or lanthanides) are typically formed in relatively high yields (sometimes only exceeded by empty-cage C₆₀ and C₇₀, but yields may decrease with increasing TNT cluster size), and exhibit high chemical and thermal stability. In this Account, we give an overview of TNT-EMF research, starting with the discovery of these structures and then describing their synthesis and applications. First, we describe our serendipitous discovery of the first member of this class, Sc₃N@Ih-C₈₀. Second, we discuss the methodology for the synthesis of several TNT-EMFs. These results emphasize the importance of chemically adjusting plasma temperature, energy, and reactivity (CAPTEAR) to optimize the type and yield of TNT-EMFs produced. Third, we review the approaches that are used to separate and purify pristine TNT-EMF molecules from their corresponding product mixtures. Although we used high-performance liquid chromatography (HPLC) to separate TNT-EMFs in early studies, we have more recently achieved facile separation based on the reduced chemical reactivity of the TNT-EMFs. These improved production yields and

  4. Production and EPR characterization of exohedrally perfluoroalkylated paramagnetic lanthanum metallofullerenes: (La@C 82)-(C 8F 17) 2

    NASA Astrophysics Data System (ADS)

    Tagmatarchis, Nikos; Taninaka, Atsushi; Shinohara, Hisanori

    2002-04-01

    A strategy to chemically derivatize the outer sphere of endohedral metallofullerenes by using a fluorous synthesis-partitioning approach has been developed. The newly synthesized materials were found to be paramagnetic species and were characterized by electron paramagnetic resonance spectroscopy (EPR), laser desorption time-of-flight spectrometry (LD-TOF) and electronic absorption spectroscopy (UV-VIS-NIR). The fluorous-phase partitioning method (or liquid-liquid extraction), successfully applied for the first time in fullerene chemistry, aided by multi-stage recycling high performance liquid chromatography (HPLC) resulted in their isolation in isomer-free form. The present study opens the way to organic transformations of fullerene-based materials as a powerful separation technique.

  5. Endohedral metallofullerenes, M@C60 (M = Ca, Na, Sr): selective adsorption and sensing of open-shell NOx gases.

    PubMed

    Tawfik, Sherif Abdulkader; Cui, X Y; Ringer, S P; Stampfl, C

    2016-08-21

    Based on density-functional theory and non-equilibrium Green's function calculations, we demonstrate that endohedral metallofullerenes (EMFs) are reactive to open-shell gases, and therefore have the potential application as selective open-shell gas sensors. The adsorption of eight gas species (CO, H2O, H2S, NO2, NO, SO2, O2 and NH3) on three EMFs (M@C60, M = Ca, Na and Sr) shows that the adsorption energies of the EMFs towards NO2 and NO are significantly higher than the closed-shell species. Moreover, the high selectivity appears relatively insensitive to the inserted metal atoms. The calculated current-voltage characteristics of gold-M@C60-gold structures (M = Ca, Na) show that the adsorption of NO2 leads to significant change in conductivity, suggesting a potential application as an EMF gas resistive sensing device. PMID:27426253

  6. Charge transfer satellite in Pr@C82 metallofullerene observed using resonant x-ray emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamaoka, H.; Sugiyama, H.; Kubozono, Y.; Kotani, A.; Nouchi, R.; Vlaicu, A. M.; Oohashi, H.; Tochio, T.; Ito, Y.; Yoshikawa, H.

    2009-11-01

    Resonant x-ray emission spectroscopy (RXES) was performed on the metallofullerene Pr@C82 at the PrL3 absorption edge. We verify not only nearly three-electron charge transfers from the metal to the cage but also back-electron transfer observed as a charge transfer satellite. The results are compared to theoretical calculations with a single-impurity Anderson model. Theory shows that the electronic structure of endohedral atom in the cage is atomiclike. The satellite structure originates from the charge transfer, i.e., dynamical screening effect, induced by the core-hole potential in the final state rather than from the valence fluctuation of the rare-earth metal in the ground state. We also performed the RXES measurement of Pr2O3 for comparison.

  7. Sm@C1(153491)-C94: A missing isomer from Sm@C94 mono-metallofullerenes

    NASA Astrophysics Data System (ADS)

    Zhao, Pei; Guo, Yi-Jun; Zhao, Rui-Sheng; Zhao, Xiang

    2016-01-01

    The Sm-containing endohedral metallofullerene (EMF) Sm@C94 has been investigated by quantum chemical and statistical thermodynamic methods. Sm@C1(153491)-C94 and Sm@C3v(153493)-C94 which both satisfy the isolated-pentagon rule (IPR) are exposed to possess considerable thermodynamic stabilities within the fullerene-formation temperature region (500-3000 K). Sm@C3v(153493)-C94 has been indeed determined experimentally, and a novel structure, Sm@C1(153491)-C94, is reported for the first time. These two isomers are related by a single Stone-Wales transformation. Meanwhile, frontier molecular orbital, natural electron configuration, and Mayer bond order analyses were employed to uncover their electronic properties. In addition, their optical spectra were simulated to support experimental identification and characterization.

  8. Theoretical Insight into the Ambiguous Endohedral Metallofullerene Er3C74: Covalent Interactions among Three Lanthanide Atoms.

    PubMed

    Guo, Yi-Jun; Zheng, Hong; Yang, Tao; Nagase, Shigeru; Zhao, Xiang

    2015-08-17

    All of C74-based endohedral metallofullerenes (EMFs) are found to be monometallofullerenes with the same D3h(14246)-C74 cage so far. An opening question is whether other C74 cages could survive during the production of some novel C74-EMFs. Theoretically, we studied the trimetallic endohedral fullerene Er3C74, the existence of which had been proven without any further characterizations. Two thermodynamically stable Er3C74 isomers were obtained, both of which could be expressed as Er3@C74, meaning that previously synthesized Er3C74 is indeed an endohedral trierbium fullerene. Besides the isomer with well-known D3h(14246)-C74 cage which obeys isolated pentagon rule (IPR), another one possesses the C1(13771)-C74 cage with two adjacent pentagons. Notably, it is the first time an endohedral metallofullerene containing the C1(13771)-C74 cage has been reported. Frontier orbitals analysis, bonding analysis in terms of quantum theory of atoms-in-molecule (QTAIM) and Mayer bond order, together with two-dimensional maps of electron localization function (ELF) and Laplacian of electron density of Er3@D3h(14246)-C74 and Er3@C1(13771)-C74 show obvious covalent interactions not only between metallic atoms and carbon cage but also among three erbium atoms. Finally, simulated IR spectra of Er3@D3h(14246)-C74 and Er3@C1(13771)-C74 were simulated, which should be useful to distinguish those two isomers. PMID:26230214

  9. Low-toxic and safe nanomaterials by surface-chemical design, carbon nanotubes, fullerenes, metallofullerenes, and graphenes

    NASA Astrophysics Data System (ADS)

    YanEqual Contribution, Liang; Zhao, Feng; Li, Shoujian; Hu, Zhongbo; Zhao, Yuliang

    2011-02-01

    The toxicity grade for a bulk material can be approximately determined by three factors (chemical composition, dose, and exposure route). However, for a nanomaterial it depends on more than ten factors. Interestingly, some nano-factors (like huge surface adsorbability, small size, etc.) that endow nanomaterials with new biomedical functions are also potential causes leading to toxicity or damage to the living organism. Is it possible to create safe nanomaterials if such a number of complicated factors need to be regulated? We herein try to find answers to this important question. We first discuss chemical processes that are applicable for nanosurface modifications, in order to improve biocompatibility, regulate ADME, and reduce the toxicity of carbon nanomaterials (carbon nanotubes, fullerenes, metallofullerenes, and graphenes). Then the biological/toxicological effects of surface-modified and unmodified carbon nanomaterials are comparatively discussed from two aspects: the lowered toxic responses or the enhanced biomedical functions. We summarize the eight biggest challenges in creating low-toxicity and safer nanomaterials and some significant topics of future research needs: to find out safer nanofactors; to establish controllable surface modifications and simpler chemistries for low-toxic nanomaterials; to explore the nanotoxicity mechanisms; to justify the validity of current toxicological theories in nanotoxicology; to create standardized nanomaterials for toxicity tests; to build theoretical models for cellular and molecular interactions of nanoparticles; and to establish systematical knowledge frameworks for nanotoxicology.

  10. Electronic transport properties of the first all-boron fullerene B40 and its metallofullerene Sr@B40.

    PubMed

    An, Yipeng; Zhang, Mengjun; Wu, Dapeng; Fu, Zhaoming; Wang, Tianxing; Xia, Congxin

    2016-04-28

    The newly-discovered B40 is the first experimentally observed all-boron fullerene and has potential applications in molecular devices. Herein, we report the electronic transport properties of B40 and its metallofullerene, Sr@B40, using the first-principles technique. We obtain the conductance of B40 fullerene, which is about 130 μS and can be increased by embedding a strontium metal atom in the cage due to the decreased energy gap. Both the current-voltage (I-V) curves of B40 and Sr@B40 present perfect linear characteristics. Intuitively, it is assumed that the electron currents pass through the B40 fullerene mainly along the surface B-B bonds, while two types of new B-Sr-B bond currents and B→Sr→B hopping currents are presented for Sr@B40 due to Sr acting as a bridge. This study provides valuable information for the potential applications of future borospherene-based molecular devices. PMID:27067381

  11. Self-assembly of endohedral metallofullerenes: a decisive role of cooling gas and metal-carbon bonding

    NASA Astrophysics Data System (ADS)

    Deng, Qingming; Heine, Thomas; Irle, Stephan; Popov, Alexey A.

    2016-02-01

    The endohedral metallofullerene (EMF) self-assembly process in Sc/carbon vapor in the presence and absence of an inert cooling gas (helium) is systematically investigated using quantum chemical molecular dynamics simulations. It is revealed that the presence of He atoms accelerates the formation of pentagons and hexagons and reduces the size of the self-assembled carbon cages in comparison with analogous He-free simulations. As a result, the Sc/C/He system simulations produce a larger number of successful trajectories (i.e. leading to Sc-EMFs) with more realistic cage-size distribution than simulations of the Sc/C system. The main Sc encapsulation mechanism involves nucleation of several hexagons and pentagons with Sc atoms already at the early stages of carbon vapor condensation. In such proto-cages, both Sc-C σ-bonds and coordination bonds between Sc atoms and the π-system of the carbon network are present. Sc atoms are thus rather labile and can move along the carbon network, but the overall bonding is sufficiently strong to prevent dissociation even at temperatures around 2000 kelvin. Further growth of the fullerene cage results in the encapsulation of one or two Sc atoms within the fullerene. In agreement with experimental studies, an extension of the simulations to Fe and Ti as the metal component showed that Fe-EMFs are not formed at all, whereas Ti is prone to form Ti-EMFs with small cage sizes, including Ti@C28-Td and Ti@C30-C2v(3).The endohedral metallofullerene (EMF) self-assembly process in Sc/carbon vapor in the presence and absence of an inert cooling gas (helium) is systematically investigated using quantum chemical molecular dynamics simulations. It is revealed that the presence of He atoms accelerates the formation of pentagons and hexagons and reduces the size of the self-assembled carbon cages in comparison with analogous He-free simulations. As a result, the Sc/C/He system simulations produce a larger number of successful trajectories (i

  12. Self-assembly of endohedral metallofullerenes: a decisive role of cooling gas and metal-carbon bonding.

    PubMed

    Deng, Qingming; Heine, Thomas; Irle, Stephan; Popov, Alexey A

    2016-02-14

    The endohedral metallofullerene (EMF) self-assembly process in Sc/carbon vapor in the presence and absence of an inert cooling gas (helium) is systematically investigated using quantum chemical molecular dynamics simulations. It is revealed that the presence of He atoms accelerates the formation of pentagons and hexagons and reduces the size of the self-assembled carbon cages in comparison with analogous He-free simulations. As a result, the Sc/C/He system simulations produce a larger number of successful trajectories (i.e. leading to Sc-EMFs) with more realistic cage-size distribution than simulations of the Sc/C system. The main Sc encapsulation mechanism involves nucleation of several hexagons and pentagons with Sc atoms already at the early stages of carbon vapor condensation. In such proto-cages, both Sc-C σ-bonds and coordination bonds between Sc atoms and the π-system of the carbon network are present. Sc atoms are thus rather labile and can move along the carbon network, but the overall bonding is sufficiently strong to prevent dissociation even at temperatures around 2000 kelvin. Further growth of the fullerene cage results in the encapsulation of one or two Sc atoms within the fullerene. In agreement with experimental studies, an extension of the simulations to Fe and Ti as the metal component showed that Fe-EMFs are not formed at all, whereas Ti is prone to form Ti-EMFs with small cage sizes, including Ti@C28-Td and Ti@C30-C2v(3). PMID:26815243

  13. Metallofullerene-based Nanoplatform for Brain Tumor Brachytherapy and Longitudinal Imaging in a Murine Orthotopic Xenograft Model

    PubMed Central

    Shultz, Michael D.; Wilson, John D.; Fuller, Christine E.; Zhang, Jianyuan; Dorn, Harry C.

    2011-01-01

    Purpose: To demonstrate in an orthotopic xenograft brain tumor model that a functionalized metallofullerene (f-Gd3N@C80) can enable longitudinal tumor imaging and, when radiolabeled with lutetium 177 (177Lu) and tetraazacyclododecane tetraacetic acid (DOTA) (177Lu-DOTA-f-Gd3N@C80), provide an anchor to deliver effective brachytherapy. Materials and Methods: All experiments involving the use of mice were carried out in accordance with protocols approved by the institutional animal care and use committee. Human glioblastoma U87MG cells were implanted by using stereotactic procedures into the brains of 37 female athymic nude-Foxn1nu mice and allowed to develop into a tumor for 8 days. T1- and T2-weighted magnetic resonance (MR) imaging was performed in five mice. Biodistribution studies were performed in 12 mice at four time points over 7 days to evaluate gadolinium content. Survival studies involved 20 mice that received infusion of a nanoplatform by means of convection-enhanced delivery (CED) 8 days after tumor implantation. Mice in survival studies were divided into two groups: one comprised untreated mice that received f-Gd3N@C80 alone and the other comprised mice treated with brachytherapy that received 1.11 MBq of 177Lu-DOTA-f-Gd3N@C80. Survival data were evaluated by using Kaplan-Meier statistical methods. Results: MR imaging showed extended tumor retention (25.6% ± 1.2 of the infused dose at 52 days, confirmed with biodistribution studies) of the f-Gd3N@C80 nanoplatform, which enabled longitudinal imaging. Successful coupling of 177Lu to the f-Gd3N@C80 surface was achieved by using a bifunctional macrocyclic chelator. The extended tumor retention allowed for effective brachytherapy, as indicated by extended survival time (>2.5 times that of the untreated group) and histologic signs of radiation-induced tumor damage. Conclusion: The authors have developed a multimodal nanoplatform and have demonstrated longitudinal tumor imaging, prolonged intratumoral probe

  14. First soluble M@C60 derivatives provide enhanced access to metallofullerenes and permit in vivo evaluation of Gd@C60[C(COOH)2]10 as a MRI contrast agent.

    PubMed

    Bolskar, Robert D; Benedetto, Angelo F; Husebo, Lars O; Price, Roger E; Jackson, Edward F; Wallace, Sidney; Wilson, Lon J; Alford, J Michael

    2003-05-01

    M@C(60) and related endohedral metallofullerenes comprise a significant portion of the metallofullerene yield in the traditional arc synthesis, but their chemistry and potential applications have been largely overlooked because of their sparse solubility. In this work, procedures are described to solublize Gd@C(60) species for the first time by forming the derivative, Gd@C(60)[C(COOCH(2)CH(3))(2)](10), and its hydrolyzed water-soluble form, Gd@C(60)[C(COOH)(2)](10). Imparting water solubility to Gd@C(60) permits its evaluation as a magnetic resonance imaging (MRI) contrast agent. Relaxometry measurements for Gd@C(60)[C(COOH)(2)](10) reveal it to possess a relaxivity (4.6 mM(-1) s(-1) at 20 MHz and 40 degrees C) comparable to that of commercially available Gd(III) chelate-based MRI agents. An in vivo MRI biodistribution study in a rodent model reveals Gd@C(60)[C(COOH)(2)](10) to possess the first non-reticuloendothelial system (RES) localizing behavior for a water-soluble endohedral metallofullerene species, consistent with its lack of intermolecular aggregation in solution as determined by light-scattering measurements. This first derivatization and use of a M@C(60) species suggests new potential for metallofullerene technologies by reducing reliance on the chromatographic purification procedures normally employed for the far less abundant M@C(82) and related endohedrals. The recognition that water-soluble fullerene derivatives can be designed to avoid high levels of RES uptake is an important step toward fullerene-based pharmaceutical development. PMID:12720461

  15. Photoionization of Au+, Au2+, and Au3+ ions and developments in the synthesis of the metallofullerene Au@C60

    NASA Astrophysics Data System (ADS)

    Kilcoyne, A. L. David; Muller, Alfred; Schippers, Stefan; Hellhund, Jonas; Borovik, Alexander; Mueller, Allison; Gross, Dylan; Johnson, Andrea; Macaluso, David; A. L. D. Kilcoyne Collaboration

    2015-05-01

    Absolute single photoionization of Au+, Au2+, and Au3+ ions was investigated via the merged-beams technique at AMO Beamline 10.0.1.2 of the Advanced Light Source at Lawrence Berkeley National Laboratory. The absolute single photoionization yield was measured as a function of photon energy for each species from the metastable state ionization threshold region to well above the ground state ionization potential. Additional high-resolution measurements were performed for Au+ and Au2+ ions in the region of the ground and metastable state ionization thresholds to better resolve the detailed resonant structure found therein. This structure was used, along with the reported excited state energy levels of Au+, to preliminarily identify previously unreported excitation levels in all three ions. In addition and as a component of the same program, photoionization studies of the endohedral metallofullerene Au@C60+were performed using endohedral fullerene samples synthesized on-site at Beamline 10.0.1.2 of the ALS.

  16. Entrapping a Group-VB Transition Metal, Vanadium, within an Endohedral Metallofullerene: V(x)Sc(3-x)N@I(h)-C80 (x = 1, 2).

    PubMed

    Wei, Tao; Wang, Song; Lu, Xing; Tan, Yuanzhi; Huang, Jing; Liu, Fupin; Li, Qunxiang; Xie, Suyuan; Yang, Shangfeng

    2016-01-13

    So far the entrapped metals for the isolated endohedral metallofullerenes (EMFs) are primarily limited to rare earth metals, whereas except group-IVB metals, whether it is possible to entrap other d-block transition metals remains unclear. Herein we report the successful entrapment of the group-VB transition metal vanadium(V) into fullerene cage, affording the heretofore unknown V-containing EMFs. Two novel V-containing EMFs--V(x)Sc(3-x)N@C80 (x = 1, 2)--were isolated, and their molecular structures were unambiguously determined by X-ray crystallography to be I(h)(7)-C80 cage entrapping the planar VSc2N/V2ScN clusters. V(x)Sc(3-x)N@I(h)(7)-C80 (x = 1, 2) were further characterized by UV-vis-NIR and ESR spectroscopies and electrochemistry, revealing that the electronic and magnetic properties of V(x)Sc(3-x)N@I(h)(7)-C80 (x = 1, 2) are tunable upon varying the number of entrapped V atoms (i.e., x value). The molecular structures and electronic properties of V(x)Sc(3-x)N@I(h)(7)-C80 (x = 1, 2) were further compared with those of the reported analogous EMFs based on lanthanide metals and the adjacent group-IVB transition metal Ti, revealing the peculiarity of the group-VB transition metal V-based EMFs. PMID:26645852

  17. Mass spectroscopic and ESR characterization of soluble yttrium-containing metallofullerenes YC{sub 82} and Y{sub 2}C{sub 82}

    SciTech Connect

    Shinohara, Hisanori; Sato, Hiroyasu; Saito, Yahachi

    1992-04-30

    Solvent soluble, yttrium-containing fullerenes are extracted from yttrium/carbon soot produced by the carbon-arc fullerene generation method. An yttrium-graphite composite yields solvent extractable molecules such as YC{sub 82} and Y{sub 2}C{sub 82} as evidenced by a laser desorption time-of-flight (LD-TOF) mass spectroscopic analysis of the extracts. This is consistent with the very recent results by Smalley et al. where YC{sub 82} and Y{sub 2}C{sub 82} are prepared by laser vaporization of yttrium-graphite rods. The present extracts are souble by both toluene and carbon disulfide, but the solubility is much higher is CS{sub 2} than toluene. LD-TOF mass spectra also show the presence of a series of peaks due to the dimetallofullerens Y{sub 2}C{sub 2n}(2n = 84; 90 {le} 2n {le}140). The metallofullerenes YC{sub 60} and YC{sub 70} are not observed in the mildest possible LD conditions under which YC{sub 82} and the dimetallofullerenes Y{sub 2}C{sub 82} and Y{sub 2}C{sub 2n} are readily observed. ESR spectral results are also reported for the present yttrium-fullerene complexes and indicate the charge separation state of Y{sup 3+}C{sub 82}{sup 3-} as has been found for La{sup 3+}C{sub 82}{sup 3-} by Johnson et. al. 13 refs., 4 figs.

  18. Gd@C82 metallofullerenes for neutron capture therapy—fullerene solubilization by poly(ethylene glycol)-block-poly(2-(N, N-diethylamino)ethyl methacrylate) and resultant efficacy in vitro

    NASA Astrophysics Data System (ADS)

    Horiguchi, Yukichi; Kudo, Shinpei; Nagasaki, Yukio

    2011-08-01

    Poly(ethylene glycol)-block-poly(2-(N,N-diethylamino)ethyl methacrylate) (PEG-b-PAMA) was found to solubilize fullerenes such as C60, and this technique was applied to metallofullerenes. Gd@C82 was easily dissolved in water in the presence of PEG-b-PAMA without any covalent derivatization, forming a transparent complex about 20-30 nm in diameter. Low cytotoxicity was confirmed in vitro. Neutron irradiation of cultured cells (colon-26 adenocarcinoma) with Gd@C82-PEG-b-PAMA-complexed nanoparticles showed effective cytotoxicity, indicating the effective emission of gamma rays and internal conversion electrons produced from the neutron capture reaction of Gd. This result suggests a potentially valuable approach to gadolinium-based neutron capture therapy.

  19. In-depth understanding of the chemical properties of rarely explored carbide cluster metallofullerenes: a case study of Sc2 C2 @C3v (8)-C82 that reveals a general rule.

    PubMed

    Cai, Wenting; Chen, Muqing; Bao, Lipiao; Xie, Yunpeng; Akasaka, Takeshi; Lu, Xing

    2015-02-16

    The chemical properties of carbide-cluster metallofullerenes (CCMFs) remain largely unexplored, although several new members of CCMFs have been discovered recently. Herein, we report the reaction between Sc2 C2 @C3v (8)-C82 , which is viewed as a prototypical CCMF because of its high abundance, and 3-triphenylmethyl-5-oxazolidinone (1) to afford the corresponding pyrrolidino derivative Sc2 C2 @C3v (8)-C82 (CH2 )2 NTrt (2; Trt=triphenylmethyl). Single-crystal X-ray crystallography studies of 2 revealed that the reaction takes place at a [6,6]-bond junction, which is directly over the encapsulated C2 unit and is far from either of the two scandium atoms. On the basis of theoretical calculations and by considering previously reports, we have found that a hexagonal carbon ring on the cage of Sc2 C2 @C3v (8)-C82 is highly reactive toward different reagents due to the overlap of high p-orbital axis vector (POAV) angles and large LUMO coefficients. We propose that this highly concentrated area of reactivity is generated by the encapsulation of the Sc2 C2 cluster because this region is absent from the empty fullerene C3v (8)-C82 . Moreover, the absorption and electrochemical results confirm that derivative 2 is more stable than pristine Sc2 C2 @C3v (8)-C82 , thus illuminating its potential applications. PMID:25640803

  20. Gadolinium-containing MRI contrast agents: important variations on a theme for NSF.

    PubMed

    Kuo, Phillip H

    2008-01-01

    Millions of doses of gadolinium-based contrast agents (GBCAs) are administered annually to improve the clinical utility of magnetic resonance imaging. All the approved agents incorporate one atom of the rare earth metal gadolinium into a chelate to improve the safety of the ordinarily toxic free gadolinium. The undeniable epidemiologic link between GBCAs and nephrogenic systemic fibrosis (NSF) has prompted renewed investigation into the different chemical properties of the GBCAs despite their clinical interchangeability. Gadolinium-based contrast agents can be divided into different categories: linear versus macrocyclic structure, ionic versus nonionic, and non-protein-binding versus protein-binding agents. The GBCAs differ significantly with respect to transmetallation and kinetic and thermodynamic stability and therefore their propensity to release free gadolinium, which is hypothesized to induce NSF. That gadodiamide, with its susceptibility to transmetallation and relatively low thermodynamic and kinetic stability, is associated with the most cases of NSF supports this hypothesis. On the other hand, the greater stability of a macrocyclic agent hypothetically would confer a greater safety margin with regard to NSF. Because few published data on an experimental model of NSF exist, continuing vigilance is necessary to report new cases of NSF, especially with regard to the agents with small market share. PMID:18180006

  1. Gadofullerene MRI contrast agents.

    PubMed

    Bolskar, Robert D

    2008-04-01

    A promising new class of MRI contrast-enhancing agents with high relaxivities is based on gadolinium-containing metallofullerenes, which are also termed gadofullerenes. Detailed study of the water-proton relaxivity properties and intermolecular nanoclustering behavior of gadofullerene derivatives has revealed valuable information about their relaxivity mechanisms and given a deeper understanding of this new class of paramagnetic contrast agent. Here, the latest findings on water-solubilized gadofullerene materials and how these findings relate to their future applications in MRI are reviewed and discussed. PMID:18373426

  2. Self-assembly of endohedral metallofullerenes: a decisive role of cooling gas and metal–carbon bonding† †Electronic supplementary information (ESI) available: Additional information on metal–carbon bonding and MD simulations. See DOI: 10.1039/c5nr08645k Click here for additional data file.

    PubMed Central

    Deng, Qingming; Heine, Thomas

    2016-01-01

    The endohedral metallofullerene (EMF) self-assembly process in Sc/carbon vapor in the presence and absence of an inert cooling gas (helium) is systematically investigated using quantum chemical molecular dynamics simulations. It is revealed that the presence of He atoms accelerates the formation of pentagons and hexagons and reduces the size of the self-assembled carbon cages in comparison with analogous He-free simulations. As a result, the Sc/C/He system simulations produce a larger number of successful trajectories (i.e. leading to Sc-EMFs) with more realistic cage-size distribution than simulations of the Sc/C system. The main Sc encapsulation mechanism involves nucleation of several hexagons and pentagons with Sc atoms already at the early stages of carbon vapor condensation. In such proto-cages, both Sc–C σ-bonds and coordination bonds between Sc atoms and the π-system of the carbon network are present. Sc atoms are thus rather labile and can move along the carbon network, but the overall bonding is sufficiently strong to prevent dissociation even at temperatures around 2000 kelvin. Further growth of the fullerene cage results in the encapsulation of one or two Sc atoms within the fullerene. In agreement with experimental studies, an extension of the simulations to Fe and Ti as the metal component showed that Fe-EMFs are not formed at all, whereas Ti is prone to form Ti-EMFs with small cage sizes, including Ti@C28-T d and Ti@C30-C 2v(3). PMID:26815243

  3. Diagnostic Magnetic Resonance Imaging of Atherosclerosis in Apolipoprotein E Knockout Mouse Model Using Macrophage-Targeted Gadolinium-Containing Synthetic Lipopeptide Nanoparticles

    PubMed Central

    Shen, Zu T.; Zheng, Shaokuan; Gounis, Matthew J.; Sigalov, Alexander B.

    2015-01-01

    Cardiovascular disease is the leading cause of death in Western cultures. The vast majority of cardiovascular events, including stroke and myocardial infarction, result from the rupture of vulnerable atherosclerotic plaques, which are characterized by high and active macrophage content. Current imaging modalities including magnetic resonance imaging (MRI) aim to characterize anatomic and structural features of plaques rather than their content. Previously, we reported that macrophage-targeted delivery of gadolinium (Gd)-based contrast agent (GBCA-HDL) using high density lipoproteins (HDL)-like particles significantly enhances the detection of plaques in an apolipoprotein (apo) E knockout (KO) mouse model, with an atherosclerotic wall/muscle normalized enhancement ratio (NER) of 120% achieved. These particles are comprised of lipids and synthetic peptide fragments of the major protein of HDL, apo A-I, that contain a naturally occurring modification which targets the particles to macrophages. Targeted delivery minimizes the Gd dose and thus reduces the adverse effects of Gd. The aims of the current study were to test whether varying the GBCA-HDL particle shape and composition can further enhance atherosclerotic plaque MRI and control organ clearance of these agents. We show that the optimized GBCA-HDL particles are efficiently delivered intracellularly to and uptaken by both J774 macrophages in vitro and more importantly, by intraplaque macrophages in vivo, as evidenced by NER up to 160% and higher. This suggests high diagnostic power of our GBCA-HDL particles in the detection of vulnerable atherosclerotic plaques. Further, in contrast to discoidal, spherical GBCA-HDL exhibit hepatic clearance, which could further diminish adverse renal effects of Gd. Finally, activated macrophages are reliable indicators of any inflamed tissues and are implicated in other areas of unmet clinical need such as rheumatoid arthritis, sepsis and cancer, suggesting the expanded diagnostic and prognostic use of this method. PMID:26569115

  4. Thermoelectricity at the molecular scale: a large Seebeck effect in endohedral metallofullerenes

    NASA Astrophysics Data System (ADS)

    Lee, See Kei; Buerkle, Marius; Yamada, Ryo; Asai, Yoshihiro; Tada, Hirokazu

    2015-12-01

    Single molecule devices provide a unique system to study the thermoelectric energy conversion at an atomistic level and can provide valuable information for the design of organic thermoelectric materials. Here we present a comprehensive study of the thermoelectric transport properties of molecular junctions based on C82, Gd@C82, and Ce@C82. We combine precise scanning tunneling microscope break-junction measurements of the thermopower and conductance with quantitatively accurate self-energy-corrected first-principles transport calculations. We find that all three fullerene derivatives give rise to a negative thermopower (n-conducting). The absolute value, however, is much larger for the Gd@C82 and Ce@C82 junctions. The conductance, on the other hand, remains comparable for all three systems. The power factor determined for the Gd@C82 based junction is so far the highest obtained for a single-molecule device. Although the encapsulated metal atom does not directly contribute to the transport, we show that the observed enhancement of the thermopower for Gd@C82 and Ce@C82 is elucidated by the substantial changes in the electronic- and geometrical structure of the fullerene molecule induced by the encapsulated metal atom.Single molecule devices provide a unique system to study the thermoelectric energy conversion at an atomistic level and can provide valuable information for the design of organic thermoelectric materials. Here we present a comprehensive study of the thermoelectric transport properties of molecular junctions based on C82, Gd@C82, and Ce@C82. We combine precise scanning tunneling microscope break-junction measurements of the thermopower and conductance with quantitatively accurate self-energy-corrected first-principles transport calculations. We find that all three fullerene derivatives give rise to a negative thermopower (n-conducting). The absolute value, however, is much larger for the Gd@C82 and Ce@C82 junctions. The conductance, on the other hand, remains comparable for all three systems. The power factor determined for the Gd@C82 based junction is so far the highest obtained for a single-molecule device. Although the encapsulated metal atom does not directly contribute to the transport, we show that the observed enhancement of the thermopower for Gd@C82 and Ce@C82 is elucidated by the substantial changes in the electronic- and geometrical structure of the fullerene molecule induced by the encapsulated metal atom. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05394c

  5. Thermoelectricity at the molecular scale: a large Seebeck effect in endohedral metallofullerenes.

    PubMed

    Lee, See Kei; Buerkle, Marius; Yamada, Ryo; Asai, Yoshihiro; Tada, Hirokazu

    2015-12-28

    Single molecule devices provide a unique system to study the thermoelectric energy conversion at an atomistic level and can provide valuable information for the design of organic thermoelectric materials. Here we present a comprehensive study of the thermoelectric transport properties of molecular junctions based on C(82), Gd@C(82), and Ce@C(82). We combine precise scanning tunneling microscope break-junction measurements of the thermopower and conductance with quantitatively accurate self-energy-corrected first-principles transport calculations. We find that all three fullerene derivatives give rise to a negative thermopower (n-conducting). The absolute value, however, is much larger for the Gd@C(82) and Ce@C(82) junctions. The conductance, on the other hand, remains comparable for all three systems. The power factor determined for the Gd@C(82) based junction is so far the highest obtained for a single-molecule device. Although the encapsulated metal atom does not directly contribute to the transport, we show that the observed enhancement of the thermopower for Gd@C(82) and Ce@C(82) is elucidated by the substantial changes in the electronic- and geometrical structure of the fullerene molecule induced by the encapsulated metal atom. PMID:26583505

  6. Missing metallofullerene Yb@C72: A density functional theory survey

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Zhao, Xiang

    2013-09-01

    With density functional theory calculations, Yb@C72 isomers are determined to utilize two fullerene cages violating the isolated pentagon rule. Both endohedral fullerenes show high thermodynamic stability in fullerene formation temperature region. Detailed calculations on the properties such as ionization energies and electron affinities of Yb@C72 provide a profoundly understanding of these two novel molecules. In addition, electronic absorption spectra and infrared spectra of two Yb@C72 isomers have also been simulated theoretically to assist future experiments.

  7. Metallofullerene nanoparticles promote osteogenic differentiation of bone marrow stromal cells through BMP signaling pathway

    NASA Astrophysics Data System (ADS)

    Yang, Kangning; Cao, Weipeng; Hao, Xiaohong; Xue, Xue; Zhao, Jing; Liu, Juan; Zhao, Yuliang; Meng, Jie; Sun, Baoyun; Zhang, Jinchao; Liang, Xing-Jie

    2013-01-01

    Although endohedral metallofullerenol [Gd@C82(OH)22]n nanoparticles have anti-tumor efficiency and mostly deposit in the bones of mice, how these nanoparticles act in bone marrow stromal cells (MSCs) remains largely unknown. Herein, we observed that [Gd@C82(OH)22]n nanoparticles facilitated the differentiation of MSCs toward osteoblasts, as evidenced by the enhancement of alkaline phosphatase (ALP) activity and mineralized nodule formation upon [Gd@C82(OH)22]n nanoparticle treatment. Mechanistically, the effect of [Gd@C82(OH)22]n nanoparticles on ALP activity was inhibited by the addition of noggin as an inhibitor of the BMP signaling pathway. Moreover, the in vivo results of the ovariectomized rats further indicated that [Gd@C82(OH)22]n nanoparticles effectively improved bone density and prevented osteoporosis.Although endohedral metallofullerenol [Gd@C82(OH)22]n nanoparticles have anti-tumor efficiency and mostly deposit in the bones of mice, how these nanoparticles act in bone marrow stromal cells (MSCs) remains largely unknown. Herein, we observed that [Gd@C82(OH)22]n nanoparticles facilitated the differentiation of MSCs toward osteoblasts, as evidenced by the enhancement of alkaline phosphatase (ALP) activity and mineralized nodule formation upon [Gd@C82(OH)22]n nanoparticle treatment. Mechanistically, the effect of [Gd@C82(OH)22]n nanoparticles on ALP activity was inhibited by the addition of noggin as an inhibitor of the BMP signaling pathway. Moreover, the in vivo results of the ovariectomized rats further indicated that [Gd@C82(OH)22]n nanoparticles effectively improved bone density and prevented osteoporosis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr33575a

  8. Intra-tumor distribution of metallofullerene using micro-particle induced X-ray emission (PIXE).

    PubMed

    Yamamoto, Yohei; Yamamoto, Tetsuya; Horiguchi, Yukichi; Shirakawa, Makoto; Satoh, Takahiro; Koka, Masashi; Nagasaki, Yukio; Nakai, Kei; Matsumura, Akira

    2014-06-01

    To clarify the intra tumor distribution of gadlinium containing fullerene (Gd@C82), micro particle induced X-ray emission (Micro-PIXE) analysis were performed. The tumor bearing BALB/c mice were injected Gd@C82 and subcutaneous tumors were taken from 48h after the intravenous injection. Using the Micro-PIXE method, we could visualize Gd intra tumor distribution. Therefore our results indicate the possibility that Micro-PIXE is useful technique for imaging the bioditribution of Gd, and Gd@C82 is potentially useful Gd carrier for NCT. PMID:24491681

  9. In-Plane Intermolecular Interaction Assisted Assembly and Modified Electronic States of Metallofullerene Gd@C₈₂.

    PubMed

    Chen, Jian; Qin, Zhihui; Pan, Jinbo; Huang, Min; Du, Shixuan; Cao, Gengyu

    2015-10-27

    Orientational configuration and electronic states of Gd@C82 bonding to Cu(111) have been thoroughly investigated by low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/S) and differential conductance mapping complemented by first-principles calculations. We clarify that individual Gd@C82 energetically adopts tilting adsorption configuration with the scanning tunneling spectroscopy (STS) states readily assigned to the C82 cage/Cu(111) hybrid states and the Gd/cage hybrid states, respectively. Moreover, upon assembling and sufficient thermal activation, Gd@C82 fullerenes are inclined to restore the energetically favored tilting orientational configuration similar to an individual one. This suggests the feasibility of high-level integration of single-Gd@C82 based moletronic device with the performances almost unchanged by two-dimensional arrangement. Furthermore, by rationalizing the inter-Gd@C82 interaction induced slight energy offset of the electronic states, we qualitatively confirm the shown electronic hybrid states as Cu(111)-, C82 cage- and Gd-dominant hybrid states, respectively. PMID:26457573

  10. Reactivity of endohedral metallofullerene la2@c80 in nucleophilic and electrophilic attacks: vibronic coupling density approach.

    PubMed

    Haruta, Naoki; Sato, Tohru; Tanaka, Kazuyoshi

    2015-01-01

    The regioselectivities of La2@C80 in thermal nucleophilic and electrophilic attacks were theoretically investigated using vibronic coupling density (VCD) analysis. Nucleophilic and electrophilic cycloadditions to La2@C80 were experimentally reported to yield [6,6] and [6,5] adducts, respectively, as major products. VCD analysis provided a clear explanation for these experimental results. For nucleophilic reactions, it was found that the reactive [6,6] bonds did not have a large lowest unoccupied molecular orbital (LUMO) density and Fukui function but a large potential derivative with respect to a reaction mode. The VCD illustrates the origin of the interaction between the electronic and vibrational states. On the other hand, conventional reactivity indices such as frontier orbital density take only the electronic state into account. The result suggested that the stabilization due to vibronic couplings plays an important role in the regioselectivity of nucleophilic cycloadditions. The VCD with respect to the effective mode could provide a picture of the functional groups, which are the double bonds of ethylene moieties. VCD analysis with respect to hypothetical localized modes enabled the quantitative prediction of regioselectivities. PMID:25389657

  11. A singly bonded derivative of endohedral metallofullerene: La@C82CBr(COOC2H5).

    PubMed

    Feng, Lai; Nakahodo, Tsukasa; Wakahara, Takatsugu; Tsuchiya, Takahiro; Maeda, Yutaka; Akasaka, Takeshi; Kato, Tatsuhisa; Horn, Ernst; Yoza, Kenji; Mizorogi, Naomi; Nagase, Shigeru

    2005-12-14

    A novel Bingel monoadduct of La@C82 (mono-A) has been synthesized by the reaction with diethyl bromomalonate in the presence of DBU (Bingel-Hirsch reaction). Its structure has been fully determined by NMR spectroscopic and X-ray crystallographic analyses. The most distinct feature of mono-A is the single bond moiety between the functional group and fullerene cage, which is very different from the cyclopropane moiety in a conventional Bingel adduct of empty fullerenes. Further spectroscopic characterizations and calculations revealed the closed-shell structure of mono-A. Its formation mechanism was discussed according to calculation results. PMID:16332032

  12. Magnetic behavior of pure endohedral metallofullerene Ho{at}C{sub 82}: A comparison with Gd{at}C{sub 82}

    SciTech Connect

    Huang, H.J.; Yang, S.H.; Zhang, X.X.

    1999-07-22

    Magnetic properties of Ho{at}C{sub 82} and Gd{at}C{sub 82} were characterized in the temperature range of 1.8--100 K with an applied magnetic field up to 5T. The isothermal magnetization curves of Gd{at}C{sub 82} and Ho{at}C{sub 82} follow the Brillouin function down to 8 and 12 K, respectively. Unlike Gd{at}C{sub 82}, the fitting to the Curie-Wiess law for Ho{at}C{sub 82} results in an effective magnetic moment which is significantly smaller than that of a free Ho{sup 3+} ion. The magnetic moment reduction and the imperfect paramagnetic behavior of Ho{at}C{sub 82} are ascribed to the carbon cage crystal field effect, the partial hybridization of the orbitals of the entrapped Ho atom and the carbon cage, and the interactions between the metal centers.

  13. Isolation and Crystallographic Characterization of the Labile Isomer of Y@C82 Cocrystallized with Ni(OEP): Unprecedented Dimerization of Pristine Metallofullerenes.

    PubMed

    Bao, Lipiao; Pan, Changwang; Slanina, Zdenek; Uhlik, Filip; Akasaka, Takeshi; Lu, Xing

    2016-08-01

    Although the major isomers of M@C82 (namely M@C2v (9)-C82 , where M is a trivalent rare-earth metal) have been intensively investigated, the lability of the minor isomers has meant that they have been little studied. Herein, the first isolation and crystallographic characterization of the minor Y@C82 isomer, unambiguously assigned as Y@Cs (6)-C82 by cocrystallization with Ni(octaethylporphyrin), is reported. Unexpectedly, a regioselective dimerization is observed in the crystalline state of Y@Cs (6)-C82 . In sharp contrast, no dimerization occurs for the major isomer Y@C2v (9)-C82 under the same conditions, indicating a cage-symmetry-induced dimerization process. Further experimental and theoretical results disclose that the regioselective dimer formation is a consequence of the localization of high spin density on a special cage-carbon atom of Y@Cs (6)-C82 which is caused by the steady displacement of the Y atom inside the Cs (6)-C82 cage. PMID:27305624

  14. Quantum-chemical calculations of the metallofullerene yields in the X @ C74, L @ C74, and Z @ C82 series

    NASA Astrophysics Data System (ADS)

    Uhlík, Filip; Slanina, Zdeněk; Nagase, Shigeru

    2015-01-01

    The contribution reports computations for Al @ C82, Sc @ C82, Y @ C82 and La @ C82 based on encapsulation into the IPR (isolated pentagon rule) C2ν C82 cage and also on Mg @ C74, Ca @ C74, Sr @ C74 and Ba @ C74 based on encapsulation into the only C74 IPR cage as well as for three selected lanthanoids La @ C74, Yb @ C74, and Lu @ C74. Their structural and energetic characteristics are used for evaluations of the relative production yields, using the encapsulation Gibbs-energy and saturated metal pressures. It is shown that the results can be well related to the ionization potentials of the free metal atoms.

  15. Quantum-chemical calculations of the metallofullerene yields in the X@C{sub 74}, L@C{sub 74}, and Z@C{sub 82} series

    SciTech Connect

    Uhlík, Filip; Slanina, Zdeněk; Nagase, Shigeru

    2015-01-22

    The contribution reports computations for Al@C{sub 82}, Sc@C{sub 82}, Y@C{sub 82} and La@C{sub 82} based on encapsulation into the IPR (isolated pentagon rule) C{sub 2ν} C{sub 82} cage and also on Mg@C{sub 74}, Ca@C{sub 74}, Sr@C{sub 74} and Ba@C{sub 74} based on encapsulation into the only C{sub 74} IPR cage as well as for three selected lanthanoids La@C{sub 74}, Yb@C{sub 74}, and Lu@C{sub 74}. Their structural and energetic characteristics are used for evaluations of the relative production yields, using the encapsulation Gibbs-energy and saturated metal pressures. It is shown that the results can be well related to the ionization potentials of the free metal atoms.

  16. Kinetic Stability of Non-IPR Fullerene Molecular Ions.

    PubMed

    Aihara, Jun-ichi; Nakagami, Yuto; Sekine, Rika

    2015-06-18

    Many fullerenes that violate the isolated pentagon rule (IPR) form stable metallofullerenes. In general, a fullerene cage is kinetically stabilized by acquiring a given number of electrons. Kinetic stability of negatively charged non-IPR fullerenes, including the recently isolated endohedral metallofullerene with a heptagonal face, was rationalized in terms of bond resonance energy (BRE). Interestingly, molecular anions of conventional fullerenes found in most isolated metallofullerenes are kinetically stable with large positive BREs for all CC bonds. As we pointed out in 1993, the IPR does not apply to charged fullerenes because π-bonds shared by two five-membered rings are aromatized to varying extents. PMID:26020361

  17. Encapsulation of radioactive [sup 159]Gd and [sup 161]Tb atoms in fullerene cages

    SciTech Connect

    Kikuchi, Koichi; Kobayashi, Kanako; Sueki, Keisuke; Suzuki, Shinzo; Nakahara, Hiromichi; Achiba, Yohji; Katada, Motomi ); Tomura, Kenji )

    1994-10-19

    We demonstrate a novel form of metallofullerenes, namely, those with radioactive atoms encapsulated in the C[sub 82]cage. The metal atoms were made radioactive by a neutron capture reaction or through a nuclear decay process. The most important and intriguing finding of the present study is that the endohedral form of metallofullerenes is not affected by the recoil energy of the metal atom resulting from emission of electrons in the [beta] decay. Such a stability of the cage against the recoil energy of the encapsulated atom was confirmed by the elution behavior of the metallofullerene in liquid chromatography. Successful encapsulation of radioactive atoms inside the fullerene cage will greatly widen the potential use of endohedral metallofullerenes not only in basic science and technology but also in other areas, such as medicine. 14 refs., 3 figs.

  18. Energy stabilization of the s -symmetry superatom molecular orbital by endohedral doping of C 82 fullerene with a lanthanum atom

    SciTech Connect

    Feng, Min; Shi, Yongliang; Lin, Chungwei; Zhao, Jin; Liu, Fupin; Yang, Shangfeng; Petek, Hrvoje

    2013-08-01

    Energy stabilization of the superatom molecular orbitals (SAMOs) in fullerenes is investigated with the goal of involving their nearly free-electron bands in practical charge transport applications. Combining low-temperature scanning tunneling microscopy-based spectroscopic methods and density functional theory calculations on an endohedral metallofullerene La@C82, we confirm that the s-SAMO of C82 fullerene is stabilized by as much as 2 eV with respect to that of C60 by endohedral doping with the La atom. On the copper metal substrate, the s-SAMO energy is further lowered to just 1 eV above the Fermi level, making the applications of s-SAMO state in transport more plausible. We conclude that in an endohedral metallofullerene, the s-SAMO state is stabilized through the hybridization with the s-symmetry valence state of the metal atom and the stabilization energy correlates with the ionization potential of the free atom.

  19. Defect Induced Electronic Structure of Uranofullerene

    PubMed Central

    Dai, Xing; Cheng, Cheng; Zhang, Wei; Xin, Minsi; Huai, Ping; Zhang, Ruiqin; Wang, Zhigang

    2013-01-01

    The interaction between the inner atoms/cluster and the outer fullerene cage is the source of various novel properties of endohedral metallofullerenes. Herein, we introduce an adatom-type spin polarization defect on the surface of a typical endohedral stable U2@C60 to predict the associated structure and electronic properties of U2@C61 based on the density functional theory method. We found that defect induces obvious changes in the electronic structure of this metallofullerene. More interestingly, the ground state of U2@C61 is nonet spin in contrast to the septet of U2@C60. Electronic structure analysis shows that the inner U atoms and the C ad-atom on the surface of the cage contribute together to this spin state, which is brought about by a ferromagnetic coupling between the spin of the unpaired electrons of the U atoms and the C ad-atom. This discovery may provide a possible approach to adapt the electronic structure properties of endohedral metallofullerenes. PMID:23439318

  20. Endohedral fullerene with μ3-carbido ligand and titanium-carbon double bond stabilized inside a carbon cage.

    PubMed

    Svitova, A L; Ghiassi, K B; Schlesier, C; Junghans, K; Zhang, Y; Olmstead, M M; Balch, A L; Dunsch, L; Popov, A A

    2014-01-01

    In all metallofullerenes known before this work, metal atoms form single highly polar bonds with non-metal atoms in endohedral cluster. This is rather surprising for titanium taking into account the diversity of organotitanium compounds. Here we show that the arc-discharge synthesis of mixed titanium-lutetium metallofullerenes in the presence of ammonia, melamine or methane unexpectedly results in the formation of TiLu2C@I(h)-C80 with an icosahedral Ih(7) carbon cage. Single-crystal X-ray diffraction and spectroscopic studies of the compound reveal an unprecedented endohedral cluster with a μ3-carbido ligand and Ti-C double bond. The Ti(IV) in TiLu2C@I(h)-C80 can be reversibly reduced to the Ti(III) state. The Ti = C bonding and Ti-localized lowest unoccupied molecular orbital in TiLu2C@Ih-C80 bear a certain resemblance to titanium alkylidenes. TiLu2C@I(h)-C80 is the first metallofullerene with a multiple bond between a metal and the central, non-metal atom of the endohedral cluster. PMID:24699547

  1. CuCl2 for the isolation of a broad array of endohedral fullerenes containing metallic, metallic carbide, metallic nitride, and metallic oxide clusters, and separation of their structural isomers.

    PubMed

    Stevenson, Steven; Rottinger, Khristina A

    2013-08-19

    A typical arc-synthesis generates many types of fullerenes and endohedrals. Resulting soot extracts contain a complex mixture of >50 types of fullerenes, metallofullerenes, and their structural isomers. Prior to application development, novel separation methods are required to fractionate this rich array of metallic, metallic carbide, metallic nitride, and metallic oxide endohedrals, all of which can be present in a single, soot extract. Herein, we report the discovery of CuCl2 as a Lewis acid that will selectively precipitate only the more reactive members of each of these endohedral families. The more reactive Sc4O2@Ih-C80, Sc3C2@Ih-C80, and Sc3N@D3h-C78 endohedrals are quickly removed from extracts to greatly decrease the number of endohedrals present in a sample. Experiments indicate that enrichment factors of several orders of magnitude can be achieved within minutes of reaction time. CuCl2 also has sufficient selectivity to resolve and separate structural isomers, as demonstrated with Er2@C82 (isomer I, Cs(6)-C82 versus isomer III). The selective complexation of CuCl2 with fullerenes can be correlated to their first oxidation potential. We estimate a significantly lower threshold of precipitation for CuCl2 (<0.19 V) compared to stronger Lewis acids. Fullerenes and metallofullerenes having first oxidation potentials above 0.19 V tend to remain unreacted in solution. In contrast, species with first oxidation potentials below 0.19 V (vs Fc/Fc(+)) precipitate via complexation, and are easily decomplexed. CuCl2 is compared to Lewis acids having higher precipitation thresholds (e.g., FeCl3) in our goal to predict a priori which endohedrals would remain in solution versus which endohedral species would complex and precipitate. The ability to predict endohedral precipitation a priori is beneficial to the design of purification strategies for metallofullerenes. PMID:23952569

  2. Regioselective Synthesis and Crystallographic Characterization of Isoxazoline-Ring-Fused Derivatives of Sc3N@Ih-C80 and C60.

    PubMed

    Bao, Lipiao; Chen, Muqing; Shen, Wangqiang; Pan, Changwang; Ghiassi, Kamran B; Olmstead, Marilyn M; Balch, Alan L; Akasaka, Takeshi; Lu, Xing

    2016-05-01

    Highly regioselective 1,3-dipolar cycloaddition of 3,5-dichloro-2,4,6-trimethoxybenzonitrile oxide (1) to Sc3N@Ih-C80 or C60 affords the corresponding isoxazoline-ring-fused derivatives Sc3N@Ih-C80(C10H9O4NCl2) (2a) and C60(C10H9O4NCl2) (2b). 2a represents the first example of an endohedral metallofullerene derivative with an isoxazoline ring. Crystallographic and NMR spectroscopic studies reveal a [5,6]-bond addition pattern in 2a but a [6,6]-bond addition manner in 2b. PMID:27101430

  3. Fullerenes and their derivatives as inhibitors of tumor necrosis factor-α with highly promoted affinities.

    PubMed

    Wu, Gaoyin; Gao, Xuejiao J; Jang, Joonkyung; Gao, Xingfa

    2016-07-01

    Tumor necrosis factor-α (TNF-α) is a cell signalling protein involved in systemic inflammation in infectious and other malignant diseases. Physiologically, it plays an important role in regulating host defence, but its overexpression can lead to serious illnesses including cancer, autoimmune disease and inflammatory disease. Gadolinium-based metallofullerenols, e.g., Gd@C82(OH) x (x ≈ 22), are well known for their abundant biological activities with low toxicity experimentally and theoretically; however, their activity in direct TNF-α inhibition has not been explored. In this work, we investigated the inhibiting effects of four types of fullerene-based ligands: fullerenes, fullerenols, metallofullerenes, and metallofullerenols. We reported previously that fullerenes, metallofullerenes and their hydroxylated derivatives (fullerenols) can reside in the same pocket of the TNF-α dimer as that of SPD304-a known inhibitor of TNF-α [He et al. (2005) Science 310:1022, 18]. Ligand docking and binding free energy calculations suggest that, with a similar nonpolar interaction dominated binding pattern, the fullerene-based ligands, C60, C60(OH)12, Gd@C60, C82, C82(OH)12, Gd@C82, Gd@C82(OH)13 and Gd@C82(OH)21, have larger affinity than currently known inhibitors, and could be used to design novel inhibitors of TNF-α in the future. Graphical Abstract Fullerene-material/TNF-α. PMID:27316702

  4. Sm@C2v(3)-C80: site-hopping motion of endohedral Sm atom and metal-induced effect on redox profile

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Niu, Ben; Shi, Zujin; Lian, Yongfu; Feng, Lai

    2012-10-01

    A new metallofullerene Sm@C2v(3)-C80 was synthesized and characterized. X-Ray analysis showed that the endohedral Sm atom undergoes a hopping motion between several off-center sites, even at low temperature. In addition, a comparative electrochemical study between Sm@C2v(3)-C80 and Yb@C2v(3)-C80 revealed their different redox potentials, suggesting a metal-induced effect on their redox profiles.A new metallofullerene Sm@C2v(3)-C80 was synthesized and characterized. X-Ray analysis showed that the endohedral Sm atom undergoes a hopping motion between several off-center sites, even at low temperature. In addition, a comparative electrochemical study between Sm@C2v(3)-C80 and Yb@C2v(3)-C80 revealed their different redox potentials, suggesting a metal-induced effect on their redox profiles. CCDC reference number 894168. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr32193a

  5. Gd-containing conjugated polymer nanoparticles: bimodal nanoparticles for fluorescence and MRI imaging

    NASA Astrophysics Data System (ADS)

    Hashim, Zeina; Green, Mark; Chung, Pei Hua; Suhling, Klaus; Protti, Andrea; Phinikaridou, Alkystis; Botnar, Rene; Khanbeigi, Raha Ahmad; Thanou, Maya; Dailey, Lea Ann; Nicola J., Commander; Rowland, Caroline; Scott, Jo; Jenner, Dominic

    2014-06-01

    Aqueous bifunctional semiconductor polymer nanoparticles (SPNs), approximately 30 nm in diameter (as measured from electron microscopy), were synthesised using hydrophobic conjugated polymers, amphiphilic phospholipids and a gadolinium-containing lipid. Their fluorescence quantum yields and extinction coefficients were determined, and their MRI T1-weighted relaxation times in water were measured. The bimodal nanoparticles were readily taken up by HeLa and murine macrophage-like J774 cells as demonstrated by confocal laser scanning microscopy, and were found to be MRI-active, generating a linear relationship between T1-weighted relaxation rates and gadolinium concentrations The synthesis is relatively simple, and can easily result in milligrams of materials, although we fully expect scale-up to the gram level to be easily realised.

  6. Gd-containing conjugated polymer nanoparticles: bimodal nanoparticles for fluorescence and MRI imaging.

    PubMed

    Hashim, Zeina; Green, Mark; Chung, Pei Hua; Suhling, Klaus; Protti, Andrea; Phinikaridou, Alkystis; Botnar, Rene; Khanbeigi, Raha Ahmad; Thanou, Maya; Dailey, Lea Ann; Commander, Nicola J; Rowland, Caroline; Scott, Jo; Jenner, Dominic

    2014-07-21

    Aqueous bifunctional semiconductor polymer nanoparticles (SPNs), approximately 30 nm in diameter (as measured from electron microscopy), were synthesised using hydrophobic conjugated polymers, amphiphilic phospholipids and a gadolinium-containing lipid. Their fluorescence quantum yields and extinction coefficients were determined, and their MRI T₁-weighted relaxation times in water were measured. The bimodal nanoparticles were readily taken up by HeLa and murine macrophage-like J774 cells as demonstrated by confocal laser scanning microscopy, and were found to be MRI-active, generating a linear relationship between T₁-weighted relaxation rates and gadolinium concentrations The synthesis is relatively simple, and can easily result in milligrams of materials, although we fully expect scale-up to the gram level to be easily realised. PMID:24941427

  7. "Dancing inside the ball": the structures and nonlinear optical properties of three Sc2S@C3v(8)-C82 isomers.

    PubMed

    Gao, Feng-Wei; Gao, Ying; Wang, Li-Jie; Xu, Hong-Liang; Sun, Shi-Ling; Su, Zhong-Min

    2015-10-01

    Recently, the crystal structures and electrochemical properties of the isomers (Sc2S "trapped" in C82) have been reported, in which the Sc2S is located inside the different positions of the C82 cage. In the present work, three isomers of endohedral metallofullerenes Sc2S@C3v(8)-C82 (A, B, and C) have been designed to explore the effect of the position of Sc2S on their interaction energies and nonlinear optical properties. Among three isomers, the Sc2S is located in different positions of the C82 cage: the angles of Sc-S-Sc in A, B, and C are 104.9, 114.8, and 115.7°, respectively. Furthermore, the analysis of natural bond orbital (NBO) charge indicates that the electron-transfer is from the Sc2S to the adjacent carbon atoms of the C82 cage. The interaction energy of B is the smallest among three isomers which is -226.2 kcal mol(-1). It was worth mentioning that their first hyperpolarizabilities (β tot) were studied, we found that their β tot values were related to the positions of Sc2S: C (2100) > B (1191) > A (947 au). We hope that the present work can provide a new strategy to promote the nonlinear optical properties of endohedral metallofullerenes by changing the positions of the encapsulated molecular. Graphical abstract Three isomers of endohedral metallofullerenes Sc2S@C3v(8)-C82 (A, B, and C) have been designed to explore the position effect of Sc2S on the interaction energies and nonlinear optical properties. Among three isomers, the Sc2S in B has the most stable position. Significantly, the first hyperpolarizability is related to the position of Sc2S inside the C82 cage, which provides a novel strategy to enhance the first hyperpolarizability by the Sc2S revolving inside the C82 cage. PMID:26373544

  8. Recent advances in fullerene science (Invited)

    SciTech Connect

    Dunk, P. W.; Marshall, A. G.; Mulet-Gas, M.; Rodriguez-Fortea, A.; Poblet, J. M.

    2014-12-09

    The development of very high resolution FT-ICR mass spectrometers (Marshall et al, 1998) has made a wide range of new measurements possible and by combining this new technology with laser vaporization supersonic beam methods of producing carbon species (chains, rings and fullerenes), new advances in understanding of the fullerene creation mechanisms and their reactivity have been possible. In this overview, new understanding has been developed with regard to: a) closed-network growth of fullerenes (Dunk et al, 2012a); b) small endohedral species such as MαC{sub 28} (Dunk et al., 2012b); c) metallofullerene and fullerene formation under conditions in stellar outflows with relevance to stardust (Dunk et al., 2013a) and d) The formation of heterofullerenes by direct exposure of C{sub 60} toboron vapor (Dunk et al., 2013b)

  9. Applications of Functionalized Fullerenes in Tumor Theranostics

    PubMed Central

    Chen, Zhiyun; Ma, Lijing; Liu, Ying; Chen, Chunying

    2012-01-01

    Functionalized fullerenes with specific physicochemical properties have been developed for cancer diagnosis and therapy. Notably, metallofullerene is a new class of magnetic resonance imaging (MRI) contrast-enhancing agent, and may have promising applications for clinical diagnosis. Polyhydroxylated and carboxyl fullerenes have been applied to photoacoustic imaging. Moreover, in recent years, functionalized fullerenes have shown potential in tumor therapies, such as photodynamic therapy, photothermal treatment, radiotherapy and chemotherapeutics. Their antitumor effects may be associated with the modulation of oxidative stress, anti-angiogenesis, and immunostimulatory activity. While various types of novel nanoparticle agents have been exploited in tumor theranostics, their distribution, metabolism and toxicity in organisms have also been a source of concern among researchers. The present review summarizes the potential of fullerenes as tumor theranostics agents and their possible underlying mechanisms are discussed. PMID:22509193

  10. Direct Observation of a Gas Molecule (H2, Ar) Swallowed by C60

    SciTech Connect

    Sawa, H.; Kakiuchi, T.; Wakabayashi, Y.; Murata, Y.; Murata, M.; Komatsu, K.; Yakigaya, K.; Takagi, H.; Dragoe, N.

    2007-01-19

    Various types of endohedral fullerene complexes are known to date. The well known metallofullerenes are generally produced by arc-discharge method, but the use of such extremely drastic conditions is apparently not suitable for encapsulation of unstable molecules or gases. We recently succeeded in incorporation of a H2 molecule or an Ar atom in 100% into a C60. In order to observe the endohedral gas molecule directly, the X-ray diffraction analysis using synchrotron radiation were carried out. We observed a gas molecule encapsulated in each fullerene cage using structure analysis and the maximum entropy method. These gas molecules are floating inside of the hollow cavities and are completely isolated from the outside.

  11. Structural interconnections and the role of heptagonal rings in endohedral trimetallic nitride template fullerenes.

    PubMed

    Gan, Li-Hua; Lei, Dan; Fowler, Patrick W

    2016-07-01

    Recent experiments indicate that fullerene isomers outside the classical definition can also encapsulate metallic atoms or clusters to form endohedral metallofullerenes. Our systematic study using DFT calculations, suggests that many heptagon-including nonclassical trimetallic nitride template fullerenes are similar in stability to their classical counterparts, and that conversion between low-energy nonclassical and classical parent cages via Endo-Kroto insertion/extrusion of C2 units and Stone-Wales isomerization may facilitate the formation of endohedral trimetallic nitride fullerenes. Close structural connections are found between favored isomers of trimetallic nitride template fullerenes from C78 to C82 . It appears that the lower symmetry and local deformations associated with introduction of a heptagonal ring favor encapsulation of intrinsically less symmetrical mixed metal nitride clusters. © 2016 Wiley Periodicals, Inc. PMID:27282122

  12. Analysis of the reactivity and selectivity of fullerene dimerization reactions at the atomic level

    NASA Astrophysics Data System (ADS)

    Koshino, Masanori; Niimi, Yoshiko; Nakamura, Eiichi; Kataura, Hiromichi; Okazaki, Toshiya; Suenaga, Kazutomo; Iijima, Sumio

    2010-02-01

    High-resolution transmission electron microscopy has proved useful for its ability to provide time-resolved images of small molecules and their movements. One of the next challenges in this area is to visualize chemical reactions by monitoring time-dependent changes in the atomic positions of reacting molecules. Such images may provide information that is not available with other experimental methods. Here we report a study on bimolecular reactions of fullerene and metallofullerene molecules inside carbon nanotubes as a function of electron dose. Images of how the fullerenes move during the dimerization process reveal the specific orientations in which two molecules interact, as well as how bond reorganization occurs after their initial contact. Studies on the concentration, specimen temperature, effect of catalyst and accelerating voltage indicate that the reactions can be imaged under a variety of conditions.

  13. Synthesis and radiation resistance of fullerenes and fullerene derivatives

    NASA Astrophysics Data System (ADS)

    Shilin, V. A.; Lebedev, V. T.; Sedov, V. P.; Szhogina, A. A.

    2016-07-01

    The parameters of an electric-arc facility for the synthesis of fullerenes and endohedral metallofullerenes are optimized. The resistance of C60 and C70 fullerenes and C60(OH)30 and C70(OH)30 fullerenols against neutron irradiation is studied. It is established that the radiation resistance of the fullerenes is higher than that of the fullerenols, but the radiation resistance of the Gd@C2 n endometallofullerenes is lower than that of the corresponding Gd@C2 n (OH)38 fullerenols. The radiation resistance of mixtures of Me@C2 n (OH)38 ( Me = Gd, Tb, Sc, Fe, and Pr) endometallofullerenes with C60(OH)30 is determined. The factors affecting the radiation resistance of the fullerenes and fullerenols are discussed.

  14. Isolation and Crystallographic Characterization of La2C2@Cs(574)-C102 and La2C2@C2(816)-C104: Evidence for the Top-Down Formation Mechanism of Fullerenes.

    PubMed

    Cai, Wenting; Li, Fang-Fang; Bao, Lipiao; Xie, Yunpeng; Lu, Xing

    2016-05-25

    Tubular higher fullerenes are prototypes of finite-length end-capped carbon nanotubes (CNTs) whose structures can be accurately characterized by single-crystal X-ray diffraction crystallography. We present here the isolation and crystallographic characterization of two unprecedented higher fullerenes stabilized by the encapsulation of a La2C2 cluster, namely, La2C2@Cs(574)-C102, which has a perfect tubular cage corresponding to a short (10, 0) zigzag carbon nanotube, and La2C2@C2(816)-C104 which has a defective cage with a pyracylene motif inserting into the cage waist. Both cages provide sufficient spaces for the large La2C2 cluster to adopt a stretched and nearly planar configuration, departing from the common butterfly-like configuration which has been frequently observed in midsized carbide metallofullerenes (e.g., Sc2C2@C80-84), to achieve strong metal-cage interactions. More meaningfully, our crystallographic results demonstrate that the defective cage of C2(816)-C104 is a starting point to form the other three tubular cages known so far, i.e., D5(450)-C100, Cs(574)-C102, and D3d(822)-C104, presenting evidence for the top-down formation mechanism of fullerenes. The fact that only the large La2C2 cluster has been found in giant fullerene cages (C>100) and the small clusters M2C2 (M = Sc, Y, Er, etc.) are present in midsized fullerenes (C80-C86) indicates that geometrical matching between the cluster and the cage, which ensures strong metal-cage interactions, is an important factor controlling the stability of the resultant metallofullerenes, in addition to charge transfer. PMID:27157415

  15. Nuclear design of Helical Cruciform Fuel rods

    SciTech Connect

    Shirvan, K.; Kazimi, M. S.

    2012-07-01

    In order to increase the power density of current and new light water reactor designs, the Helical Cruciform Fuel (HCF) rods are proposed. The HCF rods are equivalent to a cylindrical rod, with the fuel in a cruciform shaped, twisted axially. The HCF rods increase the surface area to volume ratio and inter-subchannel mixing behavior due to their cruciform and helical shapes, respectively. In a previous study, the HCF rods have shown the potential to up-rate existing PWRs by 50% and BWRs by 25%. However, HCF rods do display different neutronics modeling and performance. The cruciform cross section of HCF rods creates radially asymmetric heat generation and temperature distribution. The nominal HCF rod's beginning of life reactivity is reduced, compared to a cylindrical rod with the same fuel volume, by 500 pcm, due to increase in absorption in cladding. The rotation of these rods accounts for reactivity changes, which depends on the H/HM ratio of the pin cell. The HCF geometry shows large sensitivities to U{sup 235} or gadolinium enrichments compared to a cylindrical geometry. In addition, the gadolinium-containing HCF rods show a stronger effect on neighboring HCF rods than in case of cylindrical rods, depending on the orientation of the HCF rods. The helical geometry of the rods introduces axial shadowing of about 600 pcm, not seen in typical cylindrical rods. (authors)

  16. Purification of cerium, neodymium and gadolinium for low background experiments

    NASA Astrophysics Data System (ADS)

    Boiko, R. S.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Laubenstein, M.; Mokina, V. M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

    2014-01-01

    Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search), 136Ce (2β+ candidate with one of the highest Q2β). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides) was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  17. Comparison between a linear versus a macrocyclic contrast agent for whole body MR angiography in a clinical routine setting

    PubMed Central

    Seeger, Achim; Kramer, Ulrich; Fenchel, Michael; Grimm, Florian; Bretschneider, Christiane; Döring, Jörg; Klumpp, Bernhard; Tepe, Gunnar; Rittig, Kilian; Seidensticker, Peter R; Claussen, Claus D; Miller, Stephan

    2008-01-01

    Background Previous experiences of whole body MR angiography are predominantly available in linear 0.5 M gadolinium-containing contrast agents. The aim of this study was to compare image quality on a four-point scale (range 1–4) and diagnostic accuracy of a 1.0 M macrocyclic contrast agent (gadobutrol, n = 80 patients) with a 0.5 M linear contrast agent (gadopentetate dimeglumine, n = 85 patients) on a 1.5 T whole body MR system. Digital subtraction angiography served as standard of reference. Results All examinations yielded diagnostic image quality. There was no significant difference in image quality (3.76 ± 0.3 versus 3.78 ± 0.3, p = n.s.) and diagnostic accuracy observed. Sensitivity and specificity of the detection of hemodynamically relevant stenoses was 93%/95% in the gadopentetate dimeglumine group and 94%/94% in the gadobutrol group, respectively. Conclusion The high diagnostic accuracy of gadobutrol in the clinical routine setting is of high interest as medical authorities (e.g. the European Agency for the Evaluation of Medicinal Products) recommend macrocyclic contrast agents especially to be used in patients with renal failure or dialysis. PMID:19116027

  18. Aneurysm Sac Pressure Measurement with Minimally Invasive Implantable Pressure Sensors: An Alternative to Current Surveillance Regimes after EVAR?

    SciTech Connect

    Springer, Fabian Guenther, Rolf W.; Schmitz-Rode, Thomas

    2008-05-15

    Current protocols for surveillance after endovascular repair (EVAR) of abdominal aortic aneurysms are mostly based on costly and time-consuming imaging procedures and aim to detect adverse events such as graft migration, endoleaks or aneurysm sac enlargement. These imaging procedures are either associated with radiation exposure to the patients or may be harmful to the patient due to the use of iodine- or gadolinium-containing contrast agents. Furthermore the advantages of EVAR in the short term might be negated by the necessity for endograft surveillance over years. Thus, alternative modalities for follow-up are being investigated. One of these technologies provides pressure information directly from the aneurysm sac. This noninvasive, telemetric pressure sensing was tested in vitro as well as in first clinical trials and was able to identify successful aneurysm exclusion after EVAR. The telemetric pressure sensors showed a promising efficacy and accuracy in detecting type I and type III endoleaks and will help to clarify the clinical relevance of type II endoleaks. This article provides an overview of the in vitro sensors investigated as well as the first clinical trials and the sensors' potential to change the current endograft surveillance regimes.

  19. Surface Interactions with Compartmentalized Cellular Phosphates Explain Rare Earth Oxide Nanoparticle Hazard and Provide Opportunities for Safer Design

    PubMed Central

    2014-01-01

    Growing international exploitation of rare earth oxides (REOs) for commercial and biological use has increased the possibility of human exposure and adverse health effects. Occupational exposure to rare earth materials in miners and polishers leads to a severe form of pneumoconiosis, while gadolinium-containing MRI contrast agents cause nephrogenic systemic fibrosis in patients with renal impairment. The mechanisms for inducing these adverse pro-fibrogenic effects are of considerable importance for the safety assessment of REO particles as well as presenting opportunities for safer design. In this study, using a well-prepared REO library, we obtained a mechanistic understanding of how REOs induce cellular and pulmonary damage by a compartmentalized intracellular biotransformation process in lysosomes that results in pro-fibrogenic growth factor production and lung fibrosis. We demonstrate that rare earth oxide ion shedding in acidifying macrophage lysosomes leads to biotic phosphate complexation that results in organelle damage due to stripping of phosphates from the surrounding lipid bilayer. This results in nanoparticle biotransformation into urchin shaped structures and setting in motion a series of events that trigger NLRP3 inflammasome activation, IL-1β release, TGF-β1 and PDGF-AA production. However, pretreatment of REO nanoparticles with phosphate in a neutral pH environment prevents biological transformation and pro-fibrogenic effects. This can be used as a safer design principle for producing rare earth nanoparticles for biological use. PMID:24417322

  20. Isolation and Structure Determination of a Missing Endohedral Fullerene La@C70 through In Situ Trifluoromethylation.

    PubMed

    Wang, Zhiyong; Aoyagi, Shinobu; Omachi, Haruka; Kitaura, Ryo; Shinohara, Hisanori

    2016-01-01

    D5h-symmetric fullerene C70 (D5h-C70) is one of the most abundant members of the fullerene family. One longstanding mystery in the field of fullerene chemistry is whether D5h-C70 is capable of accommodating a rare-earth metal atom to form an endohedral metallofullerene M@D5h-C70, which would be expected to show novel electronic properties. The molecular structure of La@C70 remains unresolved since its discovery three decades ago because of its extremely high instability under ambient conditions and insolubility in organic solvents. Herein, we report the single-crystal X-ray structure of La@C70(CF3)3, which was obtained through in situ exohedral functionalization by means of trifluoromethylation. The X-ray crystallographic study reveals that La@C70(CF3)3 is the first example of an endohedral rare-earth fullerene based on D5h-C70. The dramatically enhanced stability of La@C70(CF3)3 compared to La@C70 can be ascribed to trifluoromethylation-induced bandgap enlargement. PMID:26530527

  1. Role of encapsulated metal cation in the reactivity and regioselectivity of the C₆₀ Diels-Alder reaction.

    PubMed

    Cui, Cheng-Xing; Liu, Ya-Jun

    2015-03-26

    Endohedral metallofullerene has novel properties because of the interaction between the encapsulated metal atom or cation and fullerene. Experiments have demonstrated that the insertion of Li(+) into C60 can greatly promote the reactivity of the Diels-Alder (DA) cycloaddition of cyclopentadiene (CpH) to C60. However, the reaction is sufficiently fast that its quantitative kinetic data cannot be obtained experimentally. In addition, knowledge regarding the effects of other alkali metal cations and metal cations with more charges on the reactivity and regioselectivity of C60 is almost nonexistent. In the current study, DA cycloadditions of CpH to M(+)@C60 (where M = Li, Na, K, Rb, and Cs) and Ca(2+)@C60 were investigated via density functional theory in the gas phase and in solvent. Via careful discussion and comparison with the results of C60, we concluded the following for the DA reaction of CpH to C60 and, more generally, for DA reactions of other fullerenes: (1) the encapsulated metal cations enhance the reactivity; (2) among alkali metal cations, Na(+) could be the best catalyst; (3) Ca(2+) is more favorable in promoting the reactivity than any alkali metal cation; (4) encapsulated metal cations with more positive charges enhance the reactivity of the 6-5 bond in C60, which is significant when the 6-5 adduct is the target product. PMID:25714730

  2. Selective complexation and reactivity of metallic nitride and oxometallic fullerenes with Lewis acids and use as an effective purification method.

    PubMed

    Stevenson, Steven; Mackey, Mary A; Pickens, Jane E; Stuart, Melissa A; Confait, Bridget S; Phillips, J Paige

    2009-12-21

    Metallic nitride fullerenes (MNFs) and oxometallic fullerenes (OMFs) react quickly with an array of Lewis acids. Empty-cage fullerenes are largely unreactive under conditions used in this study. The reactivity order is Sc(4)O(2)@I(h)-C(80) > Sc(3)N@C(78) > Sc(3)N@C(68) > Sc(3)N@D(5h)-C(80) > Sc(3)N@I(h)-C(80). Manipulations of Lewis acids, molar ratios, and kinetic differences within the family of OMF and MNF metallofullerenes are demonstrated in a selective precipitation scheme, which can be used either alone for purifying Sc(3)N@I(h)-C(80) or combined with a final high-performance liquid chromatography pass for Sc(4)O(2)@I(h)-C(80), Sc(3)N@D(5h)-C(80), Sc(3)N@C(68), or Sc(3)N@C(78). The purification process is scalable. Analysis of the experimental rate constants versus electrochemical band gap explains the order of reactivity among the OMFs and MNFs. PMID:19911812

  3. Cell Internalization Studies of Gadofullerene-(ZME-018) Immunoconjugates into A375m Melanoma Cells12

    PubMed Central

    Berger, Christopher Scott; Marks, John W; Bolskar, Robert D; Rosenblum, Michael G; Wilson, Lon J

    2011-01-01

    Fullerene (C60)-monoclonal antibody (mAb) immunoconjugates have been determined to internalize into target cells using water-soluble Gd3+ ion-filled metallofullerenes (Gd@C60[OH]x). Two separate conjugations of Gd@C60(OH)x with the antibody ZME-018 and a murine antibody mixture (MuIgG) were performed in a 1:5 mAb/Gd@C60 ratio. Characterization of the immunoconjugates was established using inductively coupled plasma mass spectrometry (ICP-MS) for Gd3+ and UV-Vis spectrometry (for Gd@C60 + C60). Once conjugated, enzyme-linked immunosorbent assays showed little change in the specific binding of ZME-018. Each immunoconjugate was exposed to two cancer cell lines, A375m (antigen positive), and T24, bladder carcinoma (antigen negative). Internalization levels of the immunoconjugate were determined at various time points during 24 hours by harvesting and digesting the cells with 70% HNO3 for Gd3+ ion analysis by ICP-MS. These results are the first to demonstrate the practicality of a targeted cancer therapy based on fullerene immunotherapy. PMID:22190999

  4. How are small endohedral silicon clusters stabilized?

    PubMed

    Avaltroni, Fabrice; Steinmann, Stephan N; Corminboeuf, Clémence

    2012-11-21

    Clusters in the (Be, B, C)@Si(n)((0,1,2+)) (n = 6-10) series, isoelectronic to Si(n)(2-), present multiple symmetric structures, including rings, cages and open structures, which the doping atom stabilizes using contrasting bonding mechanisms. The most striking feature of these clusters is the absence of electron transfer (for Be) or even the inversion (for B and C) in comparison to classic endohedral metallofullerenes (e.g. from the outer frameworks towards the enclosed atom). The relatively small cavity of the highly symmetric Si(8) cubic cage benefits more strongly from the encapsulation of a boron atom than from the insertion of a too large beryllium atom. Overall, the maximization of multicenter-type bonding, as visualized by the Localized Orbital Locator (LOL), is the key to the stabilization of the small Si(n) cages. Boron offers the best balance between size, electronegativity and delocalized bonding pattern when compared to beryllium and carbon. PMID:22968417

  5. Structural Stability and Deformation of Solvated Sm@C2(45)-C90 under High Pressure

    NASA Astrophysics Data System (ADS)

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Liu, Shijie; Du, Mingrun; Li, Quanjun; Liu, Ran; Cui, Tian; Liu, Bingbing

    2016-08-01

    Solvated fullerenes recently have been shown to exhibit novel compression behaviors compared with the pristine fullerenes. However, less attention has been focused on the large cage endohedral metallofullerenes. Here, we have firstly synthesized solvated Sm@C90 microrods by a solution drop-drying method, and then studied the transformations under high pressure. The pressure-induced structural evolutions of Sm@C90 molecules both undergo deformation and collapse. The band gaps of both samples decrease with increasing pressure. The trapped Sm atom plays a role in restraining the compression of the adjacent bonds. The solvent plays a role in protecting Sm@C90 against collapse in the region of 12–20 GPa, decreasing and postponing the change of band gap. Above 30 GPa, the carbon cages collapse. Released from 45 GPa, the compressed solvated Sm@C90 forms a new ordered amorphous carbon cluster (OACC) structure with metal atoms trapped in the units of amorphous carbon clusters, which is different from the OACC structure formed by compressing solvated C60 and C70. This discovery opens the door for the creation of new carbon materials with desirable structural and physical properties when suitable starting materials are selected.

  6. Theoretical survey on M@C80 (M = Ca, Sr, and Ba): Behavior of different alkaline earth metal impacting the chemical stability and electronic properties

    NASA Astrophysics Data System (ADS)

    Cui, Jin-Bo; Guo, Yi-Jun; Li, Qiao-Zhi; Zhao, Pei; Zhao, Xiang

    2016-08-01

    Structures of mono-metallofullerenes M@C80 (M = Ca, Sr, and Ba) that separated in early experiment are determined owning the C2v(31920)-C80 cage. The change rule of properties for M@C80 (M = Ca, Sr, and Ba) influenced by different inner metal are discussed. As the trapped metal changes from calcium to barium, performance of thermodynamic stabilities for M@C2v(31920)-C80, M@C2v(31922)-C80, and M@D5h(31923)-C80 are significantly different. Orbital analysis suggests that the lowest unoccupied molecular orbitals (LUMOs) of Ca@C2v(31920)-C80 and Ca@D5h(31923)-C80 are mostly located on the trapped metal, whereas reduction reactions of Ca@C2v(31920)-C80 and Ca@D5h(31923)-C80 occur on the fullerene cage. Natural electron configuration analyses demonstrates that the decentralized electron back-donation of Ba@C2v(31920)-C80 would take responsible for the instability of itself. Electronic properties such as electron affinities and ionization potentials are significantly affected by encapsulated metal are also found. Computational UV-visible-NIR spectra for M@C2v(31920)-C80 (M = Ca, Sr, Ba) are in perfect accord with the spectra obtained experimentally.

  7. W(CO)3(Ph2PC2H4PPh2)(η(2)-Sc3N@Ih-C80/Sc3N@D5h-C80): regioselective synthesis and crystallographic characterization of air-stable mononuclear complexes of endohedral fullerenes.

    PubMed

    Bao, Lipiao; Liu, Bin; Li, Xiaofang; Pan, Changwang; Xie, Yunpeng; Lu, Xing

    2016-08-01

    The organometallic chemistry of endohedral metallofullerenes has lagged far behind that of empty fullerenes. Herein, we report a highly regioselective coordination reaction involving two Sc3N@C80 isomers and W(CO)4(Ph2PC2H4PPh2) (1), which affords only one mononuclear complex for each Sc3N@C80 isomer (2a for Sc3N@Ih-C80 and 2b for Sc3N@D5h-C80). X-ray results demonstrate that the tungsten center coordinates with the cages in an η(2) fashion on a [6,6]-bond in both cases, forming the first derivatives with a closed three membered ring for Sc3N@C80. Although IR and absorption spectroscopic results reveal relatively weak exohedral-metal to ligand π back-donation in both 2a and 2b, they show remarkable air-stability which promises their potential uses in related fields. Moreover, the coordination has narrowed down the electrochemical gaps of the parent Sc3N@C80 isomers, making the complexes better electron donors but worse electron acceptors than the corresponding precursors. PMID:27075265

  8. Extractions of Y@C{sub 60}, Ba@C{sub 60}, La@C{sub 60}, Ce@C{sub 60}, Pr@C{sub 60}, Nd@C{sub 60}, and Gd@C{sub 60} with aniline

    SciTech Connect

    Kubozono, Yoshihiro; Maeda, Hironobu; Takabayashi, Yasuhiro; Hiraoka, Koji; Nakai, Takeshi; Kashino, Setsuo; Emura, Shuichi; Ukita, Shigeyuki; Sogabe, Toshiaki

    1996-07-24

    Recently many endohedral metallofullerenes such as M@C{sub 74}, M@C{sub 80}, and M@C{sub 82} (M: metal atom) have been successfully isolated by the high performance liquid chromatography (HPLC) technique. Some M@C{sub 60} were prepared in primary soots by an arc-heating or a laser-vaporization method, but the isolation of M@C{sub 60} has not yet been achieved because of the difficulties in extraction; only the extraction of Ca@C{sub 60} with pyridine has been reported as for. Recently we found that aniline is a suitable extraction solvent for Ca@C{sub 60} and Sr@C{sub 60}. For the isolation of M@C{sub 60} by an HPLC technique it is important to find a suitable extraction solvent for M@C{sub 60}. In the present study, we report the successful extraction of Y@C{sub 60}, Ba@C{sub 60}, La@C{sub 60}, Ce@C{sub 60}, Pr@C{sub 60}, Nd@C{sub 60}, and Gd@C{sub 60} with aniline under an air atmosphere. 14 refs., 2 figs.

  9. The ground state and electronic structure of Gd@C{sub 82}: A systematic theoretical investigation of first principle density functionals

    SciTech Connect

    Dai, Xing; Gao, Yang; Xin, Minsi; Wang, Zhigang; Zhou, Ruhong

    2014-12-28

    As a representative lanthanide endohedral metallofullerene, Gd@C{sub 82} has attracted a widespread attention among theorists and experimentalists ever since its first synthesis. Through comprehensive comparisons and discussions, as well as references to the latest high precision experiments, we evaluated the performance of different computational methods. Our results showed that the appropriate choice of the exchange-correlation functionals is the decisive factor to accurately predict both geometric and electronic structures for Gd@C{sub 82}. The electronic structure of the ground state and energy gap between the septet ground state and the nonet low-lying state obtained from pure density functional methods, such as PBE and PW91, are in good agreement with current experiment. Unlike pure functionals, the popularly used hybrid functionals in previous studies, such as B3LYP, could infer the qualitative correct ground state only when small basis set for C atoms is employed. Furthermore, we also highlighted that other geometric structures of Gd@C{sub 82} with the Gd staying at different positions are either not stable or with higher energies. This work should provide some useful references for various theoretical methodologies in further density functional studies on Gd@C{sub 82} and its derivatives in the future.

  10. Endohedral Fullerenes in Organic Thin Film Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Ross, Russel; Vankeuren, Edward; Drees, Martin; Cardona, Claudia; Holloway, Brian; Guldi, Dirk

    2008-03-01

    Cost factors in inorganic solar cells have opened up a new path to less expensive manufacturing techniques using bulk heterojunction polymer/fullerene based solar cells. Using empty cage fullerene derivatives as the acceptor material, state-of-the-art organic photovoltaics currently display ˜5% overall conversion efficiency. One of the main factors limiting the efficiency in organic solar cells is the low open circuit voltage. The open circuit voltage is governed by the molecular orbitals of the donor and acceptor material; therefore better matching of the orbitals will lead to improved voltages. We present a novel acceptor material based on TRIMETASPHERE^ carbon nanomaterials (TMS). TMS are endohedral metallofullerenes that consist of a trimetal nitride cluster enclosed in a C80 cage. First-generation TMS derivatives have been synthesized; electrochemical and photophysical studies show behavior consistent with C60 but with improved molecular orbitals. The electrochemical data suggests a maximum voltage increase of up to 280 mV over C60-PCBM-based devices. Organic solar cell devices are currently under construction and performance results will also be presented.

  11. Regioselective cage opening of La2 @D2 (10611)-C72 with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine.

    PubMed

    Yamada, Michio; Muto, Yasuhiro; Kurihara, Hiroki; Slanina, Zdenek; Suzuki, Mitsuaki; Maeda, Yutaka; Rubin, Yves; Olmstead, Marilyn M; Balch, Alan L; Nagase, Shigeru; Lu, Xing; Akasaka, Takeshi

    2015-02-01

    The thermal reaction of the endohedral metallofullerene La2 @D2 (10611)-C72 , which contains two pentalene units at opposite ends of the cage, with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine proceeded selectively to afford only two bisfulleroid isomers. The molecular structure of one isomer was determined using single-crystal X-ray crystallography. The results suggest that the [4+2] cycloaddition was initiated in a highly regioselective manner at the C-C bond connecting two pentagon rings of C72 . Subsequent intramolecular electrocyclization followed by cycloreversion resulted in the formation of an open-cage derivative having three seven-membered ring orifices on the cage and a significantly elongated cage geometry. The reduction potentials of the open-cage derivatives were similar to those of La2 @D2 -C72 whereas the oxidation potentials were shifted more negative than those of La2 @D2 -C72 . These results point out that further oxidation could occur easily in the derivatives. PMID:25536953

  12. Electronic structures of carbon nanotube peopods

    NASA Astrophysics Data System (ADS)

    Kuk, Young

    2003-03-01

    Carbon nanotubes have been successfully used for nanometer-sized devices such as diodes and transistors. These discrete devices utilize the spatially varying electronic structures of processed nanotubes by creating defect junctions or introducing substitutional or interstitial dopants. It was recently found that adsorption or insertion of molecules inside or outside of a nanotube modifies the electronic structure as observed with a low-temperature scanning tunneling microscope (LTSTM). We report a method to form spatial variation of the electronic structure by inserting various molecules such as fullerenes, metallo-fullerenes, metals or insulators. The results suggest that one can synthesize this band gap-engineered 1-dimensional wire by self-assembly instead of epitaxial growth. We propose a new type of device structure made by this processing technology. 1. J. Lee, H.J. Kim, G. Kim, Y.-W. Son, J. Ihm, S.J. Kahng, H. Kato, Z.W. Wang, T. Okazaki, H. Shinohara, and Y. Kuk, Nature, 415, 1005 (2002)

  13. Crystallographic Evidence for Direct Metal-Metal Bonding in a Stable Open-Shell La2 @Ih -C80 Derivative.

    PubMed

    Bao, Lipiao; Chen, Muqing; Pan, Changwang; Yamaguchi, Takahisa; Kato, Tatsuhisa; Olmstead, Marilyn M; Balch, Alan L; Akasaka, Takeshi; Lu, Xing

    2016-03-18

    Endohedral metallofullerenes (EMFs) have novel structures and properties that are closely associated with the internal metallic species. Benzyl radical additions have been previously shown to form closed-shell adducts by attaching an odd number of addends to open-shell EMFs (such as Sc3 C2 @Ih -C80 ) whereas an even number of groups are added to closed-shell EMFs (for example Sc3 N@Ih -C80 ). Herein we report that benzyl radical addition to the closed-shell La2 @Ih -C80 forms a stable, open-shell monoadduct instead of the anticipated closed-shell bisadduct. Single-crystal X-ray diffraction results show the formation of a stable radical species. In this species, the La-La distance is comparable to the theoretical value of a La-La covalent bond and is shorter than reported values for other La2 @Ih -C80 derivatives, providing unambiguous evidence for the formation of direct La-La bond. PMID:26918907

  14. Structural Stability and Deformation of Solvated Sm@C2(45)-C90 under High Pressure.

    PubMed

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Liu, Shijie; Du, Mingrun; Li, Quanjun; Liu, Ran; Cui, Tian; Liu, Bingbing

    2016-01-01

    Solvated fullerenes recently have been shown to exhibit novel compression behaviors compared with the pristine fullerenes. However, less attention has been focused on the large cage endohedral metallofullerenes. Here, we have firstly synthesized solvated Sm@C90 microrods by a solution drop-drying method, and then studied the transformations under high pressure. The pressure-induced structural evolutions of Sm@C90 molecules both undergo deformation and collapse. The band gaps of both samples decrease with increasing pressure. The trapped Sm atom plays a role in restraining the compression of the adjacent bonds. The solvent plays a role in protecting Sm@C90 against collapse in the region of 12-20 GPa, decreasing and postponing the change of band gap. Above 30 GPa, the carbon cages collapse. Released from 45 GPa, the compressed solvated Sm@C90 forms a new ordered amorphous carbon cluster (OACC) structure with metal atoms trapped in the units of amorphous carbon clusters, which is different from the OACC structure formed by compressing solvated C60 and C70. This discovery opens the door for the creation of new carbon materials with desirable structural and physical properties when suitable starting materials are selected. PMID:27503144

  15. Structural Stability and Deformation of Solvated Sm@C2(45)-C90 under High Pressure

    PubMed Central

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Liu, Shijie; Du, Mingrun; Li, Quanjun; Liu, Ran; Cui, Tian; Liu, Bingbing

    2016-01-01

    Solvated fullerenes recently have been shown to exhibit novel compression behaviors compared with the pristine fullerenes. However, less attention has been focused on the large cage endohedral metallofullerenes. Here, we have firstly synthesized solvated Sm@C90 microrods by a solution drop-drying method, and then studied the transformations under high pressure. The pressure-induced structural evolutions of Sm@C90 molecules both undergo deformation and collapse. The band gaps of both samples decrease with increasing pressure. The trapped Sm atom plays a role in restraining the compression of the adjacent bonds. The solvent plays a role in protecting Sm@C90 against collapse in the region of 12–20 GPa, decreasing and postponing the change of band gap. Above 30 GPa, the carbon cages collapse. Released from 45 GPa, the compressed solvated Sm@C90 forms a new ordered amorphous carbon cluster (OACC) structure with metal atoms trapped in the units of amorphous carbon clusters, which is different from the OACC structure formed by compressing solvated C60 and C70. This discovery opens the door for the creation of new carbon materials with desirable structural and physical properties when suitable starting materials are selected. PMID:27503144

  16. Preferential encapsulation and stability of La(3)N cluster in 80 atom cages: experimental synthesis and computational investigation of La(3)N@C(79)N.

    PubMed

    Stevenson, Steven; Ling, Yan; Coumbe, Curtis E; Mackey, Mary A; Confait, Bridget S; Phillips, J Paige; Dorn, Harry C; Zhang, Yong

    2009-12-16

    We report the synthesis and electronic stabilization of La(3)N@C(79)N. Unsuccessful efforts to encapsulate bulky La(3)N clusters in small C(80) cages have been attributed to large ionic radii. The preferred species for La(3)N clusters in all-carbon cages is La(3)N@C(96). A surprising finding is the synthesis of La(3)N@C(79)N, a new metallofullerene present in higher abundance than La(3)N@C(96). This reduction in cage size from 96 to 80 atoms reflects the significance and role of electronic effects. To understand the geometric and electronic properties of this first metallic nitride azafullerene (M(3)N@C(79)N, M = La), density functional theory (DFT) investigations were performed on a number of isomers. Results indicate a preferred N-substitution at the 665 junction site on the cage in lieu of a 666 substitution. The relative stabilities of different isomers can be well reproduced by using the minimum distance between the metal atom and the nitrogen atom of the cage (R(N'M)(min)). Long R(N'M)(min) values indicate distant contacts between six atoms that bear significantly large positive charges: the three metal atoms and the three carbon atoms bonded with the nitrogen atom in the cage, which are favored. These results suggest a dominant electronic effect on the stabilities of metalloazafullerenes. Interestingly, spin densities of the 665 substitution isomers of La(3)N@C(79)N are located predominantly in the metal cluster, while spin densities of the 666 substitution isomers are primarily on the cage. PMID:19995073

  17. Production of Endohedral Fullerenes by Ion Implantation

    SciTech Connect

    Diener, M.D.; Alford, J. M.; Mirzadeh, S.

    2007-05-31

    The empty interior cavity of fullerenes has long been touted for containment of radionuclides during in vivo transport, during radioimmunotherapy (RIT) and radioimaging for example. As the chemistry required to open a hole in fullerene is complex and exceedingly unlikely to occur in vivo, and conformational stability of the fullerene cage is absolute, atoms trapped within fullerenes can only be released during extremely energetic events. Encapsulating radionuclides in fullerenes could therefore potentially eliminate undesired toxicity resulting from leakage and catabolism of radionuclides administered with other techniques. At the start of this project however, methods for production of transition metal and p-electron metal endohedral fullerenes were completely unknown, and only one method for production of endohedral radiofullerenes was known. They therefore investigated three different methods for the production of therapeutically useful endohedral metallofullerenes: (1) implantation of ions using the high intensity ion beam at the Oak Ridge National Laboratory (ORNL) Surface Modification and Characterization Research Center (SMAC) and fullerenes as the target; (2) implantation of ions using the recoil energy following alpha decay; and (3) implantation of ions using the recoil energy following neutron capture, using ORNL's High Flux Isotope Reactor (HFIR) as a thermal neutron source. While they were unable to obtain evidence of successful implantation using the ion beam at SMAC, recoil following alpha decay and neutron capture were both found to be economically viable methods for the production of therapeutically useful radiofullerenes. In this report, the procedures for preparing fullerenes containing the isotopes {sup 212}Pb, {sup 212}Bi, {sup 213}Bi, and {sup 177}Lu are described. None of these endohedral fullerenes had ever previously been prepared, and all of these radioisotopes are actively under investigation for RIT. Additionally, the chemistry for

  18. Technegas: A medical application of {sup 99m}Tc for the study of buckyballs, blood clots, lung disease and AIDS

    SciTech Connect

    Willett, G.D.; Dance, I.G.; Fisher, K.J.; Burch, W.M.; Dasaklis, C.; Mackey, D.W.J.

    1994-12-31

    Radionuclide studies of lung disease have been greatly enhanced by the introduction of an Australian invention; the Technegas generator. The properties of the {open_quotes}dry radio-aerosols{close_quotes} produced by this device ensure lung images superior to those from true radio-gases such as {sup 133}Xe with the additional advantage of employing {sup 99m}Tc, the most widespread radionuclide agent. A Technegas lung scan can enable identification of pulmonary mebolism (an immediately life threatening condition) emphysema and chronic obstructive lung disease. A simple modification to the generator gas mixture produces Pertechnegas an agent useful in studies of the integrity of the alveolar epithelial membrane in immunosuppressed patients such as transplants and AIDS. Although these agents are now common in Australia and Europe, little has been proven of their chemical composites. Technegas is formed by the initial evaporation of ({sup 99m}Tc) sodium pertechnetate with the subsequent sublimation of carbon from a disposable graphite crucible at {approximately}2500{degrees}C in an atmosphere of 100% argon. {sup 99m}Tc atoms are lifted off with the crystalline layers of graphite during the vaporization. Technegas then possibly consists of {sup 99m}Tc based metallo-fullerenes and fullerenes. Technegas has an effective half life in the lung very similar to the physical half life of Technetium (6 hours) regardless of clinical condition; a result which suggests that Technegas contains endohedral fullerenes. Pertechnegas is created in an atmosphere of 97% Ar 3% O{sub 2} and has an effective half life in the lung of less than 15 minutes.

  19. Stabilization of a Chlorinated (#4348)C66:C2v Cage by Encapsulating Monometal Species: Coordination between Metal and Double Hexagon-Condensed Pentalenes.

    PubMed

    Li, Qiao-Zhi; Zheng, Jia-Jia; He, Ling; Nagase, Shigeru; Zhao, Xiang

    2016-08-01

    Carbon cages in endohedral and exohedral fullerene derivatives are usually different. A recent report suggested that chlorofullerene C66Cl10:Cs and endohedral metallofullerene (EMF) Sc2@C66 shared the same cage (#4348)C66:C2v, while it was denied by the definitive characterization of Sc2@C66, which actually possesses the (#4059)C66:C2v isomer. Here, we show that a (#4348)C66:C2v cage with a double hexagon-condensed pentalene (DHCP) moiety, which was captured by exohedral chlorination, is also capable of being stabilized by encapsulating tri- or divalent monometal (M) species. On the basis of density functional theory calculations combined with statistical mechanics analyses, (#4348)C66:C2v-based mono-EMFs M@C2v(4348)-C66 (M = Tb, La, Y, and Yb) were demonstrated to be the most stable and predominant isomers at the fullerene formation temperature region, while another chlorinated cage (#4169)C66:Cs, featured with triple sequentially fused pentagon (TSFP) moiety, is less favorable to be obtained in the form of EMFs, although these two cages can be interconverted by a simple Stone-Wales transformation. The superiority of M@C2v(4348)-C66 over M@Cs(4169)-C66 comes from the stronger interaction of M-DHCP over that of M-TSFP in both ionic and covalent bonding aspects. In addition, size-selective complexation of host [n]cycloparaphenylene ([n]CPP) and Tb@C2v(4348)-C66 was simulated, showing that [10]CPP exhibits the best affinity toward Tb@C66, which provides a new opportunity for isolation and characterization of C66-based mono-EMFs. PMID:27429293

  20. The inner-induced effects of YCN in C76 on the structures and nonlinear optical properties.

    PubMed

    Gao, Feng-Wei; Xu, Hong-Liang; Su, Zhong-Min

    2016-08-01

    Very recently, an unprecedented novel monometallic cluster of fullerenes entrapping a yttrium cyanide (YCN) cluster inside a popular C82 cage YCN@Cs(6)-C82 was synthesized and characterized. Inspired by this investigation, four non-IPR YCN@C1(17459)-C76, YCN@C2v(19138)-C76, YCN@C2(17646)-C76, and YCN@C1(17894)-C76 (1, 2, 3, and 4) containing a pair of adjacent pentagons are designed to explore the encapsulated molecular effect on their interaction energies and nonlinear optical properties. The interaction energy (E int) values of 1, 2, 3, and 4 are -481.35 (1), -477.91 (2), -482.04 (3), -482.69 (4) kcal mol(-1), respectively, which shows that the E int value of 4 is the largest. Furthermore, the electron-transfer is mainly from the YCN to C76 cage. When YCN is encapsulated into C76 cage, we can find that the α0 values of the four molecules are very close, ranging from 6.50 × 10(2) to 6.65 × 10(2) au. Significantly, the first hyperpolarizabilities are in relation to the encapsulated molecular: 1.63 × 10(3) (1) > 8.03 × 10(2) (2) > 7.76 × 10(2) (4) > 4.86 × 10(2) au (3), the results show that the βtot value of 1 is the largest. Besides this, the encapsulation of the YCN to C76 cage brings some distinctive changes in its UV-vis spectra along with its other electronic properties that might be used by the experimentalists to develop the potential nonlinear optical nanomaterials based on endohedral metallofullerenes. PMID:27383610

  1. The distribution of anthropogenic REE in the Dutch distributaries of the Rhine: the role of suspended matter

    NASA Astrophysics Data System (ADS)

    Roskam, Gerlinde; Verheul, Marc; Klaver, Gerard; Bakker, Ingrid

    2014-05-01

    In nature rare earth elements (REE) occur in fixed ratios; contamination with a single rare earth element causes a clear deviation from the natural NASC normalized REE-patterns: an anomaly. REE are progressively used in many high technology products and processes. For example, gadolinium-containing chelates have been used since the '80s as contrasting agent in MRI-imaging. The pertaining anomaly is currently used as a tracer for distinguishing waste water from water unaffected by anthropogenic contamination. In the Dutch monitoring program in the Rhine-Meuse distributaries, total (10% HNO3 digested) and dissolved (< 0.45 µm) fractions in surface water are routinely analysed, and with two-week intervals suspended matter samples are collected with a centrifuge. Since 2008, the set of analysed elements was extended with REE, enabling this study. Lobith, the entry point of the River Rhine in The Netherlands, shows an annual oscillation in the magnitude of the lanthanum (La) anomaly. This positive La-anomaly was reported by Kulaksiz and Bau in 2011; they identified the point source as a production plant for catalysts used in petroleum refining in the German city of Worms. Since the spring of 2011, samarium (Sm) is used in the same process, resulting in matching La- and Sm-anomalies. The anthropogenic La and Sm concentrations are predominantly present in the total fraction, which suggests that the anthropogenic La and Sm concentrations are associated with suspended matter. The anthropogenic La and Sm concentrations are lower in the suspended matter samples collected with the centrifuge, suggesting a bias of these La and Sm concentrations in the finer fraction of the suspended matter. The anthropogenic La en Sm concentrations remain relatively constant throughout the rivers, but close to Lake IJsselmeer and the North Sea, sedimentation causes a sharp decrease in the anthropogenic concentrations. Detailed sampling of sediments, suspended matter and water could give a

  2. Gadolinium-uptake by aquatic and terrestrial organisms-distribution determined by laser ablation inductively coupled plasma mass spectrometry.

    PubMed

    Lingott, Jana; Lindner, Uwe; Telgmann, Lena; Esteban-Fernández, Diego; Jakubowski, Norbert; Panne, Ulrich

    2016-02-17

    Gadolinium (Gd) based contrast agents (CA) are used to enhance magnetic resonance imaging. As a consequence of excretion by patients and insufficient elimination in wastewater treatment plants they are detected in high concentrations in surface water. At present, little is known about the uptake of these species by living organisms in aquatic systems. Therefore the uptake of gadolinium containing chelates by plants and animals grown in exposed water or on soil irrigated with exposed water was investigated. For this purpose two types of plants were treated with two different contrast agents. The uptake of the Gd contrast agents was studied by monitoring the elemental distribution with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). This technique allows the multi-elemental analysis of solid samples with high resolution and little sample preparation. The analysis of L. minor showed that the uptake of Gd correlated with the concentration of gadodiamide in the water. The higher the concentration in the exposed water, the larger the Gd signal in the LA-ICP-MS acquired image. Exposure time experiments showed saturation within one day. The L. minor had contact with the CAs through roots and fronds, whereas the L. sativum only showed uptake through the roots. These results show that an external absorption of the CA through the leaves of L. sativum was impossible. All the analyzed parts of the plant showed Gd signal from the CA; the highest being at the main vein of the leaf. It is shown that the CAs can be taken up from plants. Furthermore, the uptake and distribution of Gd in Daphnia magna were shown. The exposure via cultivation medium is followed by Gd signals on the skin and in the area of the intestine, while the uptake via exposed nutrition algae causes the significantly highest Gd intensities in the area of the intestine. Because there are hints of negative effects for human organism these findings are important as they show that Gd based

  3. A Review of Quantum Confinement

    SciTech Connect

    Connerade, Jean-Patrick

    2009-12-03

    A succinct history of the Confined Atom problem is presented. The hydrogen atom confined to the centre of an impenetrable sphere counts amongst the exactly soluble problems of physics, alongside much more noted exact solutions such as Black Body Radiation and the free Hydrogen atom in absence of any radiation field. It shares with them the disadvantage of being an idealisation, while at the same time encapsulating in a simple way particular aspects of physical reality. The problem was first formulated by Sommerfeld and Welker - henceforth cited as SW - in connection with the behaviour of atoms at very high pressures, and the solution was published on the occasion of Pauli's 60th birthday celebration. At the time, it seemed that there was not much other connection with physical reality beyond a few simple aspects connected to the properties of atoms in solids, for which more appropriate models were soon developed. Thus, confined atoms attracted little attention until the advent of the metallofullerene, which provided the first example of a confined atom with properties quite closely related to those originally considered by SW. Since then, the problem has received much more attention, and many more new features of quantum confinement, quantum compression, the quantum Faraday cage, electronic reorganisation, cavity resonances, etc have been described, which are relevant to real systems. Also, a number of other situations have been uncovered experimentally to which quantum confinement is relevant. Thus, studies of the confined atom are now more numerous, and have been extended both in terms of the models used and the systems to which they can be applied. Connections to thermodynamics are explored through the properties of a confined two-level atom adapted from Einstein's celebrated model, and issues of dynamical screening of electromagnetic radiation by the confining shell are discussed in connection with the Faraday cage produced by a confining conducting shell. The

  4. Interstellar fullerene compounds and diffuse interstellar bands

    NASA Astrophysics Data System (ADS)

    Omont, Alain

    2016-05-01

    Recently, the presence of fullerenes in the interstellar medium (ISM) has been confirmed and new findings suggest that these fullerenes may possibly form from polycyclic aromatic hydrocarbons (PAHs) in the ISM. Moreover, the first confirmed identification of two strong diffuse interstellar bands (DIBs) with the fullerene, C60+, connects the long standing suggestion that various fullerenes could be DIB carriers. These new discoveries justify reassessing the overall importance of interstellar fullerene compounds, including fullerenes of various sizes with endohedral or exohedral inclusions and heterofullerenes (EEHFs). The phenomenology of fullerene compounds is complex. In addition to fullerene formation in grain shattering, fullerene formation from fully dehydrogenated PAHs in diffuse interstellar clouds could perhaps transform a significant percentage of the tail of low-mass PAH distribution into fullerenes including EEHFs. But many uncertain processes make it extremely difficult to assess their expected abundance, composition and size distribution, except for the substantial abundance measured for C60+. EEHFs share many properties with pure fullerenes, such as C60, as regards stability, formation/destruction and chemical processes, as well as many basic spectral features. Because DIBs are ubiquitous in all lines of sight in the ISM, we address several questions about the interstellar importance of various EEHFs, especially as possible carriers of diffuse interstellar bands. Specifically, we discuss basic interstellar properties and the likely contributions of fullerenes of various sizes and their charged counterparts such as C60+, and then in turn: 1) metallofullerenes; 2) heterofullerenes; 3) fulleranes; 4) fullerene-PAH compounds; 5) H2@C60. From this reassessment of the literature and from combining it with known DIB line identifications, we conclude that the general landscape of interstellar fullerene compounds is probably much richer than heretofore realized

  5. Proceedings of the 9th International Symposium on Foundations of Quantum Mechanics in the Light of New Technology

    NASA Astrophysics Data System (ADS)

    Ishioka, Sachio; Fujikawa, Kazuo

    2009-06-01

    detection / T. Tanamoto, Y. Nishi, S. Fujita. Geometric universal single qubit operation of cold two-level atoms / H. Imai, A. Morinaga. Entanglement dynamics in quantum Brownian motion / K. Shiokawa. Coupling superconducting flux qubits using AC magnetic flxues / Y. Liu, F. Nori. Entanglement purification using natural spin chain dynamics and single spin measurements / K. Maruyama, F. Nori. Experimental analysis of spatial qutrit entanglement of down-converted photon pairs / G. Taguchi ... [et al.]. On the phase sensitivity of two path interferometry using path-symmetric N-photon states / H. F. Hofmann. Control of multi-photon coherence using the mixing ratio of down-converted photons and weak coherent light / T. Ono, H. F. Hofmann -- Mechanical properties of confined geometry. Rattling as a novel anharmonic vibration in a solid / Z. Hiroi, J. Yamaura. Micro/nanomechanical systems for information processing / H. Yamaguchi, I. Mahboob -- Precise measurements. Electron phase microscopy for observing superconductivity and magnetism / A. Tonomura. Ratio of the Al[symbol] and Hg[symbol] optical clock frequencies to 17 decimal places / W. M. Itano ... [et al.]. STM and STS observation on titanium-carbide metallofullerenes: [symbol] / N. Fukui ... [et al.]. Single shot measurement of a silicon single electron transistor / T. Ferrus ... [et al.]. Derivation of sensitivity of a Geiger mode APDs detector from a given efficiency to estimate total photon counts / K. Hammura, D. A. Williams -- Novel properties in nano-systems. First principles study of electroluminescence in ultra-thin silicon film / Y. Suwa, S. Saito. First principles nonlinear optical spectroscopy / T. Hamada, T. Ohno. Field-induced disorder and carrier localization in molecular organic transistors / M. Ando ... [et al.]. Switching dynamics in strongly coupled Josephson junctions / H. Kashiwaya ... [et al.]. Towards quantum simulation with planar coulomb crystals / I. M. Buluta, S. Hasegawa -- Fundamental problems in

  6. EDITORIAL: Opposites attract: nanomagnetism in theory and practice Opposites attract: nanomagnetism in theory and practice

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2012-09-01

    Applications of artificial intelligence for chemical inference. XVII. An approach to computer-assisted elucidation of molecular structure J. Am. Chem. Soc. 97 5755-62 [7] Saito S, Oshiyama A, Miyamoto Y, Hamada N and Sawada S 1992 Electronic structure of fullerenes and fullerides: artificial atoms and their solids Nanotechnology 3 167-72 [8] Shinohara H 2000 Endohedral metallofullerenes Rep. Prog. Phys. 63 843-92 [9] Heitmann D, Kern K, Demel T, Grambow P, Ploog K and Zhang Y H 1992 Spectroscopy of quantum dots and antidots Surf. Sci. 267 245-52 [10] Andergassen S, Meen V, Schoeller H, Splettstoesser J and Wegewijs M R 2010 Charge transport through single molecules, quantum dots and quantum wires Nanotechnology 21 272001 [11] Lim W H, Yang C H, Zwanenburg F A and Dzurak A S 2011 Spin filling of valley-orbit states in a silicon quantum dot Nanotechnology 22 335704