Lanthanum complexes of spheroidal carbon shells

Heath, J. R.; O’Brien, S.; Zhang, Q.; Liu, Y.; Curl, R. F.; Tittel, Frank K.; Smalley, R. E.

doi:10.1021/ja00311a102

Cited by 1,170 publications

(593 citation statements)

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“…Much like C 60 , the first EMFs were synthesised using expensive and low-yielding laser ablation. 47 Adaptations of the now-standard Krätschmer-Huffman arc discharge method have led to scaled-up synthesis of EMFs: composite graphite rods containing the desired metal oxide (most often lanthanide oxides) are used, however, yields are still generally less than 2% of the total carbonaceous material produced. 12,49 The major product of such a synthesis is monometallic fullerene, M@C 82 , which has good solubility in common organic solvents and so can be separated from other products using HPLC.…”

Section: Endohedral Metallofullerenesmentioning

confidence: 99%

Water-soluble fullerenes for medical applications

Rašović

2017

Materials Science and Technology

114

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Research on fullerenes occupies a unique position in the scientific arena. Synthesis and characterisation of this nanomaterial blur the line between materials science and chemistry; careful tuning of the processing methods gives birth to a whole family of molecules and their functionalised derivatives, whose unusual properties at this nanoscopic scale can be exploited in cutting-edge technological applications. This review focuses on the functionalisation of fullerenes for use in medical applications. The first half gives an introduction to the fullerenes themselves and how their fundamental properties lead to a very rich chemistry, enabling both exohedral (external) and endohedral (internal) functionalisations of the cage. Emphasis is placed on the need for safe and reproducible synthesis routes if fullerenes are ever going to make it to the pharmaceutical market. In line with this, a selection of exohedral functionalisation protocols receives particular attention. Coverage of endohedral fullerene synthesis routes is limited to the endohedral metallofullerenes. In the second half, myriad applications of fullerenes in biomedical contexts are introduced and certain synthesis routes are critically evaluated. Discussion of the need to water solubilise the hydrophobic fullerene cages precedes an overview of fullerene-based diagnostic and therapeutic technologies. A final moment is spent on toxicity studies of fullerenes. The concluding remarks emphasise the positive effects of incorporating fullerenes into biomedical technologies, while looking at how these are perceived by the general public. A case is made for fullerenes being the optimal choice as standard bearers in the advance of nanomaterials into the medical field. This is the winning review of the 2016 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining, run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.

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Section: Endohedral Metallofullerenesmentioning

confidence: 99%

Water-soluble fullerenes for medical applications

Rašović

2017

Materials Science and Technology

114

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“…Single metal atoms such as lanthanum or cerium can be trapped inside the cavity of these single-shell structures [5][6][7][8] creating a class of fullerenes known as endohedral fullerenes (or metallofullerenes). Giant fullerenes (C>300), however, may be single or multiple shelled.…”

Section: Introductionmentioning

confidence: 99%

Combustion synthesis of fullerenes and fullerenic nanostructures

Goel

Hebgen

Sande

et al. 2002

Carbon

116

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Fullerenes are molecules comprised entirely of sp 2 -bonded carbon atoms arranged in pentagonal and hexagonal rings to form a hollow, closed-cage structure. Buckyballs, a subset which contains C 60 and C 70 , are single-shell molecules while fullerenic nanostructures can contain many shells and over 300 carbon atoms. Both fullerenes and nanostructures have an array of applications in a wide variety of fields, including medical and consumer products. Fullerenes were discovered in 1985 and were first isolated from the products of a laminar low-pressure premixed benzene/oxygen/argon flame operating at fuel-rich conditions in 1991. Flame studies indicated that fullerene yields depend on operating parameters such as temperature, pressure, residence time, and equivalence ratio. High-resolution transmission electron microscopy (HRTEM) showed that the soot contains nanostructures, including onions and nanotubes.Although flame conditions for forming fullerenes have been identified, the process has not been optimized and many flame environments of potential interest are unstudied. Mechanistic characteristics of fullerene formation remain poorly understood and cost estimation of large-scale production has not been performed. Accordingly, this work focused on: 1) studying fullerene formation in diffusion and premixed flames under new conditions to identify optimal parameters; 2) investigating the reaction of fullerenes with soot; 3) positively identifying C 60 molecules in HRTEM by tethering them to carbon black; and 4) providing a cost estimation for industrial fullerenic soot production.Samples of condensable material from laminar low-pressure benzene/argon/oxygen diffusion flames were collected and analyzed by high-performance liquid chromatography (HPLC) and HRTEM. The highest concentration of fullerenes in a flame was always detected just above the height where the fuel is consumed. The percentage of fullerenes in condensable material increases with decreasing pressure and the fullerene content of flames with similar cold gas velocities shows a strong dependence on length. A shorter flame, resulting from higher dilution or lower pressure, favors the formation of fullerenes rather than soot, exhibited by the lower amount of soot and precursors in such flames. This indicates a stronger correlation of fullerene consumption to soot levels than of fullerene formation to precursor concentration. The maximum flame temperature seems to be of minor importance in formation. The overall highest amount of fullerenes was found for a surprisingly high dilution of fuel with argon. The HRTEM analysis showed an increase of the curvature of the carbon layers, and hence increased fullerenic character, with increasing distance from the burner up to the point of maximum fullerene concentration, after which it decreases, consistent with the HPLC analysis. The soot shows highly ordered regions that appear to have been cells of fullerenic nanostructure formation. The samples also included fullerenic nanostructures such as tubes and sp...

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“…3͒. The spin is different at each local energy minimum, and decreases from M = 5.7 to 5 then to 3, which corresponds to a change in electronic configurations of Mn from ͑M = 5.7͒ ͓Ar͔3d 5.44 4s 1 We also study the other two paths, and the behaviors are similar near the central region. However, there is only one energy minimum on each path, as shown in Fig.…”

Section: Resultsmentioning

confidence: 96%

“…Encapsulating atoms or molecules [1][2][3] inside a C 60 has attracted attention for its scientific interest and practical applications. In the past several years, some work has been done on doping C 60 and C 82 using alkali, transition, and rareearth metals [4][5][6][7][8][9][10][11][12] because of their valence level structures, such as ns, ͑n −1͒d, and ͑n −2͒f, which may exhibit different spin configurations.…”

Section: Introductionmentioning

confidence: 99%

Electronic and magnetic properties of endohedrally doped fullerene Mn@C60: A total energy study

Sabirianov

Lü

et al. 2008

The Journal of Chemical Physics

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We perform total energy calculations on a manganese atom encapsulated inside a C 60 cage using density functional theory with the generalized gradient approximation through three optimization schemes and along four paths inside the cage. We find that when Mn is located in the central region, its electronic and magnetic properties are not exactly the same as those of a free Mn atom due to weak coupling between Mn and the cage. As Mn is shifted toward to the edge, the total energy and spin start to change significantly when Mn is situated about one-third of the way between the cage center and edge, and the total energy reaches a local minimum. Finally the interaction between Mn and the cage turns repulsive as Mn approaches the edge. We also find that, along the lowest energy path, there exist three consecutive local energy minima and each of these has a different spin M. The ground state has the lowest M = 3, Mn is located about 1.6 Å away from the cage center, and the binding energy is 0.08 eV. We attribute the decrease in total energy and spin to Mn and C hybridization.

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Lanthanum complexes of spheroidal carbon shells

Cited by 1,170 publications

References 1 publication

Water-soluble fullerenes for medical applications

Water-soluble fullerenes for medical applications

Combustion synthesis of fullerenes and fullerenic nanostructures

Electronic and magnetic properties of endohedrally doped fullerene Mn@C60: A total energy study

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