Formation of Giant Solvation Shells around Fulleride Anions in Liquid Ammonia

Howard, Christopher A.; Thompson, Helen; Wasse, Jonathan C.; Skipper, Neal T.

doi:10.1021/ja046322a

Cited by 28 publications

(82 citation statements)

References 19 publications

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“…This solvation behavior is expected to be similar to that deduced from neutron diffraction studies of C 60 anions dissolved in ammonia, where isotopic labeling and the intrinsic monodispersity allowed the solvent structure to be explicitly determined. 35 However, we note that since SANS intensity typically scales as the particle volume squared, scattering from any fullerene species (as measured previously)…”

Section: Swnt Reduction In Liquid Ammoniamentioning

confidence: 55%

Scalable Method for the Reductive Dissolution, Purification, and Separation of Single-Walled Carbon Nanotubes

et al. 2011

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As synthesized, bulk singlewalled carbon nanotube (SWNT) samples are typically highly agglomerated and heterogeneous. However, their most promising applications require the isolation of individualized, purified nanotubes, often with specific optoelectronic characteristics. A wide range of dispersion and separation techniques have been developed, but the use of sonication or ultracentrifugation imposes severe limits on scalability and may introduce damage. Here, we demonstrate a new, intrinsically scalable method for SWNT dispersion and separation, using reductive treatment in sodium metal-ammonia solutions, optionally followed by selective dissolution in a polar aprotic organic solvent. In situ small-angle neutron scattering demonstrates the presence of dissolved, unbundled SWNTs in solution, at concentrations reaching at least 2 mg/mL; the ability to isolate individual nanotubes is confirmed by atomic force microscopy. Spectroscopy data suggest that the soluble fraction contains predominately large metallic nanotubes; a potential new mechanism for nanotube separation is proposed. In addition, the G/D ratios observed during the dissolution sequence, as a function of metal: carbon ratio, demonstrate a new purification method for removing carbonaceous impurities from pristine SWNTs, which avoids traditional, damaging, competitive oxidation reactions.

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Section: Swnt Reduction In Liquid Ammoniamentioning

confidence: 55%

Scalable Method for the Reductive Dissolution, Purification, and Separation of Single-Walled Carbon Nanotubes

et al. 2011

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“…24,25 The hydrogen-bonding behavior we find is similar for both solutes, specifically an increase in short distance, near-linear hydrogen-bonding contacts in S1 compared to bulk. However, C 60 shows a much larger increase compared to CH 4 . We further expand our analysis to look at three-water interactions in triangles in S1.…”

Section: Introductionmentioning

confidence: 84%

“…We simulate a single molecule of solute, CH 4 or C 60 , in a (4 nm) 3 simulation box containing over 2000 explicit water molecules using the rigid SPC water model. We have previously compared a variety of water models in the hydration of benzene and cyclohexane.…”

Section: Molecular Dynamics (Md) Simulationsmentioning

confidence: 99%

“…A set of 10 simulations of 10 ns each was run for C 60 , for a total simulation time of 100 ns, and a set of 30 simulations of 10 ns each was run for CH 4 , for a total simulation time of 300 ns. More simulation time was needed to get comparable statistical accuracy by having the same number of shell 1 (S1) water molecules sampled (C 60 has approximately 3 times as many water molecules in the first shell as CH 4 ).…”

Section: Molecular Dynamics (Md) Simulationsmentioning

confidence: 99%

“…Water forms a structured configuration surrounding C 60 , with a dense and structured first hydration shell (S1), a pronounced area of low water density, and a distinctly well-formed second hydration shell (S2). Water surrounding CH 4 shows less structure, with a more diffuse S1 and very little structure in S2. Water adopts a distinct pattern of orientations around both hydrophobic solutes.…”

Section: Introductionmentioning

confidence: 99%

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How Hydrophobic Buckminsterfullerene Affects Surrounding Water Structure

2008

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The hydrophobic hydration of fullerenes in water is of significant interest as the most common Buckminsterfullerene (C 60 ) is a mesoscale sphere; C 60 also has potential in pharmaceutical and nanomaterial applications. We use an all-atom molecular dynamics simulation lasting hundreds of nanoseconds to determine the behavior of a single molecule of C 60 in a periodic box of water, and compare this to methane. A C 60 molecule does not induce drying at the surface; however, unlike a hard sphere methane, a hard sphere C 60 solute does. This is due to a larger number of attractive Lennard-Jones interactions between the carbon atom centers in C 60 and the surrounding waters. In these simulations, water is not uniformly arranged but rather adopts a range of orientations in the first hydration shell despite the spherical symmetry of both solutes. There is a clear effect of solute size on the orientation of the first hydration shell waters. There is a large increase in hydrogenbonding contacts between waters in the C 60 first hydration shell. There is also a disruption of hydrogen bonds between waters in the first and second hydration shells. Water molecules in the first hydration shell preferentially create triangular structures that minimize the net water dipole near the surface near both the methane and C 60 surface, reducing the total energy of the system. Additionally, in the first and second hydration shells, the water dipoles are ordered to a distance of 8 Å from the solute surface. We conclude that, with a diameter of approximately 1 nm, C 60 behaves as a large hydrophobic solute.

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Addition of sulfur radicals to fullerenes

Denis

Iribarne²

2010

Int J of Quantum Chemistry

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The addition of oxygen-centered radicals to fullerenes has been intensively studied due to their role in cell protection against against hydrogen peroxide induced oxidative damage. However, the analogous reaction of sulfur-centered radicals has been largely overlooked. Herein, we investigate the addition of S-centered radicals to C 50 , C 60 , C 70 , and C 100 fullerenes by means of DFT calculations. The radicals assayed were: S, SH, SCH 3 , SCH 2 CH 3 , SC 6 H 5 , SCH 2 C 6 H 5 , and the open-disulfide SCH 2 CH 2 CH 2 CH 2 S. Sulfur, the most reactive species, prefers to be attached to a 66-bond of C 60 with a binding energy (E bind ) of 2.4 eV. For the SR radicals the electronic binding energies to C 60 are 0.77, 0.74, 0.58, 0.67, and 0.35 eV for SH, SCH 3 , SCH 2 CH 3 , SCH 2 C 6 H 5 , and SC 6 H 5 , respectively. The reactivity of C 60 toward SR radicals can be increased by lithium doping. For Li@C 60 , the E bind is increased by 0.65 eV with respect to C 60 , but only by 0.33 eV for the exohedral doping. Fullerenes act like free radical sponges. Indeed, the C 60 -SR E bind can be duplicated if two radicals are added in ortho or para positions. The enhanced reactivity because of multiple additions is mostly a local effect, although the addition of one radical makes the whole cage more reactive. Therefore, as observed for hydroxylated fullerenes, they should protect cells from oxidative damage. However, the thiolated fullerenes have one advantage, they can be easily attached to gold nanoparticles. For the addition on pentagon junctions smaller fullerenes like C 50 are more reactive than C 60 . Interestingly, C 70 is as reactive as C 60 , even for the addition on the equatorial belt. For larger fullerenes like C 100 , reactivity decreases for the carbon atoms belonging to hexagon junctions.

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Formation of Giant Solvation Shells around Fulleride Anions in Liquid Ammonia

Cited by 28 publications

References 19 publications

Scalable Method for the Reductive Dissolution, Purification, and Separation of Single-Walled Carbon Nanotubes

Scalable Method for the Reductive Dissolution, Purification, and Separation of Single-Walled Carbon Nanotubes

How Hydrophobic Buckminsterfullerene Affects Surrounding Water Structure

Addition of sulfur radicals to fullerenes

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