Generalized topological efficiency – case study with C84 fullerene

Abstract

A pure topological mechanism able to explain fullerenes stability is presented here. The non-trivial case of the C₈₄ fullerene isomers with isolated Pentagons Is in fact analyzed. This original computational approach is based on the generalization of the topological efficiency potentials which may be used to study all types of carbon allotropes.     

Fullerenes and Viruses

Abstract

It is well known that any, sometimes very small, changes in the chemical structure can lead to the dramatic changes in biological properties. Therefore it is necessary to divide into two different topics the studies of biological properties of fullerene and fullerene‐like compounds. In the enormous variety of data on the biological activity of fullerenes it is possible to select some with defined mechanism of action. This selection showed that in case of using the fullerene‐containing compositions the main mechanisms of drug action, namely unspecific, specific (ligand–receptor) interaction and membranotropic can be obtained. Therefore fullerenes as compounds with broad biological potential are very promising not only for the design of antiviral compounds, but also for the design of various types of drugs.     

Fullerenes and Nanotubes from Coal

Abstract

Graphite has normally been used to synthesise fullerenes and nanotubes. However, coal is a cheaper and more suitable industrial material. Because coal is a molecular solid, unlike graphite, the mechanism by which fullerene and nanotubes are formed is different. Moreover, other products such as polyaromatic hydrocarbons (PAHs) and microfibres are also formed. In this review, the mechanism of formation of fullerene and nanotubes from coal is discussed. It is shown that the pathway involved is other than through the C₁ intermediate route. The influence of other elements in coal such as hydrogen, oxygen, sulfur and iron is also discussed. It appears that, hydrogen, oxygen, iron and sulfur affect the yield and type of fullerenes and nanotubes formed.     

Cytoprotective activities of water-soluble fullerenes in zebrafish models

Using zebrafish (Danio rerio) embryos as a model system, we compared the antioxidant and cytoprotective effects of a series of new water-soluble fullerenes 1–12. Since zebrafish embryos are transparent during the first week of life, the effects of fullerenes on multiple organ systems, including CNS, PNS, and heart, could be assessed in situ. Both positively charged and negatively charged water-soluble fullerenes were added at concentrations between 1 and 500?µM to 96 well plates containing zebrafish embryos at 24–120 hours post fertilization (hpf). Direct toxicity of each fullerene compound was assessed by LC50. In addition, we assessed the ability of each fullerene to protect against toxicity induced by known chemical toxins in this system. Four different drug/chemical toxicity models were used in our study: (i) protection of neuromast hair cells from gentamicin-induced toxicity; (ii) protection of neuromast hair cells from cisplatinum-induced toxicity; (iii) protection of tyrosine hydroxylase-containing dopaminergic CNS neurons from 6-hydroxydopamine toxicity; and (iv) protection of total CNS neurons from 6-hydroxydopamine toxicity. Our results indicate that (i) positively charged water-soluble fullerenes tend to exhibit greater toxicity than negatively charged fullerenes with similar structures; (ii) toxicity varies considerably among negatively charged fullerenes from very low to moderate, depending on structural features; (iii) dendrofullerenes 2–7 (monoadducts of C₆₀) show stronger protection against cisplatinum toxicity in neuromast hair cells while then the e,e,e-trismalonic acid 1 (so called C3) shows stronger protection against gentamicin-induced cytotoxicity in the same cells; (iv) C3 (1) is relatively unstable in all aqueous solvents tested and breaks down mainly through decarboxylation reactions to form penta, tetra and tris carboxylated forms, which exhibit increased toxicity in vivo compared with C3 (1). Our findings indicate that water-soluble fullerenes can protect against chemical toxin-induced apoptotic cell death in a vertebrate, whole-animal model that may be useful for predicting the efficacy and toxicity of these compounds in mammals. Furthermore, the relative potential for pharmacologic use of these compounds varies considerably with respect to stability.     

Flexible Gold Nanocone Array Surfaces as a Tool for Regulating Neuronal Behavior

Accelerated neurite outgrowth of rat cortical neurons on a flexible and inexpensive substrate functionalized with gold nanocone arrays is reported. The gold nanocone arrays are fabricated on Teflon films by a bottom‐up approach based on colloidal lithography followed by deposition of a thin gold layer. The geometry of nanocone arrays including height and pitch is controlled by the overall etching time and template polystyrene beads size. Fluorescence microscopy studies reveal high viability and significant morphological changes of the neurons on the structured surfaces. The elongation degree of neurite is maximized on the nanocone arrays created with 1 µm polystyrene beads by a factor of two with respect to the control. Furthermore, the interface between the neurons and the nanocones is investigated by scanning electron microscopy and focused ion beam cross‐sectioning. The detailed observation of the neuron/nanocone interfaces reveals the morphological similarity between the nanocone tips and the neuronal processes, the existence of interspace at the interface between the cell body and the nanocones, and neurite bridging among the neighboring structures, which may induce the acceleration of neurite outgrowth. The flexible gold nanocone arrays can be a good supporting substrate of neuron culture with noble electrical and optical properties.     

Stone-Wales Rearrangement as the Double Olefin-Carbene 1,2-CC Bond Shift. Denied Role of Triplet Biradicals

Abstract

Stone-Wales rearrangement may be considered to consist of two contiguous steps of olefin-carbene 1,2-C-C bond shift. Computational study on this mechanism led to high activation energies comparable to the bond dissociation energies of C-C bonds in fullerenes and their precursors. the possibility of passing through triplet transition state is denied on computational grounds.     

Carbon nanocones: wall structure and morphology

Abstract

Large-scale production of conical carbon nanostructures is possible through pyrolysis of hydrocarbons in a plasma torch process. The resulting carbon cones occur in five distinctly different forms, and disc-shaped particles are produced as well. The structure and properties of these carbon cones and discs have been relatively little explored until now. Here we characterize the structure of these particles using transmission electron microscopy, synchrotron x-ray and electron diffraction. The carbon nanocones are found to exhibit several interesting structural features; instead of having a uniform cross-section, the walls consist of a relatively thin inner graphite-like layer with a non-crystalline envelope, where the amount of the latter can be modified significantly by annealing. The cones appear with a well-defined faceting along the cone edge, demonstrating strict long-range atomic ordering; they also present occasional examples of symmetry breaking, such as two apexes appearing in the same carbon nanocone.     

Enumeration of stereo,position and chiral isomers of polysubstituted giant fullerenes: applications to C180 and C240

Abstract

We have developed combinatorial generation function methods that combine M?bius inversion and character cycle indices for the enumeration of stereo, position and chiral isomers of icosahedral giant fullerenes C₁₈₀ and C₂₄₀. Techniques are also developed for the machine perception of symmetries of especially giant fullerenes. The techniques yield, symmetries, position, stereo and chiral isomers of giant fullerenes which we illustrate with applications to icosahedral C₁₈₀(I_h), and C₂₄₀(I_h). We have obtained combinatorial tables for the isomers of C₁₈₀X_k and C₂₄₀X_k. Our results point to errors in previous computations on C₂₄₀ permutations. We have also outlined applications to NMR and ESR spectroscopy.     

Double-Toroid,Almost-Polyhex Fullerenes

Abstract

This study presents examples of double-toroid fullerenes comprised entirely of hexagonal faces except as required by Euler's polyhedron closure rule. Kekulé structure counts give a rough idea of stability of these structures relative to each other and to other types of fullerenes with the same carbon number (C₁₂₀). Electronic constraints demanded by the various atomic arrangements are discussed, along with possible applications.     

Topological modeling of 1-Pentagon carbon nanocones – topological efficiency and magic sizes

In this article topological modeling techniques have been applied to the study of one pentagon carbon nanocones (apical angle 19°) to derive important results about preferred sizes and chemical reactivity. This theoretical model looks to the nanocone just like a 3-connected graph and considers the topological efficiency (or topological roundness) of such a system as the long-range topological potential whose local minima correspond to magic sizes of the nanocone with high probability of formation. This study moreover shows that topology alone can determine a migration of the stable regions of the nanocone along the nanocone itself, leaving in such a way the apical pentagon in a topologically reactive status. This study expands and systematizes previous works on the same subject.     

Fullerenes C60 and C70: a model for solubility by applying the correlation intensity index

Abstract

Fullerenes are materials which have many applications as in the field of chemical technology as well as in the field of biochemistry and medicine. Solubility of fullerenes in different solvents has been studied many times in the field of computational chemistry. However, analysis of different approaches which able help to solve the task of prediction of solubility fullerenes remains attractive and very important direction of scientific activity. The correlation intensity index (CII) is a new criterion of the predictive potential of models. The applying of CII together with Index of Ideality Correlation (IIC) in modeling of fullerenes solubility in various solvents by the Monte Carlo method using the CORAL software (http://www.insilico.eu/coral) indicates that applying of the CII improves the predictive potential of these models. These models can be applied for systematization of ecological, biochemical, and medicinal knowledge related to applying of fullerenes. This systematization gradually becomes a factor of key importance, since the applying of the fullerenes expanded day by day.     

Water-soluble fullerenes for medical applications

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.     

Fullerene Research at the University of New South Wales

Abstract

This paper gives an overview of our group's involvement in fullerene research which has been focussed in the two areas of mass spectrometry and production of fullerenes. The early work was mainly concentrated on the observation of fullerene ions in laser ablation mass spectrometry. We have also tried to develop other carbon sources of fullerenes besides graphite. The fullerene work continues and has led us into other areas such as the study of the reactivity of small carbon anions.     

Electronic and Field Emission Properties of Carbon Nanocones: A Density Functional Theory Investigation

Using density functional theory calculations, we investigate the electronic structures and field emission properties of carbon nanocones (CNCs). We find that the cohesive and formation energies for various types of CNCs are dependent on the cone angles, while the work function, local density of states, redistribution of the charge, and field emission pattern are sensitive to the morphologies of CNCs that are governed by the position of pentagonal rings in the cone apex. Most importantly, the nanocone with three pentagons in the cone apex exhibits the best field emission property.      

JxB Arc Jet Fullerene Producer with a Revolver Type Automatic Material Injector

Abstract

In order to produce various kinds of fullerenes efficiently, a J×B arc jet fullerene reactor with a revolver type automatic and continuous material injector has been developed. The J×B force reduces deposition of carbon vapor on a cathode and increases production rate of fullerenes. Effective production of LaC₆₀ and LaC₇₀ is also obtained by this reactor.     

Face colorings and chiral face colorings of icosahedral giant fullerenes: C80 to C240

Abstract

Combinatorial techniques based on Sheehan’s modification of P?lya’s theorem and M?bius inversion technique together with character cycle indices are applied to face colorings of giant fullerenes. These techniques are applied to icosahedral fullerenes, C₈₀ with a chamfered dodecahedron structure, a chiral fullerene C₁₄₀, icosahedral C₁₈₀ and C₂₄₀ with a chamfered truncated icosahedron geometry. The techniques are shown to provide both achiral and chiral face colorings of giant fullerenes for (a) coloring only pentagons with all hexagons painted white, (b) coloring hexagonal faces with all pentagons kept white, (c) both pentagons and hexagons painted with variable colors from a single set, and (d) both pentagons and hexagons painted with variable colors but chosen from two different sets. We have shown that in order to produce chiral colorings for the I_h fullerenes at least 2 black colors and remaining being white are needed when both pentagons and hexagons are varied. Results provide new insights into facial labeling and facial dynamics of fullerenes, while therefore being fully prepared to be inscribed in the new so called neutrosophical science (of carbon) nano-structural physical-chemistry.     

Zirconium Cage-Doped Fullerenes

Abstract

Some zirconium containing fullerenes were synthesized by vaporizing a zirconium-containing graphite anode with DC arc discharge technique, extracted by CS2 through low temperature extraction method, and characterized by field desorption mass spectra (FDMS). The results show that these doped fullerenes were zirconium cage-doped fullerenes.     

Extraction of Exotic Fullerenes and Purification of Single-Walled Nanotubes

Abstract

In this report, we presented a novel and simple extraction method, namely Hydrothermally Initiated Dynamic Extraction (HIDE) method, which allows the extraction of exotic fullerenes remaining in the fullerene soot. In the HIDE method, the soot was treated in boiling water that neither dissolved fullerenes nor produced minimal by-products but untangles the fullerenes from the soot, prior to the extraction by organic solvent. As a result, the HIDE method allowed the extraction of exotic fullerenes, such as dimeric fullerene oxides, higher fullerenes having a low symmetry and oxidized higher fullerenes. Accordingly, the single walled nanotubes (SWNTs) with a purity of 99% by wt was achieved for the first time with the application of the HIDE method.     

Carbon nanotube growth at the tip of SiO2 nanocone

A well aligned growth of carbon nanotube (CNT) at the tip of SiO₂ nanocone using chemical vapor deposition (CVD) method is described. Fe particle at the tip of a nanocone has been observed to work as the catalyst for CNT growth. Initially, a number of self organized SiO₂ nanocones were grown via thermal annealing of MnCl₂ on Si substrate in the presence of H₂ gas. The average diameters of the tip and base of the nanocones were nearly 50 nm and 1 μm, respectively, with length up to 2.4 μm. At the tip of the nanocone a CNT was grown successfully. The CNT grows from the tip of the nanocone where Fe particles accumulate after the reduction of FeCl₃ at 950 °C. The accumulation point of Fe particles depends on the orientation of the nanocone tip inside the reaction tube during CVD process. Therefore, the alignment of nanotube at the tip of SiO₂ nanocone can be controlled by orientation of the nanocone in the reaction tube.     

Computer Simulation of C60 Fullerene Fragmentation by Electron Beam

Abstract

Computer simulation of electron‐induced ionization and fragmentation of free C₆₀ fullerenes, as well as of fullerenes in fullerite films, was carried out. It was found that stable complexes of heavy fullerene's fragments are formed under electron irradiation in fullerite films. These complexes are characterized by different spatial configurations and electron structures and can cause long‐term mechanical stresses.