Fullerenes: Principles and Applications: Volume 20 - Rilegato

Rilegato

ISBN 10: 1849731365 ISBN 13: 9781849731362

Casa editrice: Royal Society of Chemistry, 2011

Riassunto

The discovery of caged carbon structures, in 1985, established a whole new field of carbon chemistry.  Unlike graphite and diamond, these structures known as fullerenes are finite in structure and are relevant to a wide variety of fields including supramolecular assemblies, nanostructures, optoelectronic devices and a whole range of biological activities.

Fullerenes: Principles and Applications discusses all aspects of this exciting field.  Sections include: the basic principles for the chemical reactivity of fullerenes, electrochemistry, light induced processes, fullerenes for material sciences, fullerenes and solar cells, biological applications and multifunctional carbon nanotube materials.   Written by leading experts in the field the book summarises the basic principles of fullerene chemistry but also highlights some of the most remarkable advances that have occurred in recent years. 

Fullerenes: Principles and Applications will appeal to researchers in both academia and industry.

Su questo libro

Informazioni sull?autore

Fernando Langa is a Professor of Organic Chemistry, University of Castilla-La Mancha, Toledo, SPAIN. His primary research interest  are in the areas of chemistry of fullerenes, nanotubes, functionalization and solar energy conversion.

Jean-François Nierengarten works at the CNRS Researcher, Toulouse, France.
His current scientific interests range from covalent chemistry of fullerenes to dendrimers and  Pi-conjugated systems with unusual electronic and optical properties.

Dalla quarta di copertina

The discovery of caged carbon structures, in 1985, established a whole new field of carbon chemistry.  Unlike graphite and diamond, these structures known as fullerenes are finite in structure and are relevant to a wide variety of fields including supramolecular assemblies, nanostructures, optoelectronic devices and a whole range of biological activities.

Fullerenes: Principles and Applications discusses all aspects of this exciting field.  Sections include: the basic principles for the chemical reactivity of fullerenes, electrochemistry, light induced processes, fullerenes for material sciences, fullerenes and solar cells, biological applications and multifunctional carbon nanotube materials.   Written by leading experts in the field the book summarises the basic principles of fullerene chemistry but also highlights some of the most remarkable advances that have occurred in recent years. 

Fullerenes: Principles and Applications will appeal to researchers in both academia and industry.

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Fullerenes

Principles and Applications

By Fernando Langa, Jean François Nierengarten

The Royal Society of Chemistry

Copyright © 2012 Royal Society of Chemistry
All rights reserved.

ISBN: 978-1-84973-136-2

Contents

Part I, 
Chapter 1 (Endo)Fullerenes: From Production to Isolation Delphine Felder-Flesch, 3, 
Chapter 2 Endohedral Fullerenes N. Chen, A. L. Ortiz and L. Echegoyen, 12, 
Chapter 3 Basic Principles of the Chemical Reactivity of Fullerenes Rubén Caballero, Pilar de la Cruz and Fernando Langa, 66, 
Chapter 4 Fullerene-Containing Polymers Francesco Giacalone, 125, 
Chapter 5 Fullerene-Containing Dendrimers: Synthesis and Properties Jean-François Nierengarten, Michel Holler and Robert Deschenaux, 162, 
Chapter 6 Hydrogen Bonding Donor–Acceptor Carbon Nanostructures Ma Ángeles Herranz, Francesco Giacalone, Luis Sánchez and Nazario Martín, 192, 
Part II, 
Chapter 7 Three Electrodes and a Cage: An Account of Electrochemical Research on C60, C70 and their Derivatives Maurizio Carano, Massimo Marcaccio and Francesco Paolucci, 237, 
Chapter 8 Electron-Transfer Processes of Fullerenes Studied with Time-Resolved Spectroscopies Osamu Ito, 270, 
Chapter 9 Nanoscopic Organisation of Fullerenes Sukumaran Santhosh Babu and Takashi Nakanishi, 329, 
Chapter 10 Interlocked Artificial Photosynthetic Model Systems Composed of Electron-Donor and [60]Fullerene Units Jackson D. Megiatto, Jr. and David I. Schuster, 354, 
Part III, 
Chapter 11 Fullerenes for Materials Science Alejandro Montellano López, Aurelio Mateo-Alonso and Maurizio Prato, 389, 
Chapter 12 Fullerene Derivatives for Organic Photovoltaics Piétrick Hudhomme and Jack Cousseau, 416, 
Chapter 13 Fullerene-Modified Electrodes and Solar Cells Hiroshi Imahori and Tomokazu Umeyama, 462, 
Chapter 14 Biological Applications of Fullerenes Alberto Bianco and Tatiana Da Ros, 507, 
Part IV: Other Carbon Nanostructures, 
Chapter 15 Covalent Approaches towards Multifunctional Carbon-Nanotube Materials Vito Sgobba, Christian Ehli and Dirk M. Guldi, 549, 
Subject Index, 613, 

CHAPTER 1

(Endo)Fullerenes: From Production to Isolation

DELPHINE FELDER-FLESCH

Institut de Physique et Chimie des Matériaux de Strasbourg, UMR CNRS-UdS 7504 – 23 rue du Loess BP 43, 67034 Strasbourg, France

1.1 Introduction

If the existence of buckminsterfullerenes had been predicted in 1970, they were eventually synthesised in the laboratory 25 years ago, but only today have they just been detected where everyone thought that they were naturally: in space. It is worth noting, however, that the geometry of the molecule is that of a regular truncated icosahedron, a shape already known to Leonardo da Vinci and Albrecht Dürer in the 16th century.

Coming back to the 20th century, exactly twenty five years ago, when Sir Harry Kroto made a success, together with Robert Curl and Richard Smalley, to synthesise a fullerene C60, the structure of this molecule, in the shape of a soccer ball, had struck the imagination. Harry Kroto thought that this kind of structures later named "buckminsterfullerenes" in reference to the geodesic domes of the American architect Richard Buckminster Fuller, had to exist in space. In fact, they had been predicted in 1970 by a Japanese chemist, Eiji Osawa, but Kroto, who had dashed at the same time into a search for carbon chains in the interstellar space, thought that they could form in the carbon stars" atmospheres. Having heard about the work of Richard Smalley and Robert Curl at Rice University, he joined these researchers to simulate these atmospheres in the laboratory and tried to detect the presence of C60 molecules. Their success, announced by a Nature article in 1985,3 won these researchers the Nobel Prize in Chemistry in 1996.

However, no solid proof of the existence of buckminsterfullerenes in space had been obtained up to now, while they were already found in certain meteorites. This has just changed, thanks to the observations made in the infrared light from Tc 1, a planetary nebula consisting of material shed by a dying star. An astronomer, Jan Cami, by means of the space telescope Spitzer, discovered the presence of the fullerene C60 and C70: indeed, buckyballs vibrate in a variety of ways – 174 ways to be exact. Four of these vibration modes cause the molecules to either absorb or emit infrared light. All four modes were detected by Spitzer. As these buckyballs are maintained at the ambient tem- perature of the nebula, they vibrate gently and thus their infrared spectrum becomes particularly easy to identify.

On Earth, fullerenes can be found in soot and in certain rocks. They are most studied in the fields of nanotechnology, hydrogen storage, superconductive materials, and in nanomedicine (endohedrals) as magnetic or nuclear probes.

1.2 Production Methods

1.2.1 The Krätschmer–Huffman Arc-Discharge Apparatus

At the time of the C60 discovery there was just one problem: the new carbon allotrope could only be detected through spectroscopic analysis; therefore, researchers could not visualise fullerenes and see the soccer-ball shape with their own eyes, so to speak. Fullerenes remained a matter of theory.

Things changed in 1990 when W. Krätschmer and R. D. Huffman invented a method for producing fullerenes in large amounts. The invention not only provided practical evidence of the 1985 discovery – and the soccer-ball shape – but it also essentially created a new field of scientific study. During the course of his studies on interstellar dust particles at the University of Arizona in the United States, Krätschmer noticed elements with strange properties among the carbon and graphite samples. What was going on? The answer arrived in 1985, when scientists Harry Kroto, Richard Smalley and Bob Curl created C60 in their laboratory while simulating the high-pressure formation of stars in the universe. Knowing that he had encountered C60 molecules in his laboratory, Krätschmer re-examined his findings. Together with Donald Huffman at the University of Arizona they worked out the "Krätschmer–Huffman method" for producing gram-sized samples of fullerenes (Figure 1.1).

This method consisted in evaporating graphite electrodes via resistive heating in an atmosphere of ~ 100 torr of helium. Although the soot contained only a few per cent by weight of C60, it could be conveniently extracted using benzene as solvent. The red-brown benzene solution could be decanted from the black insoluble soot and then dried using gentle heat, leaving a residue of dark brown to black crystalline material. Mass spectral analysis of this material showed peaks at 720 (C60) and 840 (C70) in an approximate ratio of 10:1.

Shortly after the Krätschmer–Huffman method was reported, Smalley's group at Rice University published a modified design for the "C60 generator". In the Smalley apparatus (Figure 1.2), an electric arc is established between two graphite electrodes. Hence, most of the power is dissipated in the arc and not in resistive heating of the rod. The entire electrode assembly is enclosed in a reaction chamber under a reduced pressure (~ 100 torr) of helium: black soot is produced and extraction with organic solvents yields fullerenes.

Within just three years after these methods were elaborated, scientists filed nearly 300 applications for new patent families relating to fullerenes. Thousands more have followed.

1.2.2 The Combustion Process

The possibility that fullerenes could also be formed in sooting flames had been suggested and all-carbon ions having the same mass/charge ratios as fullerenes in carbon vapour had been detected in flames and assumed to have the closedcage structure of fullerenes. In 1991, J. B. Howard and collaborators reported their observations that both C60 and C70 fullerenes were produced in varying amounts from premixed laminar benzene/oxygen/argon flames operated under ranges of conditions including pressures of 12–100 Torr and C/O ratios from 0.717 to 1.072, the critical value for soot formation being 0.760. The proper selection of flame conditions gave fullerenes in yields up to 0.26% of the fuel carbon burned and allowed control of the C70/C60 molar ratio over the range 0.26–5.7. The yield of C60 + C70 and the C70/C60 ratio were found to depend on temperature, pressure, carbon/oxygen ratio, and residence time in the flame. In order to characterise the flame-generated fullerenes, samples of condensable compounds and soot were collected from flames under different conditions and analysed using high-performance liquid chromatography with diode-array spectrophotometric detection, mass spectrometry, and infrared spectrophotometry.

In 2002, Frontier Carbon Corporation started mass production of fullerenes with a capacity of 400 kg per year by the use of such a combustion method, and the price of fullerenes was decreased drastically. The production capacity was increased 100-fold to 40 tons per year in 2003. This improved flame-based technology is most suited for mass production of fullerenes, since it is a con- tinuous process and uses inexpensive hydrocarbons as its starting materials, which is similar to that employed in the commercial carbon-black production process. Fullerene yield in the resulting soot is now around 20%, which demonstrates that the combustion method is a practical technology for fullerene-soot production. On this evolution of fullerene production, concrete market(s) will emerge in the next few years, and actual commercial usage of fullerenes has already started.

1.2.3 Chemical Synthesis

1.2.3.1 Pyrolytic Dehydrogenation or Dehydrohalogenation

As C60 consists of six dehydronaphthalene moieties located at the octahedral sites, Taylor or Scott showed that the pyrolysis of naphthalene produces C60, as does corannulene, 7,10-bis(2,2'-dibromovinyl)fluoranthene, and 11,12-benzofluoranthene.

In 2001, Scott and collaborators showed that it is possible to "stitch up" a hydrocarbon incorporating 60 carbon atoms, 13 of the 20 benzene rings, and 75 of the 90 carbon-carbon bonds required to form C60, by the use of a high-energy laser (Figure 1.3). That method, however, did not permit isolation of the fullerene produced.

One year later, the same authors were able to produce isolable quantities of C60, in 12 steps from commercially available starting materials, by rational chemical methods. A molecular polycyclic aromatic precursor bearing chlorine substituents at key positions forms C60 when subjected to flash vacuum pyrolysis at 1100 °C.

Unfortunately, the so-produced quantities are insufficient for practical applications, and no other fullerene has yet been made in this way.

1.2.3.2 Surface-Catalysed Cyclodehydrogenation

Recently, researchers have discovered a method that produces the buckyball configuration of carbon with nearly 100% conversion efficiency from aromatic precursor materials using a highly efficient surface-catalysed cyclodehydrogenation process. Indeed, scientists investigated catalysing a decomposition reaction with platinum. The authors essentially used an extension of the commonly used chemical vapour deposition process (CVD), where precursor gasses are thermally decomposed into the desired compound. A precursor molecule was prepared by bonding rings of carbon with excess hydrogen that consumed unused sites on the carbon, creating a warped disc of C60H30. The molecule was deposited on the platinum and heated to 750 K to complete the process. The strong interaction between the carbon and the platinum pinned the precursor molecule in place, flattening the bent structure, while simultaneously catalysing a reaction that stripped off the unwanted hydrogen, releasing it as a gas. As the reaction proceeded, the carbon would start to form a half-cage of sorts. At some point, the formation of the spherical buckyball is presumed to be spontaneous; leaving a ball of pure C60 pinned on the platinum surface.

Amazingly, the reaction caused a near 100% conversion of the precursor molecule to the C60. A proof-of-concept run showed that the process could be scaled up industrially using platinum nanoparticles and lower-vacuum pressure chambers, although the efficiency of this reaction was not measured. Researchers also demonstrated a similar approach for producing a triazafullerene C57N3. Also, if the process is carried out in an atmosphere containing guest species, it might even allow endohedral formation.

1.3 Isolation and Purification of Empty Fullerenes

It is important to note that the raw material obtained by the production techniques such as the Krätschmer–Huffman method, is a soot constituted by a mixture of soluble fullerenes (Cn, n<100), "giant" fullerenes (Cn, n>100), nanotubes and amorphous carbon. By sublimation or extraction techniques it is then possible to isolate the fullerenes from the soot. Afterward, repeated chromatography on neutral alumina allows separation of the various fullerene byproducts and isolation of stable solid samples of C76, C84, C90, and C94 (Figure 1.4). Of the fullerene family, C60 and C70 are the major isomers obtained with 73 and 23% yield, respectively, a variety of molecules larger than C60 and C70 representing a total amount of 3 to 4% by weight.

The colours of the fullerene family vary according to their molecular weight and symmetry: Their colours in solution are magenta (C60), port-wine red (C70), brown (C76, C78) and yellow-green (C84).

1.4 Endohedrals

Endohedral fullerenes have captivated scientists with their tantalising properties and possibilities for application. But they have also stymied research efforts because they have proven to be challenging to prepare and purify. It is not surprising, then, that practical applications for these materials remain elusive. However, in the last ten years, the variety of endohedral fullerenes has been extended tremendously. "Capturand" endohedral fullerenes are synthesised by the arc combustion of graphite (similar to the Krätschmer–Huffman method) with an admixture of metal oxide (e.g., La2O3). They are formed in situ in the carbon and metal plasma during which some carbon cages just being formed capture nearby metal atoms floating in the plasma. On the contrary, "penetrand" endohedral fullerenes are produced during the interaction of the already formed, i.e. closed cage fullerenes, with atoms of various elements. There are different production methods (Figure 1.5) like high-pressure/ high-temperature incorporation, ion-beam implantation, glow-discharge reactor, radiofrequency plasma discharge reactor, or chemical "surgery" creating holes in the carbon structure.

1.5 General Conclusions

Since fullerenes were discovered at the end of last century, many new findings and important aspects of the carbon molecules have been accumulated to form a new exciting scientific field. The high production cost of fullerenes has been the main obstacle in the development of this market. However, fullerenes are currently being utilised in high-performance lubricants, innovative fuels, new classes of superconductors and magnets, and polymers designed for data recording and storage. The global fullerene market posted total revenues of $300 million in 2008, a figure that is expected to rise to $4.6 billion in 2015.

This shows both the importance and the nontrivial challenges associated with the industrialisation of nanotechnology ending in real-world applications of these materials.

CHAPTER 2

Endohedral Fullerenes

N. CHEN, A. L. ORTIZ AND L. ECHEGOYEN

Department of Chemistry, Clemson University, Clemson, SC, 29634, USA

2.1 Introduction

Fullerenes are all-carbon compounds consisting of cages with a hollow space inside. These compounds have generated considerable interest and activity because of their unique structures and their potential practical applications. One of the most attractive properties is their ability to host atoms and small clusters inside, which was verified by the first report of an endohedral fullerene in 1985 and the isolation of La@C82 in 1991. Since then, endohedral fullerenes have been extensively studied because of their unique electronic structures that arise as a result of the interaction between the encaged species and the cages. To date, a wide variety of metal, clusters and even gas molecules, including all the lanthanides, the group II and III metals as well as their corresponding metallic nitride clusters, metallic carbides, metallic oxides, noble gases, nitrogen, and hydrogen, have been encaged by various methods. Furthermore, the successful exohedral chemical functionalisation of endohedral fullerenes has paved the way for future applications such as in molecular electronics, in electron-donor/acceptor systems, as magnetic contrast-enhancing agents and radiotracers.

(Continues...)

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Dettagli dell'edizione

• Editore: Royal Society of Chemistry
• Data di pubblicazione: 2011
• Lingua: Inglese
• ISBN 10: 1849731365
• ISBN 13: 9781849731362
• Rilegatura: Copertina rigida
• Numero edizione: 2
• Numero di pagine: 634
• Redattore: Langa Fernando, Nierengarten Jean-francois
• Contatto del produttore: non disponibile
• Persona responsabile: non disponibile