In-situ infrared spectroscopy of a photoirradiated potassium-doped C60 film

Photodimerization between C₆₀ molecules in a potassium-doped C₆₀ film (a mixture of α-C₆₀ and K₃C₆₀ phases) has been investigated using in-situ Fourier-transform (FT) infrared spectroscopy in combination with tight-binding molecular dynamics calculations. A comparison of the experimental spectrum of C₆₀ dimers, which was found to be a main product in the photoirradiated K-doped film using an FT mass spectrometer, with the theoretical spectra for several isomers of C₁₂₀ suggests that C₁₂₀ species with structures similar to a bucky peanut were formed in the photoirradiated film.     

Solubility of fullerenes in n-alkanoic acids C2–C9

The solubility of fullerene C₆₀ and a fullerene mixture [C₆₀ (75%), C₇₀ (24%), C_76–80 (1%)] in linear alkanoic acids (C₂–C₉) was determined at 20°C. The solubilities of C₆₀ and a fullerene mixture in carboxylic acids were examined in relation to the number of carbon atoms in the carboxylic acid.     

Self‐Assembly of Fullerene‐Based Janus Particles in Solution: Effects of Molecular Architecture and Solvent

Two molecular Janus particles based on amphiphilic [60]fullerene (C₆₀) derivatives were designed and synthesized by using the regioselective Bingel–Hirsh reaction and the click reaction. These particles contain carboxylic acid functional groups, a hydrophilic fullerene (AC₆₀), and a hydrophobic C₆₀ in different ratios and have distinct molecular architectures: 1:1 (AC₆₀–C₆₀) and 1:2 (AC₆₀–2C₆₀). These molecular Janus particles can self‐assemble in solution to form aggregates with various types of micellar morphology. Whereas vesicular morphology was observed for both AC₆₀–C₆₀ and AC₆₀–2C₆₀ in tetrahydrofuran, in a mixture of N,N‐dimethylformamide (DMF)/water, spherical micelles and cylindrical micelles were observed for AC₆₀–C₆₀ and AC₆₀–2C₆₀, respectively. A mechanism of formation was tentatively proposed based on the effects of molecular architecture and solvent polarity on self‐assembly.     

Polymer Nanocomposites Containing Fullerene C60 Nanofillers

Summary: The effect of fulleroids (fullerene C₆₀, mixture of C₆₀/C₇₀ and fulleroids soot which used for fullerenes production) and carbon fillers (carbon black, graphite) on mechanical properties of polymer nanocomposites based on reactoplasts (epoxy resins) and thermoplasts (polyamide-12) was investigated. The nanocomposites were prepared by in situ polymerization. It was found that additives of these fillers did not influenced on the properties of reactoplasts. Therefore, the tensile modulus and tensile strength of thermoplast based polymer nanocomposites are improved by about 30-40% with loading of 0.02-0.08 fulleroids materials. Best results were obtained for a mixture of C₆₀/C₇₀.     

Thermal behavior of a mixture of fullerenes and fullerites C60/70

The thermal behavior of a mixture of fullerites C_60/70 was studied by X-ray diffraction and IR and UV spectroscopy. The temperature range in which the molecular and crystal states degrade was determined (825?C875°C in a CO medium). In the C_60/70 mixture, fullerenes decomposed at lower temperatures than in pure C₆₀ and C₇₀; the decomposition temperature depended on the impurity (oxygen and solvent) content.     

The solubility of light fullerenes in styrene over the temperature range 20–80°C

The temperature dependence (over the range 20–80°C) of the solubility of light fullerenes (C₆₀ and C₇₀) and a mixture of fullerenes (60 wt % C₆₀, 39 wt % C₇₀, and 1 wt % C_76–90) in styrene was studied. The corresponding solubility polytherms are given and characterized.     

Synthesis of chlorinated fullerenes C60Cln (n = 2, 4) from C60Cl6 and their Arbuzov-type reaction with P(OEt)3

Reduction of C₆₀Cl₆ with triphenylphosphine was demonstrated to be a useful method for the preparation of a mixture of low-chlorinated fullerenes C₆₀Cl_n (n?=?2, 4). Individual chlorofullerene 1,4-C₆₀Cl₂ was isolated by preparative gel permeation chromatography and characterized spectroscopically for the first time. The Arbuzov-type reaction of C₆₀Cl_n with P(OEt)₃ produced C₆₀[PO(OEt)₂]₃H as a major isolable product, which was further hydrolyzed to C₆₀[PO(OH)₂]₃H.     

Theoretical studies of C60/C70 fullerene derivatives: C60O and C70O

A semiempirical (AM1) calculation on the structures and stabilities of isomers of the fullerene derivatives C₆₀O and C₇₀O is carried out. The ozonolysis reaction mechanism and the thermodynamics of the compounds are studied. The two isomers of C₆₀O (56 bond and 66 bond) formed by an oxygen atom bridging across a C-C bond have an epoxide-like or an annulene-like structure. According to the ozonolysis reaction mechanism and kinetic factor analysis, the possible products of this ozonolysis reaction are C₆₀O with oxygen bridging over the 66 bond (C_2v) as an epoxide-like isomer and that with oxygen bridging over the 56 bond (C_s) as an annulene-like isomer. Further, the sixteen isomers of C₇₀O (both epoxide-like and annulene-like structures) have been studied with respect to the same reaction mechanism. The most possible product in this ozonolysis reaction contains oxygen bridging across in the upper part (66 bond in C₇₀O-2 or C₇₀O-4) as an epoxide-like structure. The other possible product is C₇₀O-8 (annulene-like structure), in which oxygen bridges across an broken equatorial CC bond in C₇₀ (D_5h). The vibrational frequency analysis and the electronic structure of the selected C₆₀O and C₇₀O isomers are generated for experimental characterisation. The experimental results indicate that C₆₀O and C₇₀O may decompose into the odd number fullerenes C₅₉ and C₆₉. We therefore studied the structures of C₅₉ and C₆₉ also.     

The structure of fullerene films and their metallocene doping

Hexagonal close-packed (HCP) C₆₀ and C₇₀ films have been prepared by the Langmuir method and examined by electron microscopy and electron-diffraction analysis. It has been shown that the vacuum deposition of a C₆₀+C₇₀ mixture results in the formation of a film with small sized grains and a distorted C₆₀-HCP structure. The simultaneous deposition of C₆₀ and ferrocene results in the formation of a film with a changed morphology and an electron-diffraction pattern that contains a variable amount of ferrocene depending on the experimental conditions. The electron-diffraction pattern corresponds to the presence of the known molecular complex C₆₀[(C₅H₅)₂Fe]₂. The analogous simultaneous deposition of fullerene C₆₀ and cobaltocene results in the formation of a C₆₀ film stable in air and water, which contains carbon and cobalt (from the data of X-ray fluorescence, electron microscopy and microdiffraction). It has a different morphology and different diffraction patterns than pure C₆₀ films and, depending on the cobaltocene content (relative to that of fullerene), appears to be a fullerite film doped with various amounts of cobaltocenium fullende, which is an ionic compound.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1379–1383, August, 1994.The work was financially supported by the Russian Foundation for Basic Research (Projects 93-03-4676 and 93-03-18368).     

Thermal stability of the fullerene‐chain link in 6‐arm PS stars with a C60 core

The thermal stability of well‐defined hexa‐adducts (PS)₆C₆₀ in solution at temperatures around 100 °C has been studied by multi‐detector Size Exclusion Chromatography. The degradation reaction corresponds to a quantitative release of the polystyrene arms from the fullerene core through thermal cleavage of the PS‐C₆₀ link. From the kinetics of formation of cut arms and the progressive decrease of the stars' functionality, we could establish that the reaction follows a stepwise “breaking” mechanism where a 6‐arm star is first converted to a 5‐arm star, then to a 4‐arm star, and so on down to the ungrafted arm. Furthermore, not only does the thermal stability of the PS? C₆₀ bond increase if the functionality of the star decreases, but the difference is large enough to allow determination of the kinetics constants for the first three steps. The activation energy for the breaking of an arm‐C₆₀ link is about 65 kJ/mol. The stability of (PS)₆C₆₀ slightly decreases with an increase of the arm length. MALDI‐TOF mass spectroscopy has shown that both C? C bonds in α and β positions to C₆₀ can be cut, but the breaking of the direct fullerene‐arm bond is favored. We have also found that a polyisoprene? C₆₀ bond is about seven times less stable than a PS‐fullerene link upon heating. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4820–4829, 2004     

Regulation of Glucose Oxidase Activity through Interaction with Fullerene Derivatives

The 2‐(hydroxymethyl)pyridine modified C₆₀ (PY‐C₆₀) and methoxydiglycol modified C₆₀ (MDG‐C₆₀) are synthesized using Bingel‐Hirsch reaction and characterized by nuclear magnetic resonance (NMR) and mass spectra. PY‐C₆₀ and MDG‐C₆₀ can bind to glucose oxidase (GOx) and quench the fluorescence of tryptophan (Trp) residue in GOx through static mechanism. The conformation of GOx is disturbed after formation of complex with these fullerene derivatives. Kinetic analysis indicates that PY‐C₆₀ and MDG‐C₆₀ may affect the catalytic activity of GOx with a partial mixed‐type inhibition mechanism. In the plasma glucose concentration range (3.6–5.2 mmol·L^?1), PY‐C₆₀ may significantly accelerate the catalytic velocity of GOx, however, MDG‐C₆₀ exerts almost no obvious change to the initial velocity of GOx, suggesting that elaborate design of molecular structure of fullerene derivative is very important for regulating the biological activity of fullerene‐enzyme complex.     

Polythermal study of the solubility of fullerenes in pelargonic and caprylic acids

A polythermal study of the solubility of C₆₀ and a fullerene mixture (60% C₆₀ + 39% C₇₀ + 1% C₇₆–C₉₀) in pelargonic and caprylic acids was carried out at 20–80°C. The solubility polytherms are given and discussed.     

Photoinduced Electron Transfer between N,N, Nr,N' ‐Tetra‐(p‐methylphenyl)‐4, 4‐diamino‐1, 1'‐diphenyl Ether (TPDAE) and Fullerenes (C60/C70) by Laser Flash Photolysis

The photoinduced electron‐transfer reaction of N, N, N', N'‐tetra‐(p‐methylphenyl)‐4,4'‐diamino‐1,1'‐diphenyl ether (TPDAE) and fullerenes (C₆₀/C₇₀) by nanosecond laser flash photolysis occurred in benzonitrile. Transient absorption spectral measurements were carried out during 532 nm laser flash photolysis of a mixture of the fullerenes (C₆₀/C₇₀) and TPDAE. The electron transfer from the TPDAE to excited triplet state of the fullerenes (C₆₀/C₇₀) quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C₆₀/C₇₀) in benzonitrile have been evaluated by observing the transient absorption bands in the near‐IR region where the excited triplet state, radical anion of fullerenes (C₆₀/C₇₀) and radical cations of TPDAE are expected to appear.     

Solubility of light fullerenes in oleic, linoleic, and linolenic acids at 20–80°C

Solubility of light fullerenes (C₆₀, C₇₀, and the standard fullerene mixture containing (wt %): C₆₀ 65, C₇₀ 34, C _n>70 1) in the oleic, linoleic and linolenic acids, respectively, at 20–80°C was studied and the corresponding solubility polytherms were reported.     

Fluorinated fullerenes: Synthesis and characterization

The existence of the fully fluorinated fullerene, C₆₀F₆₀, is still subject to controversy. Mass spectrometric evidence shows that it exists, albeit in trace amounts five orders of magnitude in concentration below the most abundant C₆₀F_40-42. Generally, mixtures of C₆₀F_n are obtained where n ranges from 30 to 52, depending on fluorinating conditions. The species with n = 36 is particularly stable. Attempts to increase n by use of the strongly fluorinating halogen fluorides, ClF₃ or BrF₅, have led to products C₆₀F_XX_yO_z (X = Br or Cl), where the origin of the oxygen is probably hydrolysis during analysis. Fluorinated C₆₀ crystallizes as a mixture of hexagonal close packed (40%) and face-centered cubic (60%) phases. X-ray analysis yields an average C-F bond length of 1.49A. Fluorination of C₇₀ leads to mixtures with maximum average stoichiometries of C₇₀F₅₂.     

Polythermal solubility of fullerenes in higher isomeric carboxylic acids

The solubility of individual fullerenes C₆₀ and C₇₀ and a fullerene mixture enriched in higher fullerenes (C₆₀ 38.8, C₇₀ 33.0, C_76–78 5.6, C₈₄ 8.6, C₉₀ 2.6, and C₉₆ 3.3%) in higher isomeric carboxylic acids was studied within the 20–80°C temperature range; the corresponding solubility polytherms are presented.     

Metal (Co,Fe) tribenzotetraazachlorin–fullerene conjugates: Impact of direct π-bonding on the redox behaviour and oxygen reduction reaction

Novel hexabutylsulphonyltribenzotetraazachlorin–fullerene (C₆₀) complexes of iron (FeHBSTBTAC–C₆₀) and cobalt (CoHBSTBTAC–C₆₀) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoOBSPc). It is proved that electron-withdrawing substituents (–SO₂Bu and C₆₀) on phthalocyanine macrocycle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C₆₀ substituent suppressed ORR compared to the –SO₂Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of ～1 × 10⁸ cm³ mol^?1 s^?1 and a Tafel slope of ?171 mV dec^?1.     

New isomers of trifluoromethylated fullerene: C60(CF3)12 and C60(CF3)14

HPLC separation of the products of high-temperature reaction of a sublimed mixture of C₆₀–C₇₀ (10: 1) with CF₃I in a sealed ampoule allowed isolation and determination of molecular structures (X-ray crystallography and ¹⁹F NMR) of two new isomers of C₆₀(CF₃)₁₂ and one isomer of C₆₀(CF₃)₁₄. These isomers are characterized by low relative formation energies, which suggests that the trifluoromethylation process is basically under the thermodynamic control.     

Transient Absorption Spectral characterization of Electron Transfer between Fullerenes（C60／C70）and N,N,N’，N’—Tetra（p—methylphenyl）—4,4’—diamino—1,1’—diphenyl Sulphide（TPDAS）

In search of new systems with a photoexcited redox pair which exhibits a strong and stable photoinduced absorption band to understand the photophyscial and photochemical properties of electron transfer between fullernes (C60/C70) and organic donor[N,N,N’，N’-tetra(p-methylphenyl)-4,4’-diamino-1,1’-diphenyl sulphide(TPDAS)],we studied characteristic absorption spectra in the near-IR region obtained from 532nm nanosecond laser flash photolysis of a mixture of the fullerenes (C60/C70) and TPDAS in polar solvents.When fullerenes (C60/C70)were photoexcithed,the rise of the radical anion of fullerenes (C60/C70)with the rapid decay of their excited triplet states were observed in benzonitrile.It can be deduced that the electron transfer reaction does take place from TPDAS to excithed triplet state of rullerens(C60/C70).The rate consants(ket)and quantum yiekls(φet) of this process have been also evaluated.     

Water-soluble fullerene С<Subscript>60</Subscript> derivative obtained by radiation polymerization of <Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone in the presence of С<Subscript>60</Subscript>

Method of radiation polymerization of N-vinylpirrolidone (NVP) in the presence of fullerene C₆₀ has been used to obtain water soluble compound containing fullerene C₆₀. The yield of resulted product was ~10% in the case of low-temperature radiation polymerization of NVP—C₆₀ mixture in ethanol and ~40% at 300 K. The content of C₆₀ in obtained product was ~0.5 wt.%.