Reactions of chlorofullerene C60Cl6 with N-substituted piperazines

It was shown for the first time that reactions of C₆₀ halides with aliphatic amines provide a facile route for the synthesis of aminofullerenes, valuable precursors for water-soluble cationic fullerene derivatives. Particularly, chlorofullerene C₆₀Cl₆ and N-substituted piperazines were investigated in this work. It was shown that substitution of chlorine atoms in C₆₀Cl₆ by amine groups is accompanied by partial elimination of addends from the fullerene cage that yields mixtures of di-, tetra- and, hexaaminofullerenes as the final products. Separation of these mixtures by column chromatography resulted in isolation of pure 1,4-diaminofullerenes; this procedure gives much higher and more reproducible yields of these compounds than direct oxidative photoaddition of secondary amines to C₆₀. ESI mass spectrometry and NMR spectroscopy data showed that hexaaminofullerene isomers are major components in inseparable mixtures of polyaddition products. Polyaminofullerenes were found to be readily soluble in aqueous acids; these solutions are unstable because of a facile substitution of protonated amine groups with hydroxyls. Nevertheless, the use of other amine substrates in the investigated reaction can potentially allow the preparation of more stable water-soluble cationic fullerene derivatives for biological studies.     

载有C60的TiO2纳米粒子光催化活性

以水溶性C₆₀和TiO₂粒子为前驱体,采用水热法制备了载有C₆₀的锐钛矿型TiO₂纳米粒子。应用X射线衍射、透射电子显微镜、红外光谱、紫外-可见漫反射光谱、荧光光谱对产物进行了表征。以对-硝基苯酚为模型污染物研究了产物的光催化活性,结果表明适量负载C₆₀可以提高TiO₂纳米粒子的光催化活性,C₆₀起着传输电子、促进TiO₂光生载流子分离的作用,且经7次循环使用后对-硝基苯酚的降解效率仍能达到74%。讨论了载有C₆₀的TiO₂纳米粒子光催化降解对-硝基苯酚的机理。     

High-temperature and photochemical syntheses of C60 and C70 fullerene derivatives with linear perfluoroalkyl chains

New experimental results on perfluoroalkylation of C₆₀ and C₇₀ with the use of R_fI (R_f = CF₃, C₂F₅, n-C₃F₇, n-C₄F₉, and n-C₆F₁₃), along with a critical overview of the existing synthetic methods, are presented. For the selected new fullerene (R_f)_n compounds we report spectroscopic, electrochemical and structural data, including improved crystallographic data for the isomers of C₇₀(C₂F₅)₁₀ and C₆₀(C₂F₅)₁₀, and the first X-ray structural data for the dodecasubstituted perfluoethylated C₇₀ fullerene, C₇₀(C₂F₅)₁₂, which possesses unprecedented addition pattern.     

双亲性C60衍生物水相聚集行为

富勒烯C₆₀几乎不溶于水中,从而阻碍了对富勒烯的进一步研究和潜在应用。双亲性C₆₀衍生物在水相中自组装形成聚集体,在水相具有一定的溶解度,其特殊的结构及性能引起了科学家的广泛关注。本文对双亲性C₆₀衍生物在水相中聚集行为的研究现状及研究进展进行了详细系统的介绍。本文第一部分主要阐述了双亲性C₆₀衍生物的结构,根据修饰到C₆₀表面的功能基类型对双亲性C₆₀衍生物进行了分类。第二部分主要阐述了双亲性C₆₀衍生物在水相的聚集行为以及pH值、溶剂极性、浓度、温度和抗衡离子等因素对聚集行为的影响。     

Stability of functionalized C60 paramagnetic dimers and monomers

Density functional theory is used to calculate the bond dissociation energy to cleave the C₆₀C₆₀ bond of the paramagnetic X-C₆₀C₆₀-X and X-C₆₀C₆₀ dimers where X is F, OH, O and H. The results show that these dimers would not be stable much above room temperature and therefore cannot constitute the paramagnetic phase needed to form the observed ferromagnetism which has been shown to be stable up to 800 K. The calculated bond dissociation energies to remove an F, OH or H from a single C₆₀ are large suggesting that they could be the source of the unpaired spin needed for the high temperature ferromagnetism.     

C60的加成反应

富勒烯化学是以全碳分子球烯为母体的新兴有机化学领域, 在材料、医学及立体化学合成方法等方面具有广泛的应用和发展前景。本文综述了C₆₀的加成反应, 较全面地展示了富勒烯的化学性质。     

Synthesis of 4-aziridino[C60]fullerene-1,8-naphthalimide (C60-NI dyads) and their photophysical properties

A series of 4-aziridino[C₆₀]fullerene-1,8-naphthalimide (C₆₀-NI) dyads 4 ([6,6]-closed ring) were synthesized as the only addition product from the reaction of C₆₀ with the corresponding azide compounds 3 under microwave irradiation in good yield. A quenching of fluorescence was shown in dyads 4, and this decay was evidenced to be an intramolecular process.     

Reactions of fullerene C60 with organometallic azides

Reactions of fullerene C₆₀ with organometallic azides [Et₂AlN₃, EtAl(N₃)₂ and Bu₃SnN₃] led to novel 1-azido-2-alkylfullerenes. The structures of the products were confirmed by IR, ¹Н and ¹³C NMR spectroscopy and MALDI TOF mass spectrometry.     

Novel method of synthesis of C60F48 with improved yield and selectivity

A novel two-stage method of preparation of C₆₀F₄₈ with 96% purity and 80% yield is reported. A C₆₀ embedded into a MnF₂ matrix is reacted with molecular fluorine under dynamic conditions, i.e. in flow of fluorine gas and with sublimation of volatile products, which results in formation of C₆₀F₃₄-C₆₀F₃₈ mixtures with >90% yield. Subsequent fluorination of the mixture thus obtained in the closed reactor at elevated pressure directly leads to the final product. C₆₀F₄₈ thus synthesized has been characterized by means of EI-MS, MALDI-MS, IR-spectroscopy and X-ray photoelectron spectroscopy (XPS). The problems of fullerene burning and degradation in the fluorine atmosphere are discussed.     

Mechanochemical synthesis of a novel C60 dimer connected by a germanium bridge and a single bond

A novel C₆₀ dimer connected by a germanium bridge and a single bond was synthesized by the mechanochemical solid-state reaction using a high-speed vibration milling technique. The structural characterization was made by the ¹H and ¹³C NMR, APCI mass, and UV-vis spectroscopy, and the presence of the electronic interaction between the two C₆₀ cages was demonstrated by the electrochemical method.     

Photo-labeling of C60 with 3-trifluoromethyl-3-phenyldiazirine

The photochemical reaction of C₆₀ with 3-trifluoromethyl-3-phenyldiazirine affords a photo-labeled C₆₀ derivative. The derivative was characterized by mass, UV-vis absorption, NMR spectroscopy, and X-ray crystallographic analysis. The redox potentials of this derivative were also investigated by means of CV and DPV. This photo-labeling method to the fullerene surface is expected to be effective for constructing various kinds of bio-functionalized fullerenes.     

Isothermal and polythermal kinetics of depolymerization of C60 polymers

Isothermal depolymerization of the two polymers of C₆₀, i.e. of 1D orthorhombic phase (O) and of “dimer state” (DS) have been studied by means of Infra-red spectroscopy in the temperature ranges 383-423 and 453-503 K, respectively. Differential Scanning Calorimetry (DSC) has been used to obtained depolymerization polytherms for O-phase and DS. Standard set of reaction models have been applied to describe depolymerization behavior of O-phase and DS. The choice of the reaction models was based primarily on the isotherms. Several models however demonstrated almost equal goodness of fit and were statistically indistinguishable. In this case we looked for simpler/more realistic mechanistic model of the reaction. For DS the first-order expression (Mampel equation) with the activation energy E_a = 134 ± 7 kJ mol⁻¹ and preexponential factor ln(A/s⁻¹) = 30.6 ± 2.1, fitted the isothermal data. This activation energy was nearly the same as the activation energy of the solid-state reaction of dimerization of C₆₀ reported in the literature. This made the enthalpy of depolymerization close to zero in accord with the DSC data on depolymerization of DS. Mampel equation gave the best fit to the polythermal data with E_a = 153 kJ mol⁻¹ and preexponential factor ln(A/s⁻¹) = 35.8. For O-phase two reasonable reaction models, i.e. Mampel equation and “contracting spheres” model equally fitted to the isothermal data with E_a = 196 ± 2 and 194 ± 8 kJ mol⁻¹, respectively and ln(A/s⁻¹) = 39.1 ± 0.5 and 37.4 ± 0.2, respectively and to polythermal data with E_a = 163 and 170 kJ mol⁻¹, respectively and ln(A/s⁻¹) = 32.5 and 29.5, respectively.     

Investigation of fullerene C60 effect on properties of polymethylmethacrylate exposed to ionizing radiation

Effect of fullerene C₆₀ was investigated on thermal, mechanical and optical properties of polymethylmethacrylate (PMMA) under ionizing radiation. It was stated that fullerene C₆₀ behaves as an effective antirad with respect to PMMA. Fullerene C₆₀ addition raises temperature of destruction for polymer subjected to electron radiation by 20-25 °C, lowers the rate from 4 to 4.5 times and increases the activation barrier for radiated PMMA destruction reaction. Fullerene C₆₀ addition promotes improvement of strength properties of PMMA: for films containing C₆₀ addition and else subjected to electron radiation treatment a decrease in rupture strength is 10-15%, for samples containing no fullerene it equals ∼25%. Interaction of free radicals with fullerene at radiation treatment influences optical characteristics of PMMA films.     

C60 and carbon: a postbuckminsterfullerene perspective

The discovery of the fullerenes and nanotubes has completely changed our perspective on various aspects of carbon chemistry and materials science in quite fundamental ways. The experiments, which uncovered C₆₀, occurred between 1985 and 1990 and there are lessons to be learned of various kinds over the way scientific advances occur and more importantly the way misconceptions can propagate. For instance much of our received wisdom over the behaviour of carbon, in particular graphite on a microscopic scale, was really quite ill-conceived and certainly misleading. Questions might be asked as to why it took almost till the end of the 20th century for the fact to be uncovered that the elegant C₆₀ molecule had been lurking in the dark shadows of soot chemistry all the time. After all, mass spectrometric techniques were sufficiently advanced for the discovery to have been made in the 1960’s—perhaps even earlier. Some of these issues are addressed here and the discussion gives an insight into the curiously unpredictable way fundamental scientific advances sometimes occur and also highlights the limitations of applied research in this case.     

Base-promoted reaction of C60Cl6 with thioamides: an access to [60]fullereno[1,9-d] thiazoles

Regioselective reaction of C₆₀Cl₆ with thioamides via a radical annulation to form fullereno thiazole derivatives is reported. The reaction is promoted by K₂CO₃, which might deprotonate thioamide to initiate a single electron transfer from thioamide anion to C₆₀Cl₆. The experiments with various thioamides establish the proposed base-promoted reaction as a facile route for synthesis of fullereno fused thiazole derivatives starting from C₆₀Cl₆, a prevalent synthon in fullerene chemistry. In addition, the tunable electrochemical properties of the fullereno thiazole products have been investigated for their potential photovoltaic application.     

Electronic structure of the complexes of fullerene C60 with polyaromatic molecules

Electronic structure of the complexes of fullerene C₆₀ with triphenylene (TP) and 9,10-diphenylantracene (DPA) has been studied by an X-ray fluorescent spectroscopy. The C Kα spectrum of a complex was shown to be almost an additive sum of the C Kα spectra measured for fullerene and organic ligand. The quantum-chemical calculation of a DPA·C₆₀ structural unit using density functional theory (DFT) revealed a slight charge transfer from DPA molecule to the C₆₀ cage. The intermolecular interaction in the complex was found to proceed through quit energy deep molecular orbitals.     

Redox-induced hydrogen transfer from hydrofullerene C60H36 to fullerene C60

The possibility of hydrogen transfer from hydrofullerene C₆₀H₃₆ to electrogenerated radical anion C₆₀ ^.− or dianion C₆₀ ²⁻ in propylene carbonate-toluence (3∶2, v/v) was demonstrated by cyclic voltammetry. The process affords C₆₀H₂ as the product. The reaction found is the typical redox-induced process. Translated fromIzvestiya Akodemii Nauk. Seriya Khimicheskaya, No. 6, pp. 1136–1139, June, 1998.     

An all-solid-state polymeric membrane Pb-selective electrode with bimodal pore C60 as solid contact

An all-solid-state polymeric membrane Pb²⁺ ion-selective electrode (Pb²⁺-ISE) based on bimodal pore C₆₀ (BP-C₆₀) as solid contact has been developed. A BP-C₆₀ film can be readily formed on the surface of a glassy carbon electrode by electrochemical deposition. Cyclic voltammetry and electrochemical impedance spectroscopy have been employed to characterize the BP-C₆₀ film. The large double layer capacitance and fast charge-transfer capability make BP-C₆₀ favorable to be used as solid contact for developing all-solid-state ISEs. The all-solid-state BP-C₆₀-based Pb²⁺-ISE shows a Nernstian response in the range from 1.0 × 10⁻⁹ to 1.0 × 10⁻³ M with a detection limit of 5.0 × 10⁻¹⁰ M. The membrane electrode not only displays an excellent potential stability with the absence of a water layer between the ion-selective membrane and the underlying BP-C₆₀ solid contact, but also is insensitive to interferences from O₂, CO₂ and light. The proposed solid-contact Pb²⁺-ISE has been applied to determine Pb²⁺ in real water samples and the results agree well with those obtained by anodic stripping voltammetry.     

Synthesis and photovoltaic properties of novel C60 bisadducts based on benzo[2,1,3]-thiadiazole

A novel C₆₀ solar cell acceptor (BTOQC, benzo[2,1,3]-thiadiazole-o-quinodimethane-C₆₀ bisadducts) based on benzo[2,1,3]thiadiazole has been synthesized as model to study how the thiadiazole group will affect the device performance in bulk heterojunction organic photovoltaics (BHJ-OPV) with poly(3-hexylthiophene) (P3HT) as donor. The optoelectronic, electrochemistry, and photovoltaic properties of the novel bisadduct BTOQC have been fully investigated. The best device performance of this fullerene derivative in our research was obtained as 2.50% with a high V_oc of 0.74 V.