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Journal of Thermal Analysis and Calorimetry
Authors: Natalia Avramenko, M. Korobov, Aksana Parfenova, P. Dorozhko, Natalia Kiseleva, and P. Dolgov

Abstract  

In an effort to improve understanding of dissolution behaviour of fullerenes and their simple chemical derivatives the binary systems of C60, C70 and the piperazine monoadduct of [60] fullerene C60 N2C4H8 with a series of aromatic solvents have been studied by means of DSC. In certain systems solid solvates have been found to be the thermodynamically stable phases relative to saturated solution at room temperature. Identified solid solvates were characterized by their compositions, temperatures and enthalpies of incongruent melting transitions. The regularities in thermodynamic stability of the solvated crystals have been discussed along with dissolution properties of fullerenes and the derivative. Certain correlations have been observed.

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Abstract  

The positron density distributions in C60 and K6C60 have been evaluated using the positron lifetime and Doppler-broadening spectroscopy for the annihilation radiation.In C60, positrons are distributed in the interstitial sites between the C60 molecules,which has been demonstrated by measurements of the temperature dependence of the Doppler-broadening of the annihilation radiation. On the other hand, the positron density distribution must be greatly changed in K6C60, because positrons are repelled by Coulomb interactions by the positively charged K atoms. It has been observed that there is an extremely short lifetime and a small Doppler-broadening component for the positron annihilation in K6C60. This component is considered to reflect the positron annihilation inside a C60 molecule.

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Abstract  

In this paper water-soluble fullerene derivative C60(OH)xOy was radioiodinated with the iodogen method. The labeling yield was determined by radio-TLC. The effects of pH value, reaction time, temperature and amount of the iodogen on the labeling yield were studied. The labeled product was purified by Sephadex G-25 column chromatography and then the stability of 125I-C60(OH)xOy was examined . The results showed that the radiochemical purity of 125I-C60(OH)xOy solution with benzylalcohol remained 82.7% after 43 hours.

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Journal of Thermal Analysis and Calorimetry
Authors: E. Kowalska, P. Byszewski, R. Diduszko, A. Huczko, and J. Mieczkowski

Abstract  

The crystalline solvates containing fullerenes and (di)methylnaphthalenes were investigated by thermal analyses and X-ray diffraction methods. It was found that C60 with (di)methylnaphthalenes forms two types of stable solvates: either at the molar ratio 1:2 decomposing at temperatures close to 100C or at 1:1 molar ratio decomposing in the temperature range 120–214C. Crystalline lattice and thermal stability of the solvates depends on the structure of the solvent molecules. The strong solute-solvent interaction is also manifested by the modification of the C60 absorption spectra in solution. The results are discussed using semiempirical quantum chemistry methods.

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Journal of Thermal Analysis and Calorimetry
Authors: A. V. Markin, V. A. Ruchenin, N. N. Smirnova, G. V. Markin, S. Yu. Ketkov, V. A. Kuropatov, V. K. Cherkasov, G. A. Abakumov, and G. A. Domrachev

Introduction The discovery of the method for producing C 60 fullerenes in macroquantities [ 1 ] has laid a new field of research. Thus, different properties of functional fullerene derivatives with valuable characteristics

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Abstract  

Iron in the fullerite lattice binds fullerences in a sandwich type C60FeC60 complexes. At the concentration C60Fe2 it crystallizes in the monoclinic lattice. The structure is thermally unstable, with the energy release of 606 kJ·mol−1 it returns to fee lattice. Two possible sites in the reconstructed fee lattice are discussed, Fe bond to C60 and Fe inside the C60 cage.

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Abstract  

Compositions of the solid solvates of C60 with 1,2-dichlorobenzene and 1,3,5-trimethylbenzene were determined with the help of experimental procedures developed. Possible correlations between compositions and thermodynamic properties were discussed.

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Abstract  

Iron: fullerides were prepared by chemical methodes in the solution using nitric acid as activation agent. Experimental results of thermal analyses, X-ray diffraction and Mössbauer spectroscopy of the products are presented. To interpret these results, standard quantum chemistry calculations were used to determine the geometry and charge distribution in Fe:C60 complexes, which might be formed in the reaction.

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Summary  

The binary systems of C60with α-methyl- and α-chloronaphthalene have been studied by means of differential scanning calorimetry. C60was found to form the molecular complex of the van der Waals type with α-methylnaphthalene which melts incongruently below the boiling point of the solvent at temperature 382.73.0 K. The enthalpy of the desolvation reaction is 14.10.5 kJ mol-1of C60. The molar ratio of fullerene to solvent in the solvate is 1:1.5. In the system C60-α-chloronaphthalene a two-stage incongruent melting process has been observed at temperatures 314.14.6 K and 375.77.4 K with the enthalpies 8.12.6 kJ mol-1and 11.61.0 kJ mol-1, respectively. The composition of the most solvated phase equilibrated with the saturated solution at room temperature and below the first of the incongruent melting transitions was determined as 1:1.5. Based on the results obtained the thermodynamic characteristics of the incongruent melting reactions have been revealed and influence of solvate formation on solubility of C60has been discussed.

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Abstract  

Molecules that may adopt various stable conformations might be applied to store information. The conformational changes could be induced by suitable polarized tip of STM. For the STM experiments two types of fullerene:ferrocene cycloadducts (C60:Fn) were selected where ferrocene fragment is bound to C60 at the 6-6 bond by different heterocyclic pentagon rings. According to semiempirical quantum chemistry calculation one of them may be used to STM observation without any modification, while the second cycloadduct must be exposed to thermal treatment in order to obtain bistable molecule.

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