Dependence of the dimension of the associates of water-soluble tris-malonate of light fullerene -C 60 [= C(COOH) 2 ] 3 in water solutions at 25 • C Investigation of the concentration dependence of the size and type C 60 [=C(COOH) 2 ] 3 aggregation in aqueous solutions at 25 • C was accomplished with the help of a dynamic light scattering method. It was determined that three types of aggregates are realized in the solutions. The average number of C 60 [=C(COOH) 2 ] 3 molecules in smaller aggregates and all types of aggregates were calculated. One can see that over the whole concentration range, from 0.01 to 10 g/dm 3 , aqueous solutions of C 60 [=C(COOH) 2 ] 3 are characterized by sub-micro-heterogeneous behavior (because second-type aggregates with the linear dimensions -hundreds of nm are formed in all solutions). Additionally, the most concentrated solution (C = 10 g/dm 3 ) is characterized by micro-heterogeneous or colloid behavior (because third-type aggregates with the linear dimensions on the order of µm -are formed). In order to describe or explain such behavior, a stepwise aggregation model was invoked.Keywords: tris-malonate of light fullerene, method of the dynamic light scattering.

Cryometry investigations of the C 60 (OH) 24±2 -H 2 O and C 70 [=C(COOH) 2 ] 3 -H 2 O binary systems were conducted over the 0.1 -10 g concentration range of fullerenols per 1 dm 3 of solutions. The decreases of the temperatures at the onset of H 2 O -ice crystallization were determined. Excess functions of aqueous solutions -water and fullerenols (trismalonates) activities and activity coefficients and excess Gibbs energy of the solutions were calculated. All solutions demonstrated huge deviations from those of ideal solutions. The last fact, to our opinion, is caused by a very specific -hierarchical type of association of fullerenols (trismalonates) solution components, which was proved by the results of visible light scattering analysis.

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Fullerenol-d C 60 (OH) 22−24 was synthesized by the method of direct heterogeneous oxidation of fullerene C 60 , dissolved in o-xylene, by NaOH, dissolved in water, in the presence of interphase catalyst t − (C 4 H 9) 4 N OH. Identification of fullerenol-d was provided by: C-H-N elemental analysis, High performance liquid phase chromatography, IR-and Electronic spectroscopy, Mass-spectrometry. The antioxidant properties of aqueous fullerenol-d solutions were investigated against free radicals, generated by hydrogen peroxide and molecular I 2. Measurement of fullerenol antioxidant activity was based on the potentiometric titration of fullerenol solutions by hydrogen peroxide and molecular I 2 solutions and vice versa with compact Pt as working electrode. As a comparison, the very popular and strong anti-oxidant-ascorbic acid was used. Pourbaix Diagrams (pH − Eh) for hydrogen-oxygen and iodine forms were constructed. Fullerenol-d is a weaker antioxidant than ascorbic acid, but in contrast, fullerenols-d molecules are able to undergo multiply reversible absorption-desorption of some free radicals.

The article continues the development of the investigations, presented in particular in the cycle of articles, devoted to the synthesis, identification and investigation of physical-chemical properties of water soluble derivatives of light fullerene C 60 , such as: complex esters of dicarboxylic acids (malonates, oxalates); poly-hydroxylated forms (fullerenols); amino-acid derivatives (argenine, alanine). The investigation of the excess thermodynamic functions, to the best of our knowledge, has, until now, not been provided, except for two original works [Matuzenko M.Yu., Tyurin D.P., et al. (2015); Matuzenko M.Yu., Shestopalova A. A., et al. (2015)].