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Cryometry investigation of C 60(C 6H 12NaN 4O 2) H 2O solutions was made over concentrations ranging from 0.1 10 g of fullerene-arginine adduct per 1 dm 3. Freezing point depression was measured for these aqueous solutions. Excess functions for water and fullerene-arginine adduct activities, activity coefficients and excess Gibbs energy of the solutions were calculated. All solutions demonstrate huge deviations from ideality. The last fact, to our opinion, is caused by the very specific hierarchical type of association of fullerene-arginine adducts in aqueous solution components, which is proved by the results of our visible light scattering analysis.

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.

The polythermal solubility of the trismalonate C 60 [= C(COOH) 2] 3 H 2O binary system was investigated from 20 80 °C with the help of the method of isotherm saturation in ampoules. Concentration of tris-malonate C 60 [= C(COOH) 2] 3 in solutions was determined by light absorption at 330 nm. A diagram of the solubility is non-monotonic, consisting of 2 branches, which correspond to 2 different crystal-hydrates of C 60 [= C(COOH) 2] 3 and one non-variant point, corresponding to the saturation both crystal-hydrates. Complex thermal analysis of C 60 [= C(COOH) 2] 3 crystal hydrates, in equilibrium with a saturated aqueous solution at room temperature, was performed from 20 600 °C. Consecutive effects of the losses of C=O and C=O + H 2O were determined.

The volume Properties of water soluble trismalonate of light fullerene C 60 [= C(COOH) 2] 3 were investigated with the help of quartz pycnometers at 25 °C, including the concentration dependence of density, average molar volume of the solutions and partial molar volumes of C 60 [= C(COOH) 2] 3 and H 2O. Concentration dependence of the refraction index in water solutions of C 60 [= C(COOH) 2] 3 was also determined with the help of refractometer, specific and molar refraction of the components were calculated with the help of the rules of the additive refraction of solution components.

Studies of the concentration dependence of electric conductivity and pH for aqueous solutions of the light fullerene -C 60 [= C(COOH) 2] 3 trismalonate were performed at 25 °C. From both data (from the equivalent electric conductivity and pH), the apparent degree of dissociation and concentration dissociation constants of C 60 [= C(COOH) 2] 3 in aqueous solutions were calculated. Thermodynamic dissociation constants of C 60 [= C(COOH) 2] 3 in aqueous solutions, calculated for infinitely dilute solutions by the both methods, were reasonably similar.

The water soluble trismalonate adduct of light fullerene C 60 [= C(COOH) 2] 3 was produced in laboratory quantities. The product was identified by several analytical methods: elementary H-C-O-N analysis, IR-, Electronic, NMRSpectroscopy, Mass Spectrometry.