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VOLUME PROPERTIES OF WATER SOLUTIONS AND REFRACTION AT 25 C WATER-SOLUBLE TRIS-MALONATE OF LIGHT FULLERENE -
Ceo [= C(COOH)2]3
K.N. Semenov1, N. A. Charykov2,3, A. S. Kritchenkov1, I.A. Cherepkova2, O. S. Manyakina2, D.P. Tyurin2, A.A. Shestopalova2, V.A. Keskinov2, K.V. Ivanova2, N.M. Ivanova1, D.G. Letenko4, V.A. Nikitin5, E.L. Fokina1, O.V. Rakhimova3
1St. Petersburg State University, Saint-Petersburg, Russia 2St. Petersburg State Technological Institute (Technical University), Saint-Petersburg, Russia 3St. Petersburg State Electro-Technical University (LETI), Saint-Petersburg, Russia 4St. Petersburg State University Architecture Academy, Saint-Petersburg, Russia 5St. Petersburg State Technical University, Saint-Petersburg, Russia
keskinov@mail.ru
PACS 61.48.+C
The volume Properties of water soluble tris-malonate of light fullerene — C6o[=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 C60[=C(COOH)2]3 and H2O. Concentration dependence of the refraction index in water solutions of C60[=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.
Keywords: tris-malonate of light fullerene, volume properties, refraction.
Received: 19 February 2014 Revised: 14 March 2014
1. Introduction
This article further develops the investigations, which were initiated by the article [1], devoted to the description of the synthesis and identification of tris-malonate C6o[=C(COOH)2]3 (the original synthesis of this water soluble derivative was described earlier in [2]).
2. Concentration dependence of density of water solutions of tris-malonate of light fullerene - C6o[=C(COOH)2]3
The concentration dependence for the density of aqueous solutions of the tris-malonate C60[=C(COOH)2]3 at 25 °C was investigated by the method of pycnometry with the help of quartz pycnometers (Volume nearly V & 2.5 cm3), accuracy of thermostat was AT = ± 0.05
grad. Data, concerning the densities of the solutions are represented lower in the Table 1 and in Fig. 1.
Aqueous solutions of the tris-malonate C60[=C(COOH)2]3 were prepared by the following method; first, a basic solution (Ctris-malonate = 336 g/dm3) was prepared by the direct dissolution of previously-synthesized C60[=C(COOH)2]3 in the distilled water, double filtration of the solution through a 'blue' paper filter; the concentration of the solution was determined
Fig. 1. Concentration dependence of density of water solutions of tris-malonate
C6o[= C(COOH)2]3 at 25 °C
Table 1. Concentration dependence of Volume Properties of water solutions of tris-malonate C6o[= C(COOH)2]3
N of solution Concentration C (g/dm3) Density P (g/cm3) Average molar volume of solution 1/ (cm3/mole) Partial molar volume of H2O VH2O (cm3/mole) Partial molar volume of tris-malonate ^tris-malonate (cm3/mole)
1 0 0.994 18.000 18.00 1021.00
2 10.5 1.000 18.187 18.00 1021.00
3 21.0 1.008 18.382 18.00 1021.00
4 42.0 1.022 18.792 18.00 1021.00
5 84.0 1.057 19.720 18.00 1021.00
6 168 1.112 22.045 18.00 1021.00
7 224 1.142 24.041 17.99 1020.99
8 336 1.190 29.643 17.99 1020.99
gravimetrically by soft drying in a vacuum dry box at 65 °C and residual pressure « 0.1 mm Hg for 2 hours. More dilute solutions were prepared from the basic one by the direct dilution of the determined mass of the basic solution by water to the calculated volume at T = 25 ± 0.05 °C.
3. Average and partial molar volumes
Average molar volume of solution can be calculated as [3,4]:
V = V/(nH2O + Utris-malonate) , (1)
Fig. 2.1. Concentration dependence of the function V
Fig. 2.2. Concentration dependence of the function (dV/dxj)T,P
where: V — volume of 1 dm3 of the solution, ni — moles of i-th component in 1 dm3 of the solution are also represented in the Table 1 and in Fig. 2.1.
Partial molar volume of the components of the solution: Vh2o and Vtris-maianate according to the connection between average molar and partial molar functions [3,4]:
V = (dV/dni)T,p,nj = V - xj (dV/dxj)t,p,
(2)
where: xi — mole fraction of i-th component in the solution are also represented in the Table 1 (concentration dependence of the function (dV/dxj)T,P is represented in Fig. 2.2). From the obtained volume data, one can see the following:
1. the dependence V(xtris-maianate) is practically linear,
2. so, the derivative is insignificant (dV/dxtris-malonate)T,P ~ 0,
3. so, partial molar volumes of both components are practically constant: VHOH ~ 18.0, Vtris-malonate ~ 1021 cm3/mole, i.e. both components are built in the structure of the solution without any visible complicating interactions. We will try to explain the reasons for such anomalous behavior below.
Fig. 3.1. Refraction indexes of queous tris-malonate C6o[ tions at 25 °C
C(COOH)2]3 solu-
4. Refraction of the solution
Concentration dependence of the refraction index (nD) in aqueous solutions of C60[=C(COOH)2]3 was also determined with the help of a Mettler Toledo refractometer. Data is presented in Table 2 and Fig. 3.1. The specific refraction of aqueous solutions of C60[=C(COOH)2]3 was calculated according to the well-known formula:
r = (nD - 1/nD + 2) (1/P)
(3)
and is represented in Fig. 3.2.
According to the specific refraction additivity rule:
r r tris-malonate ' wtris-malonate + THOU (1 - Wtris-malonate) ,
(4)
where ri, wi — specific refraction of i-th component of the solution, we also calculated specific refraction of components — tris-malonate and H2O (see Table 2 and Fig.3.3).
We also calculated molar refraction of C60[=C(COOH)2]3 aqueous solutions according to the formula:
Fig. 3.2. Specific refraction of queous tris-malonate C60[= C(COOH)2]3 solutions at 25 °C
Fig. 3.3. Specific refraction of tris-malonate C60[= C (COOH )2]3 and water (for the comparison) in aqueous solutions at 25 °C
R =(nD - + 2)(M/p)
nD +
(5)
where M — average molar mass of the components of the solution (M = Mtris-maionate • xtris-malonate + Mh2o(1 - Xtris-malonate), Mi — mass of tris-malonate C60 (1026 a.un.) and H2O (18 a.u.), x,i — molar fraction of i-th component. Data are represented in the Fig. 4.1 and Table 2.
Table 2. Concentration dependence of refraction indexes of aqueous tris-malonate C60[= C(COOH)2]3 solutions and specific and molar refraction of the components at 25 °C
N of solution Refraction index nD (rel. un.) Specific refraction of the solution r (cm3 /g) Specific refraction of tris-malonate r tris-malonate (cm3/g) Molar refraction of the solution R (cm3/mole) Molar refraction of tris-malonate Rtris-malonate (cm3/mole)
1 1.333 0.2069 - 3.7260 -
2 1.335 0.2068 0.1954 3.7625 200.50
3 1.338 0.2068 0.2022 3.8004 207.59
4 1.342 0.2062 0.1887 3.8803 194.47
5 1.352 0.2046 0.1777 4.0611 185.52
6 1.371 0.2039 0.1868 4.5141 195.61
7 1.383 0.2043 0.1932 4.9027 201.57
8 1.409 0.2077 0.2098 5.9939 214.42
0,0 OD 0,002 0,004 Q,Q06 0,Q08 0,010 0,012 Mole fraction of С tris-malonate - x (rel.un.)
Fig. 4.1. Molar refraction of queous tris-malonate C60[= C(COOH)2]3 solutions at 25 °C 3
According to the obvious parity, connecting specific and molar (Ri) refractions of the components:
Ri = и • Mi, (6)
we also calculated last ones (see Table 2 and Fig. 4.2).
From obtained refractione data one can see the following:
1. The dependence nD (C) is nearly linear;
250
o tí
200 -
150 -
100 -
50 -
0.00
0,05 0,10 0,15 0,20 0,25
Mass fraction of trismalonate c (rel.nn.)
0,30
cQo o
^ o D
Fig. 4.2. Molar refraction of tris-malonate in aqueous solutions at 25 °C
2. Specific refraction of the solution practically is independent of the concentration (r ~ 0.205 ± 0.002 cm3/g);
3. Specific refractions for both components of the solution are also practically independent of the concentration and absolutely unexpectedly are very similar:
rtris-malonate ~ 0.195 ± 0.1 « rn2o « 0.206 ± 0.1 cm3/g; (7)
4. The concentration dependence of molar refraction of water solutions of tris-malonate at 25 °C R(xtris-maionate) is also nearly linear;
5. Molar refraction of tris-malonate Rtris-malonate is practically independent of the concentration:
Rtris-maionate ~ 201 ± 7 cm3/mole; (8)
6. That in essence the casual fact for the specific refractions'similarity of both components (at a huge difference of the molecular dimensions) determines such simple concentration behavior for the refraction characteristics. Specific refraction is accepted to be associated with the volume of electronic orbits falling on the mass unit of the phase, and in the case of our solutions, the casual equality of these components'characteristics allows to them form the mixed solution in such a way that the intermolecular forces are compensatory.
7. We also check ourselves, by calculating molar refraction of tris-malonate C60 by the additivity rule (Radd):
Radd « 69 Rc + 6RO(-oH) + 6RO(=C=O) + 6RH « 195.3 - 200.3 cm3/mole, (9)
where: Rj — atomic refraction of i-th atom in j-th functional group. Some discrepancy in the calculation connected with the choice of the different spectral lines: for the line
Ha[A = 658.3(nm)] - Radd « 195.3 cm3/mole; and for the line HY[A = 436.1(nm)] -Radd ^ 200.3 cm3/mole (data, according to Eizenlor).
Alternative calculation (according to Fogel [5]) gives the following result:
Radd « 63Rc + 6R_cooh ~ 205.2 cm3/mole, (10)
where R_COOH is the refraction of carboxylic group. In the both cases, the result of the calculation is considered more or less successful and confirms the experimental data.
5. Conclusion
Thus, the partial and average molar volume and refractive properties of aqueous solutions of the water soluble light fullerene derivative- C6o[=C(COOH)2]3, at 25 °C were investigated.
Acknowledgement
Research was performed with using the equipment of the Resource Center 'GeoModel' of Saint-Petersburg State University.
This work has been accomplished as the part of the Ministry of Education and Science of the placecountry-regionRussian Federation research assignment 'Realization of scientific research (fundamental studies, applied research and advanced developments)'. Project code: 2548.
References
[1] K.N.Semenov, N.A.Charykov, A.S.Kritchenkov, et al. Synthesis and identification water-soluble tris-malonate of light fullerene - C6o[=C(COOH)2]3. Nanosystems: Physics, Chemistry, Mathematics, 5 (2), P. 315-319 (2014).
[2] I.Lamparth, A.Hirsch. Water-soluble malonic acid derivatives of C60 with a defined three-dimensional structure. J. Chem. Soc Chem. Commun., P. 1727-1728 (1994).
[3] A.V.Storonkin. Thermodynamics of Heterogeneous Systems. Rus. Leningrad: LGU, Book 1, Part 1, 2. 467 pp. (1967).
[4] A.Muenster. Chemical thermodynamics. Rus. Transl. from Engl. Moscow: Mir (1971).
[5] Atomic refractions according to Fogel. Directory of Chemist/ red. B.P. Nikol'skiy. Rus. Leningrad: Chemistry, 1, 395 pp. (1982).
