Isobaric heat capacity and standard thermodynamic properties of NaLaTiO4 and Na2La2Ti3O10 over the range of (7–670) K

Journal of Thermal Analysis and Calorimetry - The heat capacities of layered perovskite-like oxides NaLaTiO4 and Na2La2Ti3O10 were measured by precision adiabatic vacuum calorimetry over the...     

Thermodynamic properties of carbosilane dendrimers of the seventh and ninth generations with terminal butyl groups in the temperature range from <Emphasis Type="Italic">T</Emphasis> → 0 to 600 K

Temperature dependences of the heat capacity of carbosilane dendrimers with butyl terminal groups of the seventh and ninth generations were determined in the temperature range from 6 to 600 K by precision adiabatic vacuum calorimetry and differential scanning (dynamic) calorimetry. The physical transitions were revealed and their thermodynamic characteristics were analyzed. The experimental data obtained were used to calculate the standard thermodynamic functions C _p (T), H°(T) − H°(0), S°(T), and G°(T) − H°(0) for the temperature range from T → 0 to 600 K. The thermodynamic function-molar weight isotherms for the dendrimers of the third–ninth generations with terminal butyl groups in the glassy and highly elastic state are linear. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1924–1928, October, 2007.     

Structure of nonpolarizable water/nitrobenzene interface: potential distribution, ion adsorption, and interfacial tension

Adsorption of hydrophobic and hydrophilic ions at the nonpolarizable interface between two immiscible electrolyte solutions was investigated. The results were analyzed in three different models: (i) Gouy-Chapman model, (ii) ions as hard spheres, and (iii) ion pair formation at the interface. In the Gouy-Chapman model, an analytical expression for the interfacial tension was obtained. It predicts that interfacial tension should be proportional to the square root of the electrolyte concentration, which does not agree with experimental data. Modeling ions as hard spheres only slightly improves the agreement. The third model of interfacial ion pairing as the main origin of adsorption was analyzed using the amphiphilic isotherm (Markin-Volkov isotherm). A good agreement between ion-pairing theory and experimental values was achieved. The MV isotherm takes into account the limited number of adsorption sites, final size of molecules, complex formation at the interface, and interaction between adsorbed particles. The analysis revealed repulsion between adsorbed tetraalkylammonium ions at the nitrobenzene/water interface and demonstrated linear dependence between adsorption site area and the size of a molecule.     

Formation,properties, and thermal decomposition of bisarene chromium(i) and molybdenum(i) fullerides

Fullerides [(⁶-Ph₂)₂Cr]⁺[C₆₀]^·–, [(⁶-C₁₀H₁₂)₂Cr]⁺[C₆₀]^·– (C₁₀H₁₂ is tetralin), and [(⁶-PhCH₃)₂Mo]⁺[C₆₀]^·– were synthesized. The molecular structure of [(⁶-Ph₂)₂Cr]⁺[C₆₀]^·– was established. In this compound at 100 K, radical anions C₆₀ ^–· are linked by an ordinary bond to form dimers, whereas at 293 K they are disordered and do not form dimers. The [(⁶-tetralin)₂Cr]⁺[C₆₀]^·– fulleride is stable in vacuo (10^–2 Torr) below 429 K, and [(⁶-toluene)₂Mo]⁺[C₆₀]^·– is stable below 581 K.Based on the materials presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry (Moscow, May 30–June 4, 2004) dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1973–1976, September, 2004.