Thermodynamic Model for the Solubility of NdF3(cr) in the Na+–NH 4 + –Nd3+–F−–H2O System at 25 °C

The major objective of this study, based on critical review and experimental studies, was to develop a reliable thermodynamic model for the Nd–F system at 25 °C. The SIT model was used to convert concentration constants reported in the literature to constants at zero ionic strengths for cross comparison and selection of reliable values. The critically evaluated thermodynamic constants for the formation of NdF²⁺ and NdF ₂ ⁺ were then used to interpret the extensive NdF₃(cr) solubility data in NaF and NH₄F solutions, ranging in concentrations from extremely low values to as high as 1.0 mol·kg^?1, equilibrated for different periods ranging up to as long as 72 days. These efforts have resulted in $ \log_{10} \beta_{n}^{0} $ log 10 β n 0 for the reaction [Nd³⁺ + nF^? ? NdF _n ^3?n ] of (3.81 ± 0.10), (5.89 ± 0.77), and <12.48 for n values of 1–3, respectively. The $ \log_{10} K_{\text{sp}}^{0} $ log 10 K sp 0 for the solubility of NdF₃(cr) (NdF₃(cr) ? Nd³⁺ + 3F^?) was determined to be (?20.49 ± 0.37). Because (1) Nd is an excellent analog for trivalent actinides—An(III) (i.e., Pu(III), Am(III), and Cm(III)), and (2) the available data for the An(III)–F system, especially the solubility products of AnF₃(cr), are of extremely poor quality, the critical literature review in combination with the experimental Nd–F system data have been used to assign thermodynamic constants for the An(III)–F reactions until good quality specific data for them becomes available.     

Solubility of Thiophene-, Furan- and Pyrrole-2-Carboxaldehyde Phenylhydrazone Derivatives in 2.82 mol⋅L−1 Aqueous DMSO at 298.15 K, Inhibition of Lymphoproliferation and Tubulin Polymerization: A Study Based on the Scaled Particle Theory

In this work, the solubilities of nine phenylhydrazone derivatives in water and in 2.82 mol?L^?1 aqueous DMSO at 298.15 K, expressed on the molar fraction scale, are reported. The estimated value of the standard Gibbs energy for transferring the solute from water to 2.82 mol?L^?1 DMSO, $\Delta G^{0}_{\mathrm{W}\rightarrow \mathrm{mix}}$ , for each system, indicates that it is a spontaneous process. Some of the phenylhydrazone derivatives inhibited the induction of T lymphocyte proliferation by phytohaemagglutinin (PHA) but only DPCT and NPCF efficiently inhibited Guinea pig brain tubulin polymerization. Scaled Particle Theory (SPT) was used to interpretate solubility and biological activity results. Based on the results we suggested that the difference in the work of cavity creation ΔΔG _c, associated with the transfer of the phenylhydrazone derivatives from water to 2.82 mol?L^?1 aqueous DMSO, is the dominant factor in the magnitude of $\Delta G^{0}_{\mathrm{W}\rightarrow \mathrm{mix}}$ . The later quantity was considered to be an indirect measurement of the hydrophobic character of these derivatives, and it can be used to interpret the biological results.     

Speciation of the Ternary Complexes of Vanadium(III)–Dipicolinic Acid and the Amino Acids Cysteine,Histidine, Aspartic and Glutamic Acids in 3.0 mol⋅dm<Superscript>−3</Superscript> KCl at 25 °C

In this work we present results for the speciation of the ternary complexes formed in the aqueous vanadium(III)–dipicolinic acid and the amino acids cysteine (H₂cys), histidine (Hhis), aspartic acid (H₂asp) and glutamic acid (H₂glu) systems (25 °C; 3.0 mol⋅dm⁻³ KCl as ionic medium), determined by means of potentiometric measurements. The potentiometric data were analyzed with the least-squares program LETAGROP, taking into account the hydrolysis of vanadium(III), the acid-base reactions of the ligands, and the binary complexes formed. Under the experimental conditions (vanadium(III) concentration = 2–3 mmol⋅dm⁻³ and vanadium(III): dipicolinic acid: amino acid molar ratio 1:1:1, 1:1:2 and 1:2:1), the following species [V(dipic)(H₂asp)]⁺, [V(dipic)(Hasp)], [V(dipic)(asp)]⁻, [V(dipic)(asp)(OH)]²⁻, and [V(dipic)(asp)(OH)₂]³⁻ were found in the vanadium(III)–dipicolinic acid–aspartic acid system. In the vanadium(III)–dipicolinic acid–glutamic acid system [V(Hdipic)(H₂glu)]²⁺, [V(dipic)(H₂glu)]⁺, [V(dipic)(Hglu)], [V(dipic)(Hglu)(OH)]⁻, and [V(dipic)(Hglu)(OH)₂]²⁻ were observed. In the vanadium(III)–dipicolinic acid–cysteine system the complexes [V(dipic)(H₂cys)]⁺, [V(dipic)(Hcys)], [V(dipic)(cys)]⁻, and [V(dipic)(cys)(OH)]²⁻ were present. And finally, in the vanadium(III)–dipicolinic acid–histidine system the complexes [V(Hdipic)(Hhis)]²⁺, [V(dipic) (Hhis)]⁺[\mathrm{V}(\mathrm{dipic}) (\mathrm{Hhis})]^{+}, [V(dipic)(his)], [V(dipic)(his)(OH)]⁻, and [V(dipic)(his)(OH)₂]²⁻ were observed. The stability constants of these complexes were determined. The species distribution diagrams as a function of pH are briefly discussed.     

Aqueous Uranyl Complexes 1. Raman Spectroscopic Study of the Hydrolysis of Uranyl(VI) in Solutions of Trifluoromethanesulfonic Acid and/or Tetramethylammonium Hydroxide at 25°C and 0.1 MPa

Raman spectra have been used to identify and characterize aqueous hydroxouranyl(VI) complexes from 0.0038 to 0.647M at pH from 0.24 to 14.96 adjusted witheither HCF₃SO₃ and/or (CH₃)₄NOH under ambient conditions. In acidic media(0.24 pH 5.63), the existence of four species UO²⁺ ₂,(UO₂)₂(OH)³⁺,(UO₂)₂(OH)²⁺ ₂, and (UO₂)₃(OH)⁺ ₅ was confirmed. At high uranium concentrations(U 0.1M) and in strongly acidic solutions (pH 1.94), one additional weakband was observed at 883±1 cm^–1. This band was assumed torepresent thespecies UO²⁺ ₂ with a reduced hydration number.In neutral and basic solutions(5.63 pH 14.96), five complexes were postulated: (UO₂)₃(OH)^– ₇,(UO₂)₃(OH)^2– ₈,(UO₂)₃(OH)^4– ₁₀,(UO₂)₃(OH)^5– ₁₁, andUO₂(OH)^2– ₄, based on theassigned symmetrical stretching frequencies of the UO₂ group in each complex.(UO₂)₃(OH)^– ₇ is the dominant species over mostof the pH range (4.53–12.78).The stability ranges of the other trinuclear species are:(UO₂)₃(OH)^2– ₈ (10.97 pH 13.83), (UO₂)₃(OH)^4– ₁₀ (10.97 pH 13.85) and (UO₂)₃(OH)^5– ₁₁(12.53 pH 14.10), which were identified for the first time. Finally, the monomericuranate anion OU₂(OH)^2– ₄ dominates in highly basic solution (12.48 pH 14.96). The linear correlation between the symmetrical vibrational frequency v ₁of the linear O = U = O entity and the average number of hydroxide ligandscoordinated to each uranium atom in a given species has been reaffirmed andexpanded: The v ₁ correlation was also used to predict the vibration frequencies of theundetected monomers UO₂(OH)⁺, UO₂(OH)^o ₂,UO₂(OH)^– ₃ at 848±2, 826±2, and804±2 cm^±1, respectively. Characteristic band areas for eachuranyl hydrolyzedspecies were determined by Raman spectra decomposition and their hydrolysisquotients log Q, were calculated. Structures of the four triuranylspecies are proposed.     

Thermodynamic Properties of Peptide Solutions. Part 17. Partial Molar Volumes and Heat Capacities of the Tripeptides GlyAspGly and GlyGluGly,and Their Salts K[GlyAspGly] and Na[GlyGluGly] in Aqueous Solution at 25 °C

The partial molar volumes, V^o₂, and partial molar heat capacities, C_p,2^o, at infinite dilution have been determined for the two tripeptides glycylaspartylglycine (glyaspgly) and glycylglutamylglycine (glyglugly), and also for their salts K[glyaspgly] and Na[glyglugly], in aqueous solution at 25 °C. The ionization constants at 25 °C for the aspartyl and glutamyl side-chains have also been determined. These new thermodynamic results have been combined with literature data for electrolytes to obtain the volume and heat capacity changes upon ionization of the acidic side-chains of the peptides. The results are compared with those for other carboxylic acid systems. The partial molar heat capacities and volumes have also been used to calculate the contributions of the acidic amino acid side-chains to the thermodynamic properties.     

Complex Formation of Crown Ethers and Cations in Water–Organic Solvent Mixtures: Part XI. Effects of the Preferential Solvation of Benzo-15-Crown-5 and Acid-Base Properties of the Mixtures on the Thermodynamic Functions for Complex Formation of Benzo-15-Crown-5 with Na+ in Propan-1-ol–Water Mixtures at 298.15 K

The thermodynamic functions of complex formation of benzo-15-crown-5 ether (B15C5) and sodium cation (Na⁺) in the mixtures of propan-1-ol (PrOH) with water at 298.15 K have been calculated from experimental measurements. The equilibrium constants of B15C5/Na⁺ complex formation have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by a calorimetric method. The complexes are enthalpy stabilized but entropy destabilized in the PrOH–H₂O mixtures. The effects of preferential solvation of B15C5 by molecules of the organic solvent, solvation of the sodium cation, as well as the acid-base properties of propan-1-ol–water mixtures on the complex formation processes are discussed.     

Hydrolysis of Protactinium(V). II. Equilibrium Constants at 40 and 60°C: A Solvent Extraction Study with TTA in the Aqueous System Pa(V)/H2O/H+/Na+/ClO− 4

The hydrolysis of protactinium (V) was studied at tracer scale (ca. 10^–12 M) with the solvent extraction method involving the aqueous system: Pa(V)/H₂O/H⁺/Na⁺/ClO^– ₄ at 40 and 60°C for three values of ionic strength. Extraction experiments were conducted using the chelating agent thenoyltrifluoroacetone (TTA) in toluene. Hydrolysis constants are reported for each ionic strength investigated. An SIT modeling is presented and extrapolated constants to zero ionic strength are derived, as well as interaction coefficients involving Pa(V) and perchlorate ions.     

Batch Experiments for the Determination of the Ti(IV,III) Couple Formal Potential in 1 mol⋅dm<Superscript>−3</Superscript> HCl, 2 mol⋅dm<Superscript>−3</Superscript> NaCl Medium at 25 °C

The determination of the Ti(IV,III) redox couple formal potential in 1 mol⋅dm⁻³ HCl, 2 mol⋅dm⁻³ NaCl medium at 25 °C through batch experiments involving the preparation of Ti(IV) and Ti(III) mixtures via the reaction of Ti(IV) with zinc amalgam, has been carried out with Emf measurements in order to verify the correctness of the previous value that the authors obtained by a coulometric-potentiometric investigation in the same conditions. The results from the two independent methods are in good agreement: (9±1) mV by the first method and (9±2) mV by the average batch result.     

The Liquid Junction Potential in Potentiometric Titrations. XII. The Calculation of Potentials for Emf Cells with Liquid Junctions, of the Type, AY | AY + A2MoO4+HY, Involving the Formation of Iso-Polymolybdates in the Range ?log?10[H+]��7, at [A+]=C mol?L?1, Constant, and 25?��C

Equations are derived, in a general form, and valid in the range 0.5??C??3 mol?L^?1, for the calculation of the total potential anomalies (??E _H) for emf cells where the formation of iso-polymolybdates takes place, according to the equilibria: $$p \mathrm{H}^{+} (h) + q \mathrm{MoO}_{4}^{2 -} (b)\rightleftharpoons [(\mathrm{H}^{+})_{p}(\mathrm{MoO}_{4}^{2-})_{q} ] ^{p - 2q} (cpx _{pq})$$ by measuring [H⁺]=h, in NaClO₄ ionic medium (A⁺, Y^?) at [Na⁺]=3 mol?L^?1. The total cell emf (E _H), can be defined as: $$E_{\mathrm{H}} = E_{\mathrm{0H}} + g \log_{10} h + g\log_{10} f_{\mathrm{HTS}2} +E_{\mathrm{D}} + E_{\mathrm{D}f}$$ where: E _0H is an experimental constant, E _D+E _Df =E _J, the classical liquid junction potential, and glog?₁₀ f _JTS2+E _D+E _Df =??E _H. Here, $\mathrm{MoO}_{4}^{2 -}$ is the central ??metal ion??, E _D is the ideal diffusion potential (Hendersson equation), E _Df is the contribution of the activity coefficients to E _D. f _HTS2 denotes the activity coefficient of the H⁺ ions in the terminal solution TS2. The investigations of this system made by Sasaki and Sillén are critically analyzed. Some emf cells are supposed for the determination of the interaction coefficients involved. All calculations are valid at 25?°C. The revised equilibrium constants are presented in Table 14.     

Dioxouranium(VI)-Carboxylate Complexes. Interaction of {\rm OU}_{2}^{2+} with 1,2,3,4,5,6-Benzenehexacarboxylate (Mellitate) in 0 ≤ I(NaCl a q ) ≤ 1.0 mol·L −1

The formation constants of dioxouranium(VI)—1,2,3,4,5,6-benzenehexacarboxy- late [mellitate(6?)] complexes were determined in NaCl aqueous solutions at 0.1 ≤ I ≤ 1.0 mol·L^?1 and t = 25 ^°C by ISE-[H⁺] glass-electrode potentiometry. The speciation model obtained at each ionic strength includes the following species: ML^4?, MLH^3?, MLH₂ ^{2 ?}, MLH₃ ^?, M₂L^2?, MLOH^5? and ML(OH)₂ ^6? (M = UO₂ ^{2 +} and L^6? = mellitate). The ionic strength dependence of the protonation constants of mellitate and of the metal-ligand complexes was investigated using the SIT (Specific Ion Interaction Theory) approach. Formation constants at infinite dilution are [for the generic equilibrium $p{\rm UO}_{\rm 2}^{{\rm 2 + }} + q({\rm L}^{{\rm 6} - }) + r{\rm H}^{\rm + }\rightleftharpoons({\rm UO}_{\rm 2}^{{\rm 2 +}})_p({\rm L})_q {\rm H}_r^{(2p - 6q + r)};\,\beta _{pqr}$ ]: log₁₀ β ₁₁₀ = 10.155, log₁₀ β ₁₁₁ = 16.084, log₁₀ β ₁₁₂ = 20.749, log₁₀ β ₁₁₃ = 24.038, log₁₀ β ₂₁₀ = 17.936, log₁₀ β _11?1 = 2.327 and log₁₀ β _11?2 = ?6.804. Simple linear relationships between the formation constants and the stoichiometric coefficients of reactants are reported. The sequestering capacity of mellitate towards UO₂ ²⁺ was quantified using a sigmoid Boltzman-type equation.     

Studies on solid state reactions of coordination compounds LI.Solid state syntheses of a family of Ag-Mo(W)-S cubane-like cluster compounds:Crystal structures of{Ag_3MoS_3I}(PPh_3)_3S and{Ag_3WS_3Cl}(PPh_3)_3S·0.5P(S)Ph_3·3H_2O~+

Reactions of[NH_4]_2[MS_4](M=Mo,W),AgX(X=Cl,Br,I,CN,SCN)and PPh_3in the solid state produced six new mixed-metal sulfur containing cluster compounds,two ofwhich,{Ag_3MoS_3I}(PPh_3)_3S(1)and{Ag_3WS_3Cl}(PPh_3)_3S·0.5P(S)Ph_3·3H_2O(2),were determinedby single crystal X-ray analysis.The crystal data:1,triclinic,P,a=12.114(2),b=13.420(2),c=20.346(3),α=74.53(1),β=86.73(1),γ=63.74(1)°,Z=2,R=0.043 for 4805 independentdata;2,hexagonal,R3,a=b=16.201(3),c=45.091(10),Z=6,R=0.042 for 2729 independentdata.The central unit{Ag_3MS_3X}(M=Mo,W;X=Cl,I)of the two compounds can be des-cribed as a slightly distorted cube,four corners being formed by the MS_4~(2-) ligand(with a ter-minal S atom).The remaining corners are occupied by one X(Cl or I)atom and three Agatoms(with one PPh_3 ligand bound to each of the latter).The generation of different types ofAg-Mo(W)-S cluster compounds prepared from solid state reactions under different reactiontemperatues is discussed.     

Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 °C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 °C

Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 °C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 °C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 °C). In this region below the reference concentration, and below 0 °C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than ±0.1 cm(3) mol(-1) from 0 to 50 °C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 °C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer) model has been used to calculate apparent molar volumes of H(2)SO(4) in 0-3 mol kg(-1) aqueous solutions of the pure acid and to represent directly the effect of the HSO(4)(-) ? H(+) + SO(4)(2-) reaction. The results are incorporated into the treatment of aqueous H(2)SO(4) density described here. Densities and apparent molar volumes from -20 to 50 °C, and from 0 to 100 wt % of solute, are tabulated for the electrolytes listed in the title and have also been incorporated into the extended aerosol inorganics model (E-AIM, http://www.aim.env.uea.ac.uk/aim/aim.php) together with densities of the solid salts and hydrates.