The impedance of liquid (Ga-In)-electrode of eutectic composition in aqueous electrolyte solutions in the absence and in the presence of surface-active ions

Adsorption behavior of anions at liquid (Ga-In)-electrode at a temperature of 305 K is studied by electrochemical impedance spectroscopy and cyclic voltammetry. The above-listed methods allowed evaluating the adsorbability of different ions. Equivalent circuit describing the experimental data in the presence and in the absence of ions Br⁻ and Cl⁻ is a contour comprising a resistance connected in series to a capacitance whose value remains constant over the frequency range from ∼300 Hz to 10 kHz. Analysis of the experimental data obtained by the mixed electrolyte method with excess of surface-inactive ion Cl and constant ionic strength 0.1 M in electrolyte solutions acidified down to pH 3 gave the charge of specifically adsorbed ions Br⁻ and Cl⁻ (σ₁) at the liquid (Ga-In)-electrode surface as 5.24 and 1.67 μC/cm², respectively, at the adsorbate maximal concentration and zero-charge potential. These values are characteristic of very weak specific adsorption. The σ₁ values found for the (Ga-In)-electrode were used in the calculations of different isotherms, aiming at the determination of adsorption parameters. The results of the study were compared with literature data obtained by different researchers for different metals in the presence of specifically adsorbing bromide and chloride ions.     

Electrosurface characteristics of titanium dioxide in solutions of simple electrolytes: I. Effect of nature of counterions on adsorption and electrokinetic parameters of TiO<Subscript>2</Subscript>

The adsorption and electrokinetic characteristics of different titanium dioxide samples (produced by the Merck Co. and synthesized by the sol-gel method) are studied depending on the pH, background electrolyte concentration, and the nature of counterions (halide ions and Na⁺, K⁺, Ba²⁺, and La³⁺ metal ions). It is revealed that, in the presence of an indifferent electrolyte, the points of zero charge (PZC) for the synthesized TiO₂ sample and the Merck sample correspond to pH = 6.0 ± 0.1 and 5.0, respectively. It is found that the nature of halide ions has almost no influence on the magnitude of the TiO₂ surface charge σ₀ (in the region of its positive values) and the position of PZC. An increase in the specificity of cations with a rise in the charge causes PZC shift to the acidic region and enhances the absolute values of σ₀ at both negative and positive surface charges. It is established that the positions of PZC and isoelectric point in 10⁻² M solutions of the examined 1: 1 electrolytes nearly coincide with one another. The ζ potential is found to decline in the following series of counterions: Cl⁻, Br⁻, and I⁻ due to an increase in the degree of filling of the dense part of the electrical double layer.     

Study of photoelectrochemical corrosion of lead oxide in alkaline solution by the rotating ring-disk electrode technique

Photoelectrochemical corrosion of n-type α-PbO electrodes in aqueous Fe(CN)₆ ^3−/4− and I⁻/I₃ ⁻ electrolytes using the rotating ring-disk electrode technique has been investigated. The α-PbO thin film is found to be more stable in I⁻/I₃ ⁻ (48%) than in Fe(CN)₆ ^3−/4− electrolyte (10%). Preferential adsorption of iodide ions decreases the photocorrosion reaction of holes with α-PbO. Addition of CsI (0.4 mM) to the I⁻/I₃ ⁻ electrolyte decreases the photocorrosion from 48% to less than 10%. Cs⁺ ions perhaps nullify the effect of negatively charged surface states of α-PbO, thus minimizing the trapping of holes at the surface of α-PbO and hence decrease the possibility of photocorrosion of lead oxide with holes. Received: 30 June 1998 / Accepted: 20 April 1999     

Nine-coordinate dinuclear Na6[Gd 2III (Ttha)2] · 8H2O and mononuclear (H2En)3[GdIII(Ttha)]2 · 11H2O complexes: Synthesis and structural determination

The Na₆[Gd₂^III(Ttha)₂] · 8H₂O (I) (H₆Ttha = triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetic acid) and (H₂En)₃[Gd^III(Ttha)]₂ · 11H₂O (II) (En = ethylenediamine) complexes were prepared with heat-refluxing and acidity-adjusting methods, respectively. Their composition and structures were determined by elemental analysis and single-crystal X-ray diffraction techniques. Complex I shapes a binuclear and nine-coordinated structure and crystallizes in the orthorhombic crystal system with space group Pccn. The central Gd³⁺ ion is coordinated with one Ttha ligand by three N atoms and four O atoms and with one adjacent Ttha ligand by two O atoms. The crystal data are as follows: a = 26.036(13) ?, b = 21.007(10) ?, c = 22.694(12) ?, V = 12412(11) ?³, Z = 8, c = 1.699 g/cm³, μ = 2.254 mm⁻¹, F(000) = 6368, R = 0.0602, and wR = 0.1146 for 3434 observed reflections with I ≥ 2σ(I). The GdN₃O₆ part in the [Gd₂^III(Ttha)₂]⁶⁻ complex anion forms a pseudo-tricapped trigonal prismatic geometry. Complex II is also nine-coordinate, but mononuclear and crystallizes in the monoclinic crystal system with space group P2₁/n. While the central Gd³⁺ ion is coordinated by four nitrogen atoms and five oxygen atoms from the same Ttha ligand. The crystal data are as follows: a = 17.7726(17) ?, b = 19.2942(17) ?, c = 20.6045(19) ?, β = 111.4600(10)°, V = 6575.6(10) ?³, Z = 8, c = 1.693 g/cm³, μ = 2.102 mm⁻¹, F(000) = 3428, R = 0.0333 and wR = 0.0827 for 14792 observed reflections with I ≥ 2σ(I). Otherwise, the GdN₄O₅ part in each [Gd^III(Ttha)]³⁻ complex anion adopts a pseudo-monocapped square antiprismatic polyhedron.     

Synthesis and structures of nine-coordinate K[SmIII (Edta)(H2O)3] · 2H2O and Ten-Coordinate K2[SmIII(Pdta)(H2O)2]2 · 4.5H2O complexes

The title complexes, K[Sm^III(Edta)(H₂O)₃] · 2H₂O(I)(H₄Edta = ethylenediamine-N,N,N′,N′-tetraacetic acid) and K₂[Sm^III(Pdta)(H₂O)₂]₂ · 4.5H₂O (II) (H₄Pdta = propylenediamine-N,N,N′,N′-tetraacetic acid), were prepared and their compositions and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques, respectively. Complex I has a mononuclear structure, and the Sm³⁺ ion is nine-coordinated by an Edta ligand and three water molecules, yielding a pseudo-monocapped square antiprismatic conformation, and the complex crystallizes in the orthorhombic crystal system with space group Fdd2. The crystal data are as follows: a = 19.84(5), b = 35.58(9), c = 12.15(3) ?, V = 8580(38) ?³, Z = 16, ρ _c = 1.925 g/cm³, μ = 3.010 mm⁻¹, F(000) = 4976, R = 0.0252, and wR = 0.0560 for 3510 observed reflections with I ≥ 2σ(I). Complex II has a binuclear structure and the Sm³⁺ ion is ten-coordinated by a Pdta ligand, two oxygen atoms from a carboxylic group of adjacent Pdta ligand and two water molecules, yielding a distorted bicapped square antiprismatic prism. The complex crystallizes in the triclinic crystal system with space group P $ \bar 1 $ \bar 1 . The crystal data are as follows: a = 8.9523(15), b = 10.7106(15), c = 11.6900(19) ?, α = 80.613(5)°, β = 80.397(5)°, γ = 76.530(4)°, V = 1065.7(3) ?³, Z = 1, ρc = 1.970 g/cm³, μ = 2.532 mm⁻¹, F(000) = 1620, R = 0.0332 and wR = 0.0924 for 5390 observed reflections with I ≥ 2σ(I).     

Preparation of a novel polymer gel electrolyte based on N-methyl-quinoline iodide and its application in quasi-solid-state dye-sensitized solar cell

Using poly(acrylonitrile-co-styrene) as polymer host, 1,2-propanediol carbonate, dimethyl carbonate and ethylene carbonate as mixture solvent, N-methyl-quinoline iodide and iodine as the source of I⁻/I₃ ⁻, a novel polymer gel electrolyte with ionic conductivity of 5.12 × 10⁻³ S· cm⁻¹ at 25°C was prepared by sol-gel and hydrothermal methods. Based on the polymer gel electrolyte, a quasi-solid-state dye-sensitized solar cell was fabricated. The solar cell possess better long-term stability and light-to-electrical energy conversion efficiency of 4.04% under irradiation of 100 mW· cm⁻². The influences of polymer host, solvent, N-methyl-quinoline iodide and temperature on ionic conductivity of the polymer gel electrolyte and the performance of the dye-sensitized solar cell was discussed.     

Mononuclear eight-coordinate (NH4)3[YIII(Nta)2] and one-dimensional unlimited zigzag type nine-coordinate {K[YIII(Egta) · 4H2O}n complexes: Syntheses and structural determination

The title complexes (NH₄)₃[Y^III(Nta)₂] (I) (H₃Nta = nitrilotriacetic acid) and {K[Y^III(Egta)] · 4H₂O} _n (II) (H₄Egta = ethyleneglycol-bis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) were prepared, and their molecular and crystal structures were determined by single-crystal X-ray diffraction techniques. Complex I crystallizes in the rhombohedral crystal system with R $ \bar 3 $ \bar 3 c space group. The central Y³⁺ ion is eight-coordinated by two nitrogen and six oxygen atoms, which come from two tetradentate Nta ligands. The crystal data are as follows: a = 7.9340(14) ?, c = 54.611(15) ?, V = 2977.1(11) ?³, Z = 6, ρ_calcd = 1.738 mg/cm³, μ = 3.011 mm⁻¹, F(000) = 1596, R = 0.0234 and wR = 0.0641 for 686 observed reflections with I ≥ 2σ(I). The {K[Y^III(Egta)] · 4H₂O} _n is nine-coordinated by two nitrogen and seven oxygen atoms and produces a 1D unlimited zigzag-type chain through a bridging carboxylic group. {K[Y^III(Egta)] · 4H₂O} _n crystallizes in the monoclinic crystal system with C2/c space group. The crystal data are as follows: a = 37.588(5) ?, b = 13.7101(19) ?, c = 8.6070(12) ?, β = 99.929(2)°, V = 4369.0(11) ?³, Z = 8, ρ_calcd = 1.753 mg/cm³, μ = 2.934 mm⁻¹, F(000) = 2368, R = 0.0385 and wR = 0.0800 for 4082 observed reflections with I ≥ 2σ(I).     

Synthesis and structures of nine-coordinate K[Dy(Edta)(H2O)3] · 3.5H2O, (NH4)3 [Dy(Ttha)] · 5H2O, and eight-coordinate NH4[Dy(Cydta)(H2O)2] · 4.5H2O complexes

The title complexes, K[Dy(Edta)(H₂O)₃] · 3.5 H₂O (I) (H₄Edta = ethylenediamine-N,N,N′,N′-tetraacetic acid), (NH₄)₃[Dy(Ttha)] · 5H₂O (II) (H₆Ttha = triethylenetetramine-N, N,N′,N″,N‴,N‴-hexaacetic acid), and NH₄[Dy(Cydta)(H₂O)₂] · 4.5H₂O (III) (H₄Cydta = trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid), were prepared, and their compositions and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques, respectively. In complex I, the Dy³⁺ ion is nine-coordinated by an Edta ligand and three water molecules, yielding a pseudo-monocapped square antiprismatic conformation, and the complex crystallizes in the orthorhombic crystal system with space group Fdd2. The crystal data are as follows: a = 19.751(7), b = 35.573(12), c = 12.227(4) ?, V = 8591(5) ?³, Z = 16, space group Fdd2 ρ_c = 1.877 g/cm³, μ = 3.742 mm⁻¹, F(000) = 4800, R = 0.0259, and wR = 0.0616 for 3218 observed reflections with I ≥ 2σ(I). For complex II, the Dy³⁺ ion is nine-coordinated by a Ttha ligand, yielding a pseudo-monocapped square antiprismatic conformation, and the complex crystallizes in the monoclinic crystal system with space group P2₁/c. In addition, there is a free non-coordinate carboxyl group (-CH₂COO⁻) in the [Dy(Ttha)]³⁻ complex anion. The crystal data are as follows: a = 10.353(3), b = 12.746(4), c = 23.141(7) ?, β = 91.005(5)°, V = 3053.2(15) ?³, Z = 4, space group P2₁/c ρ_c = 1.730 g/cm³, μ = 2.532 mm⁻¹, F(000) = 1620, R = 0.0332 and wR = 0.0924 for 5390 observed reflections with I ≥ 2σ(I). For complex III, the Dy³⁺ ion is eight-coordinated by a ligand Cydta and two water molecules, yielding a distorted square antiprismatic conformation, and the complex crystallizes in the triclinic system with space group P . The crystal data are as follows: a = 8.604(3), b = 10.012(4), c = 14.369(6) ?, α = 88.330(6)°, β = 75.363(6)°, γ = 88.285(6)°, space group P V = 1196.9(8) ?³, Z = 2, ρ_c = 1.776 g/cm³, μ = 3.194 mm⁻¹, F(000) = 644, R = 0.0445 and wR = 0.1041 for 3931 observed reflections with I ≥ 2σ(I). The article is published in the original.     

New nine-coordinate (NH4)3[YbIII(ttha)]·5H2O and eight-coordinate (NH4)[YbIII(pdta)(H2O)2]·5H2O complexes: Structural determination

The (NH₄)₃[Yb^III(ttha)]·5H₂O (I) (H₆ttha = triethylenetetramine-N,N,N′,N″,N‴,N‴-hexaacetic acid) and (NH₄)[Yb^III(pdta)(H₂O)₂]·5H₂O (II) (H₄pdta = propylenediamine-N,N,N′,N′-tetraacetic acid) complexes are synthesized by heat-refluxing and acidity-adjusting methods, and their structures are determined by single crystal X-ray diffraction techniques. These two complexes are all mononuclear structures. The complex I crystallizes in ttha monoclinic crystal system with the P2₁/c space group. The central Yb^III ion is nine-coordinated only by one the ligand, and one non-coordinate carboxyl group is left. The crystal data are as follows: a = 10.321(4) ?, b = 12.744(5) ?, c = 23.203(9) ?, β = 91.082(6)°, V = 3051(2) ?³, Z = 4, D _c = 1.754 g/cm³, μ = 3.150 mm⁻¹, F(000) = 1636, R = 0.0357, and wR = 0.0672 for 6203 observed reflections with I ≥ 2σ(I). The YbN₄O₅ part in the [Yb^III(ttha)]³⁻ complex anion forms a pseudo-monocapped square antiprismatic polyhedron. The complex II is coordinated with one pdta ligand and two water molecules, which form an eight-coordinate structure, and crystallizes in the triclinic crystal system with the P[`1]P\bar 1 space group. The YbN₂O₆ part in the [Yb^III(pdta)(H₂O)₂]⁻ complex anion makes a pseudo-square antiprismatic polyhedron. The crystal data are as follows: a = 9.8923(9)?, b = 10.9627(10) ?, c = 12.2618(11) ?, α = 67.284(5)°, β = 70.956(6)°, γ = 68.741(5)°, V = 1115.97(18) ?³, Z = 2, D _c = 1.843 g/cm³, μ = 4.264 mm⁻¹, F(000) = 618, R = 0.0177, and wR = 0.0409 for 4036 observed reflections with I ≥ 2σ(I).     

Hydrothermal synthesis and crystal structure of [Zn(pytpy)2][NO3]2·2H2O

The title compound, [Zn(pytpy)₂][NO₃]₂·2H₂O (pytpy = 4′-(4-pyridyl)-2,2′: 6′,2″-terpyridine), has been synthesized by the reaction of Zn(NO₃)₂·6H₂O with pytpy, and its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to tetragonal space group P4₃ with a = 0.90873(8) nm, b = 0.90873(8) nm, c = 4.4741(6) nm, V = 3.6946(7) nm³, Z = 4, D _c = 1.521 g/cm⁻³, μ = 0.736 mm⁻¹, F(000) = 1744, R = 0.0871, wR = 0.1302 for 5553 observed reflections with I > 2σ(I). X-ray analysis has revealed that the Zn^II ion is surrounded by six N atoms from two pytpy ligands leading to a distorted octahedral geometry. In the crystal structure there are numerous strong intermolecular and intramolecular H-bonds and π-π interactions.     

Structural determination of new eight-coordinate NH4[EuIII(Cydta)(H2O)2]·4.5H2O and K2[Eu 2III (pdta)2(H2O)2]·6H2O complexes

The NH₄[Eu^III(Cydta)(H₂O)₂]·4.5H₂O (I) (H₄Cydta = trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid) and K₂[Eu₂^III(pdta)₂(H₂O)₂]·6H₂O (II) (H₄pdta = propylenediamine-N,N,N′,N′-tetraacetic acid) complexes are prepared by heat-refluxing and acidity-adjusting methods respectively, and their composition and structures are determined by elemental analyses and single crystal X-ray diffraction techniques. The complex I has a mononuclear structure, crystallizes in the triclinic crystal system with the P[`1]P\bar 1 space group; the central Eu^III ion is eight-coordinated by a hexadentate Cydta ligand and two water molecules. The crystal data are as follows: a = 8.653(4) ?, b = 10.041(4) ?, c = 14.405(6) ?, α = 88.469(6)°, β = 74.892(6)°, γ = 88.256(7)°, V = 1207.5(9) ?³, Z = 1, D _c = 1.731 g/cm³, μ = 2.669 mm⁻¹, F(000) = 638, R = 0.0257, and wR = 0.0667 for 3807 observed reflections with I ≥ 2σ(I). The EuN₂O₆ part in the [Eu^III(Cydta)(H₂O)₂]⁻ complex anion forms a pseudo-square antiprismatic polyhedron. The complex II is eight-coordinate as well; it is a binuclear structure that crystallizes in the monoclinic crystal system with the C ₂/c space group; half of the central Eu^III ion is coordinated by two nitrogen atoms from one hexadentate pdta ligand and six oxygen atoms from the same pdta ligand, one water molecule and carboxylic group from the neighboring pdta ligand respectively. The crystal data are as follows: a = 19.866(3) ?, b = 9.1017(12) ?, c = 21.010(3) ?, β = 104.972(2)°, V = 3670.1(9) ?³, Z = 8, D _c = 2.046 g/cm³, μ = 3.710 mm⁻¹, F(000) = 2240, R = 0.0213 and wR = 0.0460 for 4183 observed reflections with I ≥ 2σ(I). Otherwise, the two EuN₂O₆ parts in the [Eu₂^III(pdta)₂(H₂O)₂]²⁻ complex anion form a pseudo-square antiprismatic polyhedron.     

Syntheses of the eight-coordinate NH4[ErIII(Cydta)(H2O)2] · 4.5H2O and (NH4)2[Er 2III (Pdta)2(H2O)2] · 2H2O complexes and their structural investigation

In this work, the title complexes, NH₄[Er^III(Cydta)(H₂O)₂] · 4.5H₂O (I) (H₄Cydta = trans-1,2-cyclo-hexanediamine-N,N,N′,N′-tetraacetic acid) and (NH₄)₂[Er₂^III(Pdta)₂(H₂O)₂] · 2H₂O (II) (H₄Pdta= propylene-diamine-N,N,N′,N′-tetraacetic acid), were prepared, respectively, and their composition and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. Complex I selects a mononu-clear structure with pseudosquare antiprismatic geometry crystallized in the triclinic crystal system with space group $ P\bar 1 $ P\bar 1 and the central Er³⁺ ion is eight-coordinated by the hexadentate Cydta ligand and two water molecules. The crystal data are as follows: a = 8.568(3), b = 10.024(3), c = 14.377(4) ?, α = 88.404(4)°, β = 75.411(4)°, γ = 88.332(4)°, V = 1194.2(6) ?³, Z = 1, ρ _c = 1.793 g/cm³, μ = 3.586 mm⁻¹, F(000) = 648, R = 0.0257, and wR = 0.0667 for 4169 observed reflections with I ≥ 2σ(I). Complex II is eight-coordinated as well, which selects a binuclear structure with two pseudosquare antiprismatic geometry and crystallizes in the monoclinic crystal system with space group P2₁/n. The central Er³⁺ ion is coordinated by two nitrogens and four oxygens from one hexadentate Pdta ligand. Besides, two oxygens come from one carboxylic group of the neighboring Pdta ligand and one water molecule, respectively. The crystal data are as follows: a = 12.7576(8), b = 9.3151(6), c = 14.3278(9) ?, β = 96.1380(10)°, V = 1692.93(19) ?³, Z = 4, ρ _c = 2.054 g/cm³, μ = 5.015 mm⁻¹, F(000) = 1028, R= 0.0228, and wR = 0.0534 for 2984 observed reflections with I ≥ 2σ(I).     

A polymer electrolyte containing ionic liquid for possible applications in photoelectrochemical solar cells

Various iodide ion conducting polymer electrolytes have been studied as candidate materials for fabricating photoelectrochemical (PEC) solar cells and energy storage devices. In this study, enhanced ionic conductivity values were obtained for the ionic liquid tetrahexylammonium iodide containing polyethylene oxide (PEO)-based plasticized electrolytes. The analysis of thermal properties revealed the existence of two phases in the electrolyte, and the conductivity measurements showed a marked conductivity enhancement during the melting of the plasticizer-rich phase of the electrolyte. Annealed electrolyte samples showed better conductivity than nonannealed samples, revealing the existence of hysteresis. The optimum conductivity was shown for the electrolytes with PEO:salt = 100:15 mass ratio, and this sample exhibited the minimum glass transition temperature of 72.2 °C. For this optimum PEO to salt ratio, the conductivity of nonannealed electrolyte was 4.4 × 10⁻⁴ S cm⁻¹ and that of the annealed sample was 4.6 × 10⁻⁴ S cm⁻¹ at 30 °C. An all solid PEC solar cell was fabricated using this annealed electrolyte. The short circuit current density (I _SC), the open circuit voltage (V _OC), and the power conversion efficiency of the cell are 0.63 mA cm⁻², 0.76 V, and 0.47% under the irradiation of 600 W m⁻² light.     

Crystal structures of seven-coordinate (NH4)2[MnII(edta)(H2O)]·3H2O, (NH4)2[MnII(cydta)(H2O)]·4H2O and K2[MNII(hdtpa)]·3.5H2O complexes

The title compounds, (NH₄)₂[Mn^II(edta)(H₂O)]·3H₂O (H₄edta = ethylenediamine-N,N,N′,N′-tetraacetic acid), (NH₄)₂[Mn^II(cydta)(H₂O)]·4H₂O (H₄cydta = trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid) and K₂[Mn^II(Hdtpa)]·3.5H₂O (H₅dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), were prepared; their compositions and structures were determined by elemental analysis and single-crystal X-ray diffraction technique. In these three complexes, the Mn²⁺ ions are all seven-coordinated and have a pseudomonocapped trigonal prismatic configuration. All the three complexes crystallize in triclinic system in P-1 space group. Crystal data: (NH₄)₂[Mn^II(edta)(H₂O)]·3H₂O complex, a = 8.774(3) ?, b = 9.007(3) ?, c = 13.483(4) ?, α = 80.095(4)°, β = 80.708(4)°, γ = 68.770(4)°, V = 972.6(5) ?³, Z = 2, D _c = 1.541 g/cm³, μ = 0.745 mm⁻¹, R = 0.033 and wR = 0.099 for 3406 observed reflections with I ≥ 2σ(I); (NH₄)₂[Mn^II(cydta)(H₂O)]·4H₂O complex, a = 8.9720(18) ?, b = 9.4380(19) ?, c = 14.931(3) ?, α = 76.99(3)°, β = 83.27(3)°, γ = 75.62(3)°, V = 1190.8(4)?³, Z = 2, D _c = 1.426 g/cm³, μ = 0.625 mm⁻¹, R = 0.061 and wR = 0.197 for 3240 observed reflections with I ≥ 2σ(I); K₂[Mn^II(Hdtpa)]·3.5H₂O complex, a = 8.672(3) ?, b = 9.059(3) ?, c = 15.074(6) ?, α = 95.813(6)°, β = 96.665(6)°, γ = 99.212(6)°, V = 1152.4(7) ?³, Z = 2, D _c = 1.687 g/cm³, μ = 1.006 mm⁻¹, R = 0.037 and wR = 0.090 for 4654 observed reflections with I ≥ 2σ(I). Original Russian Text Copyright ? 2008 by X. F. Wang, J. Gao, J. Wang, Zh. H. Zhang, Y. F. Wang, L. J. Chen, W. Sun, and X. D. Zhang The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 49, No. 4, pp. 753–759, July–August, 2008.     

Determination of the chemical forms of iodine with IC-ICP-MS and its application to environmental samples

An online analytical system using ion chromatography (IC) followed by inductively coupled plasma mass spectrometry (ICP-MS) was developed for the separate determination of I⁻ and IO₃⁻ in aqueous solutions with a detection limit 0.1–1 μg 1/1. The total iodine concentration was also directly determined by ICP-MS. Iodine in several environmental samples (i.e., rain, river water, brine, and soil solution) was successfully determined with information on its chemical form. The release of I⁻ into soil solution with decreasing Eh was observed in an incubation experiment with flooded soil. An iodine form other than I⁻ and IO₃⁻ was observed in several environmental samples.     

Application of a ternary complex of tungsten(VI) with 4-nitrocatechol and thiazolyl blue for extraction-spectrophotometric determination of tungsten

A new ternary ion-association complex of tungsten(VI), 4-nitrocatechol (NC), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (Thiazolyl Blue, MTT) was obtained and studied using an extraction-spectrophotometric method. The optimum pH, reagent concentrations, and extraction time were determined. The composition of the complex was found to be W(VI): NC: MTT = 1: 2: 2. The extraction process was investigated quantitatively and the key constants were calculated. The molar absorptivity of the chloroform extract at λ_max = 415 nm was 2.8 × 10⁴ dm³ mol⁻¹ cm⁻¹, and the Beer’s law was obeyed up to 8.8 μg cm⁻³ tungsten(IV). The limit of detection and limit of quantification were calculated to be 0.27 μg cm⁻³ and 0.92 μg cm⁻³, respectively. The effect of foreign ions and reagents was studied and a competitive method for determination of tungsten in products from ferrous metallurgy was developed. The residual standard deviation and the relative error were 0.53 % and 0.2 %, respectively.     

Mononuclear nine-coordinate Na[SmIII(edta)(H2O)3] · 5H2O and one dimensional unlimited ladderlike eight-coordinate {[SmIII(Hpdta)(H2O)] · 2H2}On Complexes: Synthesis and Structural Determination

The Na[Sm^III(edta)(H₂O)₃] · 5H₂O (H₄edta = ethylenediamine-N,N,N′,N′-tetraacetic acid) and {[Sm^III(Hpdta)(H₂O)] · 2H₂O} _n (H₄pdta = propylenediamine-N,N,N′,N′-tetraacetic acid) complexes were prepared with heat-refluxing and acidity-adjusting methods, respectively. And their composition and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. The Na[Sm^III(edta)(H₂O)₃] · 5H₂O complex shapes a mononuclear structure, and crystallizes in the orthorhombic crystal system with space group Fdd2. The central Sm^III ion is nine-coordinated by one hexadentate edta ligand and three water molecules. The crystal data are as follows: a = 19.139(10) ?, b = 35.00(2) ?, c = 11.928(10) ?, V = 7989(9) ?³, Z = 16, D _c = 2.014 g/cm³, μ = 3.046 mm⁻¹, F(000) = 4848, R = 0.0439, and wR = 0.0941 for 3434 observed reflections with I ≥ 2σ(I). The SmN₂O₇ part in [Sm^III(edta)(H₂O)₃]⁻ complex anion forms a pseudo-monocapped square antiprismatic polyhedron. The {[Sm_III(Hpdta)(H₂O)] · 2H₂O} _n complex is prepared with protonated pdta ligand firstly, which forms one dimensional unlimited ladderlike eight-coordinated structure, and crystallizes in the monoclinic crystal system with space group P2₁/n. The central Sm^III ion, in one construction unit, is coordinated by two nitrogen atoms from one hexadentate pdta ligand and six oxygens from the same pdta ligand, one water molecule and one carboxylic group of neighbour pdta ligand, respectively. The crystal data are as follows: a = 12.720(3) ?, b = 9.3800(19) ?, c = 14.420(3) ?, β = 96.11(3)°, V = 1710.7(6) ?³, Z = 2, D _c = 1.971 g/cm³, μ = 3.492 mm⁻¹, F(000) = 1004, R = 0.0225 and wR = 0.0607 for 3182 observed reflections with I ≥ 2σ(I). Otherwise, each part of SmN₂O₆ in {[Sm^III(Hpdta)(H₂O)] · 2H₂O} complex segment adopts a pseudo-square antiprismatic polyhedron.     

Specific adsorption of chloride ions on liquid Ga electrode from N-methylformamide solutions with constant ionic strength

Differential capacitance curves are measured by mans of an ac-bridge in the system Ga/[N-MF + 0.1m M KCl + 0.1(1 − m) M KClO₄] with the surface-active anion taken in the following molar fractions m: 0, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, and 1. As compared with the other solvents, N-methylformamide (N-MF) makes it possible to realize the highest positive charges of the Ga electrode at which the electrode remains ideally polarizable (up to 20 μC/cm²). The data on the specific adsorption of Cl⁻ ions in the mentioned system can be described qualitatively by the Frumkin isotherm in which the free energy is considered as a linear function of the electrode charge.     

Thermal and dielectric properties of PEO/EC/Pr4N+I− polymer electrolytes for possible applications in photo-electro chemical solar cells

The anion-conducting polymer electrolyte polyethylene oxide (PEO)/ethylene carbonate (EC)/Pr₄N⁺I⁻/I₂ is a candidate material for fabricating photo-electrochemical (PEC) solar cells. Relatively high ionic conductivity values are obtained for the plasticized electrolytes; at room temperature, the conductivity increases from 7.6 × 10⁻⁹ to 9.5 × 10⁻⁵ S cm⁻¹ when the amount of EC plasticizer increases from 0% to 50% by weight. An abrupt conductivity enhancement occurs at the melting of the polymer; above the melting temperature, the conductivity can reach values of the order of 10⁻³ S cm⁻¹. The melting temperature decreases from 66.1 to 45.1 °C when the EC mass fraction is increased from 0% to 50%, and there is a corresponding reduction in the glass transition temperature from −57.6 to −70.9 °C with the incorporation of the plasticizer. The static dielectric constant values, , increase with the mass fraction of plasticizer, from 3.3 for the unplasticized sample to 17.5 for the 50% EC sample. The dielectric results show only small traces of ion-pair relaxations, indicating that the amount of ion association is low. Thus, the iodide ion is well dissociated, and despite its large size and relatively low concentration in these samples, the iodide ion to ether oxygen ratio is 1:68, a relatively efficient charge carrier. A further enhancement of the ionic conductivity, especially at lower temperatures, is however desired for these applications.