Temperature dependence of the properties of ternary systems ethanol + water + an aliphatic alkane (C6-C9)

The measures and calculation of different properties such as refractive index, density, speed of sound, excess molar volume, and isentropic compressibility of the ternary heterogeneous compounds by ethanol + water + (n-hexane, n-heptane, n-octane, n-nonane) have been performed in the range 288.15–323.15 K and atmospheric pressure. Attending to the accurate results of these models, the equation of state enclosing mixing rules is indicated as a simple estimation of the procedures of these properties for this kind of multicomponent systems.     

Temperature Dependence of Excess Molar Volumes of Ethanol + Water + Ethyl Acetate

In order to design and optimize equipment needed for production of distilled alcoholic beverages, an adequate knowledge of their physical properties and phase equilibria is necessary. The key thermodynamic information needed is for those chemicals that are the main components in terms of nonideal behavior. In this paper we present the temperature dependence of the excess molar volumes of the ternary system ethanol + water + ethyl acetate in the range 288.15–323.15 K at atmospheric pressure, due to the importance of ethyl acetate among the flavor compounds contained in this type of beverage. The observed excess molar volumes are usually negative over the whole homogeneous composition range, but take on positive values as the binary ethanol + ethyl acetate system is approached and the liquid phase separation region is observed. Because the current process designs are strongly computer oriented, the accuracy of theoretical model predictions was examined. The experimental data were used to test the capability of the Soave–Redlich–Kwong (SRK) equation of state to predict the ternary mixture behavior from binary mixture interaction parameters, which were obtained from previously published data. Derived properties, such as partial the excess molar volumes, excess isobaric expansibility, and the pressure derivative of excess molar enthalpy at constant temperature were calculated, due to their importance in the study of specific molecular interactions.     

Apparent Dipole Moments of 1-Butanol, 1-Propanol, and Chlorobenzene in Cyclohexane or Benzene, and Excess Molar Volumes of (1-Propanol or Chlorobenzene + Cyclohexane or Benzene) at T = 298.15K

Apparent dipole moments and relative permittivities of {x1-butanol + (1 – x) cyclohexane}, {x1-propanol + (1 – x)cyclohexane or (1 – x)benzene} and {xchloro- benzene + (1 – x)cyclohexane or (1 – x)benzene} were determined for the mole fraction range of 0.0003 < x < 0.1 at a temperature of T = 298.15 K and at a frequency of f = 100 kHz. The apparent dipole moments were calculated using Frohlich equation. The molar excess volumes for {x1-propanol + (1 – x)cyclohexane or (1 – x) benzene} and {xchlorobenzene + (1 – x)cyclohexane} were determined by a vibrating-tube densimeter at T = 298.15 K.     

Thermophysical properties of the ternary mixture ethanol + n-hexane + n-octane in function of the temperature

This article presents the analysis of the following physical properties such as refractive indices, excess molar volumes, sound velocity and the temperature dependence of the ternary system ethanol?+?n-hexane?+?n-octane in the temperature range 288.15–323.15?K at atmospheric pressure. The derived properties are calculated from data obtained experimentally and fitted to Cibulka equation.     

Structural and thermal analysis of silicon isothiocyanates complexes of Fe(III) and Mn(II)

New complexes of Fe(III) and Mn(II) with R_xSi(NCS)_4–x as ligands have been prepared and characterized. The structure of the new compounds are discussed on the basis of their spectroscopic (IR and UV-Vis), magnetic susceptibility and thermal data.

---

Zusammenfassung Es wurden neue Fe(III)- und Mn(II)-Komplexe mit Liganden der Formel R_xSi(NCS)_4–x hergestellt und beschrieben. Bei der Diskussion der Struktur dieser neuen Verbindungen wurden spektroskopische (IR, UV), thermische Daten und Daten über die magnetische Suszeptibilität verwendet.

---

R_xSi(NCS)_4–x. ( , - ), .

     

Temperature dependence of volumetric behaviour for methyl tert-butylether+1-butanol system

Excess molar volumes and excess isoentropic compressibilities of methyl tert-butylether (MTBE)+1-butanol at 288.15, 293.15, 298.15, 303.15 and 308.15 K and atmospheric pressure have been studied. In order to analyse the temperature dependence of this mixture, isobaric expansibility a, (dV _m ^e dT) _P,xand (dH _m ^e dP ) _T,x, were computed by analytical differentiation of the density and excess molar volume fitting equations. Cubic equation of state (Soave-Redlich-Kwong) has been applied to excess molar volume correlation obtaining binary interaction parameters using different mixing rules. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of three ionic pairs of Fe(II) and Co(II) complexes with tridentate salicylideneglycine

Three new transition metal complexes, [Fe^II(H₂O)₆][(C₉H₇NO₃)₂Fe^II] · H₂O (1), H[K(H₂O)₃][(C₉H₇NO₃)₂Co^II] · H₂O (2), and [Co^II(H₂O)₆][(C₉H₇NO₃)₂Co^II] · H₂O (3), with salicylideneglycine have been synthesized and characterized by elemental analysis, IR spectra, UV-Vis spectroscopy, and X-ray crystallography. The structure analyses indicate that the tridentate salicylideneglycine binds through aliphatic nitrogen, phenoxy, and carboxylic oxygen in the anion. There are many inter- and intra-molecular hydrogen bonds among lattice water, the anion, and the cation to form a 3-D network. The thermogravimetric analyses and the quantum chemistry calculations of compounds 1, 2, and 3 are also discussed.     

Volumetric properties of 1-iodoperfluorohexane+<Emphasis Type="Italic">n</Emphasis>-octane binary system at several temperatures

New densities are reported over the whole composition range for 1-iodoperfluorohexane+n-octane system at temperatures from 288.15 to 308.15 K at atmospheric pressure. These data have been used to compute the excess molar volumes, V _m ^E. Large positive V _m ^E values have been obtained over the entire range of composition, which increases when the temperature rises. The experimental data were used to calculate the isobaric thermal expansivity, and the quantities (∂V _m ^E/∂T)_p and (∂H _m ^E/∂p)_T. Furthermore, the results have been used to investigate the volumetric prediction ability of the equations of state Soave–Redlich–Kwong, Peng–Robinson, Patel–Teja and Soave–Redlich–Kwong with volume translation.     

Searching for gallium bioactive compounds: Gallium(III) complexes of tridentate salicylaldehyde semicarbazone derivatives

In the search for gallium bioactive compounds five Ga(III) complexes, [Ga^III(L-H)₂](NO₃), with tridentate salicylaldehyde semicarbazone derivatives as ligands (L) have been synthesized and characterized in the solid state and in solution by different techniques. The crystal structure of [Ga^III(L4-H)₂](NO₃)·2H₂O, where L4 is 3-ethoxysalicylaldehyde semicarbazone, was solved by X-ray diffraction methods. The gallium(III) ion is in a distorted octahedral environment, coordinated to two nearly planar and mutually perpendicular 3-ethoxysalicylaldehyde semicarbazonato anions acting as tridentate ligands through their phenol and carbonyl oxygen atoms and their azomethine nitrogen atom. Their biological potential has been explored by evaluating their activity on Mycobacterium tuberculosis, causative agent of tuberculosis, and their cytotoxicity on tumor cell lines. Three different human tumor cell lines were selected that show different degrees of resistance to metallodrugs: ovarian A2780 (low resistance), breast MCF7 (medium resistance) and prostate PC3 (high resistance) cells. Although the complexes have not shown activity on M. tuberculosis, complexation with gallium has led to the enhancement of the cytotoxic potencies of the organic compounds. Those complexes that contain a bromide substituent at the phenolate ring have shown the highest cytotoxicities. In particular, [Ga^III(L2-H)₂](NO₃), where L2 is 5-bromosalicylaldehyde semicarbazone,·has shown a remarkable cytotoxicity on A2780 tumor cell line with an IC₅₀ value of the same order than cisplatin (IC_{50 Ga-L2} = 2.4 ± 0.3 μM; IC_{50 cisplatin} = 2.0 ± 0.1 μM, 72 h incubation at 37 °C). Interestingly, this complex has also shown moderate cytotoxicity against MCF7 and PC3 cells (IC_{50 MCF7} = 30 ± 6; IC_{50 PC3} = 18 ± 3 μM). Therefore, this gallium compound could be considered a promising wide spectrum potential anti-tumor agent.     

Syntheses,characterization, and crystal structures of ruthenium(II)/(III) complexes with tridentate salicylaldiminato ligands

Treatment of [Ru(PPh₃)₃Cl₂] with one equivalent of tridentate Schiff base 2-[(2-dimethylamino-ethylimino)-methyl]-phenol (HL) in the presence of triethylamine afforded a ruthenium(III) complex [RuCl₃(κ²-N,N-NH₂CH₂CH₂NMe₂)(PPh₃)] as a result of decomposition of HL. Interaction of HL and one equivalent of [RuHCl(CO)(PPh₃)₃], [Ru(CO)₂Cl₂] or [Ru(tht)₄Cl₂] (tht = tetrahydrothiophene) under different conditions led to isolation of the corresponding ruthenium(II) complexes [RuCl(κ³-N,N,O-L)(CO)(PPh₃)] (2), [RuCl(κ³-N,N,O-L)(CO)₂] (3), and a ruthenium(III) complex [RuCl₂(κ³-N,N,O-L)(tht)] (4), respectively. Molecular structures of 1·CH₂Cl₂, 2·CH₂Cl₂, 3 and 4 have been determined by single-crystal X-ray diffraction.     

Synthesis with structural and electronic characterization of homoleptic Fe(II)- and Fe(III)-fluorinated phenolate complexes

Four Fe(III) compounds and one Fe(II) compound containing mononuclear, homoleptic, fluorinated phenolate anions of the form [Fe(OAr)(m)](n-) have been prepared in which Ar(F) = C(6)F(5) and Ar' = 3,5-C(6)(CF(3))(2)H(3): (Ph(4)P)(2)[Fe(OAr(F))(5)], 1, (Me(4)N)(2)[Fe(OAr(F))(5)], 2, {K(18-crown-6)}(2)[Fe(OAr(F))(5)], 3a, {K(18-crown-6)}(2)[Fe(OAr')(5)], 3b, and {K(18-crown-6)}(2)[Fe(OAr(F))(4)], 6. Two dinuclear Fe(III) compounds have also been prepared: {K(18-crown-6)}(2)[(OAr(F))(3)Fe(μ(2)-O)Fe(OAr(F))(3)], 4, and {K(18-crown-6)}(2)[(OAr(F))(3)Fe(μ(2)-OAr(F))(2)Fe(OAr(F))(3)], 5. These compounds have been characterized with UV-vis spectroscopy, elemental analysis, Evans method susceptibility, and X-ray crystallography. All-electron, geometry-optimized DFT calculations on four [Ti(IV)(OAr)(4)] and four [Fe(III)(OAr)(4)](-) species (Ar = 2,3,5,6-C(6)Me(4)H, C(6)H(5), 2,4,6-C(6)Cl(3)H(2), C(6)F(5)) with GGA-BP and hybrid B3LYP basis sets demonstrated that, under D(2d) symmetry, π donation from the O 2p orbitals is primarily into the d(xy) and d(z(2)) orbitals. The degree of donation is qualitatively consistent with expectations based on ligand Br?nsted basicity and supports the contention that fluorinated phenolate ligands facilitate isolation of nonbridged homoleptic complexes due to their reduced π basicity at oxygen.     

Sedimentation potential of complexes of nitroamminecobalt(III) in aqueous solution at 25°C

Sedimentation potentials (SP) were measured for a series of nitroamminecobalt(III) chlorides in aqueous solution. The magnitudes of the sedimentation potentials varied with the number of NO ₂ ^– ligands in the complexes and a definite positive signal was observed for a neutral complex [Co(NO₂)₃(NH₃)₃]⁰. The division of the partial molar volumes of nitroamminecobalt(III) complexes based on the observed SP values resulted in comparable values of the partial molar volume for the Cl^– ion, suggesting no appreciable hydrolysis nor ionic association occur for these nitroammine-cobalt(III) complexes.     

Excess volumes,isentropic compressions,and isobaric heat capacities for methanol mixed with other alkanols at 25°C

Excess volumes, excess isentropic compressions and excess isobaric heat capacities for binary liquid mixtures of methanol with ethanol, 1-propanol and 1-butanol have been determined at 25° C. These thermodynamic functions are smaller than those for alkanol + water mixtures and are correlated with the difference in the alkyl chain length in two of the alkanol molecules. The behavior of the component molecules in solution is found to be similar to that in the pure liquid. The excess isentropic compressions of methanol + 1-butanol show an S-shaped concentration dependence with a positive lobe in the methanol rich range and a negative lobe in the methanol poor range, which resembles that of the excess Gibbs energy reported by Polak et al.     

Partial Molar Volumes and Refractions of Cobalt(III) Complexes, Part 1: Homologous Series of Hexaaminecobalt(III) Complexes

Both the partial molar volumes (V∘_solute) and refractions (R∘_solute) of the solute at infinite dilution have been determined for a series of four octahedral N₆-coordinated cobalt(III) species with increasing ligand size (ammonia, ethylenediamine, sepulchrate, and 1,2-diaminocyclohexane). The experimental values for V∘ _solute are consistent with the relative sizes of the ligands but show larger values than those generated by computer modeling as the size of the cation increases. This suggests that the void space of the cation increases with the size of the cation. It is proposed that increasing hydrophobicity of the alkane ligand frameworks contributes to larger volumes.     

The performance of nonhybrid density functionals for calculating the structures and spin states of Fe(II) and Fe(III) complexes

The local density approximation and a range of nonhybrid gradient corrected density functionals (PW91, BLYP, PBE, revPBE, RPBE) have been assessed with respect to the prediction of geometries and spin-state energy preferences for a range of homoleptic Fe(II)L6 and Fe(III)L6 complexes, where L = Cl-, CN-, NH3, pyridine, imidazole, H2O, O=CH2 and tetrahydrofuran. While the qualitative spin-state energies from in vacuo structure optimizations are reasonable the geometries are relatively poorly treated, especially for [FeCl6]3-/4-. Structural results for all the complexes are significantly improved by including environmental effects. The best compromise between structural and spin-state predictive accuracy was obtained for the RPBE functional in combination with the COSMO solvation approach. This approach systematically overestimates the energetic preference for a low spin state, which is partly due to the well-known effect of the lack of exact exchange in nonhybrid functionals and partly due to the larger solvation stabilization of low-spin complexes that have shorter bond lengths and thus smaller molecular volumes than their high-spin partners. Calculations on low spin [Fe(bipy)3]2+ and [Fe(phen)3]2+ and their ortho methyl substituted analogs, which are high spin at room temperature but cross over to low spin at low temperature, suggest the RPBE/COSMO combination generates low spin states which are too stable by approximately 13 kcal mol(-1).     

Reactivity of tris(acetylacetonato) iron(III) with tridentate [ONO] donor Schiff base as an access to newer mixed-ligand iron(III) complexes

Two new mixed-ligand iron(III) complexes, [Fe(L(n))(acac)(C(2)H(5)OH)] incorporating coordinated ethanol from the reaction solvent were accessed from the reaction of [Fe(acac)(3)] with [ONO] donor dibasic tridentate unsymmetrical Schiff base ligands derived from condensation of 2-hydroxy-1-napthaldehyde with 2-aminophenol (H(2)L(1)) or 2-aminobenzoic acid (H(2)L(2)). The thermal study (TGA-DTA) provided evidence for weakly bound ethanol which is readily substituted by neutral N-donor molecule imidazole, benzimidazole or pyridine to produce an array of newer complexes, [Fe(L(n))(acac)X] (n=1, 2; X=Im, Bim, Py). The compounds were characterized by elemental analyses, FT-IR, UV-vis, solution electrical conductivity, FAB mass, (1)H and (13)C NMR spectroscopy. Room temperature magnetic susceptibility measurements (μ(eff)～5.8 B.M.) are consistent with spin-free octahedral iron(III) complexes. Cyclic voltammetry of ethanol complexes revealed a quasi-reversible one electron redox response (ΔE(p)>100 mV) for the Fe(III)/Fe(II) couple. Low half wave redox potential (E(1/2)) values suggested easy redox susceptibility. The ground state geometries of the ethanol and imidazole complexes have been ascertained to be distorted octahedral by density functional theory using DMol3 program at BLYP/DNP level.     

Spectral,thermal, electrochemical,biological and DFT studies on nanocrystalline Co(II), Ni(II), Cu(II) and Zn(II) complexes with a tridentate ONO donor Schiff base ligand

Co(II), Ni(II), Cu(II) and Zn(II) Schiff base complexes derived from 3-hydrazinoquionoxaline-2-one and 1,2-diphenylethane-1,2-dione were synthesized. The compounds were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV–vis, ¹H NMR, ¹³C NMR, ESR, and mass spectral studies. Thermal studies of the ligand and its metal complexes were also carried out to determine their thermal stability. Octahedral geometry has been assigned for Co(II), Ni(II), and Zn(II) complexes, while Cu(II) complex has distorted octahedral geometry. Powder XRD study was carried out to determine the grain size of ligand and its metal complexes. The electrochemical behavior of the synthesized compounds was investigated by cyclic voltammetry. For all complexes, a 2 : 1 ligand-to-metal ratio is observed. The ligand and its metal complexes were screened for their activity against bacterial species such as E. coli, P. aeruginosa, and S. aureus and fungal species such as A. niger, C. albicans, and A. flavus by disk diffusion method. The DNA-binding of the ligand and its metal complexes were investigated by electronic absorption titration and viscosity measurement studies. Agarose gel electrophoresis was employed to determine the DNA-cleavage activity of the synthesized compounds. Density functional theory was used to optimize the structure of the ligand and its Zn(II) complex.     

Differences in thermal decomposition of Ag(I), Mn(II), Fe(II) and Fe(III) complexes of cyclic dithiocarbamates

The thermal decomposition of pyrrolidinedithiocarbamate (Pyr) and piperidinedithiocarbamate (Pip) complexes of Ag(I), Mn(II), Fe(II) and Fe(III) have been investigated by thermogravimetry and differential scanning calorimetry. The decomposition intermediates and final products were identified from their X-ray diffraction patterns. Changes in their IR spectra were correlated with their thermogravimetric profiles. The hydrated compounds decomposed without loss of water and oxides were detected as the final decomposition products even in nitrogen atmosphere.