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Recharge environmental conditions and residence time, can be studied by the application of different tracers. Several tracers are useful as proxies of the environmental recharge conditions, such as water stable isotopes deuterium and oxygen-18, and the dissolved noble gases. Other tracers are applied in order to know when the recharge occurred. Carbon-14 dating is a widely applied method for dating old groundwater, having an application range up to around 30 ky. Noble gases, as non-reactive and water-soluble substances, constitute useful tracers for studying different processes in hydrologic cycles. One of the applications is dating very old groundwater beyond the range of 14C. It can be done in a semi-quantitative way by the accumulation of 4He, and quantitatively through the radionuclide 81Kr (t1/2 = 229,000 y), a more robust method for dating groundwater up to 1.3 million years.The province of Buenos Aires, Argentina, hosts three deep sedimentary basins, from north to south, Salado, Claromecó and Colorado, with areas of 85,000 km2, 3,100 km2 and 125,000 km2, respectively. In these basins, a thick continental sequence of Neogene sediments contains confined thermal aquifers, at depths from hundreds meters to more than 1 km. The recharge conditions and the water age of the Neogene aquifers are studied through water stable isotopes, 4He and 81Kr tracers. 10 deep wells were sampled for δ2H, δ18O, 3H, 14C, for noble gases using clamped copper tubes, and for 81Kr with a gas extractor. 4He analyses were performed at the IAEA laboratory by mass spectrometry, and 81Kr at the ATTA laboratory of USTC.3H contents were not detectable in all of the cases, thus no young water components exist. By plotting the isotopic results in a δ2H vs δ18O diagram, four groups of samples can be recognized. Group 1 includes Colorado basin isotopically depleted samples (δ18O from -6.5 to -7.5 ‰) along a line parallel to the GMWL and the present LMWL, but with a higher deuterium-excess (d). Samples in G1 have a Ne/He ratio around 0.6. 14C and 81Kr ages were from 10 ky to 40 ky. Group 2 includes the samples of the borders of the Salado basin, being isotopically more enriched (δ18O from -3 to -4.5 ‰) and with a lower d than present precipitation, a Ne/He ratio from 0.2 to 0.8 and one sample with 81Kr age of 640 ky. Group 3 is formed by brines from the Colorado basin, a Ne/He ratio in the range of 1E-02 to 1E-04, and 81Kr in ages around 900 ky, and are along a line of slope 1.9, showing a 18O shift. Finally the Group 4 formed by samples at the axis of Salado basin, are isotopically enriched (δ18O from -0.5 to -3.7 ‰) along a line of slope 3.9 resembling and evaporation line. However, these samples of 81Kr ages of 1000 ky and Ne/He ratio of 2E-03, showed a high correlation Cl- vs δ18O, with increasing values from West to East. This suggest a mixing with a brine or an increasing water-rock interaction.

Ionic liquids (ILs) with aprotic heterocyclic anions (AHAs) have been developed primarily for CO2 capture applications. However, they have also been considered for cofluid CO2/IL vapor compression refrigeration cycles and for various electrochemical applications. In all of these cases, reducing the viscosity of the IL is of primary importance. Therefore, the focus of this work is tuning the cation to produce AHA ILs with both low viscosities and low melting points. Toward this goal we have synthesized 40 AHA ILs paired with phosphonium, ammonium and imidazolium cations, as well as a number of ILs with the bis(trifluoromethylsulfonyl)imide anion to use for comparison. The azolide anions investigated were 2-cyanopyrrolide, 4-nitropyrazolide, various substituted imidazolides, 1,2,3-triazolide, and tetrazolide. Melting points, glass transition temperatures, and decomposition temperatures were measured for all ILs. Viscosities and densities were measured from 278.15 to 343.15 K and 283.15 to 353.15 K, respecti...

Bioactive substances in the Biobio River Basin in Chile were examined by deploying Semi Permeable Membrane Devices (SPMDs) upstream and downstream of 4 pulp mill effluent discharges. Androgenic and estrogenic activity of SPMD extracts were then evaluated using in vitro fish sex steroid receptor binding assays. The results indicated the occurrence of estrogenic type compounds associated with one of the mill discharges. A significant correlation among the presence of these compounds, an increase in gonadosomatic index GSI and induction of hepatic EROD activity of two native fish species was observed. However, no significant presence of mature oocytes in female gonads was detected. Although EROD induction was observed in sites impacted by mill effluents, an increase of its activity occurred towards the downstream areas, suggesting other non-mill sources. More research is needed to understand the environmental changes in context of the new technological improvements in treatment systems to MBBR (Moving Bed Biofilm Reactor) recently implemented by the pulp mill industries.

We show that phosphonium azolide ionic liquids of interest for CO2 capture applications react with CO2 both through the normal anion channel and, at elevated temperatures, through a previously unrecognized cation channel. The reaction is caused by an interaction between the anion and cation that allows proton transfer, and involves a phosphonium ylide intermediate. The cation reaction can be mitigated by using ammonium rather than phosphonium cations. Thus, phosphonium and ammonium cations paired with aprotic heterocyclic anions (AHAs) react with CO2 through different mechanisms at elevated temperatures. This work shows that careful consideration of both physical properties and chemical reactivity of ILs based on AHA anions is needed when designing ionic liquids for CO2 separations.

Ionic liquids (ILs) have been received significant attention in recent years due to their outstanding properties, such as negligibly small vapor pressure, high thermal stability, relatively high conductivity and wide electrochemical windows. [1-3] Especially in the electrochemical field, ILs have been intensively investigated as alternatives for common flammable and volatile organic solvents. [4] A series of novel ionic liquids based on N,N′dialkyimidazolium, alkylphosphonium and N,N′dialkylpyrrolidinium cations paired with two aprotic heterocyclic anions (AHAs) were synthesized in the present study. In addition, their corresponding lithium salts were prepared. Physicochemical and electrochemical properties of the neat ILs and their lithium salt mixtures at various concentrations were measured from 283.15K to 343.15K at atmosphere pressure. Properties investigated include density (ρ), viscosity (η), electrical conductivity (σ), melting point (Tm), and thermal decomposition temperature (Td). Generally, the densities of all the neat ILs and their mixtures with the corresponding lithium salts follow a linear relationship with temperature and decrease with increasing temperature. The densities of all the IL mixtures with lithium salts increased with increasing lithium salt concentrations. The temperature dependence of the viscosity and the electrochemical conductivity were investigated for all neat ILs and lithium salt doped ILs. The empirical Vogel-Fulcher-Tammann (VFT) equation was used to analyze the viscosity and the electrical conductivity experimental results, which gave excellent fits over the temperature range studied.

Organochlorine pesticides (OCPs) use has been restricted or forbidden in Argentina since 1998 and technical endosulfan is the last currently used OCPs on the soybean-wheat production. As they persist in soil for several years after application, OCPs constitute a source of environmental pollution. This work aims to assess OCPs contamination of groundwater (Gw) and streamwater (Sw) in the Quequen Grande River watershed from south Argentinean Pampas in relation to the hydrogeological characteristics. OCPs were analyzed in Sw, Gw, surface bottom sediments, soils and borehole cutting sediments (Cs) by gas chromatograph-electron capture detector. Pesticide distribution in Cs was dependent on the characteristic of the non-saturated zone. Leached pesticides over 3 m in Cs showed the pattern: HCHs = endosulfan > chlordanes > DDTs, and from 3 to 6 m heptachlor was the main group as a consequence of the past use of this compound in the area, mainly on potato crops. Endosulfan reaches Gw during application season as well as during flooding events while a retard effect was observed for Sw. Levels of α- and β-isomers were in certain cases above national (7 ng L−1) and international (3 ng L−1) limits for aquatic biota protection. As the endosulfan sulfate metabolite was present in Gw and Sw and due to its high toxicity, it should be considered in the establishment of water quality criteria for human and environmental protection.

J. Neurochem. (2011) 119, 78–88. Abstract The importance of copper in the CNS is well documented, but the mechanisms related to its brain functions are poorly understood. Copper is released at the synaptic cleft, where it may modulate neurotransmission. To understand the functional impact of copper on the neuronal network, we have analyzed the synaptic activity of primary rat hippocampal neurons by using different approaches including whole cell patch clamp, recording of calcium transients, immunofluorescence and western blot. Here, we show that copper produces biphasic changes in neurotransmission. When copper is acutely applied to the plate it blocks neurotransmission. Interestingly, when it is applied for 3 h to hippocampal neurons it mainly increases the frequency and amplitude of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)ergic currents (control: 0.21 ± 0.05 Hz/22.9 ± 1.3 pA; copper: 0.68 ± 0.16 Hz/30.5 ± 2.5 pA), intracellular calcium transients (control: 0.05 ± 0.013 Hz; copper: 0.11 ± 0.02 Hz) and evoked AMPA currents (control: EC50 8.3 ± 0.5 μM; copper: EC50 2.9 ± 0.2 μM). Moreover, our results suggest that copper increases GluA1 subunit levels of the AMPA receptor through the anchorage of AMPA receptors to the plasma membrane as a result of PSD-95 accumulation. We also found that copper-treated neurons displayed an undistinguishable neurotransmission to control neurons after 24 h of treatment, indicating that changes in neurotransmission induced by copper at 3 h of incubation are homeostatically regulated after long-term exposure to the metal. Together, our data reveal an unexpected biphasic effect of copper on neurotransmission, which may be relevant to understand the effects of this ion in brain diseases that display copper dyshomeostasis such as that observed in Alzheimer’s disease (AD).

3,3′,5,5′-Tetrasubstituted-2,2′-biphenolate complexes of titanium(IV) with bis(diketonate) (Bob), bis(hydroxamate) (Hox) and mixed diketonate–hydroxamate (Hob) ligands have been prepared from the corresponding diisopropoxide complexes. Four of the twelve compounds have been characterized crystallographically, and in the solid state all show the (Δ,R)/(Λ,S) relative stereochemistry at titanium and the biaryloxide, respectively, as previously observed in (acac)2Ti(1,1′-bi-2-naphtholate) complexes. In solution the compounds epimerize by atropisomerization of the biphenolate moiety with ΔG‡ ≈ 14 kcal mol−1. The bis(diketonate) complexes show high diastereoselectivity except for the most electron-poor tetranitrobiphenolate. In contrast, the bis(hydroxamate) shows low to moderate selectivity which correlates with the steric but not electronic properties of the biphenolates (Br < CH3 < NO2 < tBu). The mixed diketonate–hydroxamate complexes show intermediate behaviour. These observations are rationalized on the basis of MO arguments regarding ligand-metal π bonding. Symmetrical chelates such as diketonates foster mixing of two dπ orbitals and create a dissymmetric electronic environment. This mixing does not take place with unsymmetrical ligands such as hydroxamates, which therefore do not create an environment where electronic effects contribute significantly to binding stereoselectivity.

The synthesis, complete characterization, and solid state conformation of a new series of p-tert-butylcalix[5]arene (ButC5) mono-, di-, tri- and pentaanions are reported. X-ray structures of the alkali metal salts illustrate the strong influence of the alkali metal ion on the structure of the calixanion. The strength of the alkali metal base and its reaction stoichiometry play an important role in the conformation and level of deprotonation of the resulting anion. Reaction of ButC5 in a 2:1 molar ratio with alkali metal bases M2CO3 (M = Rb, Cs), or in a 1:1 ratio with M2CO3 (M = Na, K), MOH (M = Na, K, Rb, Cs) or MH (M = Li, Na) produces ButC5 monoanions, but ButC5 reacts in a 1:1 molar ratio with M2CO3 (M = Rb, Cs) or a 1:2 molar ratio with MOC(CH3)3 (M = Na, K) to afford ButC5 dianions. Due to the steric bulkiness of the But group no polymeric structures are observed. Alkali metal salts of trianionic ButC5 were obtained in high yields from reactions of ButC5 with MOC(CH3)3 (M = Li, Na, K), BunLi, LiH and LiOH in a 1:3 molar ratio. Pentaanionic ButC5 salts were obtained by the reaction with MOC(CH3)3 (M = Li, Na, K) or BunLi in a 5:1 ratio. X-ray crystal structures of ButC5 · Na and ButC5 · Cs indicate that the size of the alkali metal influences the level of cation-π arene interactions and therefore the conformation of the ButC5 unit; for example, ButC5 · Na has a cone conformation while ButC5 · Cs shows a flattened cone conformation. Cation-π arene interactions are observed in most of the calixarene salts.

Ionic liquids (ILs) with aprotic heterocyclic anions, or AHAs, can bind CO2 with reaction enthalpies that are suitable for gas separations and without suffering large viscosity increases. In the present work, we have synthesized ILs bearing an alkyl-phosphonium cation with indazolide, imidazolide, pyrrolide, pyrazolide and triazolide-based anions that span a wide range of predicted reaction enthalpies with CO2. Each AHA-based IL was characterized by NMR spectroscopy and their physical properties (viscosity, glass transition, and thermal decomposition temperature) determined. In addition, the influence of substituent groups on the reaction enthalpy was investigated by measuring the CO2 solubility in each IL at pressures between 0 and 1 bar at 22 °C using a volumetric method. The isotherm-derived enthalpies range between -37 and -54 kJ mol(-1) of CO2, and these values are in good agreement with computed enthalpies of gas-phase IL-CO2 reaction products from molecular electronic structure calculations. The AHA ILs show no substantial increase in viscosity when fully saturated with CO2 at 1 bar. Phase splitting and compositional analysis of one of the IL/H2O and IL/H2O/CO2 systems conclude that protonation of the 2-cyanopyrrolide anion is improbable, and this result was confirmed by the equimolar CO2 absorption in the presence of water. Taking advantage of the tunable binding energy and absence of viscosity increase after the reaction with CO2, AHA ILs are promising candidates for efficient and environmental-friendly absorbents in postcombustion CO2 capture.

Both the radical cation tris(4-bromophenyl)aminium hexachloridoantimonate ('Magic Blue'), (C(18)H(12)Br(3)N)[SbCl(6)], (I), and neutral tris(4-bromophenyl)amine, C(18)H(12)Br(3)N, (II), show extremely similar three-bladed propeller structures with planar N atoms. Key geometric features, such as the C-N bond distances and the angles between the planes of the aryl groups and the central NC(3) plane, are identical within experimental uncertainty in the two structures. This contrasts with the significant structural changes observed on oxidation of more electron-rich triarylamines, where resonance contributes to the stabilization of the radical cation, and suggests that, in general, more strongly oxidizing triarylaminium cations will have lower inner-sphere reorganization energies than their lower-potential analogues.

New sterically encumbered tripodal aminetris(aryloxide) ligands N(CH(2)C(6)H(2)-3-(t)Bu-5-X-2-OH)(3) ((tBu,X)LH(3)) with relatively electron-rich phenols are prepared by Mannich condensation (X = OCH(3)) or by a reductive amination/Hartwig-Buchwald amination sequence on the benzyl-protected bromosalicylaldehyde (X = N[C(6)H(4)-p-OCH(3)](2)), followed by debenzylation using Pearlman's catalyst (Pd(OH)(2)/C). The analogous dianisylamino-substituted compound lacking the tert-butyl group ortho to the phenol ((H,An(2)N)LH(3)) is also readily prepared. The ligands are metalated by titanium(IV) tert-butoxide to form the five-coordinate alkoxides LTi(O(t)Bu). Treatment of the tert-butoxides with aqueous HCl yields the five-coordinate chlorides LTiCl, and with acetylacetone gives the six-coordinate diketonates LTi(acac). The diketonate complexes (tBu,X)LTi(acac) show reversible ligand-based oxidations with first oxidation potentials of +0.57, +0.33, and -0.09 V (vs ferrocene/ferrocenium) for X = (t)Bu, MeO, and An(2)N, respectively. Both dianisylamine-substituted complexes (R,An(2)N)LTi(acac) (R = (t)Bu, H) show similar electrochemistry, with three one-electron oxidations closely spaced at approximately 0 V and three oxidations due to removal of a second electron from each diarylaminoaryloxide arm at approximately + 0.75 V. The new electron-rich tripodal ligands therefore have the capacity to release multiple electrons at unusually low potentials for aryloxide groups.

Ionic liquids (ILs) are attractive alternatives to water, high temperature molten salts or conventional organic solvents for electrodeposition of technologically important metals. Designing ILs containing functional groups specifically targeted to interact with or even chelate metals, such as carboxylate, may increase the metal solubility and affect thermodynamic and electrochemical properties. This paper reports the synthesis and characterization of three ionic liquids comprised of one or two tetra-alkyl phosphonium cations paired with a hydrogen oxalate or oxalate anion, with the general formula [(PRRRR′)x][C2O4H2−x], R = 4,6 and R′ = 4, 14. These compounds were characterized by 1H, 13C, 31P NMR, and Raman spectroscopy. Electrochemical windows, electrical conductivities, densities and viscosities were also determined experimentally. Thermal gravimetric analysis (TGA) revealed decomposition temperatures above 200 °C and differential scanning calorimetry (DSC) analysis revealed that the two [(P66614)x][C2O4H2−x] salts have similar glass transition temperatures while [(P4444)2][C2O4] has a melting point above room temperature. Raman and powder X-ray diffraction spectroscopy confirm that Nd2O3 dissolves and complexes with [P66614][C2O4].

The carboxyl-functionalized phosphonium ionic liquid (IL), [HCTMP][Tf(2)N], enabled the directed nucleation of monomeric or dimeric uranyl(vi) compounds. This new IL is the first carboxyl-functionalized IL which is liquid at room temperature and exhibits a wider electrochemical window and lower melting point than its ammonium analogue.

A series of novel ionic liquids (ILs) based on N, N'- dialkylimidazolium, tetra-alkylphosphonium and dialkylpyrrolidinium cations paired with two aprotic heterocyclic anions (AHAs) were synthesized in the present study. In addition, lithium salts of the corresponding anions were prepared. Physicochemical and electrochemical properties of the neat ILs and their mixtures with the lithium salts at various concentrations were systematically measured from 283.15K to 343.15K at atmospheric pressure, including density (ρ), viscosity (η) and electrical conductivity (σ). The empirical Vogel-Fulcher-Tammann (VFT) was used to analyze the experimental viscosities and electrochemical conductivities. Furthermore, the Walden plot behavior of the pure ILs and ILs doped with lithium salts were investigated. The results provide some insight into the strength of the association between Li+ and the different anions. Consequently, the ILs with low viscosity and good conductivities are promising electrolytes candidates to be used in electrochemical applications.

A diarylamino-substituted N-methyl tetrahydrosalen (salan) ligand, (An2N)LH(2), is prepared in four steps and overall 53% yield from 5-bromosalicylaldehyde, with the key step a palladium-catalysed Hartwig-Buchwald amination of the tert-butyldimethylsilyl-protected 5-bromo-N-methylsalan ligand. Reaction of (An2N)LH(2) or its bromo analogue with Ti(O(i)Pr)(4) or TiF(4) results in metalation of the ligand. The isopropoxide groups are readily exchanged with α- or β-hydroxyacids to form chelated complexes. X-ray crystallography and NMR spectroscopy indicate that the salan ligands are quite flexible, with (An2N)LTiF(2), for example, showing four stereoisomers in its (19)F NMR spectrum. The major stereoisomer of (salan)Ti(X)(Y) depends principally on the trans influence of the X and Y groups. Complexes of (An2N)L show two reversible, closely spaced redox couples at approximately + 0.1 V vs. ferrocene/ferrocenium, and a second set of two closely spaced redox couples at ~ + 0.8 V vs. Fc/Fc(+).