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At the morphological and anatomical levels, the ionome, or the elemental composition of an organism, is an understudied area of plant biology. In particular, the ionomic responses of plant-pathogen interactions are scarcely described, and there are no studies on immune reactions. In this study we explored two X-ray fluorescence (XRF)-based ionome visualisation methods (benchtop- and synchrotron-based micro-XRF [mu XRF]), as well as the quantitative inductively coupled plasma optical emission spectroscopy (ICP-OES) method, to investigate the changes that occur in the ionome of compatible and incompatible plant-pathogen interactions. We utilised the agronomically important and comprehensively studied interaction between potato (Solanum tuberosum) and the late blight oomycete pathogen Phytophthora infestans as an example. We used one late blight-susceptible potato cultivar and two resistant transgenic plant lines (only differing from the susceptible cultivar in one or three resistance genes) both in control and P. infestans-inoculated conditions. In the lesions from the compatible interaction, we observed rearrangements of several elements, including a decrease of the mobile macronutrient potassium (K) and an increase in iron (Fe) and manganese (Mn), compared with the tissue outside the lesion. Interestingly, we observed distinctly different distribution patterns of accumulation at the site of inoculation in the resistant lines for calcium (Ca), magnesium (Mg), Mn and silicon (Si) compared to the susceptible cultivar. The results reveal different ionomes in diseased plants compared to resistant plants. Our results demonstrate a technical advance and pave the way for deeper studies of the plant-pathogen ionome in the future.

The structural and spectroscopic properties of the compounds [C(NH2)3]5[Gd:M(CO3)4(H2O)]·0.75H2O (1) and [C(NH2)3]5[Y:M(CO3)4]·2H2O (2) (M = Eu, Cm) were determined. The crystals contain differently hydrated tetracarbonate complexes, [M(CO3)4(H2O)]5- and [M(CO3)4]5-, which were used as structural and spectroscopic models of Eu(iii) and Cm(iii) tetracarbonate species in aqueous solutions. The luminescence spectra of the crystals were used to establish the stoichiometry and stability of the limiting species of the aqueous Eu(iii) and Cm(iii) carbonate systems at different temperatures and in a broad range of ionic strengths. By implementing this method together with the Pitzer approach used for the description of highly concentrated systems, it was possible to determine the thermodynamic functions of the reaction [Eu(CO3)3]3- + CO32- ⇆ [Eu(CO3)4]5- under standard conditions for the first time (ΔH° = 31.4 ± 2 kJ mol-1 and ΔS° = 82 ± 10 J mol-1 K-1). The proposed model for Eu(iii) carbonates is consistent with the data recorded for the Cm(iii)-carbonate systems. The presented results are important not only from the point of view of environmental issues, but also for the coordination chemistry of f-elements in general.

Solvation of europium ions in mixed aqueous-organic solvents was studied in the solutions of europium(III) triflate and chloride. Europium ions are preferentially solvated by organic solvent only in water-dimethylsulfoxide systems. In aqueous dimethylformamide and dimethylacetamide preferential hydration in water-deficient region was observed. The total solvation number was proved to decrease from 9 in neat water to 8 in neat dimethylsulfoxide and dimethylformamide and to 7 in neat dimethylacetamide. The formation of chlorocomplexes in neat water and aqueous dimethylacetamide was observed.

The 4f-5d transition of Ce

International audience; The 4f-5d transition of Ce3+ provides favorable optical spectroscopic properties such as high sensitivity and quantum yield, making it a most important dopant for lanthanide-activated phosphors. A key for the design of these materials with fine-tuned color emission is a fundamental understanding of the Ce3+ ground state and excited state structures and the dynamics of energy transfer. Such data is also crucial for deriving coordination chemistry information on Ce3+ ions in different chemical environments directly from their optical spectra. Here, by combining 4f-5d absorption and luminescence spectroscopy and highly accurate quantum chemical electronic structure calculations, we study the interplay between the local structure of Ce3+ in aqueous solutions and in crystalline hydrates, the strengths of Ce−O/Cl interactions with aqua and chloride ligands, and the resulting absorption and luminescence spectra. Experimental and theoretical absorption spectra of [Ce(H2O)9]3+ and [Ce(H2O)8]3+ with defined geometries provide a means for analyzing the equilibrium between these species in aqueous solution as a function of temperature (K(298) = 0.20 ± 0.03), while analyses of spectra of different aqua-chloro complexes reveal that eight-coordinate aqua-chloro complexes are present in solution at high chloride concentration. An intriguing feature in these systems concerns the large observed Stokes shifts, 5500−10 100 cm-1. By exploring the excited state potential energy surfaces with relativistic multireference calculations, we show that these shifts result from significant geometrical relaxation processes in the lowest 5d1 excited state. For [*Ce(H2O)8]3+ the relaxation gives shorter Ce−O bonds and a Stokes shift of ∼5500 cm-1, while for [*Ce(H2O)9]3+ the lowest 5d1 state results in a spontaneous dissociation of a water molecule and a Stokes shift of ∼10 100 cm-1. These findings are important for the understanding and optimization of luminescence properties of cerium complexes.

More than a century after its discovery the structure of the Pa(4+) ion in acidic aqueous solution has been investigated for the first time experimentally and by quantum chemistry. The combined results of EXAFS data and quantum chemically optimized structures suggest that the Pa(4+) aqua ion has an average of nine water molecules in its first hydration sphere at a mean Pa-O distance of 2.43 A. The data available for the early tetravalent actinide (An) elements from Th(4+) to Bk(4+) show that the An-O bonds have a pronounced electrostatic character, with bond distances following the same monotonic decreasing trend as the An(4+) ionic radii, with a decrease of the hydration number from nine to eight for the heaviest ions Cm(4+) and Bk(4+). Being the first open-shell tetravalent actinide, Pa(4+) features a coordination chemistry very similar to its successors. The electronic configuration of all open-shell systems corresponds to occupation of the valence 5f orbitals, without contribution from the 6d orbitals. Our results thus demonstrate that Pa(iv) resembles its early actinide neighbors. French National Research Agency/ANR-11-LABX-000

The performances of three different Raman spectrometers were compared and evaluated as a suitable tool for the analysis of a range of uranium compounds with a view to application in nuclear forensics. These included uranium ore concentrates of different chemical composition and uranium dioxide in the form of powder and sintered fuel pellet. The three spectrometers are termed as ‘portable’ or ‘hand-held’ from Ahura Scientific (785 nm), ‘Senterra’ from Bruker (532 and 785 nm), ‘T64000′ from HORIBA Jobin Yvon (488.0, 514.5, 647.1 and 752.5 nm). Figures of merit such as sensitivity, signal-to-noise ratio and detection capability were compared. The portable Raman displayed fairly good sensitivity and process related impurities could be detected despite the miniaturisation but it was unable to measure darkly coloured powders such as calcined ore concentrates or uranium dioxide powder. The bench-top spectrometer Senterra had the best sensitivity for all the seven measured uranium compounds and the best signal-to-noise ratio for six of the compounds. Laboratory T64000 had the best resolution and at the same time resulting in the poorest sensitivity among the three spectrometers for all compounds measured. However, T64000 has very low level of noise therefore leading to better signal-to-noise that were comparable, if not better than the portable or Senterra. All industrial compounds measured in this study could not be measured with higher frequency laser thus impeding the observation of N–H or O–H vibration bands, of which the latter could be observed with laboratory synthesized material.

In recent work, we have deduced that berkelium and gadolinium, which have 4f and 5f with half-filled configurations, also display similar diffusion properties. Results, using self-diffusion coefficients to study thermodynamic properties, show very similar behavior, which is understood given their similarities in charge, ionic size, mobility, conductance, and hydration number. In this paper we undertook a study of Gd3+ as an aid for deducing the thermodynamics properties of the Bk3+ .In first part we compare magnitudes of transport (self-diffusion coefficient) of the trivalent aquo ions of Gd III for two concentrations, C1 = 2 10-4 mol.L-1, C2 = 10-3 mol.L-1 , and in perchlorate and nitrate media . In second part, we studied the variation of D with the medium’s pH. Self-diffusion coefficients, D, of the trivalent f-elements aqua ions have been determined in an aqueous electrolyte support of Gd(NO3)3 and Nd(ClO4)3 and at a pH=2.5. (HNO3, HClO4 ) and at 25 °C using the open-end capillary method (O.E.C.M.).The variation of D versus pH shows three zonesWe changed the NO3- counter ion with ClO4- ,and found that measurements must be carried in perchloric acid medium so as to avoid pairing phenomena. Using association constants between Gd3+ and NO3- , and a hydration constant, we estimated self-diffusion coefficients for Gd(NO3)2+ and Gd(OH)2+ .The results justified our choice of working at pH = 2.5 which constitute an optimum condition to avoid hydrolysis and pairing phenomena. Our results were confirmed by mobility measurements using an electro migration technique.

The new compound SrNp(PO(4))(2) (orthorhombic Cmca) has been synthesized by a solid-state reaction and its crystal structure solved ab initio and refined by Rietveld analysis. Though chemically and structurally related to the cheralite CaTh(PO(4))(2), SrNp(PO(4))(2) shows alternate layers of SrO(10) and NpO(8) polyhedra instead of a disordered array of 9-fold polyhedra. Raman and IR spectroscopic measurements also account for ordered cations. This novel structural type allows one to explain the boundaries of the cheralite domain in terms of the cation size and can be proposed as an archetype for a series of other actinide-bearing phosphate compounds.

crystal-field levels of the ground state as sharp and narrowly spaced lines. The total ground-state splittings in 1 (8.0 cm -1 ), 2 (6.0 cm -1 ), and 3 (7.5 cm -1 ) are about three to four times larger than those for Cm 3+ in LaCl3 (2.0 cm -1 ), but four to six times smaller than those for Cm 3+ in [Y(H2O)8]Cl3 ·15-crown-5 (35 cm -1 ). Inhomogeneous line broadening prevents resolving the ground multiplet levels in 4. Vibronic side bands associated with the 8 S′7/2- 6 D′7/2 transition are observed in the low temperature emission and excitation spectra. The intensities of these side bands are

The optical spectra of Cm(3+) incorporated into the crystalline host structure of [Y(H(2)O)(8)]Cl(3).15-crown-5 (1) is investigated by using laser spectroscopic methods at temperatures between 20 and 293 K. The coordination geometry of the [Y(H(2)O)(8)](3+) entity in 1 is a distorted bicapped trigonal prism with approximately C(2) point symmetry, as confirmed by single-crystal X-ray diffraction at 200 K. The crystal-field splitting of the (8)S'(7/2) ground state and the (6)D'(7/2) and (6)P'(5/2) excited states of the hydrated Cm(3+) ion are measured by high-resolution fluorescence emission and excitation spectroscopy at various temperatures. The transitions between the ground state and the respective lowest crystal-field levels of the excited states exhibit narrow fluorescence lines, resolving the four crystal-field levels of the ground state as sharp, well-resolved lines at about 0, 10, 19, and 35 cm(-1). The total splittings of the (6)D'(7/2) and (6)P'(5/2) states are 670 and 170 cm(-1), respectively. Thermal population of the ground-state crystal-field levels is observed and quantified in the excitation spectra in the temperature range of 20-70 K. All spectroscopic results are consistent with the presence of one unique [Cm(H(2)O)(8)](3+) site. The ground-state splitting of Cm(3+) in 1, 35 cm(-1), is comparable to that of Cm(3+) in solid ThO(2), 36 cm(-1), which shows the strongest crystal field for Cm(3+) reported so far. For this reason the present results are different than the findings for Ln(3+) aqua ions, which show rather weak crystal field strengths.

Time-resolved laser fluorescence spectroscopy (TRLFS) is used to study the hydration of the Cm3+ ion in acidified (0.1 M perchloric acid) H2O and D2O from 20 to 200 degrees C. Strong temperature dependency is found for several of the spectroscopic quantities associated with the 6D'(7/2) --> 8S'(7/2) photoemission spectra, with similar relative changes in both solvents. The emission band shifts to lower energy with increasing temperature, which is attributed to an equilibrium between hydrated Cm3+ ions with different numbers of water molecules in the first coordination sphere, namely [Cm(H2O)9]3+ and [Cm(H2O)8]3+. Comparison with crystalline reference compounds and the analysis of hot bands corroborates the assignment of these species. The molar fraction of the octahydrated species increases from approximately 10% at room temperature to approximately 40% at 200 degrees C, indicating an entropy driven reaction. The corresponding thermodynamic parameters are obtained as Delta H degrees = + 13.1 +/- 0.4 kJ mol(-1), Delta S degrees = + 25.4 +/- 1.2 J mol(-1) K(-1), and Delta G298 = + 5.5 +/- 0.6 kJ mol(-1). Both the emission intensity and lifetime decrease with increasing temperature. The temperature dependency of the nonradiative decay rate of the emitting 6D'(7/2) level follows an Arrhenius equation with the activation energy 26.5 kJ mol(-1) (2250 cm(-1)) in both H2O and D2O, which is somewhat lower than the energy gap between 6D'(7/2) and 6P'(5/2) exited state levels.

Hexakis(dimethyl sulfoxide)scandium(III) iodide, [Sc(OS(CH(3))(2))(6)]I(3) contains centrosymmetric hexasolvated scandium(III) ions with an Sc-O bond distance of 2.069(3) angstroms. EXAFS spectra yield a mean Sc-O bond distance of 2.09(1) angstroms for solvated scandium(III) ions in dimethyl sulfoxide solution, consistent with six-coordination. Raman and infrared absorption spectra have been recorded, also of the deuterated compound, and analysed by means of normal coordinate methods, together with spectra of dimethyl sulfoxide. The effects on the vibrational spectra of the weak intermolecular C-H...O interactions and of the dipole-dipole interactions in liquid dimethyl sulfoxide have been evaluated, in particular for the S-O stretching mode. The strong Raman band at 1043.6 cm(-1) and the intense IR absorption at 1062.6 cm(-1) have been assigned as the S-O stretching frequencies of the dominating species in liquid dimethyl sulfoxide, evaluated as centrosymmetric dimers with antiparallel polar S-O groups. The shifts of vibrational frequencies and force constants for coordinated dimethyl sulfoxide ligands in hexasolvated trivalent metal ion complexes are discussed. Hexasolvated scandium(iii) ions are found in dimethyl sulfoxide solution and in [Sc(OSMe(2))(6)]I(3). The iodide ion-dipole attraction shifts the methyl group C-H stretching frequency for (S-)C-H...I(-) more than for the intermolecular (S-)C-H...O interactions in liquid dimethyl sulfoxide.

Surface sensitive grazing incidence XAFS measurements of mineral sorbed metal cations are used to characterize the metal sorbed at reactive surface sites. Two different systems are studied: (1) Hf(IV) sorbed onto the (001) basal plane of freshly cleaved mica and a surface oxidized silicon wafer and (2) U(VI) sorbed onto the (110) surface of α-Al2O3 at two different concentrations and two different orientations of the crystal surface plane to the polarization vector of the incident synchrotron radiation. Similar to findings reported for Hf(IV) sorbed onto amorphous silica, the EXAFS metrical parameters for Hf(IV) on both the mica (001) basal plane and on the oxidized silicon surface show that a mononuclear surface species forms. The cations are bound to silanol/aluminol groups present as defects on the mica surface in a fashion equivalent to binding to clay (hk0) edge sites. The polarization dependency of the XANES/EXAFS spectra of the α-Al2O3 surface sorbed U(VI) uranyl moiety shows that the linear uranyl cations exhibit a preferred orientation on the (110) surface. Comparison of the XANES spectral trends with data previously recorded for UO2(CH3CO2)2·2H2O single crystals and fits to the EXAFS data allows identification of the reactive sites as the AlO6 octahedral edges on the α-Al2O3 (110) surface.

The extended dynamic model of liquid water which considers five different hydrogen-bonded states (including three dominant states) and two major positions of the water molecule in equilibrium, is presented based mostly onthe analysis of near-infrared overtone spectra for the O-D stretching vibration of pure liquid D 2 O, obtained and evaluated within the temperature range of 278 - 358 K (5 - 85 °C). In agreement with the earlier data of Luck and Ditter (1969), and Angell and Rodgers (1984), it was found that the integrated intensity (but not the shape) of the specified (composite) overtone band, situated within the spectral range of 4250 - 5750 cm - 1 , is almost independent of temperature, and displays a quasi-isosbestic point at ca. 5100 cm - 1 . Moreover, the density-corrected difference spectra taken with intervals of 10, 20 and 40 K clearly indicate that the temperature effect is determined by the intensity redistribution between two major components (sub-bands) of the total of five forming the composite overtone contour. These two sub-bands according to their center-of-mass positions, and on the basis of published structural (Bosio et al., 1983), static spectroscopic (Berglund et al., 1978, Walrafen et al., 1986, 1996), and MD simulation (Scortino et al., 1990-1992, Sato and Hirata, 1999) data, can be attributed to the "normal" and temperature-distorted ("T-bifurcated", but not "totally broken") hydrogen-bonded states of O-D oscillators, respectively. In addition, the global Gaussian-contour analysis of obtained composite spectra clearly revealed the existence of O-D oscillator states corresponding to the fraction of presumably pressure-responsive ("P-bifurcated") hydrogen bonds promoted by formation of additional "rigid" five-coordinated water configurations (furnished also by forming of quasi-linear O-O-O trimers within the hexagonal Ih ice-like lattice). The integrated intensity due to this fraction of hydrogen-bonded states does not display any change with temperature, over the whole range of existence of liquid water, as indicated earlier by Luck, Angell, and their co-workers. The whole variety of structural, static spectroscopic, and MD simulation data, together with the results of dielectric relaxation temperature dependence studies (Ronne et al., 1997, 1999, Buchner et al., 1999) can be readily explained in the framework of dynamic "tetrahedral displacement" model first formulated by Agmon (1996). This model implies the temperature-dependent "flip-flop" equilibrium between two major positions for a given water molecule (corresponding to the tetrahedral four-neighbor and the interstitial five-neighbor configurations), the exchange between which is accomplished by the breakage and formation of a net "normal" and a net "T-bifurcated" (and vice versa) hydrogen bond, respectively. The extended van't Hoff analysis indicate that the transition between two states of water at ca. 313 K (40 °C) takes place with almost zero equilibrium free energy, but significant counterbalanced enthalpy and entropy contributions (3.3 kcal mol - 1 and 10.5 cal mol - 1 K - 1 , respectively). In contrast, the effect of high pressure, according to the published data, can be viewed as leading to the "tetrahedral displacements" thanks to the highly-cooperative process of formation of "P-bifurcated" hydrogen bonds only, without altering the quasi-equilibrium between "normal" and "T-bifurcated" fractions.

The structure and bonding in bisaquamercury(II) trifluoromethanesulfonate, [Hg(OH2)2(CF3SO3)2]∞, and trisaquathallium(III) trifluoromethanesulfonate, [Tl(OH2)3(CF3SO3)3], have been studied by means of single-crystal X-ray diffraction, EXAFS and vibrational spectroscopy. The crystal structure of bisaquamercury(II) trifluoromethanesulfonate shows an unusual connectivity pattern. The mercury(II) ion strongly binds two water molecules axially with the Hg–O bond distance 2.11 A, and four oxygen atoms from four trifluoromethanesulfonate ions complete a tetragonally compressed octahedral coordination geometry, at the mean Hg–O distance 2.53 A. Two trifluoromethanesulfonate ions form double bridges between the bisaquamercury(II) entities giving rise to infinite >Hg(OH2)2 Hg(OH2)2< chains. The parallel chains are held together in layers by relatively strong hydrogen bonds with O(–H)⋯O distances in the range 2.688(9)–2.735(9) A. The O–D stretching vibrational frequencies of the hydrogen bonds in the partly deuterated compound occur in a broad band at about 2400 cm−1, bandwidth ca. 170 cm−1. The layers are connected only via van der Waals interactions between the protruding CF3 groups, consistent with the fragile sheet-like structure of the crystalline compound. Trisaquathallium(III) trifluoromethanesulfonate crystallises as molecular complexes where each thallium(III) ion binds three water molecules and three oxygen atoms from trifluoromethanesulfonate ions, with Tl–O bond distances in the range 2.18–2.24 A. A hydrogen bond network between the water molecules and trifluoromethanesulfonate ions with O(–H)⋯O distances in the range 2.65(1)–2.80(1) A holds the structure together. Raman and infrared spectra have been recorded and analysed. The changes in force constants and vibrational frequencies have been correlated with bond lengths for the S–O bond in the coordinated trifluoromethanesulfonate ion and for the Hg–O and Tl–O bonds, also including the hexaaquaions in the comparisons.

The structure of the hydrated calcium(II) ion in aqueous solution has been studied by means of extended X-ray absorption fine structure spectroscopy (EXAFS), large-angle X-ray scattering (LAXS), and molecular dynamics (MD) methods. The EXAFS data displayed a broad and asymmetric distribution of the Ca-O bond distances with the centroid at 2.46(2) A. LAXS studies on four aqueous calcium halide solutions (1.5-2 mol dm(-)(3)) gave a mean Ca-O bond distance of 2.46(1) A. This is consistent with a hydration number of 8 determined from correlations between mean distances and coordination numbers from crystal structures. The LAXS studies showed a second coordination sphere with a mean Ca.O(II) distance of 4.58(5) A, and for the hydrated halide ions the distances Cl.O 3.25(1) A, Br.O 3.36(1) A, and I.O 3.61(1) A were obtained. Molecular dynamics simulations of CaCl(2)(aq) were performed using three different Ca(2+)-OH(2) pair potentials. The potential from the GROMOS program gave results in agreement with experiments, i.e., a coordination number of 8 and an average Ca-O distance of 2.46 A, and was used for further comparisons. Theoretical EXAFS oscillations were computed for individual MD snapshots and showed very large variations, though the simulated average spectrum from 2000 snapshots gave satisfactory agreement with the experimental EXAFS spectra. The effect of thermal motions of the coordinated atoms is inherent in the MD simulation method. Thermal disorder parameters evaluated from simulated spatial atom distribution functions of the oxygen atoms coordinated to the calcium ion were in close agreement with those from the current LAXS and EXAFS analyses. The combined results are consistent with a root-mean-square displacement from the mean Ca-O distance of 0.09(2) A in aqueous solution at 300 K.

Theoretical extended X-ray absorption fine structure (EXAFS) spectra have been computed from molecular dynamics (MD) simulation data. Based on MD-generated molecular geometries, EXAFS spectra were generated with the FEFF6 program, commonly used in the analysis of experimental EXAFS spectra. The effects of multiple scattering and second-shell neighbors on the theoretical spectra were evaluated for CaCl2(aq) and AlCl3(aq), i.e., for two solutions with very different cation hydration structures. The effects are significantly larger for the more structured Al3+ solution, The theoretical Ca2+(aq) spectra are compared with new experimental EXAFS data.

The structure of the solvated yttrium(III) ion in the oxygen donor solvents dimethyl sulfoxide, N,N-dimethylformamide and N,N′-dimethylpropyleneurea, OCN2Me2(CH2)3, has been studied by means of XAFS and large angle X-ray scattering. The yttrium(III) ion co-ordinates eight solvent molecules in dimethyl sulfoxide and N,N-dimethylformamide solution with the mean Y–O bond distance 2.36(1) A. The slightly asymmetric distribution was modelled by the cumulant expansion method for the XAFS data. The Y⋯S distance of the [Y(OSMe2)8]3+ ion in dimethyl sulfoxide solution was found to be 3.54(1) A, corresponding to a mean Y–O–S angle of 132°. For the [Y(OCHNMe2)8]3+ ion in N,N-dimethylformamide the Y⋯C distance is 3.34(1) A, giving a Y–O–C angle of 133°. In N,N′-dimethylpropyleneurea solution the steric effect of the bulky solvent molecules reduces the co-ordination number to six and the mean Y–O bond distance to 2.24(1) A. The mean Y⋯C distance at 3.48(2) A agrees with an analysis of the angular-sensitive multiple scattering contributions, which gave a Y–O–C angle of about 165°. The crystal structures of [Y(OCN2Me2(CH2)3)6]I3 and [Y(OSMe2)8]I3, determined by X-ray diffraction at room temperature, show the ionic radii of yttrium(III) to increase about 0.12 A from six to eight co-ordination.

The yttrium(III) ion is found by means of extended X-ray absorption fine-structure spectroscopy (EXAFS) and large angle X-ray scattering (LAXS) to be hydrated by eight water molecules in aqueous so...

International audience; N-donor ligands such as n-Pr-BTP (2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine) studied here preferentially bind An(III) over Ln(III) in liquid-liquid separation of trivalent ac-tinides from spent nuclear fuel. The chemical and physical processes responsible for this selectivity are not yet well understood. We present systematic comparative near-edge X-ray absorption structure (XANES) spectroscopy investigations at the Gd L-3 edge of [GdBTP3](NO3)(3), [Gd(BTP)(3)](OTf)(3), Gd(NO3)(3), Gd(OTf)(3) and N K edge of [Gd(BTP)(3)](NO3)(3), Gd(NO3)(3) complexes. The pre-edge absorption resonance in Gd L3 edge high-energy resolution X-ray absorption near edge structure spectra (HR-XANES) is explained as arising from 2p(3/2) -> 4f/5d electronic transitions by calculations with the FEFF9.5 code. Experimental evidence is found for higher electronic density on Gd in [Gd(BTP)(3)](NO3)(3) and [Gd(BTP)(3)](OTf)(3) compared to Gd in Gd(NO3)(3) and Gd(OTf)(3), and on N in [Gd(BTP)(3)](NO3)(3) compared to n-Pr-BTP. The origin of the pre-edge structure in the N K edge XANES is explained by density functional theory (DFT) with the ORCA code. Results at the N K edge suggest a change in ligand orbital occupancies and mixing upon complexation but further work is necessary to interpret observed spectral variations

The effect of potassium chloride and pH on the interfacial water layer around Teflon particles and flat Teflon surfaces was investigated. Electrokinetic measurements and potentiometric titrations were carried out as well as contact angle measurements for some selected pH values. The electrokinetic measurements at flat Teflon plates in contact with potassium chloride aqueous solution shows that the isoelectric point is at pHiep ≈ 3.7. The electrokinetic potential of Teflon depends on ionic strength. Potentiometric mass titrations of Teflon suspensions in different concentrations of potassium chloride show that the point of zero charge lies in the same pH region (pHpzc ≈ 3.5) as the pHiep. A minimum of the contact angle was observed in the acidic region, at pH ≈ 3, close to the pHpzc and pHiep. Interestingly, the calculated surface charge densities were found to be independent of the electrolyte concentration. As a possible and widely brought forward explanation it is suggested that the concentrations of OH− and H+ ions within the interfacial water layer depend on pH and are not equal. All findings together support the hypothesis that the interfacial water layer around Teflon is the origin of the interfacial charge.

BaTh(PO4)2 is synthesized from a gel obtained from aqueous solutions of Th(NO3)4, Ba(NO3)2, and NH4H2PO4 by annealing at 1250 °C (72 h).

International audience; BaTh(PO4)2 has been synthesized by a wet chemistry route and the new isotype BaNp(PO4)2 by solid-state reaction. Although the former has been the subject of several studies since the early 1980s, the crystal structures of both compounds are reported here for the first time. Rietveld analysis shows Ba layers alternating with An(PO4)2 slabs along the a axis. Although those compounds are isostructural to RbEu(SO4)2, these phosphates can be seen as modified yavapaiite derivatives with increased coordination numbers for Ba (XIV) and Th/Np (VIII). Raman and electron absorption spectra highlight the similarities and differences with chemically related compounds.

The formation of hydrated CmF2+ and CmF2+ species in aqueous solutions are studied in the temperature range of 20−90 °C at different fluoride concentrations and at constant ionic strength as well as at constant fluoride concentration and different ionic strengths by means of time-resolved laser fluorescence spectroscopy (TRLFS). The molar fractions of the Cm3+ aqua ion, CmF2+, and CmF2+ species are determined by peak deconvolution of the emission spectra. An increase of the mono- and difluoro complexes is observed with increasing fluoride concentration and/or increasing temperature. Using the specific ion interaction theory (SIT), the thermodynamic stability constants log K10 (CmF2+) and log K20 (CmF2+) as well as the values of Δε1 and Δε2 are determined as a function of temperature. The log K10 values increase from 3.56 ± 0.07 to 3.98 ± 0.06 and the log K20 values increase from 2.20 ± 0.84 to 3.34 ± 0.21 with increasing temperature from 20 to 90 °C. The value of Δε1 determined at 25 °C is in good agreement with literature data and shows a negligible temperature dependency in the studied temperature range. The value of Δε2 also shows only a moderate variation in the studied temperature range. The thermodynamic standard state data (ΔrHm0, ΔrSm0, ΔrGm0) are determined from the temperature dependence of the equilibrium constants at Im = 0 using the integrated Van’t Hoff equation. The fluorescence lifetime of the 6D′7/2(Cm3+) state is found to be constant at 63 ± 5 μs with increasing fluoride concentration. A model based on density functional theory (DFT) calculations is introduced to account for the additional quenching occurring through the near second sphere waters in the [Cm(H2O)8F]2+(H2O)18 complex.

The new title compound is prepared by solid state reaction of 237NpO2, Sr(NO3)2, and excess (NH4)2HPO4 (argon; 1.

The strongly hydrogen bonded species (CH3)2SO...H3O+ formed in concentrated hydrochloric acid displays a new low energy feature in its sulfur K-edge X-ray absorption near edge structure (XANES) spectrum. Density Functional Theory-Transition Potential (DFT-TP) calculations reveal that the strong hydrogen bonding decreases the energy of the transition S(1s) --LUMO, which has antibonding sigma*(S-O) character, with about 0.8 eV. Normal coordinate force field analyses of the vibrational spectra show that the SO stretching force constant decreases from 4.72 N cm(-1) in neat liquid dimethyl sulfoxide to 3.73 N cm(-1) for the hydrogen bonded (CH3)2SO...H3O+ species. The effects of sulfur coordination on the ambidentate dimethyl sulfoxide molecule were investigated for the trans-Pd((CH3)2SO)2Cl2, trans-Pd((CD3)2SO)2Cl2 and cis-Pt((CH3)2SO)2Cl2 complexes with square planar coordination of the chlorine and sulfur atoms. The XANES spectra again showed shifts toward low energy for the transition S(1 s) --LUMO, now with antibonding sigma*(M-Cl, M-S) character, with a larger shift for M = Pt than Pd. DFT-TP calculations indicated that the differences between the XANES spectra of the geometrical cis and trans isomers of the M((CH3)2SO)2Cl2 complexes are expected to be too small to allow experimental distinction. The vibrational spectra of the palladium(II) and platinum(II) complexes were recorded and complete assignments of the fundamentals were achieved. Even though the M-S bond distances are quite similar the high covalency especially of the Pt-S bonds induces significant increases in the S-O stretching force constants, 6.79 and 7.18 N cm(-1), respectively.

The formation of aqueous Cm(III) nitrate complexes is studied in the temperature range from 5 to 200 °C by time resolved laser fluorescence spectroscopy (TRLFS). The experiments are performed in a custom build high pressure and high temperature fluorescence cell. The complex formation is measured at nitrate concentrations ranging from 0.10 to 4.61 mol/kg H 2 O. The mono- and dinitrate complexes are quantified by peak deconvolution of the fluorescence spectra and the complexation constants are determined as a function of the temperature. The conditional equilibrium constants are extrapolated to zero ionic strength using the specific ion interaction theory (SIT) and the thermodynamic standard state data (Δ r H° m , Δ r S° m , Δ r G° m , Δ r C° p,m ) are determined from the temperature dependence of the equilibrium constants at I = 0. The equilibrium constants up to 75 °C are well described by the Van't Hoff equation (Δ r H° m independent of T and Δ r C° p,m = 0). Modelling of the data at higher temperatures requires an extended equation including a term for the heat capacity changes (Δ r C° p,m ).

The structure of the solvated mercury(II) ion in water and dimethyl sulfoxide has been studied by means of large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) techniques. The distribution of the Hg-O distances is unusually wide and asymmetric in both solvents. In aqueous solution, hexahydrated [Hg(OH(2))(6)](2+) ions in a distorted octahedral configuration, with the centroid of the Hg-O distance at 2.38(1) A, are surrounded by a diffuse second hydration sphere with HgO(II) distances of 4.20(2) A. In dimethyl sulfoxide, the six Hg-O and HgS distances of the hexasolvated [Hg{OS(CH(3))(2)}(6)](2+) complex are centered around 2.38(1) and 3.45(2) A, respectively. The crystal structure of hexakis(pyridine 1-oxide)mercury(II) perchlorate has been redetermined. The space group R(-)3 implies six equal Hg-O distances of 2.3416(7) A for the [Hg(ONC(5)H(5))(6)](2+) complex at 100 K. However, EXAFS studies of this compound, and of the solids hexaaquamercury(II) perchlorate and hexakis(dimethyl sulfoxide)mercury(II) trifluoromethanesulfonate, also with six equidistant Hg-O bonds according to crystallographic results, reveal in all cases strongly asymmetric Hg-O distance distributions. Vibronic coupling of valence states in a so-called pseudo-Jahn-Teller effect probably induces the distorted configurations.

In the original publication of this paper, the affiliation of the third and the fourth author were interchanged. The correct affiliation for William H. Casey is: Department of Chemistry, University of California, Davis, CA, 95616, USA. The correct affiliation for Gerhard Furrer is: Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich, Universitatstrasse 8, 8092 Zurich, Switzerland. Remi Marsac has moved to Ecole Nationale Superieure de Chimie de Rennes, UMR CNRS 6226, 11 Allee de Beaulieu, F-35708 Rennes Cedex 7, France, as of 01.05.2015.

Trivalent lanthanide-like metal ions coordinate nine water oxygen atoms, which form a tricapped trigonal prism in a large number of crystalline hydrates. Water deficiency, randomly distributed over the capping positions, was found for the smallest metal ions in the isomorphous nonahydrated trifluoromethanesulfonates, [M(H2O)n](CF3SO3)3, in which M = Sc(III), Lu(III), Yb(III), Tm(III) or Er(III). The hydration number n increases (n = 8.0(1), 8.4(1), 8.7(1), 8.8(1) and 8.96(5), respectively) with increasing ionic size. Deuterium (2H) solid-state NMR spectroscopy revealed fast positional exchange between the coordinated capping and prism water molecules; this exchange started at temperatures higher than about 280 K for lutetium(III) and below 268 K for scandium(III). Similar positional exchange for the fully nonahydrated yttrium(III) and lanthanum(III) compounds started at higher temperatures, over about 330 and 360 K, respectively. An exchange mechanism is proposed that can exchange equatorial and capping water molecules within the restrictions of the crystal lattice, even for fully hydrated lanthanoid(III) ions. Phase transitions occurred for all the water-deficient compounds at approximately 185 K. The hydrated scandium(III) trifluoromethanesulfonate transforms reversibly (DeltaH degrees = -0.80(1) kJ mol(-1) on cooling) to a trigonal unit cell that is almost nine times larger, with the scandium ion surrounded by seven fully occupied and two partly occupied oxygen atom positions in a distorted capped trigonal prism. The hydrogen bonding to the trifluoromethanesulfonate anions stabilises the trigonal prism of water ligands, even for the crowded hydration sphere of the smallest metal ions in the series. Implications for the Lewis acid catalytic activity of the hydrated scandium(III) and lanthanoid(III) trifluoromethanesulfonates for organic syntheses performed in aqueous media are discussed.

The time dependent changes of Lu speciation (used as Am(III) homologue), initially sorbed onto 2-line ferrihydrite at pH 5.9, during tempering (70 degrees C) to stable crystalline transformation products, goethite and hematite, is studied. Microscopies (AFM, SEM), XRD and FTIR spectroscopy confirm transformation to both goethite and hematite, with a predominance of hematite. XRD investigation of another transformation series at pH 8.0 (75 degrees C, [Lu(III)initial] 7 times higher) shows that the cell volume of hematite increases, suggesting the incorporation of Lu in the crystal structure. Extended X-ray absorption fine structure (EXAFS) (pH 5.9 series, 70 degrees C) reveals a shortening of the Lu-O bond distance and an increase in asymmetry of the first shell with increasing tempering time in the intermediate temper time samples. The intensity of the second peak in the Fourier transform (FT) of the EXAFS increases and splits into two components. The EXAFS data of the end product can be modeled well using a hematite-like cluster, with an isotropic expansion of distances to account for incorporation of Lu into the hematite structure. These results demonstrate that the Lu is incorporated in the crystal lattice of the transformation product, as opposed to being occluded or remaining a sorbed species on the surface.

The structure of the hydrated gallium(III), indium(III), and chromium(III) ions has been determined in aqueous perchlorate and nitrate solutions by means of the large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) techniques. The EXAFS studies have been performed over a wide concentration range, 0.005-1.0 mol.dm(-)(3) (2.6 mol.dm(-)(3) for chromium(III)), while the LAXS studies are restricted to concentrated solutions, ca. 1.5 mol.dm(-)(3). All three metal ions were found to coordinate six water molecules, each of which are hydrogen bonded to two water molecules in a second hydration sphere. The metal-oxygen bond distance in the first hydration sphere of the gallium(III), indium(III), and chromium(III) ions was determined by LAXS and EXAFS methods to be 1.959(6), 2.131(7), and 1.966(8) A. The LAXS data gave mean second sphere M.O distances of 4.05(1), 4.13(1), and 4.08(2) A for the gallium(III), indium(III), and chromium(III) ions, respectively. The perchlorate ion was found to be hydrogen bonded to 4.5(7) water molecules with the O.O distance 3.05(2) A and Cl.O 3.68(3) A. Analyses of the Ga, In, and Cr K-edge EXAFS data of the aqueous perchlorate and nitrate solutions showed no influence on the first shell M-O distance by a change of concentration or anion. The minor contribution from the second sphere M.O distance is obscured by multiple scattering within the tightly bonded first shell. EXAFS data for the alum salts CsM(SO(4))(2).12H(2)O, M = Ga or In, showed the M-O bond length of the hexahydrated gallium(III) and indium(III) ions to be 1.957(2) and 2.122(2) A, respectively.

The structure of the solvated lanthanum(III) ion has been determined in aqueous, dimethyl sulfoxide, and N,N'-dimethylpropyleneurea solution by means of the EXAFS and large-angle X-ray scattering (LAXS) techniques. The close agreement between the EXAFS spectra of solid nonaaqualanthanum(III) trifluoromethanesulfonate and of an aqueous lanthanum(III) perchlorate solution shows that the hydrated lanthanum(III) ion in aqueous solution most probably has the same structure as in the solid, i.e., nine water molecules coordinated in a tricapped trigonal prismatic configuration. The data analysis from EXAFS and LAXS measurements of the aqueous solution resulted in the La-O bond distances 2.52(2) and 2.65(3) A to the water molecules in the prism and the capping positions, respectively. The LAXS study shows a second hydration sphere consistent with approximately 18 water molecules at 4.63(2) A. The EXAFS spectra of solid octakis(dimethyl sulfoxide)lanthanum(III) trifluoromethanesulfonate and a dimethyl sulfoxide solution of this salt are also similar. The data analysis of EXAFS and LAXS measurements assuming eight-coordination around lanthanum yielded an La-O bond distance of 2.50(2) A, and an La...S distance of 3.70(3) A, giving an La-O-S angle of 133(2) degrees. The EXAFS data of an N,N'-dimethylpropyleneurea solution of lanthanum(III) trifluoromethanesulfonate gave the La-O bond distance 2.438(4) A and the La...C distance 3.41(2) A, which correspond to an La-O-C angle of 131(2) degrees. The La-O bond distance is consistent with seven-coordination around lanthanum, on the basis of the variation of the ionic radii of the lanthanum(III) ion with different coordination numbers.

The title compound, [Y(C2H6OS)2(H2O)6]Cl3, contains the cation [Y(H2O)6{(CH3)2SO}2]3+ with a distorted square antiprismatic geometry of the eight coordinated O atoms. The six water mol­ecules are coordinated with an average Y—O distance of 2.38 (2) A, ranging from 2.360 (3) to 2.404 (3) A. Each water mol­ecule forms two hydrogen bonds to the chloride anions with O—Cl distances ranging from 3.068 (4) to 3.422 (4) A. The two di­methyl­ sulfoxide ligands, situated in the cis position with the O—Y—O angle equal to 83.22 (11)°, have Y—O distances of 2.269 (3) and 2.278 (3) A.

Complexation between hexavalent neptunium and nitrate was studied in aqueous nitric acid solution using optical absorption, vibrational and X-ray absorption spectroscopies. Distributions of aqueous [NpO2](2+), [NpO2(NO3)](+) and [NpO2(NO3)2] species were obtained as a function of nitric acid concentration between 0 and 14 M. The crystal structure of [NpO2(NO3)2(H2O)2]·H2O was determined.

Measurement of the polarization dependence of surface sensitive grazing incidence (GI) x-ray absorption fine structure (XAFS) spectra at the U L3 edge is applied to identify reactive U(VI) sorption sites on various mineral surfaces. We use the known polarization dependence of the dioxouranium(VI) or 'uranyl' cation, [O=U=O]2+, to experimentally determine its orientation when sorbed onto single crystal mineral surfaces (α-Al2O3, CaCO3). The GIXAFS signal measured at different orientations of a U(VI) sorbed α-Al2O3 (11-20) wafer relative to the polarization vector of the incident synchrotron radiation, e, indicates that the uranyl surface species exhibit a preferred surface orientation. Analysis of the EXAFS substantiates our previous findings, identifying the reactive sorption sites as AlO6 octahedral edges on the surface. Initial results of uranyl sorbed onto freshly cleaved (10-14) surface of natural calcite indicate that uranyl cations sorb onto terrace step edges and not onto the surface plane or with an orientation of the [O=U=O]2+ unit parallel to the (10-14) surface.