Search results for "FACES"
showing 10 items of 3167 documents
Kinetics of Zn2+ complexation by a ditopic phenanthroline-azamacrocyclic scorpiand-like receptor.
2012
Coordination of Zn(2+) to a ditopic phenanthroline-macrocycle receptor takes place in three steps, the first one being the coordination to the phenanthroline, followed by the slow movement of the metal to the polyamine macrocycle and a final re-arrangement to coordinate the pendent arm.
The azido ligand: a useful tool in designing chain compounds exhibiting alternating ferro- and antiferro-magnetic interactions
1997
A one-pot reaction of NiII 1, CoII 2, FeII 3 and MnII 4 with 2,2A-bipyridine (bipy) and azide in water leads to [M(bipy)(N3)2]n chains where the metal ion is alternatively bridged by double end-on (EO) and end-to-end (EE) azido bridges; theoretical analysis of the variable-temperature magnetic susceptibility data of 1 and 4 reveals the occurrence of intrachain alternating ferro- (through EO) and antiferro-magnetic (through EE) interactions. Julve Olcina, Miguel, Miguel.Julve@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es ; Clemente Juan, Juan Modesto, Juan.M.Clemente@uv.es
Systematic trends in (0 0 1) surface ab initio calculations of ABO 3 perovskites
2018
This work was supported by the Latvian Council of Science Grant No. 374/2012 and the Latvian National Research Program IMIS2. Many stimulating discussions with D. Vanderbilt, K.M. Rabe, M. Rohlfing, E. Heifets, J. Maier, G. Borstel and E.A. Kotomin are greatly acknowledged.
Spontaneous growth of 2D coordination polymers on functionalized ferromagnetic surfaces
2018
2D coordination polymers grow spontaneously on reactive surfaces due to surface oxidation. The growth process is observed in real time.
Electron Transfer from Organic Aminophenyl Acid Sensitizers to Titanium Dioxide Nanoparticle Films
2009
Electron transfer from three conjugated amino-phenyl acid dyes to titanium and aluminum oxide nanocrystalline films was studied by using transient absorption spectroscopy with sub 20 fs time-resolution over the visible spectral region. All the dyes attached to TiO2 showed long-lived ground state bleach signals indicative of formation of new species. Global analysis of the transient kinetics of the dyes on TiO2 revealed stimulated emission decays of about 40 fs and less than 300 fs assigned to electron injection. The same dyes on Al2O3 substrates displayed long stimulated emission decays (ns) suggesting that electron transfer is blocked in this high band gap semiconductor. For two of the dye…
Mobility and fluxes of major, minor and trace metals during basalt weathering and groundwater transport at Mt. Etna volcano (Sicily)
2000
Abstract The concentrations and fluxes of major, minor and trace metals were determined in 53 samples of groundwaters from around Mt Etna, in order to evaluate the conditions and extent of alkali basalt weathering by waters enriched in magma-derived CO 2 and the contribution of aqueous transport to the overall metal discharge of the volcano. We show that gaseous input of magmatic volatile metals into the Etnean aquifer is small or negligible, being limited by cooling of the rising fluids. Basalt leaching by weakly acidic, CO 2 -charged water is the overwhelming source of metals and appears to be more extensive in two sectors of the S-SW (Paterno) and E (Zafferana) volcano flanks, where out …
Geochemical mapping of magmatic gas–water–rock interactions in the aquifer of Mount Etna volcano
2001
Abstract Systematic analysis of major and minor elements in groundwaters from springs and wells on the slopes of Mt. Etna in 1995–1998 provides a detailed geochemical mapping of the aquifer of the volcano and of the interactions between magmatic gas, water bodies and their host rocks. Strong spatial correlations between the largest anomalies in pCO2 (pH and alkalinity) K, Rb, Mg, Ca and Sr suggest a dominating control by magmatic gas (CO2) and consequent basalt leaching by acidified waters of the shallow (meteoric) Etnean aquifer. Most groundwaters displaying this magmatic-type interaction discharge within active faulted zones on the S–SW and E lower flanks of the volcanic pile, but also in…
Acid-Base Properties of 2:1 Clays. I. Modeling the Role of Electrostatics
2010
We present a theoretical investigation of the titratable charge of clays with various structural charge (sigma(b)): pyrophyllite (sigma(b) = 0 e x nm(-2)), montmorillonite (sigma(b) = -0.7 e x nm(-2)) and illite (sigma(b) = -1.2 e x nm(-2)). The calculations were carried out using a Monte Carlo method in the Grand Canonical ensemble and in the framework of the primitive model. The clay particle was modeled as a perfect hexagonal platelet, with an "ideal" crystal structure. The only fitting parameters used are the intrinsic equilibrium constants (pK(0)) for the protonation/deprotonation reactions of the broken-bond sites on the lateral faces of the clay particles, silanol, =SiO(-) + H(+) --=…
Acid–Base Properties and Surface Charge Distribution of the Water-Soluble Au102(pMBA)44 Nanocluster
2016
The pKa of the p-mercaptobenzoic acid (pMBA) ligands in the Au102(pMBA)44 nanocluster was measured by using acid–base and IR titration. The observed macroscopic pKa = 6.18 ± 0.05 is significantly more basic than that of free pMBA (pKa = 4.16), and the protonation behavior is anticooperative according to the Hill coefficient n = 0.64 ± 0.04. The cluster is truly water-soluble when more than 22 and insoluble when fewer than 7 ligands are in the deprotonated state. In order to obtain more insight into the anticooperative character, the cluster was modeled at pH ∼6.2 using constant pH molecular dynamics simulations. The pKa values of the individual pMBAs are in the range of 5.18–7.58, depending…
Carbon-Coated Anatase TiO2Nanotubes for Li- and Na-Ion Anodes
2014
aInstitute of Physical Chemistry and MEET Battery Research Centre, University of Muenster, 48149 Muenster, Germany bHelmholtz-Institute Ulm (HIU), Electrochemistry I, 89081 Ulm, Germany cKarlsruher Institute of Technology (KIT), 76021 Karlsruhe, Germany dInstitute for Organic Chemistry, University of Mainz, 55128 Mainz, Germany eGraduate School Materials Science in Mainz, 55128 Mainz, Germany fInstitute for Inorganic and Analytical Chemistry, University of Mainz, 55128 Mainz, Germany gMax Planck Institute for Polymer Research, 55128 Mainz, Germany