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The electron density descriptors are calculated for the complexes of metalloproteinase-2 with the APP-IP inhibitor and its mutant forms, and it is shown that the electron localization function (ELF) of the coordination bond of the zinc cation and the ligand atom shows differences in the experimentally observed inhibition constants.

Carbonic anhydrases (CAs) catalyze the physiological hydration of carbon dioxide and are among the most intensely studied pharmaceutical target enzymes. A hallmark of CA inhibition is the complexation of the catalytic zinc cation in the active site. Human (h) CA isoforms belonging to different families are implicated in a wide range of diseases and of very high interest for therapeutic intervention. Given the conserved catalytic mechanisms and high similarity of many hCA isoforms, a major challenge for CA-based therapy is achieving inhibitor selectivity for hCA isoforms that are associated with specific pathologies over other widely distributed isoforms such as hCA I or hCA II that are of critical relevance for the integrity of many physiological processes. To address this challenge, we have attempted to predict compounds that are selective for isoform hCA IX, which is a tumor-associated protein and implicated in metastasis, over hCA II on the basis of a carefully curated data set of selective and nonselective inhibitors. Machine learning achieved surprisingly high accuracy in predicting hCA IX-selective inhibitors. The results were further investigated, and compound features determining successful predictions were identified. These features were then studied on the basis of X-ray structures of hCA isoform-inhibitor complexes and found to include substructures that explain compound selectivity. Our findings lend credence to selectivity predictions and indicate that the machine learning models derived herein have considerable potential to aid in the identification of new hCA IX-selective compounds.

The employment of the hexyl-substituted anion [HexCB11 Cl11 ]- allowed the synthesis of a ZnII species, Zn[HexCB11 Cl11 ]2 , 3, in which the Zn2+ cation is only weakly coordinated to two carborate counterions and that is soluble in low polarity organic solvents such as bromobenzene. DOSY NMR studies show the facile displacement of at least one of the counterions, and this near nakedness of the cation results in high catalytic activity in the hydrosilylation of 1-hexene and 1-methyl-1cyclohexene. Fluoride ion affinity (FIA) calculations reveal a solution Lewis acidity of 3 (FIA=262.1 kJ mol-1 ) that is higher than that of the landmark Lewis acid B(C6 F5 )3 (FIA=220.5 kJ mol-1 ). This high Lewis acidity leads to a high activity in catalytic CO2 and Ph2 CO reduction by Et3 SiH and hydrogenation of 1,1-diphenylethylene using 1,4-cyclohexadiene as the hydrogen source. Compound 3 was characterized by multinuclear NMR spectroscopy, mass spectrometry, single crystal X-ray diffraction, and DFT studies.

Introduction: On account of the current COVID-19 pandemic, we have explored the importance of azithromycin and zinc in the treatment of the coronavirus disease by studying the interaction between the cation Zn++ and azithromycin with the tools of the semi-empirical quantum mechanics PM3 method. Methods: By this approach, the niche in which Zn++ is located was determined. Zn++ creates a strong clastic binding between an amine and a hydroxyl group located on the amino-hexose side-chain. Such an interaction serves as a shuttle and allows zinc cation to invade endocellular structures. Results: In this triple collaborative association, the role of hydroxychloroquine would be more that of a chaotropic agent at plasmic membranes, which facilitates access to the azithromycin-Zn++ equipage into key internal compartments. Conclusion: Finally, we show that both azithromycin and Zn++ are susceptible to play a direct role against the replication and the assembly of SARS-CoV-2 particles.

Aggregation-induced emission (AIE) compounds display a photophysical phenomenon in which the aggregate state exhibits stronger emission than the isolated units. The common term of “AIEgens” was coined to describe compounds undergoing the AIE effect. Due to the recent interest in AIEgens, the search for novel hybrid organic–inorganic compounds with unique luminescence properties in the aggregate phase is a relevant goal. In this perspective, the abundant, inexpensive, and nontoxic d10 zinc cation offers unique opportunities for building AIE active fluorophores, sensing probes, and bioimaging tools. Considering the novelty of the topic, relevant examples collected in the last 5 years (2016–2021) through scientific production can be considered fully representative of the state-of-the-art. Starting from the simple phenomenological approach and considering different typological and chemical units and structures, we focused on zinc-based AIEgens offering synthetic novelty, research completeness, and relevant applications. A special section was devoted to Zn(II)-based AIEgens for living cell imaging as the novel technological frontier in biology and medicine.

International audience; Scaling process is the main problem encountered in industrial plants using water. Several factors, (pH, temperature, hydrodynamic conditions, metal surface, and especially, water composition),can affect the scaling kinetics of calcium carbonate (CaCO3), one of the main component of scaling. In addition, some foreign ions added can considerably modified the scaling rates. In thiswork, the inhibiting effects of Zn2+ and Cu2+ cations on CaCO3 precipitation were studied in a 50°F synthetic carbonic solution by using fast controlled precipitation (FCP) and scaling quartz crystal microbalance (SQCM) methods, for homogeneous and heterogeneous scaling deposition, respectively. Results showed that Zn2+ and Cu2+ ions are efficient, at high concentrations (≥ 1mg/L), to delay or even to prevent nucleation/growth of CaCO3. FCP measurements showed a complete inhibition of the homogeneous CaCO3 precipitation after 120 min in synthetic solutioncontaining 5 mg/L and 4 mg/L of Cu2+ and Zn2+, respectively. SQCM measurements showed that the surface coverage of the metallic substrate by a layer of CaCO3 is reduced when the amount of these cations increased. Zn2+ cations inhibited the heterogeneous CaCO3 precipitation moree fficiently than Cu2+. SEM and XRD results indicated that both cations affect calcium carbonatenucleation by changing the morphology of CaCO3 crystals

This work aims to study the impact of zinc cation and 2-mercaptobenzoxzole (MBO) on the corrosion protection of a silane sol-gel coating on mild steel. First, effectiveness of the organic and inorganic inhibitors on the corrosion of bare mild steel in a NaCl solution was shown to be linked to formation of a surface film. Using electrochemical data as well as results of surface analysis, a sharp inhibition synergism was found when an equal mole percentage of ZnCl 2 and MBO was added to the NaCl solution. Finally, electrochemical data indicated superior performance of the coating with the combination of inhibitors.

Copyright © All rights are reserved by Carlota Saldanha. This work is licensed under Creative Commons Attribution 4.0 License, The biochemical effects of hydroxychloroquine, ivermectin, azithromycin molecules, and the zinc cation on functional properties of human erythrocyte will be presented. Among a wide range of therapeutically applications attributed to hydroxycloroquine the anti-inflammatory role will be herein highlight as well as for the azithromycin. The intervention of the ivermectin molecules into cell abortion mechanism of the virus replication will be described. The action of hydroxychloroquine, ivermectin, azithromycin molecules, and of zinc cation to prevent the spread and the replication SARS2-CoV2 Virus, as a first therapeutic approach for Covid-19 symptomatic patients, will be the aim of the present opinion.

The zinc cation in the structure has a N2O3 coordination set, arranged in a trigonal–bipyramidal configuration. The bridging mode of the organic ligands leads to the formation of a polymeric layer structure parallel to the ab plane., The crystal structure of the title polymer, {[Zn(C8H4O6S)(C10H8N2S)(H2O)]·0.26H2O}n, is characterized by a layered arrangement parallel to the ab plane. The zinc cation is five-coordinated in a slightly distorted trigonal–bipyramidal coordination environment defined by two pyridine ligands, two carboxyl­ate groups of two thio­phene di­carboxyl­ate ligands, and by one water mol­ecule. The ethyl­ene bridge in the dioxine ligand is disordered over two sets of sites [occupancy ratio 0.624 (9):0.376 (9)]. Several hydrogen-bonding inter­actions of the types O—H⋯O, C—H⋯O, C—H⋯S and C—H⋯N ensure the cohesion within the crystal structure.

International audience; Numerous adsorbent materials are developed and are able to face specific types of pollution, but none of them can manage the whole pollution. The purpose of this work is to develop a novel hybrid adsorbent, based on chitosan (CS) biopolymer, clay minerals and activated carbon (AC), having complementary adsorption properties and achieving a wide-spectrum water decontamination in a single treatment. Hybrid CS beads, containing dispersed clay and AC, were prepared from dispersions of solid adsorbents in a CS solution and its further coagulation in a basic medium. The porosity and the homogeneity of the hybrid beads were characterized by N 2 adsorption at 77 K and Cryo-Scanning Electron Microscopy respectively. The interaction between CS and clay was characterized using X-ray diffraction. Water content and the amount of each adsorbent in the hydrogel beads were determined by thermogravimetric analysis. Such a composite material was still porous and presented a wide adsorption spectrum. As shown by their adsorption kinetics, hydrophobic anionic clofibric acid (CBA) and cationic metoprolol (MTP) were well adsorbed on AC containing beads (21 and 26 mg/g), respectively. Clays containing beads showed interesting adsorption properties towards cationic Zn 2+ and MTP. The obtained composite beads were able to adsorb all the pollutant types: Zinc cations, and hydrophobic-charged organic molecules, such as pharmaceutical derivatives (clofibric acid and MTP).

A new imidazolium macrocycle based on tetraphenylethylene (TPE) has been synthesized. This positively charged macrocycle showed a typical aggregation-induced emission (AIE) effect but fluorescence emission could not be induced by common inorganic anions in aqueous solution, including pyrophosphate bearing four negative charges. However, in the presence of a half equivalent of zinc(II) ions, the addition of pyrophosphate anions could arouse a strong fluorescence while other common inorganic anions gave almost no response. The macrocycle has an inherent cavity with the correct size for binding a pyrophosphate anion, so that the pyrophosphate anion can be easily aggregated together with the macrocycle and a zinc cation, which selectively triggers a turn-on fluorescence.

International audience; We report the solid-state structure of an unexpected trinuclear zinc dimeric porphyrin complex resulting of zinc insertion into a single strap porphyrin. The latter bears an overhanging carboxylic acid which usually interacts with metal cations either in out-of-plane (OOP) or in hanging-atop (HAT) coordination mode by changing its location above the porphyrin coordination site. However, in the present studies, the overhanging carboxylic group acts as a bidentate ligand and binds the OOP-bound zinc cation together with another zinc cation bridging two porphyrin units.

Direct voltammetric determination of oxytetracycline (OTC) at a zinc cation-exchanged montmorillonite modified glassy carbon electrode (Zn-Mt/GCE) was described. The OTC yielded one well-defined oxidation peak at the Zn-Mt/GCE. The experimental parameters, which influence the voltammetric responses of OTC, e.g., the pH value, scan rate and accumulation condition, were optimized. The oxidation peak current changed with the OTC concentration over the range from 0.80 to 40 μM. The detection limit was 0.12 μM for an accumulation time of 4 min. The coefficient of variation, determined at 10 μM OTC, was 3.4% (n = 10). Using this method, OTC in the real food and feedstuff samples was determined.

This study was focused on the determination of contaminant transport parameters of heavy metal Zinc moving through saturated soft Bangkok undisturbed clay under high hydraulic gradients. These parameters were compared with contaminant transport determined under concentration gradient alone (pure diffusion). In total fifteen column tests were conducted and a mathematical model was applied to determine the coefficients. Two different source concentrations conditions, constant and decreasing, were applied. Testing periods were ranged from 15-60 days while hydraulic gradients were ranged from 0-500. The curves between relative concentration and time and pore volume were developed for the constant source condition whereas curves between source reservoirs concentrations and time were developed for decreasing source condition. The effective diffusion and distribution coefficients, De and Kd, were determined by curve fitting using the computer code POLLUTE v 6.3. The results showed that diffusion coefficient increases and distribution coefficient decreases as hydraulic gradient increases from 0 to high value of 500 due to contribution of dispersion and additional molecular diffusion at high advective velocity. Thus, testing at high gradients ensures the safe performance of earthen barriers under worse conditions.

This study is the analysis of the adsorption process of the CO2 molecule on the cationic sites of the DOH zeolite. Based on the DFT method, we have been able to identify several adsorption sites containing extra-framework cations and evaluate the value of the adsorption energy with respect to the distance from the adsorption site. The zinc cation has been found to cause the strongest interaction with the CO2 molecule. Subsequently, the adsorption process has been investigated by means of the Molecular Dynamics simulations. The results of the MD simulations are consistent with the geometry optimizations, and confirm the activation of CO2 molecule adsorbed in the Zn site. (C) 2013 Elsevier Inc. All rights reserved.

Multi cage-like zinc oxides were prepared via a facile hydrothermal method. The as-synthesized materials were characterized by means of XRD, TG-DTA, SEM, EDS, and N2 adsorption. The results indicate that the molar ratio of glucose to zinc cation has a significant effect on the morphology, surface area, pore size and distribution of the obtained products. This method is attractive for its merits such as simplicity, commercial feasibility, environmentally benign, surfactant-free, and good potential for scale-up.

Basic properties of bis[5-(3-oxyphenyl)-2,8,12,18-tetrabutyl-3,7,13,17-tetramethylporphyrinyl]-3,6,9-trioxyundecane-1,11 and bis[5-(3-oxyphenyl)-2,8,12,18-tetrabutyl-3,7,13,17-tetramethylporphyrinyl]-3,6,9,12-tetraoxytetradecane-1,14 were studied spectrophotometrically in an ethanol-sulfuric acid system; the influence of the basicity of the inner cycle nitrogen atom on the complexation properties of these polyethylene oxide-substituted porphyrins towards zinc cation in ethanol was considered.

A new 3D porous zinc phosphonate, Zn6(HL)4 · 6H2O 1 (H4L = C6H11N(CH2PO3H2)2) has been synthesized by hydrothermal reaction at 180 °C and structurally characterized by X-ray diffraction as well as by infrared spectroscopy, elemental and thermogravimetric analysis. The structure of compound 1 features a 3D open-framework built from ZnO4 tetrahedra linked together by bridging phosphonate groups. Each zinc cation is tetrahedrally coordinated by four phosphonate oxygen atoms from four ligands, each of which connects with six zinc atoms, resulting in channel systems of different size.

This Perspective starts with the discussion of the properties of an interesting metalloenzyme (carbonic anhydrase, CA) that performs extremely successfully the activation of carbon dioxide. Conclusions from that are important for many synthetic procedures and include experimental and theoretical investigation (DFT calculations) of such metal mediated processes in the condensed and in the gas phase in which the zinc cation plays a dominant role. This is extended to the bio-analogue activation of further heterocumulenes such as COS, an important atmospheric trace gas, and CS(2). Novel metal complexes which serve as useful catalysts for the reactions (copolymerisations and cyclisation) of CO(2) and oxiranes are discussed subject to the inclusion of recently published DFT calculations. We continue with the discussion of the very general aspect of the insertion of CO(2) into metal-nitrogen bonds (formation of carbamates). This again is closely related to many biological or bio-analogue processes. We describe the synthesis and mechanistic aspects of characteristic metal carbamates of a wide variety of metals and include a discussion of the mechanistic aspects, especially for the formation of Mg(2+) and Li(+) carbamates and the formation of related cyclic products after addition of the heterocumulenes CO(2), Ph-NCO or CS(2) to novel ligands, the 4H-pyridin-1-ides which finally result in the formation of e.g. 1,3-thiazole-5(2H)-thiones.

The synthesis of four new tetraamido-type p-tert-butylcalix[4]arenes presenting two proximal binding subunits is reported. Complexation of alkalimetals and zinc picrates with these ligands have been carried out and monitored by 1H-NMR inCDCl3. It is shown that hard cations are included in the tetraamido cavity while thezinc cation is chelated to the pyridine rings of one of the ligands. The formation of a 1:1:1heterobinuclear complex is also described

1,1-Diacetates were produced from a variety of aromatic aldehydes using Zn-montmorillonite as a catalyst. The procedure generally resulted in good yields (98%) of aromatic aldehydes including those carrying electron donating- or withdrawing substituents. The great advantage of the application of Zn-montmorillonite catalyst is that the reaction takes place under mild conditions. In addition, the zinc cation exchanged form of montmorillonite has a minimal environmental impact.

The structure of the title complex, [ZnCl2(C11H9N3)2], comprises two 2-(phenyldiazenyl)pyridine ligands coordinating to a central ZnIIdichloride unitviathe pyridyl N-atom donors, resulting in a slightly distorted tetrahedral geometry. The complex exhibits twofold rotation symmetry, with the rotation axis bisecting the zinc cation. The structure is stabilized by weak intermolecular C—H...Cl interactions [C...Cl = 3.411 (2) and 3.675 (2) Å], connecting neighbouring molecules into layers perpendicular to thecaxis.

The hydrogen bond network influence on the carbonic anhydrase II (CAII) zinc binding site has been studied theoretically by using the semiempirical AM1 method. To this aim, quantum mechanical reduced models of wild-type CAII and several CAII variants have been constructed. We have shown that, when a direct metal ligand donates a hydrogen bond to an indirect metal ligand, the first-shell residues enhance their electrostatic interaction with the zinc cation. Thus, the hydrogen-bond network is able to modulate the zinc binding affinity and the zinc-water pKa.Key words: hydrogen bond network, carbonic anhydrase II, Zn2+ metalloenzyme ligands.

We report the selective modification of cysteine residues engineered in peptides that have two additional cysteine residues as part of a Cys2His2 zinc finger motif. The chemoselective modification is achieved, thanks to the protecting effect exerted by the zinc cation upon coordination with the native cysteines and histidines of the zinc-finger fold. The strategy allows a straightforward synthesis of DNA binding zinc finger constructs We acknowledge the support from the Spanish grants SAF2010-20822-C02, CTQ2009-14431/BQU, CSD2007-00006, the Xunta de Galicia GRC2010/12, GRC2013-041 and INCITE09 209 084PR. J. R. thanks the Fundación Gil Dávila and the Xunta de Galicia and J. M. the Spanish MCINN for their PhD fellowships SI

This review describes what is presently known about the role of positively charged ions in the colonization and degradation of wood by brown rot fungi. General patterns of cation accumulation and the roles of iron, manganese, calcium and other cations in the fungal environment are discussed. The physiology of brown rot fungi and mechanisms of wood cell wall breakdown are emphasized.

From a solution of [Zn(H2O)6](NO3)2 and acetyl­enedicarb­oxylic acid in deionized water, single crystals of zinc acetyl­ene­dicarboxyl­ate dihydrate, {[Zn(C4O4)(H2O)2]}n, were obtained by slow evaporation of the solvent. The asymmetric unit consits of one zinc cation which is located on a centre of symmetry, half of an acetyl­enedicarboxyl­ate anion, the anion lying on a twofold axis, and one water mol­ecule in a general position. Thus, zinc is octa­hedrally coordinated by four O atoms of acetyl­enedicarboxyl­ate anions and two water mol­ecules in trans positions. These octa­hedra are connected by dicarboxyl­ate ligands into a three-dimensional network.

Fifteen selected vegetables and fruits were processed by conventional procedures with modified blanching conditions. The texture of blanched and processed samples was determined. Low-Temperature-Long-Time (LTLT) blanching considerably increased the final firmness of sterilized carrot, endive and green bean samples, as well as pasteurized cherry samples. After screening experiments, green bean and endive were chosen for further research. Analysis of variance revealed that LTLT blanching treatments in a blanching solution containing calcium and zinc cation significantly affected the texture and color of processed green bean and endive. The blanching treatments were optimized to improve the texture and color of sterilized green bean and endive.

Energies and structures of six different isomers resulted of complex between glycylglycine dipeptide and zinc cation were calculated at the BLYP and B3LYP levels of theory with 6-311G** and 6-311++G** basis sets. The energies of the glycylglycine-Zn2+different complexes at the BLYP/6-311++G** obtained more stable than another methods. In this method, the most stable complex was zinc cation bound to the two oxygen sites of the glycylglycine zwitterion and acted as a bidentate ligand. The vibrational frequencies, thermodynamic and electronic properties, HOMO, LUMO, and energy gap for the most stable isomer in different solvents were calculated at the BLYP/6-311++G** level of theory.

Di-aza-benzo crown etherp-tert-butyl calix[4]arene (1) has been prepared by hydrogenating the already known Schiff-base precursor (2). The metal ion complexing ability of (1) toward zinc cation is presented. The formation of a 2:1 (Zn: (1) complex and the location of zinc cations were deduced from1H-NMR investigations.

The asymmetric unit of the title compound, [Zn(NCS)(2)(C(6)H(7)N)(2)], consists of one Zn(2+) cation and two thio-cyanate anions, all situated on special positions with site symmetry .m., and one 3-methyl-pyridine ligand. The zinc cation is coordinated by four N atoms of two terminal N-bonded thio-cyanate anions and of two symmetry-related 3-methyl-pyridine co-ligands, defining a slightly distorted tetra-hedral coordination polyhedron.

The combination of tectons based on the [1111]metacyclophane backbone blocked the 1,3-alternate conformation bearing two imidazoly or pyrazolyl groups located on the same side with metal halide complexes leads to the formation of either discrete metallmacrobicycles or infinite 1-D coordination networks. The same backbone bearing two sets of two different coordinating poles composed of two pyridyl and two pyrazolyl units, owing to its non-centrosymmetric nature, forms a directional 2-D network packed in an anti-parallel fashion.

In diacetato-O,O',-O-(2,9-dimethyl-1,10-phenanthroline-N,N')zinc(II), [Zn(C 2 H 3 O 2 ) 2 (C 14 H 12 N 2 )], the zinc cation has a pentacoordinated environment consisting of the two N atoms of 2,9-dimethyl-1,10-phenanthroline, one O atom from a monodentate acetate group and two O atoms from a bidentate acetate group.

In the crystal structure of the title compound, [Zn(H2O)6](C(6)H(2)N(3)O(7))2.3H2O, the zinc cation complexes and picrate anions are stacked separately, extending along the b axis. No picrate species ligate to the metal cation. This lack of picrate coordination is atypical among metal picrate salts. We speculate that the size of the metal-aqua complex as related to the intermolecular distance of the picrate anions in the pi stack can be a measure of the formation of such separated stacks in the crystal structures of divalent metal complexes with picrate anions. Picrate ions are linked to each other with short intermolecular C...C contacts of 3.223 (6) and 3.194 (6) A in the stack.

In the title complex, [Zn(C7H4NO3S)2(C8H22N4)]·H2O or [Zn(sac)2(paen)]·H2O [sac = saccharinate and paen = N,N′-bis(3-aminopropyl)ethylenediamine], the zinc cation is octahedrally coordinated. The equatorial plane of the octahedron is formed by N atoms of the paen ligand, whereas the axial positions are occupied by the carbonyl O atoms of the two sac ligands. One of the sulfonyl groups of the sac ligands shows disorder and was modelled with two different orientations and site occupancies of 0:38 (1):0.62 (1). The molecular packing is stabilized by intermolecular O—H...O and N—H...O hydrogen bonds between water molecules and neighbouring [Zn(sac)2(paen)] molecules, which form chains running parallel to [010]. The crystal used was an inversion twin.

A simple determination of cyclopiazonic acid by HPLC is elucidated. The zinc cation in the mobile phase and indomethacin as an internal standard made quantitation higher and peak identification of cyclopiazonic acid easier. In the combination with a TLC analysis, production of cyclopiazonic acid by some species of aspergilli could be analyzed both in a liquid culture and in a solid culture on wheat bran without a prior clean-up operation.

The zinc cation (Zn2+) binding to human serum albumin (HSA) was studied using a non-equilibrium approach in order to prove two HSA binding sites. The effect of the bulk solvent pH and column temperature T on this binding and the corresponding thermodynamic data were also investigated. It appeared that the association process can be divided into two pH value ranges due to a predominant Zn2+ interaction with either HSA site I or site II. It was also demonstrated that the Zn2+ affinity for the site II was weakly affected by modifying the mobile phase pH whereas for the site I, the affinity constant increased strongly with increasing the pH of the bulk solvent.

Ab initio molecular orbital methods in combination with DFT calculations were used to study the structural and thermodynamic properties of 17 complexes containing zinc cation and four first-shell ligands as models of active site of metalloenzymes (e.g. angiotensin converting enzyme, thermolysin). The geometry of the complexes was relaxed by complete optimization by ab initio molecular orbital methods at Hertree-Fock level with 3-21G* basis set. Following single point calculation with tight SCF criteria at the B3LYP level with 6-311+G(2d,p) basis set was used to calculate accurate interaction enthalpies. The structure and thermodynamics of optimized complexes are discussed from the point of view of their biological importance.

2-(3,5,6-Trifluoro-2-hydroxy-4-methoxyphenyl)benzoxazole (3) and benzothiazole analogue (4) are prepared by the two-step procedures from the corresponding 2-(pentafluorophenyl)benzazoles. Benzoxazole 3 is applicable to a fluorescent probe sensing magnesium cation, and 4 is suitable for sensing zinc cation. Both fluorophores 3 and 4 are sensitive to the pH change at pH 7−8, resulting in large fluorescence enhancement under basic conditions. Their high sensitivity to pH and selectivity in metal cations are ascribed to the high acidity of the fluorophenol moiety.

In this paper we will show the potentialities of density functional theory to build-up the potential energy surfaces of a series of reactions in which metals are involved. The studied processes are: • A1CN—AINC • A1 + H2O • Cu+ + Glycine • Sc+ + H2O • CO2 activation in carbonic anhydrase

Recently, cadmium-containing additives for plastics have been designated as undesirable environmentally. Prior to this adverse characterization of cadmium derivatives most flexible vinyl in the United States involving severe stabilizer demand during processing or service utilized metal blends based on cadmium salts. As a result many vinyl formulators have been forced to find suitable alternatives. Replacement of a stabilizer composed of specific levels of barium/cadmium salts in flexible vinyl with another containing the same levels of barium/zinc has been found to give dramatically reduced performance in heat stability tests. Results of this study has shown that satisfactory replacement of barium/cadmium/zinc or barium/cadmium systems in flexible vinyl is possible with barium/zinc stabilizers. This replacement appears to depend on higher barium-to-zinc ratios than those utilized in barium/cadmium analogs, use of special ligands that compensate for the smaller sized zinc cation; and prevention of their destruction by inadvertent addition of competitors.

The title compound, [Zn(NO3)(C8H8N2O)2]NO3·H2O, consists of a tris-chelated zinc cation and a nitrate anion, along with an uncoordinated water mol­ecule. These inter­act through O—H⋯O and N—H⋯O hydrogen bonds, giving rise to a three-dimensional network structure. The ZnII ion has an octa­hedral coordination.

The increased availability of catalytically active iron after silica exposure can present an oxidative injury to a living system. Sequestration of reactive iron would, therefore, confer a protective effect. The intracellular storage of iron by ferritin within macrophages can limit the potential for radical generation and cellular injury resulting from exposure to a metal chelate. We tested the hypothesis that in vitro exposure of human alveolar macrophages to silica increases the expression of ferritin through a posttranscriptional mechanism. Exposure of 1.0 x 10(6) macrophages to 100 microg/ml silica for 4 h increased light-subunit (L)-ferritin protein concentrations in both cell supernatants and lysates. Inclusion of 1.0 mM deferoxamine in the reaction mixtures inhibited increases in ferritin after silica. To test for a posttranscriptional regulation of ferritin protein expression, cells were incubated with acid-washed particles, silica with complexed zinc cation, and silica with complexed iron cation. L-ferritin protein concentrations were increased in both cell supernatants and lysates after 4 h of exposure to silica with complexed iron cation. There were no increases in L-ferritin after incubations with acid-washed particles or silica with complexed zinc cation. There were no significant differences in levels of L-ferritin cDNA between any of the exposures, suggesting a posttranscriptional control of ferritin expression.

The title compound, [Zn(C8H4N4O2)]n, is a coordination polymer prepared by the hydro­thermal reaction of zinc chloride and 3-(1H-tetrazol-5-yl)­benzoic acid. The zinc cation is tetrahedrally coordinated by two N atoms and two O atoms from four ligands, resulting in a three-dimensional framework encapsulating one-dimensional channels.

ZnAPO-34 and MnZnAPO-34 materials were synthesised hydrothermally in the presence of tetraethylammonium hydroxide as a template. Rietveld refinement and EXAFS studies indicate the incorporation of zinc cation into tetrahedral framework sites of AlPO 4 -34 and imply the presence of extra-framework manganese atoms located in cavities.

The asymmetric unit of the title compound, [Zn(NCSe)(2)(C(4)H(4)N(2))(2)](n), consists of one Zn(2+) cation located on a special position with site symmetry 2/m, one seleno-cyanate anion on a mirror plane and one pyrimidine ligand on a twofold rotation axis. The zinc cation is coordinated by six N atoms of four pyrimidine ligands and two N-bonded seleno-cyanate anions in mutually trans orientations within a slightly distorted octa-hedral coordination environment. The Zn atoms are μ-1,3-bridged via the pyrimidine ligands into a polymeric layer extending parallel to (100).

Elastomere de masse moleculaire 8000 neutralise avec: Ca 2+ , Sr 2+ , Ni 2+ , Zn 2+ et Cd 2+

Bei der ionotropen Gelbildung von anionischen Cellulosederivaten wurde Ionenspezifitat und Synergismus von Pb-, La-, Tl- und Zn-Kationen auf die Kapillarbildung bei gleichzeitiger Anwesenheit von zwei verschiendenen, auf unterschiedliche Gegenionen ansprechende anionische Gruppen (Carboxymethyl- und Xanthogenatgruppen) an der gleichen Polymerkette untersucht. Dabei wurde das System des doppelanionischen Polyelektrolyten mit der Mischung aus Carboxymethylcellulose und Cellulosexanthogenat verglichen. Die mittels Licht- und Elektronenmikroskopie erhaltenen Ergebnisse zur Morphologie werden mitgeteilt und interpretiert. The ion specifity and the synergism of Pb, La, T1 and Zn cations in the capillar formation in presence of two different anionic groups (carboxymethyl and xanthate groups), responding to different counter ions, at the same polymer chain have been investigated. The double-ionic polyelect,rolyte was compared with the mixture of carboxymethyl cellulose and cellulose xanthate. The optical and electron microscopic results with respect to the morphology of these gel structures are presented and interpreted.