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The alkyl salicylaldoxime has attracted more and more attention recently due to the complex branched alkyl groups. In this study, a novel alkyl salicylaldoxime, tert-octylsalicylaldoxime, was successfully synthesized by the one-pot method. The yield and purity by the elemental analysis were 96.17 and 94.13%, respectively. The structure was confirmed by elemental analysis, FT-IR, 1H NMR (Nuclear Magnetic Resonance), 13C NMR spectroscopy, and MS. Results showed that tert-octylsalicylaldoxime with a new structure exhibited excellent extraction ability and selectivity for Cu(II) and can be successfully used to recover Cu from copper-nickel alloy electroplating wastewater. Thus, this product has the potential to be used as a powerful copper extractant in the future.

Two novel mononuclear Fe(III) complexes derived from azo-containing salicylaldoxime ligands were synthesized and characterized by elemental analyses, spectroscopic data i.e. IR, 1H NMR, UV-Vis, electrospray ionization mass spectra, molar conductivity, and magnetic susceptibility measurements. Both the experimental and theoretical results strongly suggest that the ligands have a major contribution to the azo enol imine form instead of the hydrazo keto imine and azo keto amine forms in solution/solid-state. The electronic spectra of the ligands and their iron(III) complexes were calculated theoretically for the band assignments by using DFT and TD-DFT/CPCM methods. DNA binding, cleavage, and antioxidative activities of the investigated compounds were studied. It has been shown that the ligands and their iron (III) complexes tested bind to DNA via the intercalative mode. It was observed that all molecules tested inhibited topoisomerase I almost to the same degree. One of the most striking results among the antioxidant activity tests is that the hydroxyl radical scavenging activities of the ligands and complexes are higher than the standard antioxidant mannitol.

Effects of common ions, namely hydroxyl ions and carbonate, on the adsorption and flotation of malachite with salicylaldoxime as a collector was investigated, making use of solubility, micro-flotation, zeta potential, contact angle, FTIR, and XPS measurements. The results suggested that hydroxyl and carbonate ions affect malachite recovery through altering solubility of this mineral. Under conditions of lower solubility, more stable copper atoms acted as adsorption sites for retaining salicylaldoxime on the malachite surface, and the collector consumed by copper species in slurry was reduced. This allowed more collectors to get adsorbed onto malachite surface, resulting in improved malachite recovery. Zeta potential, FTIR, and XPS measurements indicated that salicylaldoxime chemically adsorbs onto malachite by forming copper salicylaldoxime chelates, in which two salicylaldoxime molecules react with one copper atom by N atom and the O atom combined with benzene ring.

The phenolic hydroxyoxime-based extractant has been discovered to degrade gradually in commercial copper solvent extraction plant. The main degradation products occurred through hydrolysis rather than oxidation or Beckmann rearrangement, which were identified as 1-(2-hydroxy-5-nonylphenyl)propan-1-one and 5-nonyl salicylaldehyde through instrumental analysis. The degradation products could reduce the extraction isotherm, the stripping isotherm and the transfer of copper. Moreover, the extractant regeneration of 5-nonyl salicylaldoxime from 5-nonyl salicylaldehyde was achieved with hydroxylamine sulfate. It was observed that the copper loading capacity of regenerated extractant increased by 64%, compared to the copper loading of untreated hydroxyoxime extractant.

We report the synthesis and characterization of four new tetranuclear Ni(II) complexes, C1–C4, all of which exhibit defective dicubane cores. C1–C4 are derived from the same salicylaldoxime derived ligand, H2L1. Complexes C1 and C4 have isostructural cores, differing in structure only by solvate molecules. Magnetic and computational analyses have revealed that complexes C1, C2, and C4 exhibit competing ferro- and antiferromagnetic interactions, however the different solvated species in C1 and C4 leads to notably different magnitudes in their magnetic coupling constants. Theoretical magneto-structural studies show that the pairwise magnetic exchange interaction is highly dependent on the Ni–X–Ni angle, as revealed by orbital overlap calculations.

Herein, we present a scalable approach for the synthesis of a hydrogen-bonded organic–inorganic framework via coordination-driven supramolecular chemistry, for efficient remediation of trace heavy metal ions from water. In particular, using copper as our model ion of interest and inspired by nature’s use of histidine residues within the active sites of various copper binding proteins, we design a framework featuring pendant imidazole rings and copper-chelating salicylaldoxime, known as zinc imidazole salicylaldoxime supramolecule. This material is water-stable and exhibits unprecedented adsorption kinetics, up to 50 times faster than state-of-the-art materials for selective copper ion capture from water. Furthermore, selective copper removal is achieved using this material in a pH range that was proven ineffective with previously reported metal–organic frameworks. Molecular dynamics simulations show that this supramolecule can reversibly breathe water through lattice expansion and contraction, and that water is initially transported into the lattice through hopping between hydrogen-bond sites., Heavy metals and metalloids pose major threats to health and environmental ecosystems, thus systems for low-cost remediation are needed. Here the authors report the scalable design of a hydrogen-bonded organic–inorganic framework for selective removal of trace heavy metal ions from water.

The crystal structures of three salicyaldoxime compounds, namely 2-hydroxy-4-methylbenzaldehyde oxime, C8H9NO2,1, 2,4-dihydroxybenzaldehyde oxime, C7H7NO3,2, and 2-hydroxy-4-methoxybenzaldehyde oxime, C8H9NO3,3, are discussed. In each compound, the hydroxyl groups are essentially coplanar with their attached phenyl group. The interplanar angles between the C=N—O moieties of the oxime unit and their attached phenyl rings are 0.08 (9), 1.08 (15) and 6.65 (15)° in1,2and3, respectively. In all three molecules, the 2-hydroxy group forms an intramolecular O—H...N(oxime) hydrogen bond. In compound (1), intermolecular O—H(oxime)...O(hydroxyl) hydrogen bonds generateR22(14) dimers, related by inversion centres. In compound2, intermolecular O—H(oxime)...O(4-hydroxy) hydrogen bonds generateC9 chains along theb-axis direction, while O—H(4-hydroxyl)...O(2-hydroxyl) interactions form zigzagC6 spiral chains along the c-axis direction, generated by a screw axis at 1,y, 1/4: the combination of the two chains provides a bimolecular sheet running parallel to thebaxis, which lies between 0–1/2cand 1/2–1c. In compound3, similarC9 chains, along theb-axis direction are generated by O—H(oxime)...O(4-methoxy) hydrogen bonds. Further weaker, C—H...π (in1), π–π (in2) and both C—H...π and π–π interactions (in3) further cement the three-dimensional structures. Hirshfeld surface and fingerprint analyses are discussed.

The effective combination of dopamine (DA) and oxime-containing molecules can significantly improve adsorption performance. To characterize the role of the mass ratio of DA to oxime-containing molecules, novel polydopamine/salicylaldoxime-functionalized magnetic graphene oxides (MGO-PDA/oxime) with different mass ratios of DA to salicylaldoxime (i.e., 1:0.5, 1:1, 1:2, and 1:4) were synthesized successfully via rapid one-step polymerization. The mass ratios of DA to salicylaldoxime influence the thickness of the polymer shell, functional groups, crystallinity, surface charge, and consequently adsorption capacity of composites. According to the results of batch experiments, MGO-PDA/oxime with a DA/salicylaldoxime ratio of 1:2 (i.e., MGO-PDA/oxime-2) shows the best performance for Pb(II) removal, with a maximum adsorption capacity of 261.55 ​mg ​g−1. The adsorption of Pb(II) on MGO-PDA/oxime-2 is fast, and pH- and temperature-dependent. The remarkable Pb(II) adsorption efficiency, easy separation and good reusability imply that MGO-PDA/oxime-2 can be regarded as a suitable material for heavy metal pollution cleanup.

To withstand the complex natural environment and ecological system in the ocean, adsorbents with high strength, rapid rate, and antifouling ability are urgently needed for uranium extraction. Herein, instead of the traditional poly(amidoxime) structures, we design an anti-adhesive adsorbent (Anti-LS/SA) by conjugating functional ligands of salicylaldoxime (SA) and hyaluronic acid (HA) on the porous biomass via a facile one-step process. The interconnected microchannels in the porous biomass can accelerate seawater transport, along with the micromolecular uranium-adsorbing ligand, endowing the Anti-LS/SA with a very fast uranium adsorption ability; the average adsorption rates reach up to 131 ± 1.8 mg g−1 hour−1 (in uranium spiked seawater with concentration of 8 ppm) and 0.1176 mg g−1 day−1 (in natural seawater) in the main adsorption stages, exceeding the currently used oxime-based adsorbents. Owing to the high hydration of HA, the adsorbents exhibit excellent hydrophilicity and anti-bacterial adhesion properties, as demonstrated by the bacteria adhesion testing and extraction experiments in bacteria-spiked seawater. Furthermore, the Anti-LS/SA displays a long service life and a very high tensile strength (62.63 MPa) to withstand strong ocean waves. Kinetics models and XPS data are used to analyze the extraction mechanisms. Considering its high efficiencies, structural advantages, as well as the facile and massive construction, we believe that the Anti-LS/SA will be a promising candidate for the large-scale uranium extraction from seawater.

Novel copper (II) ion imprinted polymers (Cu(II)-IIPs) were designed and synthesized as solid phase absorbents for the selective deep removal of Cu 2 + from concentrated zinc sulfate solution. Salicylaldoximes, used as chelating ligands, were anchored onto the polymer networks through quaternary ammonium cation spacers. The effect of pH, temperature, contact time, and swelling on the adsorption selectivity and the copper removal efficiency of Cu(II)-IIPs were investigated in a laboratory-scale cell. The results showed that the adsorption of Cu 2 + increased significantly with increasing pH from 1 to 7, and increased with decreasing operation temperature. The equilibrium Cu 2 + adsorption capacity of Cu(II)-IIPs from the zinc sulfate aqueous solution was 96 mg·g − 1 at 25 °C in pH 5.0 for 10 min. Under optimized processing conditions, the copper removal efficiency reached 99.9%, and the concentration of the residual copper (II) ions in the purified ZnSO 4 aqueous solution is 35 μg·L − 1 , significant lower than the maximum acceptable value as 100 μg·L − 1 in the hydrometallurgical zinc process.

A water-soluble salicylaldoxime-functionalized poly(ethylene glycol)-grafted dicationic ionic liquid was successfully developed as an efficient ligand for palladium acetate-catalyzed Mizoroki–Heck reactions in water. A series of aryl bromides and terminal olefin were applied to this catalytic system and the corresponding coupling products were produced in high yields. The reusability tests demonstrated that the catalyst system could be recycled for six runs with only a slightly decreased activity.

The effects of adenine, salicylaldoxime and 4(5)-methylimidazole on brass corrosion in NaCl were investigated. The investigation comprised electrochemical techniques, scanning electron microscopy and quantum chemical calculation. The results obtained by polarization measurements show that the examined compounds successfully inhibited the corrosion of brass. Additionally, the quantum mechanical calculations indicate that there is a correlation between energy gap and inhibition efficiency. Moreover, the inhibition mechanism includes the adsorption of the inhibitor on active sites on the electrode surface, which was confirmed by SEM-EDS analysis of the brass.

A new series of novel nonquaternary conjugates and non-oxime reactivators for reactivation of both nerve agents and pesticides inhibited hAChE were described in this paper. Conjugates with piperazine linked to the substituted salicylaldoxime emerged as efficient reactivators for VX inhibited hAChE. The in vitro reactivation experiment showed that some of them were equal or more efficient reactivators for pesticides inhibited hAChE than obidoxime. It was also found that some non-oxime derivatives of Mannich phenols displayed obvious reactivation potency for VX, sarin and pesticides inhibited hAChE even in very low concentration. It has been proved that introduction of peripheral site ligands with widespread aromatic system and amide substitutions could increase binding affinity for inhibited hAChE in most cases, which contribute to the reactivation efficiency.

Samples inside and outside the Arctic Ocean's TransPolar Drift (TPD) have been analyzed for Fe‐binding organic ligands (Lt) with Competitive Ligand Exchange Adsorptive Stripping Voltammetry (CLE‐AdCSV) using salicylaldoxime (SA). This analysis is compared to prior analyses with CLE‐AdCSV using 2‐(2‐thiazolylazo)‐p‐cresol (TAC). The TPD's strong terrestrial influence is used to compare the performance of both CLE‐AdCSV methods in representing the nature of natural organic ligands. These measurements are compared against direct voltammetric determination of humic substances (HS) and spectral properties of dissolved organic matter. The relationship between the two CLE‐AdCSV derived [Lt] versus HS in the TPD has a comparable slope, with a 40% offset toward higher values obtained with SA. Higher [Lt] values inside the TPD, most probably due to HS, explain high dissolved Fe concentrations transported over the Arctic Ocean by the TPD. Outside of the TPD in the surface Arctic Ocean HS occur as well but at lower concentrations. Here changes in HS relate to changes in dissolved Fe concentration and to [Lt] obtained with SA, whereas [Lt] obtained with TAC remain constant. Moreover, with decreasing HS the offset between the methods using TAC and SA decreases. We surmise that in the presence of HS, the TAC method detects HS only either at higher concentrations or of specific composition. On the other hand, the SA method might overestimate [Lt], as an offset with the TAC method that remains constant where HS are not detected. Regardless, HS are the dominant type of Fe‐binding organic ligand in the surface of the Arctic Ocean.

Competitive ligand exchange – adsorptive cathodic stripping voltammetry (CLE-AdCSV) is a widely used technique to determine dissolved iron (Fe) speciation in seawater, and involves competition for Fe of a known added ligand (AL) with natural organic ligands. Three different ALs were used, 2-(2-thiazolylazo)-p-cresol (TAC), salicylaldoxime (SA) and 1-nitroso-2-napthol (NN). The total ligand concentrations ([Lt]) and conditional stability constants (log K′Fe’L) obtained using the different ALs are compared. The comparison was done on seawater samples from Fram Strait and northeast Greenland shelf region, including the Norske Trough, Nioghalvfjerdsfjorden (79N) Glacier front and Westwind Trough. Data interpretation using a one-ligand model resulted in [Lt]SA (2.72 ± 0.99 nM eq Fe) > [Lt]TAC (1.77 ± 0.57 nM eq Fe) > [Lt]NN (1.57 ± 0.58 nM eq Fe); with the mean of log K′Fe’L being the highest for TAC (log ′KFe’L(TAC) = 12.8 ± 0.5), followed by SA (log K′Fe’L(SA) = 10.9 ± 0.4) and NN (log K′Fe’L(NN) = 10.1 ± 0.6). These differences are only partly explained by the detection windows employed, and are probably due to uncertainties propagated from the calibration and the heterogeneity of the natural organic ligands. An almost constant ratio of [Lt]TAC/[Lt]SA = 0.5 – 0.6 was obtained in samples over the shelf, potentially related to contributions of humic acid-type ligands. In contrast, in Fram Strait [Lt]TAC/[Lt]SA varied considerably from 0.6 to 1, indicating the influence of other ligand types, which seemed to be detected to a different extent by the TAC and SA methods. Our results show that even though the SA, TAC and NN methods have different detection windows, the results of the one ligand model captured a similar trend in [Lt], increasing from Fram Strait to the Norske Trough to the Westwind Trough. Application of a two-ligand model confirms a previous suggestion that in Polar Surface Water and in water masses over the shelf, two ligand groups existed, a relatively strong and relatively weak ligand group. The relatively weak ligand group contributed less to the total complexation capacity, hence it could only keep part of Fe released from the 79N Glacier in the dissolved phase.

Reverse and forward titrations coupled with the competitive ligand equilibration (CLE) technique were, for the first time, used to investigate the chemical organic speciation of copper ions in an aqueous extract of Eichhornia crassipes (E.C) plant growing in Egypt. Salicylaldoxime (SA) was used as the competitive ligand. Two samples were collected from huge submerged masses in the Nile water at Sohag and Mansura cities. In this study the concentration of the natural complexing ligands (CLn) and their conditional stability constants with copper ( K CuLn ′ ) in the aqueous extract were determined by linear and nonlinear modeling. Reverse titration resulted in two classes of copper complexation (CuL1 and CuL2) in both samples. The strongest class, CuL1, is predominant in Sohag-sample with average log K CuL 1 ′ and CL1 of 15.66 and 435.5 nM, respectively, and also dominated in the Mansura-sample with average 16.77 and 162 nM, respectively. The second class (CuL2) is minor in both samples. For comparison, forward titration was performed for the Sohag-sample. The results indicated that reverse titration showed a breakthrough ability to detect, for the first time, different types of metal complexation present in equilibrium in the aqueous extracts of biological samples. Moreover, the presence of E.C in Nile water is so useful in transforming free Cu ions to less toxic forms by organic complexation.

A polymerizable complex of copper(II) ion with unsaturated quaternary ammonium cation-modified salicylaldoxime ligand was prepared and used to synthesize a novel copper(II) ion imprinted polymers (Cu(II)-IIPs). Elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), and NMR spectroscopy confirmed the structures of the polymerizable complex and Cu(II)-IIPs. Thermogravimetric analysis (TGA), Brunauer–Emmett–Teller surface area analysis (BET), and scanning electron microscopy (SEM) characterized physical properties and morphologies of synthesized metal complex and corresponding polymers. The effect of pH, contact time, and initial Cu2+ and SO42− concentration on the simultaneous adsorption of Cu2+ and SO42− ions of Cu(II)-IIPs were investigated. Cu(II)-IIPs showed high hydrophilicity and simultaneously rapid adsorption of Cu2+ and SO42− from solution. Moreover, Cu(II)-IIPs displayed highest adsorption capacity in the pH range of 5.0–6.5, the separation factor (β) between Cu2+ with respect to Fe3+ was 1866, the equilibrium adsorption capacities for Cu2+ and SO42− were almost the same and close to 0.13 mmol g−1 at 25 °C. Stripping experiments revealed that 1.5 mol L−1 H2SO4 was an effective eluent for desorbing copper (II) ions from Cu(II)-IIPs. In additional, Cu(II)-IIPs exhibited good recyclability and reusability for 5 cycles without deterioration of its selective ion-absorbing capacity. Keywords: Cu(II) ion-imprinted polymers, Polymerizable copper (II) complex, Selective adsorption, Salicylaldoxime, Hydrometallurgy

The replacement of chromate-based corrosion inhibitors is a requirement for the aerospace sector. New developments demand additional studies to find synergistic combinations of inhibiting species. This paper discusses the synergistic effect resulting from various corrosion inhibitor mixtures proposed for the corrosion protection of aluminum alloy 2024-T3. The corrosion inhibition efficiency and the synergistic factors were determined for AA2024-T3 coupons immersed in 0.05 M NaCl solutions, containing either a single inhibitor or binary combinations of inhibitors. The following inhibitors were tested: Ce 3 + , 8-hydroxyquinoline (8HQ), salicylaldoxime (SAL), and 2,5-dimercapto-1,3,4-thiadiazolate (DMTD). Electrochemical impedance spectroscopy (EIS) and ATR-FTIR in Kretschmann geometry were used to evaluate the chemical and electrochemical variations during the exposure of bare coupons to inhibitor-containing NaCl solutions. The results allowed calculating the synergistic effect for binary mixtures and the most effective mixtures were those containing 8HQ-SAL and DMTD-8HQ. The synergistic effect was also determined for coated coupons. A water-based epoxy coating was modified with calcium carbonate microparticles, loaded beforehand with single inhibitors or with binary mixtures. EIS measurements were performed in 0.5 M NaCl and the results revealed that the epoxy coatings modified with CaCO 3 microparticles, loaded with inhibitor mixtures, provided enhanced corrosion protection. The most effective corrosion protection was observed for two mixtures: CaCO 3 (8HQ + SAL) and CaCO 3 (Ce + SAL). Interestingly, the results revealed that the synergistic effect on bare AA2024-T3 can be different from the situation where the same inhibitor mixtures are used in smart, anti-corrosive coatings.

The intramolecular O–H···O resonance-assisted hydrogen bonds in crystal structures of mononuclear gallium (III) complexes with salicylaldoximes are investigated. The molecular structures of these compounds were taken from X-ray crystal structures and further used to perform theoretical calculations at B3LYP/6-311G(d, p) level. The geometrical parameters of O–H···O intramolecular H-bonds were analyzed. The natural bond orbital theory (NBO) and the atoms in molecules theory (AIM) were also applied to get a more precise insight into the nature of such H-bond interactions. The bond critical points and the ring critical points were determined and their characteristics were also analyzed.

The reaction of MnCl2·4H2O with salicylaldoxime (H2salox) and the sodium salt of 1,3-bis(carboxypropyl)tetramethyldisiloxane (H2L) in a 1:1:1 molar ratio led to the self-assembly of {[Mn6O2(salox)6(H2salox)(H2O)3(μ-L)]H2salox·1.2H2O}n, a 1D coordination polymer consisting of hexamanganese(III) salicylaldoximate cluster as secondary building unit (SBU) and tetramethyldisiloxane-based dicarboxylate linker, namely, 1,3-bis(carboxypropyl)tetramethyldisiloxane. The structure of the compound was established by single crystal X-ray diffraction. The Mn(III) clusters consist of two staggered μ3-oxo-bridged Mn3 triangles held together by the oxygen atoms of the oxime groups. Because of Jahn–Teller distortion, the Mn–O distances reach 2.5 A for the oxygen atoms located above and below the triangles mean planes. The compound showed a glass transition peak at around 14 °C in the differential scanning calorimetry (DSC) curve. The magnetic susceptibility data were fitted with a set of three intracluster antiferromagneti...

Conjugated coordination polymers attract attention as materials for electrochemical energy storage, mostly as cathode materials for supercapacitors. Faradaic capacity may be introduced to such materials using redox-active building blocks, metals, or ligands. Using this strategy, a novel hybrid cathode material was developed based on a Ni2+ metal-organic polymer. The proposed material, in addition to double-layer capacitance, shows high pseudocapacitance, which arises from the contributions of both the metal center and ligand. A tailoring strategy in the ligand design allows us to minimize the molecular weight of the ligand, which increases its gravimetric energy. According to computational results, the ligand makes the prevailing contribution to the pseudocapacitance of the material. Different approaches to metal–organic polymer (MOP) synthesis were implemented, and the obtained materials were examined by FTIR, Raman spectroscopy, powder XRD, SEM/EDX (energy-dispersive X-ray spectroscopy), TEM, and thermal analysis. Energy-storage performance was comparatively studied with cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD). As a result, materials with an excellent discharge capacity were obtained, reaching the gravimetric energy density of common inorganic cathode materials.

The straightforward room temperature synthesis of hybrid polymetallic manganese clusters is investigated, exploit-ing complementary ligand combinations of p-tert-butylcalix[4]arene and salicylaldoximes. Eight new [MnIII7MnII] clusters have been prepared wherein the simple substitution of alkyl or aryl groups at well-defined positions of the salicylaldoxime scaffold leads to two distinct structure types that, while exhibiting the same general topology, contain the unique MnII ion in different positions. Incorporation of a methyl, ethyl or isopropyl group at the 3-position of the aromatic skeleton or a phenyl group at the oximic carbon gives structure type A that displays competing weak ferromagnetic and antiferromagnetic interactions. Substitution of a methyl or ethyl group at the oximic carbon atom invokes structure type B, incorporating an additional bulky chloride or nitrate into the metal-lic core due to the smaller steric imposition and position of the methyl or ethyl group. The distortion of the cluster core is conse-quently enhanced, switching the magnetic properties and resulting in single-molecule magnet behavior. The presence of tert-butyl groups at the 3- and 5-positions of the salicylaldoxime skeleton leads to a new [MnIV2MnIII2] cluster that is found to be a single-molecule magnet. The bulky tert-butyl group in the 3-position is too large to facilitate Mn8 cluster formation, and thus assembly occurs by an alternative pathway. Characteristic bonding modes of the constituent ligands are retained in every case, and the results presented here give insight into the potential of ligand combinations in future studies, highlighting the importance of steric factors in evaluating their relevant compatibilities.

The interaction of Mn(ClO4)2·6H2O with salicylaldoxime (H2sao) in the presence of nonsteroidal anti-inflammatory drug (NSAID) sodium diclofenac (Nadicl) or indomethacin (Hindo) leads to the formation of the hexanuclear Mn(III) clusters [Mn6(O)2(dicl)2(sao)6(CH3OH)6] (1) and [Mn6(O)2(indo)2(sao)6(H2O)4] (2) both characterized as stepladder inverse-9-metallacrown-3 accommodating dicl- or indo- ligands, respectively. When the interaction of MnCl2·4H2O with Nadicl or Hindo is in the absence of H2sao, the mononuclear Mn(II) complexes [Mn(dicl)2(CH3OH)4] (3) and [Mn(indo)2(CH3OH)4] (4) were isolated. The complexes were characterized by physicochemical and spectroscopic techniques, and the structure of complexes 1 and 2 was characterized by X-ray crystallography. Magnetic measurements (dc and ac) were carried out in order to investigate the nature of magnetic interactions between the magnetic ions and the overall magnetic behavior of the complexes.

To separate one base metal mineral from another by flotation, it is indispensable to identify chemical reagents that specifically interact with the surface metal sites of one mineral or a group of minerals. This work studies the interactions of chelating collectors which offer the best potential for collecting abilities and mineral specificity with a typical refractory oxide mineral (malachite). Zeta potential, adsorption and Fourier transform infrared (FTIR) measurements are applied to differentiate the interactions of salicylaldoxime and salicyl hydroxamate on the malachite surface. Salicylaldoxime and salicyl hydroxamate are of molecular structures that resemble each other, but with different bond distances in the ligand atoms which result in their unusual adsorption behavior and collecting ability. Thus, the flotation of malachite behaves differently with the two chelating collectors. This study might provide useful clues for designing novel collectors in base metal oxide flotations.

WOS: 000400487900018, In this study, two new O, O type azo-aldehydes (HL1 and HL2), their N, O type salicylaldoxime derivatives containing azo chromophore group (HL3 and HL4) and Cu(II) and Ni(II) complexes were synthesized and characterized by elemental analysis, H-1-C-13 NMR, FT-IR, mass spectroscopies. Solid state structures of the HL3 and HL4 were also determined by single crystal X-ray diffraction method. Absorption and photoluminescence behaviours of the ligands and their metal complexes were investigated in DMF solution. Superoxide dismutase (SOD) activity of the Cu(II) and Ni(II) complexes were compared with the literature values. The K-cat values for SOD activity show that the complexes possess significant catalytic activity for the dismutation of superoxide compared to the data of some complexes and natural SOD enzymes given in the literature. The K-cat values for SOD activities of the complexes were found to be lower than natural enzymes. The complex [Cu(L-3)(2)] is the SOD mimic amongst the tested complexes with K-cat of 1.4 x 10(7) M-1 s(-1). (C) 2017 Elsevier B.V. All rights reserved., Kahramanmaras Sutcu Imam University Science Project unit [2015/3-42 YLS], The authors are grateful to Kahramanmaras Sutcu Imam University Science Project unit for the financial support for this study (Project Number: 2015/3-42 YLS). The authors also acknowledge Scientific and Technological Research Application and Research Center, Sinop University, Turkey, for the use of the Bruker D8 QUEST diffractometer. Gaussian calculations in this paper are performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA Resources).

In addition to the sulfonamides and their isosteres, recently novel carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) which act by binding to the metal ion from the active site were discovered. Based on the X-ray crystal structure of the CA II–trithiocarbonate adduct, dithiocarbamates, xanthates and thioxanthates were shown to potently inhibit α- and β-CAs. The hydroxamates constitute another class of recently studied CAIs both against mammalian and protozoan enzymes. Another chemotype for which CA inhibitory properties were recently reported is the salicylaldoxime scaffold. X-ray crystal structures were reported for CA II complexed with dithiocarbamates and hydroxamates, whereas the xanthates and salicylaldoximes were investigated by kinetic measurements and docking studies. The dithiocarbamates and the xanthates showed potent antiglaucoma activity in animal models of the disease whereas some hydroxamates inhibited the growth of Trypanosoma cruzii probably by inhibiting the protozoan CA.

Organic dissolved iron (dFe)–binding ligands were measured by competitive ligand exchange–adsorptive cathodic stripping voltammetry (CLE-ACSV) at multiple analytical windows (side reaction coefficient of salicylaldoxime, aFe(SA)2 ~30, 60, and 100) in surface and benthic boundary layer (BBL) samples along the central California coast during spring and summer. The weakest ligands were detected in the BBL at the lowest analytical window with average log K cond FeL,Fe’ ~10:2 + 0:4 in the summer and 10.8 6 0.2 in the spring. Between 3% and 18% of the dFe complexation in the BBL was accounted for by HS, which were measured separately in samples by ACSV and may indicate a source of dFe-binding ligands from San Francisco Bay. The strongest ligands were found in nearshore spring surface waters at the highest analytical window with average log K cond FeL,Fe’~11:9 + 0:3, and the concentrations of these ligands declined rapidly offshore. The ligand pools in the surface and BBL waters were distinct from each other based on principal components analysis, with variances in the BBL ligand pool explained by sample location, and variance in surface waters explained by water mass. The use of multiple analytical window analysis elucidated several distinct iron-binding ligand pools, each with unique distributions in the central California Current system.

In this work, a wide range of pH-sensitive fluorescent probe has been designed by the responsive double hydrophilic block copolymer (DHBCs), which containing the fluorescein (Methacrylic salicylaldoxime, SHMa) and rhodamine (Rhodamine B methacryl hydrazide, RhSAMa) derivatives in the DHBCs. The pH-sensitive fluorescent probe gave blue and red fluorescence emissions at basic pH and acidic pH, respectively. Moreover, the fluorescent probe exhibited changes in fluorescence intensity with an alteration of turbidity of the block copolymer induced by temperature. Furthermore, we have developed a model that combines with the mobile phone for quantitative and qualitative measurement of pH value. The color extract APP for real-time pH measurement in mobile phone was constructed and used to detect the pH of the water samples.

In this study, previously published multiple analytical window datasets of competitive ligand exchange—adsorptive cathodic stripping voltammetry titrations for dissolved copper with salicylaldoxime as the competing ligand were reanalyzed. A new numerical method was applied, the Sander-Wells (S-W) method, which is able to simultaneously analyze multiple analytical window titrations as a unified dataset and calculate parameters for one to three ligand classes in the samples. The two datasets used were from separate sampling events at Dumbarton Bridge, San Francisco Bay. The aim of this study was to see if discrete ligand classes can be resolved from these data, and how these compare with results obtained by applying commonly used manual calculations of individual analytical window titrations separately: Scatchard and van den Berg/Ružic linearizations, and the Gerringa non-linear regression. The united multiple analytical window dataset could only be analyzed simultaneously by the S-W method, and two or three discrete ligand classes were resolved for each sample. Applying the four different data analysis methods independently to each of the five analytical windows resulted in solutions spanning a continuum of conditional stability constants and ligand concentrations. It was shown that the sensitivity S, as well as data structure and iterative optimization, are the major reasons for different results. This study demonstrates the utility of simultaneous analysis of multiple analytical window titration curves to better determine the distribution of trace metal species in aqueous systems and the advantages of adopting such a ‘unified data set’ approach over fitting individual titration curves.

The syntheses, structures and magnetic properties of seven new iron complexes, (Fe4O2(sao)4(tacn)2)·2MeOH·H2O (1·2MeOH·H2O), (Fe4O2(Me-sao)4(tacn)2)·2MeCN (2·2MeCN), (Fe4O2(Et- sao)4(tacn)2)·MeOH (3·MeOH), (Fe9NaO4(Et-sao)6(hmp)8)·3MeCN·Et2O (4·3MeCN·Et2O), (Fe4(Et-sao)4(hmp)4)·Et-saoH2 (5·Et-saoH2), (Fe4(Ph-sao)4(hmp)4)·2MeCN (6·2MeCN) (Fe9O3(sao)(pdm)6(N3)7(H2O)) (7), stabilised with salicylal- doxime (saoH2) or derivatised salicylaldoxime (R-saoH2) ligands in conjunction with either 1,4,7-triazocyclononane (tacn), 2-(hydroxymethyl)pyridine (hmpH) or 2,6-pyridinedimethanol (pdmH2) are discussed.

New compounds containing a novel zinc binding group (salicylaldoxime system) were identified as effective inhibitors of carbonic anhydrases (CAs). This structural motif seems to bind the catalytic zinc ion of CAs, revealing itself as a new valid alternative to the sulfonamide group. Computational procedures were used to investigate the binding mode of this class of compounds, within the active site of CAII. This study suggests that the salicylaldoxime moiety binds the zinc ion through the oxime oxygen atom that also forms an H-bond with T199. The results herein obtained will allow the development of new CA-inhibitors bearing the salicylaldoxime moiety.

In recent years, electrospray-ionization mass spectrometry (ESI-MS) has been increasingly used to complement the bulk determination of metal-ligand equilibria, for example via competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV). However, ESI-MS speciation analyses may be impacted by instrumental artifacts such as reduction reactions, fragmentation, and adduct formation at the ESI source, changes in the ionization efficiencies of the detected species in relation to sample matrix, and peak overlaps in response to increasing sample complexity. In our study, equilibria of the known artificial ligands citrate, ethylenediaminetetraacetic acid (EDTA), 1-nitroso-2-naphthol (NN), and salicylaldoxime (SA) with iron (Fe) and copper (Cu) were investigated by ultra-high resolution ESI-MS, Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), under a variety of sample matrix and ionization settings. The acquired mass spectra were compared with metal-ligand equilibrium data from the literature as well as an adapted speciation model. Overall, the mass spectra produced representative species mentioned in previous reports and predicted by the speciation calculations, such as Fe(Cit), Cu(Cit)2, Fe(EDTA), Cu(EDTA), Fe(NN)3, and Cu(SA)2. The analyses furthermore revealed new species which had been hypothesized but not measured directly using other methods, for example ternary complexes of citrate with Fe and Cu, Cu(SA) monomers, and the dimer Fe(SA)2. Finally, parallel measurements of a Cu+SA calibration series and a Cu+SA+EDTA competition series indicated that FT-ICR-MS can produce linear responses and low detection limits analogous to those of ACSV. We propose that ultra-high resolution FT-ICR-MS can be used as a representative tool to study interactions of trace metals with artificial as well as natural, unknown ligands at the molecular level.

The main purpose of this study was to achieve a substantial increase in the sensitivity of the uranium determination using UV-Vis spectrometry. To achieve this goal, ion-imprinted polymers were prepared for the uranyl (imprint) ion by the formation of a ternary (salicylaldoxime and 4-vinylpyridine) complex in 2-methoxy ethanol (porogen) following copolymerization with methacrylic acid. The synthesized polymers were characterized by FTIR analysis and thermogravimetric analysis. In the preconcentration step, the optimal pH was determined to be between values of 3.5 and 6.5. The adsorbed UO22+ was completely eluted by 10 mL of 3.0 mol L−1 HClO4. The developed method was applied to uranium (VI) determination in natural water samples. By using the initial volume of 500 mL and final volume of 5 mL, a concentration of 1 μg L−1 can be determined by applying the developed method in this study.

Hydrothermal vent fluids are highly enriched in iron (Fe) compared to ambient seawater, and organic ligands may play a role in facilitating the transport of some hydrothermal Fe into the open ocean. This is important since Fe is a limiting micronutrient for primary production in large parts of the world's surface ocean. We have investigated the concentration and speciation of Fe in several vent fluid and plume samples from the Nifonea vent field, Coriolis Troughs, New Hebrides Island Arc, South Pacific Ocean using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-AdCSV) with salicylaldoxime (SA) as the artificial ligand. Our results for total dissolved Fe (dFe) in the buoyant hydrothermal plume samples showed concentrations up to 3.86 mu M dFe with only a small fraction between 1.1 and 11.8% being chemically labile. Iron binding ligand concentrations (M) were found in mu M level with strong conditional stability constants up to logK(FeL,Fe)(3+) of 22.9. Within the non-buoyant hydrothermal plume above the Nifonea vent field, up to 84.7% of the available Fe is chemically labile and [L] concentrations up to 97 nM were measured. [L] was consistently in excess of Fe-lab, indicating that all available Fe is being complexed, which in combination with high F-lab values in the non-buoyant plume, signifies that a high fraction of hydrothermal dFe is potentially being transported away from the plume into the surrounding waters, contributing to the global oceanic Fe budget.

The pH of aqueous solutions is known to impact the chemical speciation of trace metals. In this study we conducted titrations of coastal seawaters with iron and copper at pH 7.91, 7.37 and 6.99 (expressed on the total pH scale). Changes in the concentration of iron and copper that complexed with the added ligands 1-nitroso-2-napthol and salicylaldoxime respectively were determined by adsorptive cathodic stripping voltammetry - competitive ligand equilibrium (AdCSV-CLE). Interpretation of the results, assuming complexation by a low concentration of discrete ligands, showed that conditional stability constants for iron complexes increased relative to inorganic iron complexation as pH decreased by approximately 1 log unit per pH unit, whilst those for copper did not change. No trend was observed for concentrations of iron and copper complexing ligands over the pH range examined. We also interpreted our titration data by describing chemical binding and polyelectrolytic effects using non-ideal competitive adsorption in Donnan-like gels (NICA-Donnan model) in a proof of concept study. The NICA-Donnan approach allows for the development of a set of model parameters that are independent of ionic strength and pH, and thus calculation of metal speciation can be undertaken at ambient sample pH or the pH of a future, more acidic ocean. There is currently a lack of basic NICA-Donnan parameters applicable to marine dissolved organic matter (DOM) so we assumed that the measured marine dissolved organic carbon could be characterized as terrestrial fulvic acids. Generic NICA-Donnan parameters were applied within the framework of the software program visual MINTEQ and the metal –added ligand concentrations [MeAL] calculated for the AdCSV-CLE conditions. For copper, calculated [MeAL] using the NICA-Donnan model for DOM were consistent with measured [MeAL], but for iron an inert fraction with kinetically inhibited dissolution was required in addition to the NICA-Donnan model in order to approximate the trends observed in measured [MeAL]. We calculated iron and copper speciation in Northwest European shelf water samples at ambient alkalinity and projected increased pCO2 concentrations as a demonstration of the potential of the approach.

The design of new ligands and investigation of UO2(2+) complexations are an essential aspect of reducing the cost of extracting uranium from seawater, improving the sorption efficiency for uranium and the selectivity for uranium over competing ions (such as the transition metal cations). The binding strengths of salicylaldoxime-UO2(2+) complexes were quantified for the first time and compared with the binding strengths of salicylic acid-UO2(2+) and representative amidoxime-UO2(2+) complexes. We found that the binding strengths of salicylaldoxime-UO2(2+) complexes are ∼2-4 log β2 units greater in magnitude than their corresponding salicylic acid-UO2(2+) and representative amidoxime-UO2(2+) complexes; moreover, the selectivity of salicylaldoxime towards the UO2(2+) cation over competing Cu(2+) and Fe(3+) cations is far greater than those reported for salicylic acid and glutarimidedioxime in the literature. The higher UO2(2+) selectivity can likely be attributed to the different coordination modes observed for salicylaldoxime-UO2(2+) and salicylaldoxime-transition metal complexes. Density functional theory calculations indicate that salicylaldoxime can coordinate with UO2(2+) as a dianion species formed by η(2) coordination of the aldoximate and monodentate binding of the phenolate group. In contrast, salicylaldoxime coordinates with transition metal cations as a monoanion species via a chelate formed between phenolate and the oxime N; the complexes are stabilized via hydrogen bonding interactions between the oxime OH group and phenolate. By coupling the experimentally determined thermodynamic constants and the results of theoretical computations, we are able to derive a number of ligand design principles to further improve the UO2(2+) cation affinity, and thus further increase the selectivity of salicylaldoxime derivatives.

The paper presents application of multiwall carbon nanotubes (MWCNTs) modified with 5-dodecylsalicylaldoxime to copper(II) flow-injection on-line preconcentration and flame atomic absorption spectrometric (FAAS) determination. Two new sorbents were obtained by impregnation of MWCNTs with Cu(II)-LIX 622® complex, however in the first case modification was preceded by carbon wall activation via oxidization (Cu-LIX-CNT-A sorbent), and in the second one no surface activation was performed (Cu-LIX-CNT sorbent). It was found that effective leaching of initially introduced copper and Cu(II) retained in preconcentration process could be realized with the use 7% and 5% (v/v) nitric acid, for particular sorbents. Testing the influence of loading solution pH and rate of loading on sorption it was found out that optimal range of loading solution pH was about 4.5–6.3 for activated and 6.15–6.25 for non-activated CNT. Investigation of sorption kinetics showed that the process can be described by pseudo-second order reaction model. Sorption equilibrium conditions (90% sorption) for LIX-CNT-A and LIX-CNT were obtained after 8–15 min, respectively and maximum sorption capacity for the new sorbents amounted to 18.1 mg g−1 and 31.6 mg g−1, respectively. For the examined sorbents enrichment factors increased with extension of loading time up to 180 s: linearly for activated and non-linearly for non-activated MWCNTs. Influence of potential interferents such as Cd(II), Zn(II), Fe(III), Mg(II) and Ca(II) ions on copper(II) sorption on the new CNT materials was examined individually and with the use of 25–2 factorial design. The study revealed significant interference from iron, magnesium and calcium ions at relatively high concentrations. Applicability of the proposed sorbents was tested for Cu(II) determination in various kinds of water samples and the results were compared with those obtained with the use of ICP MS as a reference technique. Copper(II) determination in two certified reference materials: waste water (EU-H-3) and ground (ES-H-2) water was performed in order to assess trueness of the evaluated preconcentration procedures. Satisfactory values of relative errors were obtained for both procedures.