Nano level detection of Cd(II) using poly(vinyl chloride) based membranes of Schiff bases

The construction and performance characteristics of polymeric membrane electrodes based on two neutral ionophores, 2,2′-(1Z,1′Z)-(1E,1′E)-(1,2-phenylenebis(methan-1-yl-1-ylidene))bis(azaan-1-yl-1-ylidene)bis(methylene)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-ylidene)diphenol (L₁) and 4,4′-(1E,1′E)-(butane-1,4-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-1-ol (L₂) for quantification of cadmium ions, are described. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with the electrode having a membrane composition (w/w) of (L₁) (2.6%):PVC (31.6%):DOP (63.2%):NaTPB (2.6%). The proposed electrode exhibits Nernstian response in the concentration range 5.0 × 10⁻⁹ to 1.0 × 10⁻¹ M Cd²⁺ with limit of detection 3.1 × 10⁻⁹, performs satisfactorily over wide pH range (2.0-8.5) with a fast response time (11 s). The electrode has been found to work satisfactorily in partially non-aqueous media up to 40% (v/v) content of methanol, ethanol and acetonitrile and could be used for a period of 2.5 months. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of cadmium in cigarette samples. The practical utility of the membrane electrode has also been observed in the presence of surfactants.     

Formation of polymeric chain assemblies of transition metal complexes with a multidentate Schiff-base

The new multidentate Schiff-base (E)-6,6′-((1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-ylidene))bis(4-methyl-2-((E)(pyridine-2-ylmethylimino)methyl)phenol) H₂L and its polymeric binuclear metal complexes with Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) are reported. The reaction of 2,6-diformyl-4-methyl-phenol with ethylenediamine in mole ratios of 2:1 gave the precursor 3,3′-(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1ylidene))bis(methan-1-yl-1-ylidene)bis(2-hydroxy-5-methylbenzaldehyde) W. Condensation of the precursor with 2-(amino-methyl)pyridine in mole ratios of 1:2 gave the new N₆O₂ multidentate Schiff-base ligand H₂L. Upon complex formation, the ligand behaves as a dibasic octadentate species with the involvement of the nitrogen atoms of the pyridine groups in coordination for all complexes. The mode of bonding and overall geometry of the complexes were determined through physico-chemical and spectroscopic methods. These studies revealed octahedral geometries for Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) complexes of general formulae [Cr₂^III(L)Cl₂]Cl₂, [Ni₂^II(L)(H₂O)₂]Cl₂ and [M₂(L)Cl₂] and five co-ordinate Zn(II) complex of general formula [Zn₂^II(L)]Cl₂.     

Synthesis, structure and property of one porous Zn(salen)-based metal-metallosalen framework

Chiral Schiff-base ligand L was synthesized through six steps in good overall yield from readily available 2-tert-butylphenol and was used to construct one chiral porous metal-metallosalen framework,[Zn5(μ3-OH)2(ZnL)4(H2O)2]·18H2O(1,L=5′,5″-(1E,1′E)-(1R,2R)-cyclohexane-1,2-diylbis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(3′-tert-butyl-4′-hydroxybiphenyl-4-carboxylic acid),under mild reaction conditions.1 was characterized by IR,TGA,CD,UV,PL,single-crystal and powder X-ray crystallography.The structure of 1 displays a 3-fold interpenetrating 3D framework with 1D channel of 1.14 nm×0.58nm and imparts unique Zn(salen)units on the surface of the pore,in which(ZnL)2dimer acts as multi-functionlized metalloligand.1 is thermally robust with network decomposition temperature of 400oC and it also exhibits strong photoluminescence in the visible region.     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Hydrothermal syntheses and characterization of cobalt(II) and nickel(II) complexes of 1,3-adamantanedicarboxylic acid and 1,10-phenanthroline

Two coordination complexes, namely [Co(phen)(H₂O)L]·H₂O and [Ni₂(phen)₂(H₂O)₂L₂]·4H₂O (phen = 1,10-phenanthroline, H₂L = 1,3-adamantanedicarboxylic acid) have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. [Co(phen)(H₂O)L]·H₂O consists of 1D chains of the complex plus lattice H₂O molecules. Interchain hydrogen bonds and π–π stacking interactions assemble the 1D chains into 2D layers. [Ni₂(phen)₂(H₂O)₂L₂]·4H₂O is a binuclear complex which is assembled into a 3D supramolecular structure by strong hydrogen bonds and π–π stacking interactions. Both complexes were characterized by physico-chemical and spectroscopic methods.     

Studies on the magnetic properties of two cobalt(II) complexes bearing 1,4-phenylenediacetate ligands

One reported compound [Co(PDA)(4,4′-bipy)]_n·nH₂O and one new compound [Co(PDA)(Im)₂(H₂O)₂]_n·nH₂O were prepared by the reactions of Co(NO₃)₂·6H₂O or Co(OH)₂ with 1,4-phenylenediacetic acid (H₂PDA) in the presence of the ancillary ligands 4,4′-bipyridine (4,4′-bipy) or imidazole (Im), and their magnetic properties were investigated. The presence of 4,4′-bipy in [Co(PDA)(4,4′-bipy)]_n·nH₂O results in a μ ₃-bridging mode of the PDA²⁻ ligand with one μ ₂-carboxylato group and one chelating carboxylato group and the construction of a 2D framework as reported in the literature. The introduction of Im ligand in [Co(PDA)(Im)₂(H₂O)₂]_n·nH₂O helps to construct a one dimensional chain with the two carboxylato groups of PDA²⁻ ligand in monodentate coordination modes. The magnetic studies reveal the presence of dominant antiferromagnetic interaction in [Co(PDA)(4,4′-bipy)]_n·nH₂O with a field-induced magnetic transition due to spin-flop. Magnetically, [Co(PDA)(Im)₂(H₂O)₂]_n·nH₂O presents a mononuclear structure. This work reveals that the introduction of ancillary ligands in the Co(II)-PDA system adjusts the linking modes of PDA²⁻ and therefore the resulting frameworks and their magnetic properties.     

Studies of Co(II), Ni(II), Cu(II) and Cd(II) chelates with different phosphonic acids

Co(II), Ni(II), Cu(II) and Cd(II) chelates with 1-aminoethylidenediphosphonic acid (AEDP, H₄L¹), α-amino benzylidene diphosphonic acid (ABDP, H₄L²), 1-amino-2-carboxyethane-1,1-diphosphonic acid (ACEDP, H₅L³), 1,3-diaminopropane-1,1,3,3-tetraphosphonicacid (DAPTP, H₈L⁴), ethylenediamine-N,N′-bis(dimethylmethylene phosphonic)acid (EDBDMPO, H₄L⁵), O-phenylenediamine-N,N′-bis(dimethyl methylene phosphonic)acid (PDBDMPO, H₄L⁶), diethylene triamine-N,N,N′,N′,N″N″-penta(methylene phosphonic)acid (DETAPMPO, H₁₀L⁷) and diethylene triamine-N,N″-bis(dimethyl methylene phosphonic)acid (DETBDMPO, H₄L⁸) have been synthesised and were characterised by elemental and thermal analyses as well as by IR, UV–VIS, EPR and magnetic measurements. The first stage in the thermal decomposition process of these complexes shows the presence of water of hydration, the second denotes the removal of the coordinated water molecules. After the loss of water molecules, the organic part starts decomposing. The final decomposition product has been found to be the respective MO·P₂O₅. The data of the investigated complexes suggest octahedral geometry with respect to Co(II) and Ni(II) and tetragonally distorted octahedral geometry with respect to Cu(II). Antiferromagnetism has been inferred from magnetic moment data. Infrared spectral studies have been carried out to determine coordination sites.     

Synthesis and study of cobalt(II), nickel(II), and copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

New complexes of Co(II), Ni(II), and Cu(II) nitrates, chlorides, and perchlorates with 4-(4-hydroxyphenyl)-1,2,4-triazole (L) were obtained and examined by single-crystal X-ray diffraction, X-ray powder diffraction, and electronic absorption and IR spectroscopy. The cations of all the complexes have linear trinuclear structures. Ligand L is coordinated to the metal ions in a bidentate bridging fashion through the N(1) and N(2) atoms of the heterocycle. The coordination polyhedron of the metal atoms is a distorted octahedron. The molecular and crystal structures of the complexes [Co₃L₆(H₂O)₆](ClO₄)₆ · 3C₂H₅OH · 3.75H₂O and [M₃L₆(H₂O)₆](ClO₄)₆ · 6H₂O (M = Cu²⁺ and Ni²⁺) were determined.     

Synthesis,Structural Characterization,and Antimicrobial Activities of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Triazole‐based Azodyes

The synthesis and characterization of new transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3‐(2‐hydroxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL¹ ) and 3‐(2‐hydroxy‐3‐carboxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL² ) have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and ¹H NMR spectra indicated that HL¹ and HL² coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV‐Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [Mn L¹ (AcO)(H₂O)₃] ( 1 ), [Co L¹ (AcO)(H₂O)₃]·H₂O ( 2 ), [Mn L² (AcO)(H₂O)₃] ( 6 ) and [Co L² (AcO)(H₂O)₃] ( 7 ), [Ni L¹ (AcO)(H₂O)] ( 3 ), [Zn L¹ (AcO)(H₂O)]·H₂O ( 5 ), [Ni L² (AcO)(H₂O)] ( 8 ), [Zn L² (AcO)(H₂O)]·10H₂O ( 10 ) have tetrahedral geometry, whereas [Cu L¹ (AcO)(H₂O)₂] ( 4 ) and [Cu L² (AcO)(H₂O)₂]·5H₂O ( 9 ) have square pyramidal geometry.. The mass spectra of the complexes under EI‐con‐ ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of ⁵⁵Mn, ⁵⁹Co, ⁵⁸Ni, ⁶³Cu and ⁶⁴Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats‐Redfern method. HL² and complexes 6 – 10 were found to have moderate antimicrobial activities against Staphylococcus aureus (gram positive), Escherichia coli (gram negative) and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.     

Size and stability of chelate rings in coordination compounds of cobalt(II), manganese(II), iron(III) and palladium(II) with vicinal oxime-imine ligands

Summary Two types of the Co^II complexes L¹Co (H₂L¹=N,N-ethylenebis(isonitrosoacetylacetoneimine) were prepared. In type (a) the chelate rings are five-membered whereas in type (b) they are six-membered. The type (b) complexes were converted to type (a) in refluxing solutions. Half-ionization of the ligand is observed in the complexes HL¹ Co(O₂CMe) and HL¹MnCl, where the chelate rings are five- and six-membered respectively. The octahedral complex L¹FeCl·H₂O has chelate rings of type (a) as does the complex L²Co (H₂L²=unsymmetric Schiff baseN,N-ethylene(isonitrosoacetylacetoneimineacetylacetoneimine). Twocis complexes (L_a ²L_b ³)Pd and (L_a ³)₂Pd are characterized (HL³=isonitrosoacetylacetoneimine, (a) and (b) denote the type of chelate ring). Structures for the metal complexes and the sizes of the chelate rings are suggested on the basis of analytical and spectral evidence.     

Synthesis,Characterization and Anti-oxidative Activity of Cobalt(II), Nickel(II) and Iron(II) Schiff Base Complexes

Six complexes, M(HL)₂ · nH₂O (M=Co, Ni and Fe; n=4) with two ligands, 2-carboxy-benzaldehydebenzoylhydrazone (H₂L¹) and 2-carboxybenzaldehyde-(4′-methoxy)benzoylhydrazone (H₂L²), have been synthesized and characterized on the basis of elemental analyses, molar conductivities, i.r. spectra and thermal analyses. In addition, the suppression ratio for O₂^- (a) and the suppression ratio for OH^· (b) were determined with a 72 spectrophotometer. The 50% inhibition [IC₅₀ (a) and IC₅₀ (b)] of the complexes were studied. This study demonstrated that the complexes have activity in the suppression of O₂^- (a) and OH^· (b). In general, the antioxidative activities increased as the concentration of these complexes increased up to a selected extent. The complexes exhibit more effective antioxidants than the ligands and the series of the ligand (H₂L²) are better than the series of the ligand (H₂L¹) do.     

Coordination compounds of cobalt(II), nickel(II), and copper(II) with 4-(3-hydroxyphenyl)-1,2,4-triazole: Synthesis and study

New Co(II), Ni(II), and Cu(II) complexes with 4-(3-hydroxyphenyl)-1,2,4-triazole (L) with the compositions [Co₃L₆(H₂O)₅(C₂H₅OH)](NO₃)₆ · 2H₂O · C₂H₅OH (I), [Ni₃L₆(H₂O)₆](NO₃)₆ · 2H₂O (II), and [M₃L₆(H₂O)₆](ClO₄)₆ · nH₂O (M = Co2⁺, n = 2 (III); Ni²⁺, n = 2 (IV); Cu²⁺, n = 0 (V)) are synthesized. The complexes are studied by X-ray structure analysis, X-ray diffraction analysis, UV and IR spectroscopy, and the statistical magnetic susceptibility method. All compounds have the linear trinuclear structure. Ligand L is coordinated to the metal ions by the N(1) and N(2) atoms of the heterocycle according to the bidentate bridging mode. In all compounds the coordination polyhedron of the metal atom is a distorted octahedron. The molecular and crystal structures of compound I, [Co₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IIIa), and [Ni₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IVa) are determined.     

Complexes of Mn(II), Co(II), Ni(II) and Cu(II) with 4,4'-bipyridine and dichloroacetates

New mixed-ligand complexes with empirical formulae M(4-bpy)L₂·1.5H₂O (M(II)=Mn, Co), Ni(4-bpy)₂L₂ and Cu(4-bpy) L₂·H₂O (where: 4-bpy=4,4'-bipyridine, L=CC L2HCOO^-) have been isolated in pure state. The complexes have been characterized by elemental analysis, ir spectroscopy, conductivity (in methanol, dimethylformamide and dimethylsulfoxide solutions) and magnetic and x-ray diffraction measurements. The Mn(II) and Co(II) complexes are isostructural. The way of metal-ligand coordinations discussed. the ir spectra suggest that the carboxylate groups are bonded with metal(II) in the same way (Ni, Cu) or in different way (Mn, Co). The solubility in water is in the order of 19.40·10^-3÷1.88·10^-3ł mol dm^-3ł. During heating the hydrate complexes lose all water in one step. The anhydrous complexes decompose to oxides via several intermediate compounds. A coupled TG-MS system was used to analyse the principal volatile products of obtained complexes. The principal volatile products of thermal decomposition of complexes in air are: H₂O₂ ⁺, CO₂ ⁺, HCl⁺, Cl₂ ⁺, NO⁺ and other. This revised version was published online in July 2006 with corrections to the Cover Date.     

Supramolecular cobalt(II) complexes: syntheses,crystal structures and solvent effects

Two Co^II complexes, namely {[CoL(MeOH)(μ-OAc)]₂Co}·2MeCN·2MeOH (1) and {[CoL(EtOH)(μ-OAc)]₂Co}·3EtOH (2) (H₂L=3,3′-dimethoxy-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol), have been synthesized and characterized by X-ray crystallography. Both complexes contain octahedral coordination geometries, comprising three Co^II atoms, two deprotonated bisoxime L²⁻ units in which four μ-phenoxo oxygen atoms form two [CoL(X)] (X = MeOH or EtOH) units, two acetate ligands coordinated to three Co^II centers through Co–O–C–O–Co bridges, and coordinated and non-coordinated solvent. Both complexes exhibit 2D supramolecular networks through different intermolecular hydrogen-bonding interactions.     

New complexes of Mn(II), Co(II), Ni(II) AND Cu(II) with 2,2’- OR 2,4’-bipyridine and formates (Synthesis, thermal and other properties)

New mixed-ligand complexes with empirical formulae: Mn(2-bpy)_1.5L₂·2H₂O, M(2-bpy)₂L₂·3H₂O (M(II)=Co, Cu), Ni(2-bpy)₃L₂·4H₂O and M(2,4’-bpy)₂L₂·2H₂O (where 2-bpy=2,2’-bipyridine, 2,4’-bpy=2,4’-bipyridine; L=HCOO^– ) have been obtained in pure solid-state. The complexes were characterized by chemical and elemental analysis, IR and VIS spectroscopy, conductivity (in methanol and dimethylsulfoxide). The way of metal-ligand coordination discussed. The formate and 2,4’-bpy act as monodentate ligands and 2-bpy as chelate ligand. The new complexes with ligand isomerism were identified. During heating the complexes lose water molecules in one or two steps. Thermal decomposition after dehydration is multistage and yields corresponding metal oxides as final products. A coupled TG-MS system was used to analysis principal volatile thermal decomposition (or fragmentation) products of Ni(2,4’-bpy)₂(HCOO)₂·2H₂O under dynamic air or argon atmosphere.     

3- and 4-Pyridinecarboxylic acidN-oxide complexes with manganese(II), cobalt(II) and nickel(II) chlorides

Summary During interaction of ethanol-triethyl orthoformate solutions of nicotinic or isonicotinic acidN-oxides (LH and LH, respectively) with MCl₂ (M = Mn, Co, Ni), only one true adduct, of the Ni(LH)₃Cl₂ · 2 H₂O type was obtained. In all other cases, partial substitution of Cl^– ions with the corresponding pyridinecarboxylateN-oxide anionic ligands (L or L) occurred. As a result, mixed ligands (LH-L or LH-L) were precipitated, as follows: Mn(LH)₂LCl, Co(LH)LCl, Mn(LH)LCl · 4H₂O, Co(LH)LCl · H₂O and Ni₂(LH)LCl₃ · 6 H₂O. The insolubility of the new complexes in all common solvents, combined with the pronounced tendency of the 3- and 4-pyridinecarboxylates and theirN-oxides to function as bidentate bridging ligands, favours bi- or polynuclear structures. Spectral data suggest that Ni(LH)₃Cl₂ · 2 H₂O is hexacoordinate, and the rest of the new complexes pentacoordinate. Bi- or polynuclear structures, involving double -M-(L)₂-M- or-M-(LH)₂-M- and single -M-(L)-M- or-M(L)-M-(LH)-M- bridges, were proposed on the basis of the overall evidence; additional features of the proposed structural types are: exclusively coordinated chloro ligands, in all cases; aqua ligands [Co(LH)LCl · H₂O]; lattice water [Ni(LH)₂Cl₂ · 2H₂O]; both lattice and coordinated H₂O [Mn(LH)LCl · 4H₂O, and Ni₂(LH)LCl₃ · 6H₂O]; and, with the exception of Ni₂(LH)LCl₃ · 6 H₂O, terminal, unidentate, N-O oxygen-bonded LH or LH ligands.Abstracted in part from the Ph.D. Thesis (in preparation) of L. S. Gelfand, Drexel University.     

Synthesis and characterization of 2,3-bis(hydroxyimino)-1,2,3,4-tetrahydro-pyrido[2,3-b]pyrazine and its nickel(II), cobalt(II), copper(II), palladium(II), cadmium(II) and cobalt(III) complexes

Summary 2,3-Bis(hydroxyimino)-1,2,3,4-tetrahydro-pyrido[2,3-b]pyrazine (H₂L), prepared from 2,3-diaminopyridine and cyanogen-di-N-oxide has been converted into nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) complexes (H₂L) with a 12 metal:ligand ratio. The ligands coordinate through the two N atoms, as do most vicinal dioximes. [(LH)Cl(H₂O)Cd], contains a six-membered chelate ring. [Co(HL)₂(L)Cl] has also been prepared using triphenylphosphine, triphenylarsine, thiophene and chloride as axial ligands. The structure of thevic-dioxime and its complexes are proposed on the basis of elemental analysis, i.r.,¹H-n.m.r. and uv-visible measurements.     

Studies on solid state synthesis and the oxygenation property of cobalt (II) Schiff base (vanilline polyamine) complexes

Three new cobalt complexes were synthesized by solid-state reaction at room temperature and the resultant Co complexes reacted with two equivalent oxygen molecules at room temperature to produce the oxygenated complexes [Co·(L₁)₂·(O₂)₂](NO₃)₂·2H₂O (L₁ = N, N’-bis(4-hydroxyl-3-methoxy-benzyl)-diethylenetriamine), [Co·(L₂)₂·(O₂)₂](NO₃)₂·2H₂O (L₂ = N, N’-bis(4-hydroxyl-3-methoxy-benzyl)-triethylenetetramine), and [Co·(L₃)₂·(O₂)₂](NO₃)₂·2H₂O (L₃ = N, N’-bis(4-hydroxyl-3-methoxy-benzyl-tetraethylenepentamine). The oxygenated complexes were characterized by elemental analysis, IR (Infrared), ¹H-NMR (Nuclear Magnetic Resonance), and UV-Vis (Ultraviolet Visual) spectrometry, and TG/DTA (Thermogravimetry/Differential Thermal Analysis) analysis, and molar conductance. The coordinated oxygen contents in the oxygenated complexes were also determined by weight method. It was supposed that only one O₂ molecule coordinated to the Co ion forming a superoxo type oxygenated complex. Translated from Acta Chimica Sinica, 2006, 64(15): 1517–1522 (in Chinese)     

Deprotonated and non-deprotonated cobalt(II) complexes of the bis-amide tetradentate ligand N,N′-(dipicolyl)-1,8-naphthylene diamine. Three different modes of coordination by the ligand

The preparation and some properties of the cobalt(II) complexes Co(LH₂)Cl₂·2H₂O, Co(LH₂(NCS)₂ and CoL·H₂O (whereLH₂=N,N-(dipicolyl)-1,8-naphthylenediamine) are reported. On the basis of magnetic moments, visible reflectance and IR data, the structure is proposed to be pseudo-octahedral for Co(LH₂)Cl₂·2 H₂O, pseudo-tetrahedral for Co(LH₂)(NCS)₂ and square planar for CoL·H₂O.

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Deprotonierte und Nicht-deprotonierte Co(II)-Komplexe des vierzähnigen Bisamid-Liganden N,N-(Dipicolyl)-1,8-naphthyldiamin. Drei verschiedene Koordinationstypen

Zusammenfassung Es werden die Darstellung und einige Eigenschaften der Kobalt(II)-Komplexe Co(LH₂)Cl₂·2 H₂O, Co(LH₂)(NCS)₂ und CoL·H₂O [LH₂=N,N-(dipicolyl)-1,8-naphthylendiamin] diskutiert. Auf der Grundlage von magnetischen Momenten, von Daten der sichtbaren Reflektions-und IR-Spektren wird eine pseudooctaedrische Struktur für Co(LH₂)Cl₂·2H₂O, eine pseudotetraedrische für Co(LH₂)(NCS)₂ und eine planar-quadratische für CoL·H₂O vorgeschlagen.

     

Vanadium(IV) catalysed oxidation of organosulfur compounds in heavy fuel oil

The deleterious effects of refractory polyaromatic hydrocarbons found in fuels such as organo-sulfur compounds are such that they emit SO_x to the environment when combusted, thereby reducing air quality. Herein, oxidative desulfurization (ODS) which is a complementary step to hydrodesulfurization (HDS) was carried out in an attempt to eliminate sulfur compounds in fuels. Refractory organosulfur compounds were oxidized using tert-butyl hydroperoxide as an oxidant and a poly[VO(allylSB-co-EGDMA)], (vanadium(IV) functionalized polymer of 6,6′-(1E,1′E)-(1,2-phenylenebis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)bis(2-allylphenol) crosslinked with ethyleneglycol dimethacrylate) as a catalyst to convert sulfur compounds to polar sulfones. Some of the organosulfones were adsorbed via the use of molecularly imprinted polybenzimidazole nanofibers. The sulfur in heavy fuel oil after the oxidation/adsorption method fell below 8900 ± 200 ppmw S from the initial value of 17 920 ± 100 ppmw S.