Competitive complexation in the copper(II) chloride-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide-Aerosil system

Competitive complexation in the copper(II) chloride-N,N-dimethylformamide (DMF)-Aerosil system was studied by IR spectroscopy. It was found that adsorption from organic solutions containing copper(II) chloride and DMF resulted in the formation of the following three types of DMF complexes: self-associates of DMF, DMF complexes with surface hydroxyl groups, and DMF complexes with Cu(II) ions. The removal of DMF resulted in the sequential degradation of, initially, self-associates; next, complexes with silanol groups; and, finally, complexes with copper ions.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 917–920.Original Russian Text Copyright © 2004 by Golubeva, Zubareva.     

Spectral study of the catalytic reaction of hydrosiloxanes with vinylsiloxanes

¹H, ¹³C, and IR spectroscopy and gas chromatography-mass spectrometry were used to study addition of hydrosiloxanes to vinylsiloxanes in the presence of Pt(II) complexes. Along with hydrosilylation, dehydrocondensation and disproportionation of hydrosiloxanes occur.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 9, 2004, pp. 1426–1433.Original Russian Text Copyright © 2004 by de Vekki, Viktorovskii, Skvortsov.This revised version was published online in April 2005 with a corrected cover date.     

Thermal and electrical studies of some polychelates

Polychelates of Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) with 4,4′-dihydroxy-3,3′-diacetylbiphenyl-dithioxamide (DDBDO) have been prepared. Their structures were determined by visible reflectance spectroscopy and magnetic measurements in conjunction with thermogravimetric and IR measurements. Elemental analysis indicates a 1∶1 metal-ligand stoichiometry and the association of water molecules with the central metal. The decomposition temperature of the chelates is in the order Ni(II)>Fe(II)>Co(II)>Mn(II)>Cu(II). Thermal activation energies (E _a ), calculated with the help of Freeman-Carroll and Sharp-Wentworth methods, are in agreement with each other. The polychelates were found to be semiconductive, and the activation energy obtained from semiconducting behavior follows the order Co(II)>Ni(II)>Fe(II)>Cu(II)>Mn(II). The probable structure, such as six coordinated octahedral for Mn(II) and Fe(II) polychelates and four coordinated square planar for Co(II), Ni(II), and Cu(II) polychelates, have been suggested.     

An infrared spectroscopic based method for mercury(II) detection in aqueous solutions

A new method that uses solid phase extraction (SPE) coupled with FTIR spectroscopy to detect Hg(II) in aqueous samples is described. The technique is envisioned for on-site, field evaluation rather than lab-based techniques. This paper presents the “proof of principle” of this new approach toward measurements of Hg(II) in water and identifies mass transport issues that would need to be overcome in order to migrate from a lab based method to field operation. The SPE material supported on a Si wafer is derivatized with an acylthiosemicarbazide, which undergoes a reaction in the presence of aqueous Hg(II) to form an oxadiazole ring. The progress of the reaction is monitored by IR spectroscopy. Following EPA guidelines, the method of detection limit (MDL) for the SPE/IR was 5 μg of Hg(II) cm⁻². In a 1 L sample and a 1 cm² Si wafer, this translates to a detection limit of 5 ppb. This system shows a high selectivity toward aqueous Hg(II) over other thiophilic heavy metal ions such as Pb(II), Cd(II), Fe(III), and Zn(II) and other metal ions such as Ni(II), Mn(II), Co(II), Cu(II), In(III), Ru(III), Na(I), and Ag(I) in aqueous solutions.     

Synthesis and Thermal Analysis of 2,2′-bipyridine Divalent Transition Metal Hexachloroplumbates

Several complex salts of the general formula [M(II) (bipy)_x(H₂O)_y]PbCl₆ (where x=2–3, y=0–2 and M=Mn(II), Fe(II), Ni(II), Co(II), Cu(II), Zn(II), Cd(II) and Hg(II)) were synthesized and investigated by DTA, TG and DTG. Some of the decomposition products were identified by IR spectroscopy and other methods. The compounds decompose with the liberation of water (in the case of hydrates), chlorine (sometimes causing chlorination of organic fragments), organic molecules (sometimes chlorinated) and sometimes hydrogen chloride. The residues comprise metal(II) chlorides and PbCl₂. This revised version was published online in August 2006 with corrections to the Cover Date.     

Influence of the synthesis media in the properties of CuO obtained by microwave-assisted hydrothermal method

Copper monoxide (CuO) was successfully obtained by microwave-assisted hydrothermal method, using different conditions—in a solution without base, in a solution alkalinized with NaOH or with NH₄OH. The powders were analyzed by thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared spectroscopy, UV–Visible spectroscopy, and scanning electronic microscopy. XRD results showed that CuO was obtained with monoclinic structure and without secondary phases. Thermal analysis and infrared spectra indicated the presence of acetate groups on the powder surface. TG curves also showed a mass gain assigned to the Cu(I) oxidation indicating that a reduction possibly occurred during synthesis. The high and broad absorption band in the UV–Vis spectroscopy from 250 to 750 nm indicated the coexistence of Cu(II) and Cu(I), confirming the Cu(II) reduction, inside the CuO lattice. It was also possible to confirm the Cu(II) reduction by a displacement of the Me–O vibration bands observed in the IR spectra at around 500 cm⁻¹.     

Crosslinked chitosan nanofiber mats fabricated by one-step electrospinning and ion-imprinting methods for metal ions adsorption

The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were fabricated by one-step electrospinning and ion-imprinting methods and their application as adsorbents for metal ions was also investigated.The resulting chitosan nanofiber mats were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermal gravimetric analysis(TGA).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were used as adsorbents for the removal of Pb(Ⅱ)ions from aqueous or acid solutions.The effects of p H values,contact time,content of crosslinker(glutaraldehyde)on Pb(Ⅱ)ions adsorption were studied.The results indicated that the Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had the highest adsorption capacity of 110.0 mg/g at p H 7.The kinetic study demonstrated that the adsorption of Pb(Ⅱ)ions followed the pseudo-second-order model.The equilibrium isotherm data showed that the Langmuir model was the most suitable for predicting the adsorption isotherm of the studied system.The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had good adsorption selectivity,which illustrates the equilibrium adsorption capacity in the order of Pb(Ⅱ)Cu(Ⅱ)Zn(Ⅱ)Cd(Ⅱ)Ni(Ⅱ).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were stable and had good reuse ability.     

Some divalent metal(II) complexes of novel potentially tetradentate Schiff base N,N′‐bis(2‐carboxyphenylimine)‐2,5‐thiophenedicarboxaldhyde: Synthesis,spectroscopic characterization and bioactivities

A novel tetradentate dianionic Schiff base ligand, N ,N ′‐bis(2‐carboxyphenylimine)‐2,5‐thiophenedicarboxaldhyde (H₂L) and some first row d‐transition metal chelates (Co(II), Cu(II), Ni(II) and Zn(II)) were synthesized and characterized using various physicochemical and spectroscopic methods. The spectroscopic data suggested that the parent Schiff base ligand coordinates through both deprotonated carboxylic oxygen and imine nitrogen atoms. The free Schiff base and its metal chelates were screened for their antimicrobial activities for various pathogenic bacteria and fungi using the agar well diffusion method. The antibacterial and antifungal activities of all the newly synthesized compounds are significant compared to the standard drugs ciprofloxacin and nystatin. The antioxidant activities of the compounds were determined by reduction of 1,1‐diphenyl‐2‐picrylhydrazyl and compared with that of vitamin C as a standard. DNA binding ability of the novel Schiff base and its complexes was investigated using absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and thermal denaturation. The obtained results clearly demonstrate that the binding affinity with calf thymus DNA follows the order: Cu(II) complex > Ni(II) complex > Zn(II) complex > Co(II) complex >H₂L. Furthermore, the DNA cleavage activity of the newly synthesized ligand and its metal complexes was investigated using supercoiled plasmid DNA (pUC18) gel electrophoresis.     

Synthesis of new ionic β-cyclodextrin polymers and characterization of their heavy metals retention

In this study, a new aqueous insoluble ionic β-cyclodextrin polymer (PYR), synthesized by reaction of β-cyclodextrin with pyromellitic anhydride [1], is characterized by IR spectroscopy, showing typical cyclodextrin and carboxylic absorptions. pH-metric titrations of the acidic functions with standard NaOH solutions followed by a refinement of protonation constants, with specific software for equilibrium in solution, have been performed. Through this approach, the pK _a values of the functional groups have been calculated. The complexation capabilities of PYR towards metal ions [Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II), Pt(IV), Tl(I), and U(IV)] have been evaluated in aqueous solution (pH 3–5). The retention is mainly pH dependent and higher than 70% for Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II) and U(IV). For Tl(I) and Pt(IV) the retention is about 60% and 40% respectively.     

Synthesis and characterization of some penicillins modified with germanium‐containing moieties

Penicillin derivatives, penicillin G ( 1 ), penicillin V ( 2 ) and ampicillin ( 3 ), were modified with germanium‐containing moieties and their structures were confirmed based on NMR spectroscopy and MALDI‐TOF. Their antibacterial ability was tested. None of these exhibited activity stronger than the parent penicillins. Copyright © 2004 John Wiley & Sons, Ltd.     

Electrical conductivity of some hydrazones and binary complexes with transition metals

Summary The electrical behaviour of some hydrazones was studied in the temperature range of 290–435 K. The effect of complex formation with Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) on the electrical conductivity of the hydrazones was investigated. The structure of the hydrazones was characterized using¹H and¹³C NMR spectroscopy. Conductometric titration and IR spectroscopy were used to illustrate the structure of the hydrazone complexes. Both the structures of the hydrazones and the complexation process play an effective role in the conduction process.

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Elektrische Leitfähigkeit einiger Hydrazone und ihrer binären Komplexe mit Übergangsmetallen

Zusammenfassung Das elektrische Verhalten einiger Hydrazone und ihrer Komplexe mit Mn(II), Fe(II), Co(II), Ni(II) und Cu(II) wurde im Temperaturbereich von 290 bis 435K untersucht. Die Strukturen der Hydrazone wurden mittels¹H- und¹³C-NMR-Spektroskopie charakterisiert, jene ihrer Komplexe durch konduktometrische Titration und IR-Spektroskopie. Sowohl die Strukturen der Hydrazone als auch der Komplexbildungsvorgang spielen eine wesentliche Rolle beim Leitungsvorgang.

     

Palladium(II) and platinum(II),(IV) complexes of 2-aminopyrimidine derivatives

Palladium(II) and Platinum(II),(IV) complexes with 2-aminopyrimidine derivatives (L1)–(L3), prepared by reacting the corresponding metal halide with the ligand in the required stoichiometric ratio, were characterised by chemical analyses and physical measurements. The structures have been assigned on the basis of i.r. spectroscopy, electronic reflectance spectra and molar conductivities.     

Novel heteroligand complexes of Co(II), Cu(II), Ni(II) and Mn(II) formed by 2,2′-dipyridyl or 1,10-phenanthroline and phosphortriamide ligands: Synthesis and structure

This paper presents examples of mixed-ligand Co(II), Cu(II), Ni(II) and Mn(II) complexes, with a distorted octahedral coordination geometry, with 2,2′-dipyridyl or 1,10-phenanthroline and phosphortriamide ligands. The complexes of the general type ML₂·Lig (where M = Co(II), Cu(II), Ni(II), Mn(II); L⁻ = {Cl₃C(O)NP(O)R₂}⁻ (R = NHBz, NHCH₂CHCH₂, NEt₂); Lig = 2,2′-dipyridyl or 1,10-phenanthroline) were synthesised and characterised by means of X-ray diffraction, IR and UV–Vis spectroscopy. The phosphortriamide ligands are coordinated via oxygen atoms of phosphoryl and carbonyl groups involved in six-membered metal cycles. The additional ligands 2,2′-dipyridyl or 1,10-phenanthroline are coordinated to the central atom, forming five-membered cycles.     

Surface structure and thermal oxidative degradation of the reaction products of polyethylene with PCl3 and VOCl3 vapors

Reaction products of phosphorus(III) chloride and vanadium(V) oxychloride with low-density polyethylene were studied by chemical analysis and physicochemical (IR spectroscopy and atomic-force microscopy) methods. Thermaloxidative transformations of the initial and modified samples were studied by differential thermal analysis.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1872–1876.Original Russian Text Copyright © 2004 by Trifonov, Sosnov, Malygin.     

Poly(crotonic acid-co-2-acrylamido-2-methyl-1-propanesulfonic acid)-metal complexes with copper(II), cobalt(II), and nickel(II): Synthesis, characterization and antimicrobial activity

Poly(crotonic acid-co-2-acrylamido-2-methyl-1-propanesulfonic acid) [P(CrA-co-AMPS)] (44.22:55.78) copolymer was prepared in N,N-dimethylformamide solution using the benzoyl peroxide (Bz₂O₂) as initiator. Cu(II), Ni(II) and Co(II) chelates of the copolymer were prepared and the formation constants of each complex were determined by the mole-ratio method using UV-vis spectroscopy. UV-vis studies showed that the complex formation tendency increased in the followed order: Cu(II) > Ni(II) > Co(II). The copolymer and its metal chelates were characterized by FTIR, TGA, X-ray diffraction and SEM analysis. Also, in vitro antimicrobial activity of the polymers were tested on various bacteria, and yeast.     

Novel crown-containing porphyrin and its complexes with transition metals

The novel crown-containing porphyrin 5-{4-[(4-hydroxybenzo-15-crown-5)-5-yldiazo]phenyl}-10,15,20-triphenylporphyrin (H₃L) and its transition metal complexes MHL (M = Co(II), Ni(II), Cu(II), and Zn(II)) and AgH₂L were obtained. The compositions and structures of all the compounds were studied by MALDI-TOF mass spectroscopy, electronic absorption and IR spectroscopy. The diamagnetic compounds were additionally characterized by ¹H NMR spectroscopy. It was proved that Co(II), Ni(II), Cu(II), and Zn(II) are coordinated through the pyrrole N atoms, while Ag(I) is coordinated through the hydroxyl O atom and the diazo N atom of H₃L.     

Synthesis of iminooxime derivatives and investigation of their complexes

Three novel ligands, a-pycolyliminoisonitrosoacetophenone (L¹H · HCl), α-pycolylimino-p-methylisonitrosoacetophenone (L²H · HCl), and a-pycolylimino-p-chloroisonitrosoacetophenone L³H, were synthesized. Their metal complexes with Co(II), Cu(II), and Ni(II) were prepared. The mononuclear complexes of these ligands with Co²⁺, Cu²⁺, and Ni²⁺ ions were obtained in ethanol. The structures of the ligands and their complexes were characterized by 1H NMR, IR spectroscopy, elemental analyses, and magnetic susceptibility. The text was submitted by the authrs in English.     

Spectral, magnetic, thermal, antimicrobial, and eukaryotic DNA studies on acetone [N-(3-hydroxy-2-naphthoyl)]hydrazone complexes

Abstract  

Acetone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H₂AHNH) has been prepared and its structure confirmed by elemental analysis and ¹H NMR spectroscopy. It has been used to produce diverse complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and U(VI)O₂ ions. The complexes obtained have been investigated by thermal analysis, spectral studies (¹H NMR, IR, UV–visible, ESR), and magnetic measurements. IR spectra suggest that H₂AHNH acts as a bidentate ligand. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The ESR spectra give evidence for the proposed structure and the bonding for some Cu(II) complexes. Thermal decomposition of the Ni(II) and Cu(II) complexes afforded metal oxides as final products. Kinetic data were obtained for each stage of thermal degradation of some of the complexes using the Coats–Redfern method. The formation of complexes in solution was studied pH-metrically and the order of their stability constants (log K) was found to be U(VI)O₂ > Cu(II) > Zn(II) > Ni(II) > Cd(II) > Co(II). Antimicrobial and eukaryotic DNA studies were carried out.     

DNA binding and antimicrobial studies of some polyethyleneimine-copper(II) complex samples containing 1,10-phenanthroline and l-theronine as co-ligands

The polymer–copper(II) complex samples, [Cu(phen)(l-Thr)(BPEI)]ClO₄ · 2H₂O (l-Thr = l-theronine, phen = 1,10-phenanthroline and BPEI = branched polyethyleneimine), with varying degrees of copper(II) chelate content in the polymer chain, were prepared by ligand substitution method in water–ethanol medium and characterized by Infra-red, UV–Vis, EPR spectral and elemental analysis methods. The binding of these complex samples with calf thymus DNA (CT-DNA) has been investigated by absorption spectroscopy and emission spectroscopy and gel electrophoresis techniques. The experimental results indicate that the polymer–copper(II) complex is an avid DNA binder and the binding constant increased with the increase in amount of copper(II) chelate content in the polymer chain. Besides the electrostatic interaction between a negatively charged DNA molecule and a positively charged polymer–copper(II) complex molecule, other binding modes, such as van der Waals interaction, hydrogen bonding and partial intercalation binding modes may also exist in this system. A sample of polymer–copper(II) complex was tested for its antibacterial and antifungal activity and it was found to have good antibacterial and antifungal activities.     

Coordination compounds of biological interest: Thermal properties of some compounds of saccharin (o-benzoic sulphimide) with nickel(II) and zinc(II)

The thermal properties of nickel(II) and zinc(II) complexes of saccharin (sacc) (o-benzoic sulphimide) have been studied and compared both with those of cobalt(II) and copper(II) previously studied and with those of ternary complexes of nickel(II) and zinc(II) having both saccharin and pyridine as ligands. The thermal behaviour is discussed in terms of the interaction between metal and ligands, interaction studied by IR spectroscopy, and by reflectance spectroscopy.The classical thermal stability scale Co(II) > Ni(II) > Cu(II) > Zn(II) is always obtained.