Synthesis and Characterization of Some Poly(1,2-Phenylenedithiocarbamate)–Metal Complexes

Poly(1,2-phenylenedithiocarbamate) (PPDTC) was prepared by the reaction of 2-aminothiophenol with carbon disulfide followed by condensation through the removal of H₂S gas. PPDTC was used as a ligand to prepare four poly(1,2-phenylenedithiocarbamate)–metal complexes of iron(II), cobalt(II), copper(II), and lead(II), by refluxing with the metal salts. The polymer and its metal complexes were investigated by elemental analyses, UV–visible and IR spectroscopy, inherent viscosity, and magnetic susceptibility. The DC electrical conductivity variation with the temperature in the range 298–498 K of PPDTC and its polymeric copper complex was measured. Both polymer and polymer metal complexes showed an increase in electrical conductivity with an increase in temperature: typical semiconductor behavior. The proposed structure of the complexes is (MLX₂·mH₂O) _n .     

Electrospray Ionization Mass Spectrometry Investigation of BTBP – Lanthanide(III) and Actinide(III) Complexes

In the framework of nuclear waste reprocessing, the separation processes of minor actinides from fission products are developed using liquid‐liquid extraction. To gain an understanding of the mechanism involved in the extraction process, a complex formation of actinides and lanthanides with BTBPs (6,6′‐bis(5,6‐dialkyl‐1,2,4‐triazin‐3‐yl)‐2,2′‐bipyridines) was characterized using the Electrospray Ionization Mass Spectrometry (ESI‐MS) technique. This study was carried out to compare the influence of diluents and side groups of the extractants on complex formation. Three different diluents, nitrobenzene, octanol and cyclohexanone, and two extractants, C5‐BTBP and CyMe₄‐BTBP, were selected for this experiment. It was found that the change of the diluent and of the substituent on the BTBP moiety does not modify the stoichiometry of the complexes which is L₂M(NO₃)₃. It is proposed that one nitrate is directly coordinated to the metal ion, the two other anions probably remaining in the outer coordination sphere. The difference observed in extracting properties is probably due to the solvation of the complexes by the diluent. The noncovalent force that holds complexes together are likely to be largely governed by electrostatic interactions even if the hydrophobic exterior of the complexes plays an important role in the complexation/extraction mechanism. The study of the stability of the ions in the gas phase shows that the C5‐BTBP ligand has a labile hydrogen atom, which is a fragility point of C5‐BTBP.     

Extraction of Copper(II) with N′,N′-Dialkylhydrazides of Benzoic and Phenylacetic Acids

This article is concerned with the study of the extraction of Cu(II), Co(II), Ni(II), and Zn(II) with N′,N′-dialkylhydrazides of benzoic and phenylacetic acids. The applied reagents are able to extract Cu(II) from ammoniac media efficiently. The influence of the length and structure of alkyl chains on the extraction of Cu(II) has been analyzed. It is shown that N′,N′-dibytil- and N′,N′-dihexylhydrazides of benzoic acid exhibit the most promise for extracting Cu(II) from ammoniac media, and N′,N′-dihexylhydrazide of phenylacetic acid as an extractant is worse than the analogous benzoic acid derivative. Copper stripping has been studied for various concentrations of H₂SO₄, and the copper extraction constants have been calculated. The data obtained indicate that the degree of Cu(II) extraction decreases with increasing concentration of ammonium salts.     

Metal-Ion Type Effect on the Crystal Structure and Optical Properties of 2,2′-bipyridine Complexes of Pb(II) and Cd(II)

To investigate the effect of metal ion type on the crystal structure and optical and thermal behaviors of coordination compounds, two homometal and one heterometal 2,2′-bipyridine complexes of Pb(II) and Cd(II) have been synthesized and characterized by elemental analysis, PXRD, FT-IR and single crystal X-ray diffraction. Crystal structure analysis of heterometal coordination polymer, [Pb₂Cd(2,2′-bipy)₄(NO₃)₆]_n, displays the attendance of a centrosymmetric 1D coordination polymer that crystallizes in the triclinic system with the space group of \({\text{p}}_{1}^{ - }\). Thermal behavior of prepared coordination compounds was examined under air atmosphere by thermogravimetric analysis. The study of optical properties of compounds showed that metal ion type of coordination compounds is influential on their photophysical properties. Moreover, heterometal coordination polymer was doped into a PVK:PBD blend in two different concentrations as a light emitting material in the fabrication of two organic light-emitting diodes.     

Synthesis and properties of polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane

A new kind of polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane was prepared by the anionic polymerization with a “seed solution” as initiator. The synthesis of monomers N,N′-bis(hydroxydiphenylsilyl)tetraphenylcyclodisilazane (BHPTPC), N,N′-bis(chlorodiphenylsilyl)tetraphenylcyclodisilazane (BCPTPC), and 1,3-dichloro-1,1,3,3-tetraphenyldisilazane (DCTPS) are all reported in this study. The synthesized polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane was characterized by ¹H–NMR, ²⁹Si–NMR, gel permeation chromatography (GPC), and intrinsic viscosity. The thermal stability of the polysiloxane was studied by isothermal gravimetric analysis (IGA). The results demonstrated that the synthesized polysiloxane containing N,N′-bis(diphenylsilyl)tetraphenylcyclodisilazane had excellent thermal stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 929–933, 2001     

Extraction of Uranium(VI) and Thorium(IV) from Nitric Acid Solution by N,N,N′,N′ – Tetraoctylglutaricamide

Synthesis and characterization of N,N,N′,N′-tetraoctylglutaricamide (TOGA) was carried out and used for extraction of U(VI) and Th(IV) from nitric acid solutions. The processes of extraction were determined by the slope analysis and by analyzing a function that allows the simultaneous treatment of all the experimental points obtained in different conditions. The different factors affecting the extraction distribution ratio(D) of U(VI) and Th(IV) (extraction concentration, concentrations of nitric acid, salting-out agent NaNO₃ concentration, equilibration time, temperature, and types of diluents) were investigated. The results obtained indicated that the extraction species of U(VI) and Th(IV) are mainly extracted as UO₂(NO₃)₂·1.0TOGA and Th(NO₃)₄·1.5TOGA. The apparent equilibrium constant of U(VI) and Th(IV) extraction determined are 3.35 ± 0.03 L³/mol³ and 1.87 ± 0.01 L⁵/mol⁵ at 298 ± 1 K. Thermodynamic parameters such as the free energy(ΔG), enthalpy(ΔH), and entropy(ΔS) changes associated with the extraction processes could be evaluated. Back-extraction of U(VI) and Th(IV) from organic phases was also studied.     

Oxidation of Benzene Catalyzed by 2,2′-Bipyridine and 1,10-Phenantroline Cu(II) Complexes

The use of mononuclear Cu(II) 2,2′-bipyridine and 1,10-phenantroline complexes as catalysts in the oxidation of benzene, using hydrogen peroxide and tert-butyl hydroperoxide as oxidant in CH₃CN/H₂O solution is presented. The reactions were carried out at 25 and at 50 °C. The complexes [Cu(bipy)₃]Cl₂ · 6H₂O (1), [Cu(bipy)₂Cl]Cl · 5H₂O (2), [Cu(bipy)Cl₂] (3), [Cu(phen)₃]Cl₂ · 7H₂O (4), [Cu(phen)₂Cl]Cl · 5H₂O (5), [Cu(phen)Cl₂] (6) were able to oxidize benzene into phenol, hydroquinone and p-benzoquinone. Highest conversion (22%) was obtained using [Cu(Phen)Cl₂] (6) as catalyst.     

Synthesis and Thermal Decomposition Studies of Silicon (IV) Compounds with N,N’-Bis(Salicylidene)Ethylenediimine

The silicon (IV) compounds possessing SiN₄O₂ (6), SiN₂O₂C₂ (7, 8), SiN₂O₂CCl (9) and SiN₄O₄ (10) coordinating frameworks have been synthesized in high yield by the reaction of the O,N,N,O- donor salen-type ligand N,N’-bis(salicylidene)ethylenediimine L with different silanes i.e. diethoxydiisocyanatosilane-(C₂H₅O)₂Si(NCO)₂ 1, dichlorodiphenylsilane-Ph₂SiCl₂ 2, dichloromethyl- phenylsilane-MePhSiCl₂ 3, trichlorophenylsilane-PhSiCl₃ 4 and silicon tetrachloride-SiCl₄ 5. The compounds 6–10 have been characterized by elemental analysis, IR, ¹H, ¹³C and ²⁹Si NMR and mass spectrometry. The decomposition reactivity of these compounds has been studied using a Thermal Gravimetric Analyzer (TGA) at a heating rate of 10°C/minute in an inert atmosphere.     

Coordination Behaviors and Supramolecular Interactions of 2-(2′-Pyridyl) Imidazoline: Crystal Structure of Its Two Cu(II) Complexes

Two new copper coordination complexes, [Cu(PI)(OX)(H₂O)]·H₂O (1) and [Cu(PI)(fum)(H₂O)]·H₂O (2) [PI = 2-(2′-pyridyl) imidazoline, OX^2? = dianion of oxalic acid and fum^2? = dianion of fumaric acid], were synthesized by interface diffusion method based on Cu(II) ions, PI ligands and aliphatic dicarboxylic acids. Complex 1 is a mononuclear complex which spreads into a 3D (4,9)-connected supramolecular network via hydrogen bond interactions, while complex 2 features a 1D zigzag chain with two different orientations. These two compounds are characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, infrared spectra, and thermogravimetric analyses.     

Thermal and Fluorescence Properties of New Nanostructured Hg(ll) -2,2′-Bipyridine Derivative Complexes

Two new nano-structured Hg(II) supramolecular complexes, [Hg(5,5′-di-t-but-bpy)(μ-Br)Br]₂[Hg(5,5′-di-t-but-bpy)Br₂](1) and [Hg(5,5′-di-t-but-bpy)I₂] (2) were synthesized by the sonochemical method. The structures of 1 and 2 were characterized by elemental analysis, IR, ¹H-NMR, and ¹³C-NMR spectroscopy and single crystal X-ray diffraction. Their thermal stabilities were studied by thermogravimetric and differential thermal analyses. Solid-state luminescent spectra of 1 and 2 indicate a fluorescent broad emission band between 304 and 404 nm with excitation at 284 nm. These nanostructured coordination polymers were characterized by scanning electron microscopy, elemental analysis, and IR spectroscopy.     

Synthesis,characterization, thermal constant and relaxation of gadolinium(III), iron(III) and manganese(II) chelates of diethylenetriamine-bis-inositol-N,N′,N″-triacetic acid

The reaction of the bicyclic anhydride of diethylenetraiamine-pentaacetic acid (DTPAA) with inositol gave diethylenetriamine-inositol-biester-N,N^′,N″-triacetic acid (DTPA-BI) (1). (1) was characterized by FAB-MS, ¹HNMR, IR and elemental analysis. Its chelates of Gd(III), Fe(III) and Mn(II) holding promise of magnetic resonance imaging (MRI) were synthesized. Gd(III) complex was obtained from Gd₂O₃ and the acid form of (1). Thermodynamic stability constant and relaxation of Gd(III) complex with DTPA-BI were determined. The spin–lattice relaxivity (R₁=5.6 l mmol⁻¹ s⁻¹) of chelate was slightly larger than that of [GdDTPA]²⁻. The results showed that the complex is a prospective MRI agent, although thermodynamic stability constant of DTPA-BI K_[GdDTPA-BI]⁻=10^18.2 was a little less than that of [GdDTPA]²⁻ (K_[GdDTPA]²⁻=10^20.73).     

Synthesis and Characterization of Tripodal Oxy-Schiff base (2,4,6-Tris(4-Carboxymethylenephenylimino-4′-formylphenoxy)-1,3,5-triazine) and the Thermal and Magnetic Properties of its Fe(III)/Cr(III) Complexes

Eight new trinuclear Fe(III)/Cr(III) complexes involving tetradentate (N₂O₂) and pentadentate (N₃O₂) Schiff bases of (salenH₂), (salophenH₂), (saldetaH₂) and (salpyrH₂) with 2,4,6-tris(4-carboxymethylenephenylimino-4′-formylphenoxy)-1,3,5-triazine were synthesized. The structure of ligand and complexes were identified using elemental and thermal analysis, magnetic susceptibility, and LC–MS, ICP-AES, ¹H NMR and FT-IR spectral data. All complexes are tripodal–trinuclear. The complexes are low-spin (S = 1/2) distorted octahedral salen- or salophen-capped Fe(III), high-spin (S = 5/2) distorted octahedral saldeta- or salpyr-capped Fe(III) and distorted octahedral (S = 3/2) salen-, salophen-, saldeta- or salpyr-capped Cr(III).     

Understanding the Potential In Vitro Modes of Action of Bis(β-diketonato) Oxovanadium(IV) Complexes

To understand the potential in vitro modes of action of bis(β-diketonato) oxovanadium(IV) complexes, nine compounds of varying functionality have been screened using a range of biological techniques. The antiproliferative activity against a range of cancerous and normal cell lines has been determined, and show these complexes are particularly sensitive against the lung carcinoma cell line, A549. Annexin V (apoptosis) and Caspase-3/7 assays were studied to confirm these complexes induce programmed cell death. While gel electrophoresis was used to determine DNA cleavage activity and production of reactive oxygen species (ROS), the Comet assay was used to determine induced genomic DNA damage. Additionally, Förster resonance energy transfer (FRET)-based DNA melting and fluorescent intercalation displacement assays have been used to determine the interaction of the complexes with double strand (DS) DNA and to establish preferential DNA base-pair binding (AT versus GC).     

Mössbauer Spectroscopy Study of Macromolecular Complexes of Polycarbosilazane Coordinated with Fe(II), Fe(III) and Mixed Valence Fe(II-III) Chlorides

A series of iron-polyethylenediaminecarbosilazane (PEDCSZ-Fe) macromolecular chloride macromolecular complexes were prepared by the reaction of Fe(II), Fe(III), and mixed valence Fe(II-III) chlorides with polyethylenediaminecarbosilazane matrix in toluene under inert atmosphere. The mixed valence macromolecular complexes composed of three different ratios of Fe(II)/Fe(III) (1:2, 1:1, and 2:1). Mössbauer spectra were recorded for the samples at room temperature. The spectra of the PEDCSZ-Fe(II) and PEDCSZ-Fe(III) macromolecular complexes showed pure paramagnetic phase, whereas, the spectra for the mixed valence PEDCSZ-Fe(II-III) showed both magnetic and paramagnetic splitting. The magnetic splitting is so broad such that it was fitted with three magnetic sextets and one quadrupole doublet. The relative intensity of the magnetic phase was the highest for the PEDCSZ-Fe(II-III) with 1:1 ratio. The magnetic phase could be attributed to an iron oxide phase (Fe₃O₄ or FeOOH phase) in a fine powder form as it is clear from the Mössbauer parameters. The XRD patterns of the PEDCSZ-Fe(II-III) with 1:1 ratio contained additional diffraction peaks similar to those observed for Fe₃O₄ in a fine particle form.     

Evaluation of the Hydrophilic Complexant N,N,N’,N’-tetraethyldiglycolamide (TEDGA) and its Methyl-substituted Analogues in the Selective Am(III) Separation

ABSTRACT

N,N,N’,N’-tetraethyldiglycolamide (TEDGA) is used in the French EXAm (extraction of americium) process to separate Am(III) from Cm(III) and Ln(III). In this study, the complexation behavior of TEDGA towards actinides(III) and lanthanides(III) was compared to its methyl-substituted derivatives Me-TEDGA and Me₂-TEDGA under experimental conditions applying to the EXAm process. Using the EXAm solvent, 0.6 mol/L N,N’-dimethyl-N,N’-dioctyl-hexylethoxymalonamide (DMDOHEMA) and 0.45 mol/L bis(2-ethylhexyl)-phosphoric acid (HDEHP), An(III) and Ln(III) distribution ratios increase in the order TEDGA < Me-TEDGA < Me₂-TEDGA. This is explained by differences in the strength of complexation in the aqueous phase: Conditional stability constants for the formation of [Cm(DGA)_x]³⁺ complexes decrease in the order TEDGA > Me-TEDGA > Me₂-TEDGA, as shown by time-resolved laser fluorescence spectroscopy (TRLFS). TRLFS measurements verified the exclusive existence of [Cm(DGA)₃]³⁺ complexes in the aqueous phase. Both the homoleptic [Cm(DMDOHEMA)_n]³⁺ and the heteroleptic [Cm(DGA)_x(DMDOHEMA)_y]³⁺ complexes were detected in the organic phase, as postulated in the literature.^[14]     

Synthesis and Structure of 1D Copper(II) Polymers with Dissymmetrical N,N′-Bis(substituted)oxamide Ligands: Cytotoxicity and DNA-Binding Property

Two one-dimensional copper(II) coordination polymers with different dissymmetrical N,N′-bis(substituted)oxamide ligands were synthesized, namely {[Cu₂(dmaepox)(dabt)]pic·H₂O}_n (1) and {[Cu₂(dmapob)(dabt)]NO₃·0.6H₂O}_n (2), where H₃dmaepox and H₃dmapob stand for N-(2-carboxylatophenyl)-N′-[3-(methylamino)propyl]oxamidate and N-(2-carboxylatophenyl)-N′-[3-(dimethylamino)propyl]oxamidate, respectively, and dabt is 2?2′-diamino-4?4′-bithiazole. Polymer 1 was characterized by elemental analyses, IR and electronic spectra and single-crystal X-ray diffraction. The crystal structure reveals that polymer 1 consists of many binuclear copper(II) units bridged by cis-oxamide and carboxylate groups. The two copper(II) ions are located in square-planar and square-pyramidal coordination environments, respectively. The separations of the Cu(II) atoms bridged by oxamide and carboxylate groups are 5.2035(7) and 5.1196(7) Å, respectively. The crystal structure of polymer 2 has been reported in our previous paper. However, its relative properties were not studied. In order to compare the influence of different bridging ligands on the cytotoxicities and DNA-binding properties, the cytotoxicities and reactivities towards DNA of polymers 1 and 2 were investigated. The results suggest that the two polymers can interact with herring sperm DNA in the mode of intercalation with binding affinities following the order of 1 > 2, and this is consistent with their in vitro cytotoxicities.     

Electrochemical study of the stability of the electron-donor—acceptor (EDA) complex between N,N,N′,N′-tetramethyl-p-phenylendiamine and m-dinitrobenzene in acetonitrile

The stability constant of the EDA complex between N,N,N′,N′-tetramethyl-p-phenylendiamine and m-dinitrobenzene in acetonitrile has been studied by cyclic voltammetry and potentiometric titration at constant finite current. For comparison, spectral measurements were made. The spectroscopic techniques allowed us to assume the formation of a 1:1 EDA complex of which stability in acetonitrile is lower than that previously reported in chloroform. This solvent effect is expected for such weak complexes. The electrochemical techniques give a higher value of the stability constant in similar conditions. The possible causes of the discrepancies are discussed. However, the enthalpy and entropy values for the process closely agree in both electrochemical and spectroscopic methods. This is good evidence that both techniques are accounting for the same type of interaction. The electrochemical techniques, and particularly cyclic voltammetry, seem to be fast and sensible methods to study EDA complex interactions in polar aprotic solvents.     

Stoichiometric Reductive C?N Bond Formation of Arylgold(III) Complexes with N‐Nucleophiles

The reductive formation of substituted anilines from amines and three well‐defined aryl‐ gold(III) complexes, i.e., dichloro(2,6‐lutidine)phen‐ ylgold(III) ( 2 ), dichloro(2,6‐lutidine)‐p‐tolylgold(III) ( 3 ), and chlorobis(triphenylphosphine)phenylgold(III) chloride ( 4 ) was studied. The reaction is stoichiometric in gold and represents a key step of a potential gold‐catalyzed intermolecular amination reaction of arenes. It proceeds smoothly with a broad range of N‐nucleophiles in the presence of sodium acetate (NaOAc) and enables the selective formation of N‐substituted anilines in good yields. A mechanistic pathway is proposed and discussed as well.     

Mechanistic Differences Between Kraft and Soda-AQ Pulping of Hardwoods with Regard to Lignin–Carbohydrate Complexes (LCC)

The literature on biomass research contains many references to lignin–carbohydrate complexes (LCC) decreasing the rate of delignification in chemical pulping, decreasing the yield of cellulosic ethanol via fermentation, and decreasing forage digestibility. Regarding wood delignification, there are a few reports on the formation and/or cleavage of lignin–carbohydrate (L–C) bonds during alkaline pulping. The behavior of LCC was investigated to find a potential explanation for the differences between the soda-anthraquinone (soda-AQ or SAQ) and kraft processes with regard to delignification rate in the residual phase of pulping and in the bleaching process. Enzymatically isolated lignin (EL) was prepared from two soda, nine SAQ, and twelve kraft pulps from sugar maple, a hardwood. The range of kappa numbers, after correction for hexenuronic acid (HexA), was 10–60. The bound sugars on each EL were hydrolyzed and converted to monomers by H₂SO₄ at 121°C. There was evidence in the data suggesting that the bound glucan and xylan on the ELs from soda, SAQ, and kraft pulps were native to the wood. The bound galactan data were somewhat ambiguous, and there was no detection of bound mannan on any EL. The reproducibility and repeatability of bound arabinan attached to ELs (BA) were excellent. Although not conclusive, the totality of the data is suggestive of both L–C bond formation and cleavage involving arabinose units during both kraft and SAQ pulping. There was no decrease in BA when SAQ was used to lower the c-kappa number (HexA-corrected) from ～60 to ～25. The case was similar when kraft was used in the range of ～60 to ～40. However, there were significant decreases in BA content when c-kappa number was lowered below ～25 by both SAQ and kraft. A common mechanism was proposed to explain essentially no decrease in BA content at higher kappa numbers, but distinctly different mechanisms were proposed to explain BA cleavage at c-kappa number <25. A mechanism favorable to subsequent bleaching was proposed for kraft, but an unfavorable mechanism was proposed for SAQ.