Homonuclear tris-dithiocarbamato ruthenium(III) complexes as single-molecule precursors for the synthesis of ruthenium(III) sulfide nanoparticles

Tris(N-phenyldithiocarbamato) ruthenium(III) complexes, [Ru(L¹)₃] (1); tris(N-(4-methylphenyl)dithiocarbamato)) ruthenium(III), [Ru(L²)₃] (2); and tris(N-(4-methoxyphenyl)dithiocarbamato)) ruthenium(III), [Ru(L³)₃] (3) were synthesized and characterized by elemental analysis, thermogravimetric analysis, FTIR, UV–VIS and NMR spectroscopy. TGA analyses show major degradation of all complexes in the range 120–350°C, leading to the formation of residual weight corresponding to ruthenium (III) sulfides. The ¹H-NMR spectra of the ligands and complexes are in agreement with the proposed structures. FTIR studies confirmed that the ligands coordinate the Ru³⁺ ion in a bidentate chelating mode. The complexes were thermolysed at 180°C to prepare hexadecylamine-capped Ru₂S₃ nanoparticles. Powder X-ray diffraction patterns revealed the formation of hexagonal-phase Ru₂S₃ nanoparticles with average crystallite sizes ranging from 8.3 to 9.5?nm. TEM images showed the crystalline clusters with shapes ranging from square to hexagonal, while SEM images elucidated that the particles were agglomerated. Energy-dispersive X-ray spectra confirmed the presents of Ru₂S₃ nanoparticles.     

Imidazole-based dithienylethenes as a selective chemosensors for iron(III) ions

Four novel imidazole-based dithienylethenes have been successfully synthesized in good yields. Their structures have been confirmed by NMR spectrometry, mass spectrometry, and elemental analyses. UV/Vis absorption spectra indicated that these dithienylethenes can easily isomerize between the open-ring and closed-ring isomers upon irradiation with UV or visible light in solution, and that the respective closed-ring isomers show decreased fluorescence properties compared with the open-ring isomers. Moreover, the open-ring and closed-ring isomers display high selectivity toward Fe³⁺, such that the addition of Fe³⁺ obviously suppresses their fluorescence intensity.     

Electrodeposited amorphous iron(III) oxides as anodes for photoelectrolysis of water

Deposition of amorphous iron(III)-oxide films on a conducting glass substrate was achieved via a cathodic bias in a 0.1 M hydrated ammonium iron(II) sulfate ((NH₄)₂Fe(SO₄)₂·6H₂O) solution at −1.6 V versus Ag/AgCl. Analysis by X-ray absorption near edge structure confirmed the iron(III) feature of the amorphous films. The deposited films exhibited n-type semiconducting characteristics by showing photoresponses under an anodic bias. The Mott–Schottky method and cyclic voltammetry were employed to characterize the semiconducting properties of the deposited films, which included the band gap (2.2 eV), the potentials of the conduction and valence band edges and flat band (−0.6, +1.6 and −0.58 V versus Ag/AgCl at pH 7, respectively), and the donor density (1 × 10²²/cm³). The deposited iron(III)-oxide films were suitable to serve as an anode for water splitting under illumination.     

基于Fe(III) 和邻苯二胺显色反应快速检测硫化物

本研究系统地比较了不同金属离子对邻苯二胺（OPD）的氧化能力,基于Fe3+ 能直接氧化邻苯二胺(OPD) 产生黄色发荧光的产物,发展了Fe3+-OPD显色体系。硫化物的加入促使Fe3+-OPD显色液的颜色,吸光度和荧光成比例下降,而其他还原性物质及硫醇对硫化物的检测无干扰,基于此发展了选择性检测硫化物的比色法。实验结果表明,向OPD溶液中加入Fe3+,吸光度和荧光随着Fe3+浓度上升成比例增加,溶液从无色变为黄色,在50-1000 μmol/L范围内具有良好的线性关系,检测限为10μmol/L。向Fe3+-OPD显色液加入硫化物,在硫化物浓度1～300 μmol/L 范围内,吸光度和荧光强度成比例下降,溶液的黄色褪去,检测限为0.1μmol/L。在此基础上,将Fe3+-OPD显色体系结合纸芯片,所构建的纸基比色体系蓝色分析色道值即B值与硫化物的浓度在20～150μmol/L浓度范围内呈现良好的线性关系,检测限为 2 μmol/L,可用于定量加标自来水和血清中硫化物含量。     

Morphology and properties tuning of PLA/cellulose nanocrystals bio-nanocomposites by means of reactive functionalization and blending with PVAc

A novel method for the preparation of PLA bio-nanocomposites containing cellulose nanocrystals (CNCs) is reported. In order to enhance interfacial adhesion and dispersion of nanocrystals into PLA matrix, functionalization of PLA and CNCs by radical grafting of glycidyl methacrylate (GMA) and pre-dispersion of CNCs in poly (vinyl acetate) (PVAc) emulsion were applied. Morphologies, thermal and mechanical properties of nanocomposites for CNCs content of 1–6 wt.% were examined. Addition of functionalized components (PLA-GMA, CNC-GMA) and/or PVAc dispersed CNCs both improved the phase distribution of nanofiller and tensile properties, compared to the binary PLA/CNC nanocomposites. Thermal analyses demonstrated that glass transition, melting temperature and crystallinity of PLA were affected by the PVAc amount. Nanocomposites with PVAc dispersed CNCs exhibited higher thermal resistance than other composites. The filler effectiveness (CFE) was evaluated for all samples on the basis of storage modulus values: CNC-GMA and PVAc dispersed CNCs (3 wt. %) resulted the most effective fillers.     

Development and characterization of bionanocomposites based on poly(3‐hydroxybutyrate) and cellulose nanocrystals for packaging applications

Poly(3‐hydroxybutyrate) (PHB)‐based bionanocomposites were prepared using various percentages of cellulose nanocrystals (CNCs) by a solution casting method. CNCs were prepared from microcrystalline cellulose using sulfuric acid hydrolysis. The influence of CNCs on PHB properties was evaluated using differential scanning calorimetry, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetry and tensile testing. Vapor permeation and light transmission of the materials were also measured. Differential scanning calorimetric tests demonstrated that CNCs were effective PHB nucleation agents. Tensile strength and Young's modulus of PHB increased with increasing CNC concentration. Moreover, the PHB/CNC bionanocomposites exhibited reduced water vapor permeation compared to neat PHB and had better UV barrier properties than commodity polymers such as polypropylene. It was found that nanocomposites with 6 wt% of CNCs had the optimum balance among thermal, mechanical and barrier properties. © 2016 Society of Chemical Industry     

Ethanosolv pretreatment of barley straw with iron(III) chloride for enzymatic saccharification

BACKGROUND: Barley straw is a potential lignocellulosic biomass for the production of bioethanol because of its high cellulose and hemicelluloses content. Ethanosolv pretreatment catalyzed with inorganic acids has some undesirable effects, and thus, inorganic salts, such as FeCl₃, were studied as the catalyst in order to enhance enzymatic digestibility. RESULTS: The addition of 0.1 mol L^?1 FeCl₃ (Iron(III) chloride) had a particularly strong effect on the enzymatic digestibility, reaching a value as high as 89%, with cellulose recovery as high as 90% after the ethanosolv pretreatment. The enzymatic digestibility was 89% and 55% after the addition of 0.1 mol L^?1 FeCl₃ and H₂SO₄ (adjusted to the same pH), respectively. The enzymatic hydrolysis rate was significantly accelerated as the ethanosolv temperature increased, reaching the highest enzymatic digestibility of 89% after 72 h at 170 °C. The concentrations of HMF(5‐hydroxy‐2‐ methyl furfural) and furfural were 0.011 and 0.148 g L^?1 in the hydrolysate during FeCl₃‐ethanosolv treatment, which were lower than the concentrations quantified during H₂SO₄‐ethanosolv treatment. After the pretreatment, 88.5% of FeCl₃ was removed through the filtration process. CONCLUSION: The addition of several inorganic salts significantly accelerated enzymatic digestibility in the ethanosolv. FeCl₃ had a particularly strong effect on enzymatic digestibility and cellulose recovery. The formation of HMF and furfural and the remaining amount of FeCl₃ were investigated, and FeCl₃ had no effect on the subsequent processes after pretreatment. Copyright © 2010 Society of Chemical Industry     

Characterization of iron(III) oxide nanoparticles prepared by using ammonium acetate as precipitating agent

The effect of precipitating agent on the preparation of iron(III) oxide particles was investigated. Iron(III) oxide particles were prepared by precipitation of aqueous ferric nitrate solution by using ammonium acetate and ammonium hydroxide as precipitating agents. Particle size, shape, chemical composition, crystalline formation rate, crystallinity and magnetic property were measured for Fe₂O₃ particles obtained by precipitating with ammonium acetate, and compared with those of particles formed by using ammonium hydroxide. TGA, DTA, IR, XRD, TEM and VSM were used to characterize the particles. The nanoparticles synthesized with ammonium acetate showed a narrow size distribution, spherical shape, fast crystalline formation rate, high crystallinity and complete hysteresis loop. The better properties of particles formed by using ammonium acetate were originated from the chelating effect of carboxylate ions and higher crystallinity than those synthesized with ammonium hydroxide.     

Photopolymerization of Methyl Methacrylate Sensitized by Tris(2,2′-bipyridine)iron(III)

The photopolymerization of methyl methacrylate (MMA) sensitized by tris(2,2′-bipyridine)iron(III ) complex, [Fe(bpy)₃]³⁺, was studied at 35°C in the presence of an electron donor, triethylamine (TEA) with UV radiation of wavelength 254nm. The initial rate of polymerization, R_p, shows a linear dependence on [MMA] with an exponential value of 1·18±0·04. R_p varies linearly with the square root of the photosensitizer concentration up to 2·00×10^-4moll^-1, and above this concentration, R_p decreases with the increase of photosensitizer concentration. The rate of polymerization is not affected by the concentration of the co-initiator, [TEA]. A suitable mechanism for the reaction is proposed to explain the kinetics of the reaction. © 1997 SCI.     

Impedance measurements of a chalcogenide membrane iron(III)-selective electrode in contact with aqueous electrolytes

The electrochemical characterization of a chalcogenide-based iron(III)-selective electrode [Fe(III) ISE] [i.e., Fe_2.5(Se₆₀Ge₂₈Sb₁₂)_97.5] was achieved using impedance spectroscopy. The influence of electrolyte composition (i.e., NO₃⁻, Cl⁻, and pH) on the membrane oxidation reaction has been examined, and a mechanism for its action is proposed. Equivalent circuit analysis was undertaken to determine the interfacial charge transfer resistance and corresponding double layer capacitance as a function of electrolyte composition and immersion time. Variations were detected in the charge transfer time constant, and this was attributed to changes in the dielectric/conduction properties of the surface layer. It was found that the Fe_2.5(Se₆₀Ge₂₈Sb₁₂)_97.5 oxidation kinetics depend on the pH, and the interfacial reaction is dictated by sluggish charge transfer. By contrast, chloride was shown to accelerate the rate of membrane oxidation presumably via the formation of soluble metal-chloride complexes. Electrochemical impedance spectroscopy (EIS) aging studies of the Fe_2.5(Se₆₀Ge₂₈Sb₁₂)_97.5 membrane in chloride electrolyte under alkaline conditions showed that the charge transfer resistance decreases with exposure time. However, extended aging revealed a change in the rate of oxidation, which was attributed to a combined diffusion/passivation effect. It is proposed that the development of a modified surface layer (MSL) and passive surface layer (PSL) are partly responsible for the electrochemical stability of the chalcogenide membrane. This paper attempts to clarify and address some of the misconceptions/issues reported previously in the literature on the chalcogenide iron(III)-selective electrode.     

Self-assembled bright luminescent hierarchical materials from a tripodal benzoate antenna and heptadentate Eu(III) and Tb(III) cyclen complexes

The europium heptadentate coordinatively unsaturated (Eu(III)) and the terbium (Tb(III)) 1,4,7,10-tetraazacyclododecane (cyclen) complexes 1 and 2 were used in conjunction with ligand 3 (1,3,5-benzene-trisethynylbenzoate) to form the supramolecular self-assembly structures 4 and 5;this being investigated in both the solid and the solution state. The resulting self-assemblies gave rise to metal centered emission (both in the solid and solution) upon excitation of 3, confirming its role as a sensitizing antenna. Drop-cased examples of ligand 3, and the solid forms of 4 and 5, formed from both organic and mixture of organic-aqueous solutions, were analyzed using Scanning Electron Microscopy, which showed significant changes in morphology;the ligand giving rise to one dimensional structures, while both 4 and 5 formed amorphous materials that were highly dense solid networks containing nanoporous features. The surface area (216 and 119 m2·g^-1 for 4 and 5 respectively) and the ability of these porous materials to capture and store gases such as N2 investigated at 77 K. The self-assembly formation was also investigated in diluted solution by monitoring the various photophysical properties of 3–5. This demonstrated that the most stable structures were that consisting of a single antennae 3 and three complexes of 1 or 2 (e.g., 4 and 5) in solution. By monitoring the excited state lifetimes of the Eu(III) and Tb(III) ions in H2O and D2O respectively, we showed that their hydration states (the q-value) changed from -2 to 0, upon formation of the assemblies, indicating that the three benzoates of 3 coordinated directly to the each of the three lanthanide centers. Finally we demonstrate that this hierarchically porous materials can be used for the sensing of organic solvents as the emission is highly depended on the solvent environment;the lanthanide emission being quenched in the presence of acetonitrile and THF, but greatly enhanced in the presence of methanol.     

Optimum reaction conditions for polypyrrole film deposition with some iron(III) compounds

The optimum reaction conditions for the deposition of smooth conductive polypyrrole (PP) films were monitored using a quartz crystal microbalance technique. This is for oxidative polymerization of pyrrole with some iron(III) compounds. The FeCl₃ · 6H₂O/pyrrole system in aqueous solution at 20 ± 0.5°C was examined in some detail. The effect of the initial molar ratio of the reactants on the yield and the growth rate of the PP film deposition was studied. The optimum molar ratio was found to be approximately 2.4 ± 0.1. A comparison between the growth rate of the PP films was made when different iron(III) compounds were used. The rate is shown to be affected by the nature of the anions in these compunds.     

Benzyl and Methyl Fatty Hydroxamic Acids Based on Palm Kernel Oil as Chelating Agent for Liquid-Liquid Iron(III) Extraction

Liquid-liquid iron(III) extraction was investigated using benzyl fatty hydroxamic acids (BFHAs) and methyl fatty hydroxamic acids (MFHAs) as chelating agents through the formation of iron(III) methyl fatty hydroxamate (Fe-MFHs) or iron(III) benzyl fatty hydroxamate (Fe-BFHs) in the organic phase. The results obtained under optimized conditions, showed that the chelating agents in hexane extract iron(III) at pH 1.9 were realized effectively with a high percentage of extraction (97.2% and 98.1% for MFHAs and BFHAs, respectively). The presence of a large amount of Mg(II), Ni(II), Al(III), Mn(II) and Co(II) ions did affect the iron(III) extraction. Finally stripping studies for recovering iron(III) from organic phase (Fe-MFHs or Fe-BFHs dissolved in hexane) were carried out at various concentrations of HCl, HNO(3) and H(2)SO(4). The results showed that the desired acid for recovery of iron(III) was 5 M HCl and quantitative recovery of iron(III) was achieved from Fe(III)-MFHs and Fe(III)-BFHs solutions in hexane containing 5 mg/L of Fe(III).     

Synthesis of the cotton cellulose based Fe(III)-loaded adsorbent for arsenic(V) removal from drinking water

A novel macroporous bead adsorbent, Fe(III)-loaded ligand exchange cotton cellulose adsorbent [Fe(III)LECCA], is synthesized for selective adsorption of arsenate anions [As(V)] from drinking water in batch and column systems. As(V) adsorption on Fe(III)LECCA was independent of pH, especially in drinking water pH range. Film diffusive control mechanism will benefit As(V) exchange with Fe(III)LECCA whether in batch or in column experiments. When treating the tap water at 26.0 BV/h, the column still preserves 83% of the original saturation adsorption capacity of the As(V) aqueous solution. These results have indicated that Fe(III)LECCA has the potential to act as an adsorbent for the removal of As(V) from drinking water considering its availability, nontoxicity and cost-effectiveness.     

Selective removal of Cr (VI) from hydrometallurgical effluent using modified cellulose nanocrystals (CNCs) with succinic anhydride and ethylenediaminetetraacetic acid: Isotherm,kinetics, and thermodynamic studies

Biological sources are renewable basic resources that may be used for several purposes, including the development of green materials for the removal of heavy metal ions. Cellulose nanocrystals (CNCs) extracted from waste papers via acid hydrolysis were modified and utilized as adsorbents to remove Cr (VI) ions from metallurgical effluent in this work. X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and zeta potentiometer were used to characterize the CNCs. The CNCs treated with succinic anhydride and ethylenediaminetetraacetic acid tetrasodium salt have thin particle sizes and are porous. The carboxylate functional group is primarily engaged in the coordination and selective removal of metal ions (–COO²⁻) and thermal degradation of 85%, observed at temperatures between 250–380°C. On the surface of the modified CNCs, the zeta potential data showed a decrease in negative value. The results revealed that the modified CNCs had a maximum adsorption capacity of 387.25 ± 0.88 mg L⁻¹ at pH 5, at CNCs doses of 25 and 400 mg L⁻¹ as starting concentrations. The adsorption equilibrium period was 300 min and the temperature was 313 K. The equilibrium results fit the Langmuir isotherm model with an R² of 0.993 and a qmax of 340 ± 0.97. The Chi-square (X²) and Marquardt's percent standard deviation tests confirmed that the adsorption process was pseudo-second-order with an R² of 0.998, and the Elovich model revealed that Cr (VI) complexed with the adsorbent's functional groups. The reaction was endothermic due to positive ΔH and spontaneous due to negative ΔG. The positive ΔS indicates that the adsorption process enhances the unpredictability of the solid/liquid interface, according to thermodynamic analysis. After acid treatment, the CNCs may be effectively reused for six cycles with an adsorption capacity of 220 ± 0.78 mg g⁻¹.     

Kinetics of absorption of hydrogen sulfide into aqueous Fe(III) solutions

In our recent studies, absorption of H₂S into the aqueous Fe₂(SO₄)₃ and FeCl₃ solutions with various values of ionic strength and pH was investigated in an agitated vessel with a flat interface. The experimental results for both systems revealed that the species which reacts with H₂S is FeOH²⁺. The absorption rates were explained by the theory of gas absorption with an irreversible (l,l)-th order reaction between H₂S and FeOH₂₊. The reaction rate constants were independent of the ionic strength of the solution and correlated as a function of temperature. In this paper, kinetics and mechanism of these absorption reactions are reviewed and the identity for both systems is emphasized.     

Water Soluble PDCA Derivatives for Selective Ln(III)/An(III) and Am(III)/Cm(III) Separation

The synthesis and solvent extraction behavior of dipicolinic acid (pyridine-2,6-dicarboxylic acid, PDCA) and their derivatives have been studied for possible use in selective back-extraction of actinides, especially americium. The extraction was performed from an organic phase containing a mixture of trivalent actinides and lanthanides pre-extracted with N,N,N’,N’-tetraoctyl diglycolamide (TODGA). The efficiency of the back-extraction was enhanced when the picolinate platform was used in a heterocyclic decadentate ligand called h₄tpaen. Beyond selective An/Ln extraction, the aqueous soluble h₄tpaen ligand seemed a potential reagent for an intra-group Am(III)/Cm(III) separation with a separation factor SF_Cm/Am of about 3.5.     

Homogeneous catalysts for ethylene polymerization based on bis(imino)pyridine complexes of iron, cobalt, vanadium and chromium

Results of a comparative study of ethylene polymerization activity and the structure of polyethylene (PE) produced over homogeneous catalysts based on bis(imino)pyridine complexes with close ligand frameworks and different transition metal centers (Fe(II), Co(II), Cr(III) and V(III)) are reported. The effects of the activator nature and polymerization conditions on the activity of these complexes and the resulting PE structure (molecular weight, molecular weight distribution, content of methyl and vinyl groups) have been studied. The experimental data obtained under comparable conditions demonstrate a pronounced effect of transition metal center on the catalytic properties of bis(imino)pyridine complexes (polymerization activity, copolymerization reactivity, thermal stability, PE structure, composition of optimal activator, formation of single-site or multiple-site catalytic system).     

Half-sandwich samarium (III) diketiminate bromide as a catalyst for methyl methacrylate polymerization

Half-sandwich samarium(III) diketiminate bromide was successfully synthesized and was shown to be active in methyl methacrylate (MMA) polymerization. The effects of temperature, polymerization time and catalyst concentration were studied. Activities of ca. 18 kg of polymethacrylate (PMMA) per mol of samarium per hour were obtained under optimum conditions (0 °C and a MMA/catalyst molar ratio of 100/1), giving a polymer with a molar mass M_n>24,000 g mol⁻¹ and a molar mass distribution (M_w/M_n)<1.4. After 1 h of polymerization, conversions of MMA as high as 96% were observed.     

Synthesis of Bismuth(III)Neodecanoate and Its Application to Poly(Vinyl Chloride) as a Thermal Stabilizer

The bismuth(III)neodecanoate (Bi(Ne)₃) was synthesized via the method of co-reaction of bismuth oxide, neodecanoic acid, and acetic anhydride and then characterized by Fourier transform infrared spectroscopy (FTIR) and elemental analysis (EA). The effect of Bi(Ne)₃ as a thermal stabilizer on poly(vinyl chloride) (PVC) was assessed by thermal aging test, Congo red test, conductivity measurement, and thermogravimetric analysis, respectively. The results showed that Bi(Ne)₃ significantly provided PVC with a good initial color and long-term stability. Bi(Ne)₃ played a role in improving the stabilizing efficiency of PVC through absorbing hydrogen chloride (HCl) and displacing labile chlorine atoms in PVC molecular chains.