Dinitrophenyl Triazoles – “A Class of Energetic Azoles”: Synthesis,Characterisation, and Performance Evaluation Studies

Energetic azoles have shown great potential as powerful energetic molecules, which find various applications in both military and civilian fields. This work describes the synthesis, characterization and performance evaluation of two energetic triazole derivatives, viz. N‐(2,4‐dinitrophenyl)‐3‐nitro‐1H‐1,2,4‐triazole ( 1a ) and N‐(2,4‐dinitrophenyl)‐3‐azido‐1H‐1,2,4‐triazole ( 1b ). The compounds were synthesized from 3‐nitro‐1,2,4‐triazole and 3‐azido‐1,2,4‐triazole, by a simple synthetic route and structurally characterized using FT‐IR and NMR (¹H, ¹³C) spectroscopy as well as elemental analysis. Thermal analyses on the molecules were performed using simultaneous TG‐DTA. Both compounds ( 1a , 1b ) showed good thermal stability with exothermic decomposition peaks at 348 °C and 217 °C, respectively, on DTA. The energetic and sensitivity properties of both compounds like friction sensitivities and heats of formation are reported. The heats of combustion at constant volume were determined using oxygen bomb calorimetry and the results were used to calculate the standard molar heats of formation (Δ_fH^m). The azido derivative ( 1b ) showed a higher positive heat of formation. The thermo‐chemical properties of the compounds as well as the thermal decomposition products were predicted using the REAL thermodynamic code.     

Behaviour and mechanism of enhanced phosphate sorption on loess modified with metals: equilibrium study

BACKGROUND: Phosphate is one of the main contaminants responsible for the eutrophication of surface waters. In developing countries, algae blooming in lakes have threatened the quality of drinking water due to the lack of proper management of phosphate‐containing wastewaters from mining sites and industry. MAJOR RESULTS: The sorption behaviour of phosphate on loess modified by metals (Zn(II), Cu(II) and Pb(II)) was investigated in this paper. Zn(II) and Cu(II) sorption on the loess was attributed to the constituent silicate minerals while the sorption of Pb(II) was assigned to natural carbonate in the loess. The sorption affinity of phosphate towards the modified sorbent was as follows: Pb(II) (221.3–832.2 L g⁻¹) > Cu(II) (20.26 L g⁻¹) > Zn(II) (0.77–1.90 L g⁻¹) > loess (0.11 L g⁻¹) with regard to the partition coefficient. The sorption isotherms were well fitted by an extended Henry's law with multi‐linearity. Several factors including metal loading, pH, sorbent dosage and temperature were investigated and all were found to correlate positively with phosphate sorption. The enthalpy and entropy changes during phosphate sorption on Pb(II) loaded loess were predicted as 14.32 kJ mol⁻¹ and 128.45 J mol⁻¹ K⁻¹, respectively. The sorption mechanism for phosphate on Pb(II) doped loess was investigated by FT‐IR spectra from which the sorption was attributed to chemical bonding with lead carbonate and physisorption with surface adsorbed phosphate as well as diffusion through micropores into the sorbent. CONCLUSIONS: Pb(II) loaded loess shows the best performance for phosphate removal from aqueous solution. The optimum conditions for sorption were pH = 9.5, lead modified loess sorbent dosage = 10 g L⁻¹, temperature = 35 °C and Pb(II) loading 295 mg g⁻¹. Copyright © 2008 Society of Chemical Industry     

Studies on Energetic Compounds Part 27: Kinetics and Mechanism of Thermolysis of Bis(Ethylenediamine)Metal Nitrates and Their Role in the Burning Rate of Solid Propellants

Four bis(ethylenediamine)metal(II) nitrate (BEMN) complexes, i.e. [M(EDA)₂](NO₃)₂, where M=Cu, Co, Ni and Zn, have been prepared and characterized. Thermolysis of these complexes induced by heat and drop‐weight impact has been investigated by TG‐DTG, DTA, explosion delay (D_E), explosion temperature (T_E) and impact sensitivity measurement. The kinetics of early thermolysis reaction prior to fast decomposition have been evaluated. Contracting area (CA, n=2) and contracting cube (CC, n=3) equations were found to give the best fits in isothermal TG data among all tested nine mechanism‐based kinetic models. The values of activation energy (E_a), T_E, D_E and activation energy for explosion (E*) have been found to be quite lower for the copper complex as compared to cobalt, nickel and zinc complexes. A mechanism of thermolysis has also been proposed. All these complexes were found to be insensitive towards impact of 2 kg weight up to the height of 110 cm. These complexes were used as energetic burning rate modifiers in the combustion of hydroxy‐terminated polybutadiene (HTPB)‐ammonium perchlorate (AP) composite solid propellants. A two‐fold increase in burning rate was observed with copper and cobalt complexes at low concentration (2% by wt.). The in situ freshly formed metal oxides with large number of active sites in their crystallites seem to be better additives for combustion of propellants.     

New Application of Hydroxyl Groups: Ligands for High Density Metal Organic Frameworks

Energetic metal organic frameworks (MOFs) with energetic anions as ligands can be used as new‐generation explosives. Many powerful anions have been introduced into energetic MOFs to improve the properties; however, the hydroxyl as a common group for energetic MOFs has rarely been studied. In this article, we present two examples of energetic MOFs ([Cu(atz)(NO₃)(OH)]_n) and [Zn(ata)(OH)] (atz=4‐amino‐1,2,4‐triazole; ata=5‐amino‐1H‐tetrazole) with the hydroxyl group as the ligand. Crystal structure analyses reveal that the two compounds possess compact two‐dimensional (2‐D) structures with densities up to 2.41 g cm⁻³ and 2.54 g cm⁻³, respectively. These two compounds have excellent physicochemical properties. The results demonstrate that a hydroxyl group as the ligands could commendably increase the densities of energetic MOFs, thereby enhancing the detonation performance. It is anticipated this work will open a new direction for the development of energetic MOFs.     

Polystyrene anchored vanillin Schiff base—Complexation and ion removal studies

A set of six new polystyrene anchored metal complexes have been synthesized by the reaction of the metal salt with the polystyrene anchored Schiff base of vanillin. These complexes were characterized by elemental analyses, Fourier transform infrared spectroscopy, diffuse reflectance studies, thermal studies, and magnetic susceptibility measurements. The elemental analyses suggest a metal : ligand ratio of 1 : 2. The ligand is unidentate and coordinates through the azomethine nitrogen. The Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) complexes are all paramagnetic while Zn(II) is diamagnetic. The Cu(II) complex is assigned a square planar structure, while Zn(II) is assigned a tetrahedral structure and Mn(II), Fe(III), Co(II), and Ni(II) are all assigned octahedral geometry. The thermal analyses were done on the ligand and its complexes to reveal their stability. Further, the application of the Schiff base as a chelating resin in ion removal studies was investigated. The polystyrene anchored Schiff base gave 96% efficiency in the removal of Ni(II) from a 20‐ppm solution in 15 min, without any interference from ions such as Mn(II), Co(II), Fe(III), Cu(II), Zn(II), U(VI), Na⁺, K⁺, NH₄⁺, Ca²⁺, Cl^?, Br^?, NO₃^?, NO₂^?,and CH₃CO₂^?. The major advantage is that the removal is achieved without altering the pH. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1536–1539, 2005     

New polymeric Schiff base and its metal complexes

A novel polymeric Schiff base was synthesized by the reaction of a Schiff base from 2,4‐dihydroxy benzaldehyde and aniline with acryloyl chloride and was polymerized in methyl ethyl ketone at 70°C with benzoyl peroxide as a free‐radical initiator. Polychelates were obtained in an alkaline solution of poly(2‐hydroxy‐4‐acryloyloxy‐N‐phenylbenzylidine) with aqueous solutions of metal ions such as Cu(II), Ni(II), Co(II), Ca(II), Cd(II), Mn(II), and Zn(II). The polymeric Schiff base and polychelates were characterized with elemental analysis and spectral studies. The elemental analysis of the polychelates suggested that the metal‐to‐ligand ratio was 1:2. The IR spectral data of the polychelates indicated that the metals were coordinated through the nitrogen and oxygen of the phenolic ? OH group. Diffuse reflectance spectra, electron paramagnetic resonance, and magnetic moment studies revealed that the polychelates of the Cu(II) complex were square‐planar, those of the Ni(II), Mn(II), and Co(II) complexes were octahedral, and those of the Ca(II), Cd(II), and Zn(II) complexes were tetrahedral. X‐ray diffraction studies revealed that the polychelates were highly crystalline. The thermal properties of the Schiff base and polychelates were also examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 494–500, 2004     

Modified activated carbon for the removal of copper,zinc, chromium and cyanide from wastewater

Modified activated carbon are carbonaceous adsorbents which have tetrabutyl ammonium iodide (TBAI) and sodium diethyl dithiocarbamate (SDDC) immobilised at their surface. This study investigates the adsorption of toxic ions, copper, zinc, chromium and cyanide on these adsorbents that have undergone surface modification with tetrabutyl ammonium (TBA) and SDDC in wastewater applications. The modification technique enhance the removal capacity of carbon and therefore decreases cost-effective removal of Cu(II), Zn(II), Cr(VI) and CN⁻ from metal finishing (electroplating unit) wastewater. Two separate fixed bed modified activated carbon columns were used; TBA-carbon column for cyanide removal and SDDC-carbon column for multi-species metal ions (Cu, Zn, Cr) removal. Wastewater from electroplating unit containing 37 mg l⁻¹ Cu, 27 mg l⁻¹ Zn, 9.5 mg l⁻¹ Cr and 40 mg l⁻¹ CN⁻ was treated through the modified columns. A total CN⁻ removal was achieved when using the TBA-carbon column with a removal capacity of 29.2 mg g⁻¹ carbon. The TBA-carbon adsorbent was found to have an effective removal capacity of approximately five times that of plain carbon. Using SDDC-carbon column, Cu, Zn and Cr metal ions were eliminated with a removal capacity of 38, 9.9 and 6.84 mg g⁻¹, respectively. The SDDC-carbon column has an effective removal capacity for Cu (four times), Zn (four times) and Cr (two times) greater than plain carbon.     

Pseudo-isomeric zinc/copper coordination polymers based on 3-(2-pyridyl)pyrazole-5-carboxylic acid

Reaction of 3-(2-pyridyl)pyrazole-5-carboxylic acid (H₂L) with Zn(II) or Cu(II) perchlorate yielded [ZnL]_n (1) and [CuL]_n (2) with similar composition. The ligand L^2 − adopts the same μ₃κ⁵ coordination mode. The Zn(II) and Cu(II) atom takes square pyramid coordination polyhedron with some discrepancy. Bigger difference in the dimeric secondary building blocks leads to distinct two-dimensional metal–organic frameworks. The Zn(II) complex fluoresces stronger than the free ligand. The Cu(II) polymer displays strong antiferromagnetic intra-dimer exchange and ferromagnetic inter-dimer exchange.     

Influence of the metal centers of 2,6‐bis(imino)pyridyl transition metal complexes on ethylene polymerization/ oligomerization catalytic activities

Much work on bis(imino)pyridyl complexes with Fe(II) and Co(II) as ethylene polymerization catalysts has been reported in terms of designing new analogous ligands, while little work has been dedicated to the study of the effect of the metal center on catalyst performance. A series of bis(imino)pyridyl‐MCl₂ (M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II)) transition metal complexes were synthesized, for which single crystals of the Co(II) and Cu(II) complexes were obtained. The crystal structures indicated that these complexes had similar coordination geometries. Being applied to ethylene polymerization at 25 °C and employing 500 equiv. of methylaluminoxane as co‐catalyst, the complexes with Fe(II), Co(II) and Ni(II) centers showed, respectively, catalytic activities of 1.25 × 10⁶ g (mol Fe)^?1 h^?1 Pa for ethylene polymerization, and 3.98 × 10⁵ g (mol Co)^?1 h^?1 Pa and 5.13 × 10³ g (mol Ni)^?1 h^?1 Pa for ethylene oligomerization. In contrast, the complexes with Cu(II) and Zn(II) centers were inactive. Crystal structure data showed that the coordination interactions provided a comparatively reliable quantification of the selectivity of the bis(imino)pyridyl ligand for the studied metal ions, which was in reasonable agreement with the Irving–Williams list. Moreover, for the Ni(II) and Cu(II) complexes, the strong coordination bonds and small N(imino)? M? N(imino) angles were unfavorable for several steps in the mechanism, such as ethylene coordination to the metal center, ethylene migratory insertion and olefin chain growth. All of these will reduce the speed of the overall reaction, indicating a decrease of catalytic efficiency in a given period. The poor activity of the Zn(II) complex for ethylene polymerization may be related to the reduction process by the alkylating agent. Copyright © 2010 Society of Chemical Industry     

New antimicrobial agents: The synthesis of Schiff base polymers containing transition metals and their characterization and applications

A new polymeric Schiff base containing formaldehyde and 2‐thiobarbituric acid moieties was synthesized by the condensation of a monomeric Schiff base derived from 2‐hydroxyacetophenone and hydrazine. Polymer–metal complexes were also synthesized by the reaction of the polymeric Schiff base with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) acetate. The polymeric Schiff base and its polymer–metal complexes were characterized with magnetic moment measurements, elemental analyses, and spectral techniques (infrared, ¹H‐NMR, and ultraviolet–visible). The thermal behaviors of these coordination polymers were studied by thermogravimetric analysis in a nitrogen atmosphere up to 800°C. The thermal data revealed that all of the polymer–metal complexes showed higher thermal stabilities than the polymeric Schiff base and also ascribed that the Cu(II) polymer–metal complex showed better heat resistant properties than the other polymer–metal complexes. The antimicrobial activity was screened with the agar well diffusion method against various selected microorganisms, and all of the polymer–metal complexes showed good antimicrobial activity. Among all of the complexes, the antimicrobial activity of the Cu(II) polymer–metal complex showed the highest zone of inhibition because of its higher stability constant and may be used in biomedical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermochemical,Sensitivity and Detonation Characteristics of New Thermally Stable High Performance Explosives

The M06‐2X/6‐311G(d,p) and B3LYP/6‐311G(d,p) density functional methods and electrostatic potential analysis were used for calculation of enthalpy of sublimation, crystal density and enthalpy of formation of some thermally stable explosives in the gas and solid phases. These data were used for prediction of their detonation properties including heat of detonation, detonation pressure, detonation velocity, detonation temperature, electric spark sensitivity, impact sensitivity and deflagration temperature using appropriate methods. The range of different properties for these compounds are: crystal density 1.51–2.01 g cm⁻³, enthalpy of sublimation 346.4–424.7 kJ mol⁻¹, the solid phase enthalpy of formation 500.4–860.6 kJ mol⁻¹, heat of detonation 13.64–17.57 kJ g⁻¹, detonation pressure 33.0–37.0 GPa, detonation velocity 8.5–9.5 km s⁻¹, detonation temperature 5488–6234 K, electric spark sensitivity 7.89–9.47 J, impact sensitivity 21–38 J, deflagration temperature 560–586 K and power [%TNT] 207–276. The results show that two novel energetic compounds N,N′‐(diazene‐1,2‐diylbis(2,3,5,6‐tetranitro‐4,1‐phenylene))bis(5‐nitro‐4H‐1,2,4‐triazol‐3‐amine) (DDTNPNT3A) and 1,1′‐(diazene‐1,2‐diylbis(2,3,5,6‐tetranitro‐4,1‐phenylene))bis(3‐nitro‐1H‐1,2,4‐triazol‐5‐amine) (DDTNPNT5A) can be introduced as thermally explosives with high detonation performance.     

New stabilizers for polystyrene based on 2-thioacetic acid benzothiazol complexes

The photostabilization of polystyrene (PS) films by 2-thioacetic acid benzothiazol with Sn(II), Cd(II), Ni(II), Zn(II), and Cu(II) complexes was investigated. The PS films containing complexes of concentration 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl and hydroxyl indices with irradiation time. The changes in viscosimetric average molecular weight of PS with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (ϕ_cs) of these complexes in PS films was evaluated and found to range between 3.60 × 10⁻⁶ and 7.78 × 10⁻⁶. The results obtained showed that the rate of photostabilization of PS in the presence of the additive is in the following trend: Ni(L)₂ > Cu(L)₂ > Zn(L)₂ > Cd(L)₂ > Sn(L)₂. According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among UV absorption, peroxide decomposer and radical scavenger for photostabilizer additive mechanisms were suggested. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

5‐Amino‐3,4‐dinitropyrazole as a Promising Energetic Material

The nitrogen‐rich energetic compound 5‐amino‐3,4‐dinitropyrazole (5‐ADP) was investigated using complementary experimental techniques. X‐ray diffraction indicates the strong intermolecular hydrogen bonding in 5‐ADP crystals. Compound exhibits low impact sensitivity (23 J) and insensitivity to friction. The activation energy of thermolysis determined to be 230±5 kJ mol⁻¹ from DSC measurements. Accelerating rate calorimetry indicates the lower thermal stability (173 °C) of 5‐ADP than that of RDX, which is probably the main concern about using this compound. 5‐ADP also exhibits good compatibility with common energetic materials (viz. TNT, RDX, ammonium perchlorate), including an active binder. The burning rate of 5‐ADP monopropellant is higher than that of benchmark HMX, while the pressure exponent 0.51±0.04 is surprisingly low. Addition of ammonium perchlorate does not affect the pressure exponent of 5‐ADP, while the burning rate increases. The 5‐amino‐3,4‐dinitropyrazole exhibits a notable combination of combustion performance, low sensitivity, and good compatibility, which renders it as a promising energetic material.     

Water‐soluble copolymers of 1‐vinyl‐2‐pyrrolidone and acrylamide derivatives: synthesis,characterization, and metal binding capability studied by liquid‐phase polymer‐based retention technique

Radical copolymerizations of 1‐vinyl‐2‐pyrrolidone with acrylamide and N,N′‐dimethylacrylamide at different feed ratios were investigated. The copolymers were characterized by Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR spectroscopy. The copolymer composition was determined from the ¹H NMR spectra and found to be statistical. The metal complexation of poly(acrylamide‐co‐1‐vinyl‐2‐pyrrolidone) and poly(N,N′‐dimethylacrylamide‐co‐1‐vinyl‐2‐pyrrolidone) for the metal ions Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Pb(II), Fe(III), and Cr(III) were investigated in an aqueous phase. The liquid‐phase polymer‐based retention method is based on the retention of inorganic ions by soluble polymers in a membrane filtration cell and subsequent separation of low‐molecular compounds from the polymer complex formed. The metal ion interaction with the hydrophilic polymers was determined as a function of the pH and the filtration factor. Poly(N,N‐dimethylacrylamide‐co‐1‐vinyl‐2‐pyrrolidone) showed a higher affinity for the metal ions than poly(acrylamide‐co‐1‐vinyl‐2‐pyrrolidone). According to the interaction pattern obtained, Cr(III) and Cu(II) formed the most stable complexes at pH 7. Pb(II) and Zn(II) were not retained. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 741–750, 1999     

Novel building blocks for oligonuclear copper complexes derived from β‐ketoenamines of histidine

Condensation products of L‐histidine with the 3‐oxoenolethers diethyl‐ethoxymethylene‐malonate ( 1 ) and ethyl‐ethoxymethylene‐cyanoacetate ( 2 ) react with copper(II) as di‐anionic ligands to give neutral 1:1 complexes Cu‐ His1 and Cu‐ His2 . Both complexes crystallize as oligonuclear units, even from strongly donating solvents like N‐methylimidazole (Meim) (Cu‐ His1 ) and pyridine (Cu‐ His2 ). X‐ray structure analyses show supramolecular structures, formed of two (Cu‐ His1 ) or four (Cu‐ His2 ) formula units of the complex, which arrange to macrocycles by means of intermolecular coordination of the imidazole‐N. Strong H‐bridges result in a face‐to‐face orientation of the hydrophilic sites of two great rings. ESI‐MS investigations in pyridine solution give evidence for the existence of dimeric, tetrameric and – in case of Cu‐ His2 – trimeric units, besides the monomeric adducts with one pyridine. In contrast to the dimeric or tetrameric (“cubane‐like”) copper(II) complexes of amino alcohols and their β‐ketoenamines, the complexes Cu‐ His1 and Cu‐ His2 show no significant spin coupling from room temperature down to 4 K. The complexes Cu‐ His1 and Cu‐ His2 give no electrochemically reversible Cu^II/I reduction in pyridine. However, the isolation of a stable diamagnetic copper(I) complex of the methylester derivative, Cu^I‐ HisMe1 , supports the assumption, that similar histidine‐derived copper complexes should display reversible redox behaviour and catalytic activity in reactions with O₂.     

Metal ion interaction of water‐soluble copolymers containing carboxylic acid groups in aqueous phase by membrane filtration technique

This article reports the synthesis of poly(N‐maleoylglycine‐co‐itaconic acid) by radical copolymerization under different feed mole ratios and its properties to remove various metal ions, such as Cu(II), Cr(III), Co(II), Zn(II), Ni(II), Pb(II), Cd(II), and Fe(III), in aqueous phase with the liquid‐phase polymer‐based retention(LPR) technique. The interactions of inorganic ions with the hydrophilic water‐soluble polymer were determined as a function of pH and filtration factor. Metal ion retention was found to strongly depend on the pH. Metal ion retention increased as pH and MG content units in the macromolecular backbone increased. The copolymers were characterized by elemental analysis, FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopy. Additionally, intrinsic viscosity, molecular weight, and polydispersity have been determined for the copolymers. Copolymer and polymer–metal complex thermal behavior was studied using differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques under nitrogen atmosphere. The thermal decomposition temperatures (TDT) were influenced by the copolymer composition. The copolymers present lower TDT than the polymer–metal complex with the same copolymer composition. All copolymers present a single T_g, indicating the formation of random copolymers. A slight deviation of the T_g for the copolymers and its complexes can be observed. The copolymer T_g is higher than the T_g value for the polymer–metal complexes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis of poly‐N‐(thiazol‐2‐yl)methacrylamide: Characterization,complexation, and bioactivity

Cu(II) complexes with N‐(thiazol‐2‐yl)methacrylamide (NTM) and its polymer PNTM have been synthesized. The ligands (NTM and PNTM) and their Cu(II) complexes have been characterized by FTIR and ¹H‐NMR. EDX was performed to know the elemental composition and X‐ray powder diffractometry (XRD) analysis was applied to detect the crystallinity of the complexes. The morphology of these complexes was investigated with scanning electron microscopy (SEM) and proves that the monomer complexes have a strongly crystalline structure compared with the polymer complexes, which show that it is only weakly crystalline. These results from SEM are in agreement with results obtained from XRD. Thermal properties of the ligands and their complexes have been studied by thermogravimetric analysis and differential scanning calorimetry. The activity of the ligands and their complexes has been screened against S. aureus, E. coli, Pseudomonas, and Candida albicans. The synthesized compounds have shown good affinity as antibacterial and antifungal agents, which increased on complexation with Cu(II) ion. The results of these studies show the Cu(II) complexes to be more thermal stable as compared with NTM and PNTM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Resin I: Synthesis,characterization, and ion‐exchange properties of terpolymer resins derived from 2,4‐dihydroxypropiophenone,biuret, and formaldehyde

Terpolymers (2,4‐DHPBF) were synthesized by the condensation of 2,4‐dihydro‐xypropiophenone, biuret, and formaldehyde in the presence of acid catalyst with varying the molar ratio of reacting monomers. Terpolymer composition has been determined on the basis of their elemental analysis and their number–average molecular weight of these resin were determined by conductometric titration in nonaqueous medium. The viscosity measurements were carried out in N,N‐dimethyl formamide which indicate normal behavior. IR spectra were studied to elucidate the structure. The terpolymer resin has been further characterized by UV–visible and ¹H‐NMR spectra. The newly synthesized terpolymers proved to be selective chelating ion‐exchange terpolymers for certain metals. The chelating ion‐exchange properties of this terpolymer was studied for Fe (III), Cu (II), Hg (II), Cd (II), Co (II), Zn (II), Ni (II), and Pb (II) ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurement of the distribution of a given metal ion between the terpolymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The terpolymer showed a higher selectivity for Fe (III), Hg (II), Cd (II), and Pb (II) ions than for Cu (II), Co (II), Zn (II), and Ni (II) ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Selective separation and concentration of Pd(II) from Fe(III), Co(II), Ni(II), and Cu(II) ions using thiourea‐formaldehyde resin

Thiourea‐formaldehyde (TUF), a well‐known chelating resin, has been synthesized and it was used in the adsorption, selective separation, and concentration of Pd(II) ions from Fe(III), Co(II) Ni(II), and Cu(II) base metal ions. The composition of the synthesized resin was determined by elemental analysis. The effect of initial acidity/pH and the adsorption capacity for Pd(II) ions were studied by batch technique. The adsorption and separation of Pd(II) were then examined by column technique. FTIR spectra and SEM/EDS analysis were also recorded before and after the adsorption of Pd(II). The optimum pH was found to be 4 for the adsorption. The adsorption data fitted well to the Langmuir isotherm. The maximum adsorption capacity of the TUF resin for Pd(II) ions was found to be 31.85 mg g⁻¹ (0.300 mmol g⁻¹). Chelating mechanism was effective in the adsorption. Pd(II) ions could be separated efficiently from Fe(III), Cu(II), Ni(II), and Co(II) ions using TUF resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Production of GST–SOD fusion protein by recombinant E coli XL1 Blue

A recombinant plasmid was constructed by inserting a DNA fragment with the coding region of Cu/Zn–superoxide dismutase (Cu/Zn–SOD) cDNA from sweet potato, Ipomoea batatas (l) Lam cv Tainong 57, into the 3′ end of the open reading frame of the glutathione S‐transferase (GST) gene in an expression vector, pGEX‐2T. The constructed plasmid was transformed into E coli XL1 Blue. Fusion proteins of Cu/Zn–SOD and GST (GST–SOD) were produced from the recombinant E coli. About 6 mg of GST–SOD fusion proteins could be obtained from 1 dm³ of cultural broth after induction with 0.075 mmol dm⁻³ Isopropyl‐β‐D ‐thiogalactoside (IPTG). Lactose was not an efficient inducer. High cell density culture was performed by fed‐batch fermentation using a glucose analyzer to control glucose concentration at 1 g dm⁻³. The cell density of the fed‐batch culture reached an OD₆₀₀ of 30, the total amount of GST–SOD fusion protein was 100 mg dm⁻³ which is about 14 times more than that of the batch culture. Most of the fusion proteins were shown to be in an active monomeric form, and the molecular weight was estimated to be 45 kDa by SDS–PAGE and 47 kDa by gel filtration. The specific activity of the purified fusion proteins was about 1200 mg⁻¹ and equal to 3200 unit per mg of SOD domain only. © 2000 Society of Chemical Industry