Electrocatalytic Oxidation of Hydrazine at the Poly(Glutamic Acid) Chemically Modified Electrode and Its Amperometric Determination

ABSTRACT

The electrochemical polymerization of glutamic acid at the glassy carbon electrode was investigated in phosphate buffer solution by cyclic voltammetry. The applied voltage range, pH of electrolyte, cyclic number were explored for optimal polymerization conditions. The resulting film exhibits an electrocatalytic ability to hydrazine, reducing the overpotential by 500mV. The electrocatalytic response of hydrazine is evaluated with regard to pH, scan rate, applied voltage, hydrazine concentration and other variables. The rate constant of the catalytic reaction was 1.2 × 10⁴ M^?1.s^?1. When used as amperometric detector, the modified electrode yields a detection limit of 1 × 10^?8 M hydrazine. The electrode is rather stable even after use for a month and a reproducible response was obtained.     

Photodegradation of Poly[methyl(phenyl)silylene] in the Presence of Modifying Substances

Summary: Efficiency of the photodegradation of poly[methyl(phenyl)silylene] can be increased by electron acceptor additives with unstable anion radicals. The best chain degradation yield was obtained using benzoyl peroxide as an additive. The model for the photodegradation process is supported by quantum chemical calculations.     

Application of Ni(II)-imprinted cross-linked poly(methacrylic acid) synthesised through double-imprinting method for the on-line preconcentration of Ni(II) ions in aqueous media

The present paper describes the feasibility of on-line preconcentration of nickel ions from aqueous medium on Ni(II)-imprinted cross-linked poly(methacrylic acid) (IIP) synthesised through a double-imprinting method and their subsequent determination by FAAS. The proposed method consisted in loading the sample (20.0 mL, pH 7.25) through a mini-column packed with 50 mg of the IIP for 2 min. The elution step was performed with 1.0 mol L^?1 HNO₃ at a flow rate of 7.0 mL min^?1. The following parameters were obtained: quantification limit (QL) – 3.74 µg L^?1, preconcentration factor (PF) – 36, consumption index (CI) – 0.55 mL, concentration efficiency (CE) – 18 min^?1, and sample throughput – 25 h^?1. The precision of the procedure assessed in terms of repeatability for ten determinations was 5.6% and 2.5% for respective concentrations of 5.0 and 110.0 µg L^?1. Moreover, the analytical curve was obtained in the range of 5.0–180.0 µg L^?1 (r = 0.9973), and a 1.64-fold increase in the method sensitivity was observed when compared with the analytical curve constructed for the NIP (non-imprinted polymer), thus suggesting a synergistic effect of the Ni(II) ions and CTAB on the adsorption properties of the IIP. The practical application of the adsorbent was evaluated from an analysis of tap, mineral, lake and river water. Considering the results of addition and recovery experiments (90.2–100 %), the efficiency of this adsorbent can be ensured for the interference-free preconcentration of the Ni(II) ions.     

Preparation,characterization and thermal stability of poly[2-(Dimethylamino)ethyl acrylate]

Poly[2-(dimethylamino)ethyl acrylate] (PDAEA) and polymer complexes of 2-(dimethylamino)ethyl acrylate (DAEA) with nickel(II), copper(II), iron(III) and cobalt(II) chlorides were prepared and characterized by means of IR, electronic spectra and elemental analysis. The thermal stability of the homopolymer was compared with those of the polymer complexes, and the order of stability was given. The activation energies of the polymer complexes were calculated.     

A New PVC-Membrane Electrode Based on a Macrocyclic Ionophore for Selective Determination of Ni (II) Ions

A poly(vinyl chloride)-based membrane of 3,4:12,13-dibenzo-1,6,10,15-tetraazacyclooctadecane with sodium tetraphenyl borate (NaTPB) as an anion excluder and dibutylphthalate (DBP), dibutylbutylphosphonate (DBBP), tris(2-ethylhexyl) phosphate (TEHP) and tributyl phosphate (TBP) as plasticizing solvent mediator was prepared and investigated as a Ni(II)-selective electrode. The best performance was observed with the membrane having the ligand-PVC-TEHP-NaTPB composition 1:4:1:1, which worked well over a wide concentration range (2.82 ×10⁻⁶−1.00 × 10⁻¹ M) with a Nernstian slope of 30.5 mV per decade of activity between pH 2.5–7.5. This electrode showed a fast response time of 18 s and was used over a period of 4 months with good reproducibility (S=0.4 mV). The selectivity coefficient over mono-, di- and trivalent cations indicate excellent selectivity for Ni (II) ions over a large number of cations. Anions such as Cl⁻ and NO₃⁻ do not interfere and the electrode also works satisfactorily in a partially non-aqueous medium. It has been used successfully for determination of Ni (II) in real samples.     

Complexation of N-bis[2-(1,2-dicarboxyethoxy)ethyl]aspartic acid with Fe(II), Co(II), and Ni(II) in aqueous solution

In a search for environment-friendly metal chelating ligands for industrial applications, the protonation and complex formation equilibria of N-bis[2-(1,2-dicarboxyethoxy)ethyl]aspartic acid (BCA6) with Fe(II), Co(II), and Ni(II) ions in aqueous 0.1 M NaCl solution were studied at 25°C by potentiometric titration. The model for complexation and the stability constants of different complexes were determined for each metal ion using SUPERQUAD. In all cases, complex formation was dominated by stable ML^4? complexes.     

Synthesis and Crystal Structure of [Ni(II)(L)(py)_3]·(py)

1 INTRODUCTION Schiff bases and their metal complexes are useful reagents in organic synthesis[1], and they have exhi- bited some biological activities as anticancer and antitumor drugs[2]. The crystal structures and physi- cal and chemical properties of many Schiff bases and their transition metals complexes have been re- ported[3~5]. Further interest in the coordination che- mistry of nickel(II) arises from the role of these complexes in several catalytic reactions, such as electrocat…     

Electrochemical Detection of Pb(II) by Glassy Carbon Electrode Modified with Amine-Functionalized Magnetite Nanoparticles

An amine-Fe₃O₄ modified glassy carbon (GC) electrode was constructed for detecting Pb(II) ions in wastewater. The electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Square wave anodic stripping voltammetry (SWASV) was used to detect the Pb(II), and the detection limit of Pb(II) was 0.15 µM. The sensitivity of the electrode to detect Pb(II) was about 10.07 µA/µM, with a correlation coefficient of 0.991, which was approximately 10 times bigger than that of a pure Fe₃O₄ modified electrode. The electrode also showed good selectivity and stability. This results indicated that the amine-magnetite material could have some potential applications in heavy metal ions detection in wastewater.     

Anodic Stripping Voltammetry Determination of Pb(II) and Cd(II) at a Bismuth/Poly(aniline) Film Electrode

Abstract

A novel voltammetric method—anodic—using a bismuth/poly(aniline) film electrode has been developed for simultaneous measurement of Pb(II) and Cd(II) at low µg L^?1 concentration levels by stripping voltammetry. The results confirmed that the bismuth/poly(aniline) film electrode offered high‐quality stripping performance compared with the bismuth film electrode. Well‐defined sharp stripping peaks were observed for Pb(II) and Cd(II), along with an extremely low baseline. The detection limits of Pb(II) and Cd(II) are 1.03 µg L^?1 and 1.48 µg L^?1, respectively. The bismuth/poly (aniline) electrode has been applied to the determination of Pb(II) in tap water samples with satisfactory results.     

Synthesis and Characterization of a Novel Aqueous Dispersion Poly[urethane-（disperse blue 14）-urethane] Dye

A novel polymeric dye of aqueous dispersion poly[urethane-(disperse blue 14)-urethane] was synthesized based on poly(propylene glycol) (PPG), 2, 4-tolylene diisocyanate (TDI), dimethylol propionic acid (DMPA), disperse blue 14 and triethylamine (TEA) depending on a modified acetone process. Fourier transform infrared spectroscopy (FTIR) was used to identify the structure of the polymeric dye, indicating an obvious carbonyl stretching absorption in disperse blue 14. The polymer was also characterized by the analysis of DSC, TGA, WAXD and UV-Vis spectroscopy.     

Self-optimization of binding sites by Ni(II) ion on carboxypyrazine-containing poly(ethylenimine)

To test the concept of self-optimization of own binding site by a metal ion, host molecules for Ni(II) ion were built on poly(ethylenimine) (PEI) by using the ethylenediamine portions of PEI and 2-carboxypyrazinyl (CP) group. Two derivatives of PEI containing CP were prepared: one by random acylation of PEI with pyrazine-2,5-dicarboxylic acid mono-(2,5-dioxo-pyrrolidin-1-yl) ester (PC-DP), and the other by acylation of PEI with PC–DP in the presence of Ni(II) ion. Between these two CP derivatives of PEI, Ni(II) binding ability was more than 10³ times greater for the latter. Optimization by Ni(II) ion of its own binding site built on the polymer was attributed to the preassemblage of PC–DP and PEI with Ni(II) ion and the subsequent attack at PC–DP by an amino group of PEI located in an optimal position. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 533–537, 1997.     

聚(丙烯酸钠-4-乙烯基吡啶)的生物降解性和功能性研究

用自由基共聚法制备了一系列可生物降解的功能聚合物聚(丙烯酸钠-4-乙烯基吡啶)[P(SA-co-4VP)],研究了其组成和分子量与生物降解性、资合性及分散性间的关系.结果表明:聚合物中小乙烯基吡啶含量越大,P(SA-co-4VP)的生物降解越显著.分子是一定时,少量的个乙烯基吡啶引入聚丙烯酸钠主链是增强聚合物生物降解性和保持原有功能特性的有效途径.     

5-氟尿嘧啶-聚[N-(2-羟乙基)-L-谷酰胺]的合成及缓释性能研究

以聚谷氨酸苄酯为原料,用乙醇胺进行胺解得水溶性的可生物降解的聚[N-(2-羟乙基)-L-谷酰胺];用光气/甲苯液活化5-氟尿嘧啶,将其以共价键形式键合在高分子上,得5-氟尿嘧啶的高分子前药。用IR、UV、1HNMR及DSC对其结构进行表征,用紫外光谱测定其药物含量,载药高分子的接药率约为38.4%,高分子前药在pH=7.2的磷酸盐介质中42天内的药物累积释放量为57.53%。实验结果表明,5-氟尿嘧啶以共价键的形式键合在聚[N-(2-羟乙基)-L-谷酰胺]之上,在体外有明显的缓释效果。     

Syntheses,structural characterizations and microbial activities of Ni(II) and Zn(II) 5-aminoisophthalate coordination polymers

Two coordination polymers with 5-aminoisophthalic acid (H₂aip), [Ni(μ-aip)(H₂O)₂(tmeda)]_n (1) and {H₂dap[Zn₂(μ-aip)(μ₃-aip)₂]?9H₂O}_n (2) (H₂aip = 5-aminoisophthalic acid, tmeda = N,N,N′-N′-tetramethylethylenediamine, dap = 1,3-diaminopropane) have been synthesized. Elemental and thermal analyses, magnetic susceptibilities, IR, AAS, mass and UV–vis spectroscopic studies have been performed to characterize the compounds. Nickel(II) has octahedral geometry by two oxygens of different carboxylates, bidentate, tmeda as bidentate chelating and two water ligands. Zn(II) has tetrahedral geometry by three oxygens of different carboxylate groups and one nitrogen by amine of aip. 1 crystallizes in the orthorhombic crystal system with space group Pccn and 2 in monoclinic crystal system with space group P2₁/c. Complex 2 exhibits photoluminescence properties in the solid state at room temperature. This study determined the susceptibility patterns of 1 and 2 against bacterial, yeast and mold micro-organisms. Antimicrobial activities were done on 12 different micro-organisms using the micro-dilution method. Tested microbial species were inhibited by 1 with a Minimum inhibitory concentrations (MIC) of 375–3000 μg mL^?1. Compound 2 showed antimicrobial activities against tested micro-organisms with a MIC of 188–1500 μg mL^?1. Compound 2 showed antibacterial activity against Legionella pneumophila sg1 375 μg mL^?1 (MIC value).     

Kinetics of weight loss and chain scission in the thermooxidative degradation of poly[1-(trimethylsilyl)-1-propyne] films

The kinetic model of thermooxidative degradation in air, proposed to be valid for poly(2-hexyne) in predicting the lifetime of substituted polyacetylenes, was applied to poly[1-(trimethylsilyl)-1-propyne] films, with the differences in the oxidative behavior of both polyacetylenes noted. The effect of the molecular weight of the sample on the degradation process was analyzed. Kinetics of weight loss and chain scission were modeled, and the kinetic parameters were calculated. Also, the evolution of weight loss was related to the chain scission. The proposed model was validated with data reported in the literature. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4309–4317, 1999     

Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone

Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)(2)(SO(4)) and Cu(L)(2)(SO(4)) [where L=L(1) and L(2)] which are of five coordinated square pyramidal geometry.     

大环金属铜(II)、镍(II)配合物的模板合成与晶体结构

用模板法合成了1个大环金属铜(II)配合物[CuLCl₂]·3H₂O (1)和3个大环金属镍(II)配合物[NiLCl₂] (2)，[NiL](ClO₄)₂ (3)和[NiLH₂](ClO₄)₄ (4)(L=3,10-二乙基-1，3，5，8，10，12-六氮杂十四烷)，通过X-射线衍射单晶结构分析测定了它们的晶体结构。晶体结构显示：配合物1和2的金属离子与大环配体的4个氮原子及大环平面轴向的2个氯离子以八面体配位方式配位；配合物3和4的金属离子与大环配体的4个氮原子以平面正方形配位方式配位，配合物4的侧链氮原子的质子化导致侧链结构翻转，使得其侧链与大环平面共面。     

Novel Isatin-Schiff Base Cu (II) and Ni(II) Complexes. X-ray Crystal Structure of Bis[3-(4-hexylphenylimino)-1H-indol-2(3H)-one]-dichlorocopper(II) Complex

Schiff bases of isatin were reported to possess antibacterial, antifungal, antiviral, anti-HIV, antiprotozoal, and anthelmintic activities1. They also exhibit significantanticonvulsant activity, apart from other pharmacological properties2. Conductingsubs…     

聚吖啶红修饰电极的制备及其应用

扑热息痛;聚吖啶红修饰电极的制备及其应用