A New Sensor for Perchlorate Ion

Abstract

A potentiometric sensor for perchlorate anion was developed by mixing a silica gel, chemically modified with 1,4-diazabicyclo (2.2.2) octane, with an epoxy polymer and carbon. The electode showed Nernstian response to the perchlorate ion in the concentration range of 10^?1 and 10^?4 mol L^?1.     

Polymers to Selectively Remove Oxidizing Anions from Non-Oxidizing Anions and NO3 − and NO2 − and NO2 − From Polluted Waters

Abstract

A copolymer of 1-phenyl-2-diethylaminoethyl-p-aminobenzoate and polyvinyl-benzyl chloride was found to have a greater capacity for NO₃ ^? and NO₂ ^? than a previously reported nitron polymer but did not react as rapidly. The resin is readily regenerated with NH₄OH or NH₄Cl and is not affected by the pH of the water over the range of 4–10.

A copolymer of 1-(4′-nitrophenyl)-2-diethyl aminoethyl-p-nitrobenzoate and polyvinylbenzyl chloride was found to react nearly as fast as the nitron polymer and have a larger capacity for NO₃ ^? and NO₂ ^?.     

Novel Potentiometric Sensor Based on Molecular Imprinted Polyacrylamide for the Determination of Shikimic Acid in Herbal Medicine

ABSTRACT

A novel potentiometric sensor based on a molecular imprinted polymer was developed for the determination of shikimic acid in herbal medicine. The imprinted polymer was synthesized via bulk polymerization of the functional monomer in the presence of trimethylolpropane triacrylate as the cross-linker with 2,2′-azo-bisisobutyronitrile as the initiator and shikimic acid as the template. The sensing membrane was constructed by the inclusion of imprinted polymer in the polyvinyl chloride matrix. The effect of the identity of the imprinted polymer on the potentiometric response was observed. The optimal imprinted polyacrylamide was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The performance of the imprinted membrane based sensor, including the effects of pH, response time and selectivity coefficient, was investigated. The imprinted sensor exhibited a fast near-Nernstian response in the concentration range of 1?×?10^?5 to 1?×?10^?1?mol/L with a detection limit of 9?×?10^?6?mol/L. The analytical performance of the sensor supported the direct determination of shikimic acid in herbs, and the obtained results were validated by ultraviolet-visible absorption spectrophotometry. Advantages of the potentiometric sensor include enhanced sensitivity, high selectivity, long-term stability and low-cost fabrication, suggesting the device offers promise for the analysis of Chinese herbal medicine.     

Synthesis,crystal structure,and third-order non-linear optical properties of a new Cd(II) polymer constructed from pyrazine-2-carboxylic acid

A new cadmium(II) pyrazine-2-carboxylate coordination polymer, {[Cd(L)(H₂O)₂(SO₄)_0.5]₂·H₂O}_n (1) (HL = pyrazine-2-carboxylic acid), has been synthesized by low-temperature solid-state reaction. Single-crystal X-ray analyses reveal that 1 possesses a 3-D framework structure. The polymer 1 was characterized by elemental analyses, thermogravimetric analyses, X-ray powder diffraction analyses, IR spectra, and UV–visible spectra. The third-order non-linear optical properties were also investigated and they exhibit nice non-linear absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 1.30 × 10^?30 esu for 1 in a 2.01 × 10^?4 M?dm^?3 DMF solution.     

[Hydroxy(tosyloxy)iodo]benzene as Thermal initiator for the Radical Polymerization of Methyl Methacrylate

Abstract

The thermal polymerization of methyl methacrylate in a solution of N,N-dimethylacetamide has been studied using [hydroxy(tosyloxy)- iodo]benzene (HTIB) as the initiator. The rate of polymerization was a direct function of the monomer and initiator concentrations. The initiator and monomer exponent values expressing this dependence were found to be 1.0 and 0.8, respectively. The overall activation energy of polymerization was estimated to be 45 kJ·mol^?-1. The polymerization was inhibited in the presence of hydroquinone. The effect of various solvents on the polymerization rate was studied. The polymer prepared with HTIB (0.47 × 10^?3 mol·L^?-1) had a number-average molecular weight of 138,000 and a glass transition temperature of 106°C. The polymer showed good thermal stability as determined by thermogravimetric analysis.     

Ti(IV) ion-imprinted polymer as a new selective sorbent for extraction and pre-concentration of trace amounts of titanium ions in different samples

ABSTRACT

In this paper, a novel, simple, selective and effective solid phase extraction method based on ion-imprinted polymer (IIP) technology and flame atomic absorption spectrometry (FAAS) for separation and pre-concentration of trace amounts of titanium (IV) ions was reportd?. It was obtained by precipitation polymerisation by using 2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one titanium (IV) complex abbrivated as Ti(IV)-(morin), as the template molecule. After polymerisation, leaching the polymer in HNO₃ (50% (v/v) solution caused formation cavities in the polymer. Characterisation studies of the ?Ti(IV)-imprinted polymer (Ti-IP) was performed by FT-IR, UV-Vis and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) techniques and then, the effective factors on extraction were optimised. A sensitive response to Ti(IV) within a concentration range between 0.01 and 4.0 μg mL^?1 was achieved under the optimum conditions. A total of 10.0 ng mL^?1 and 80.0 mg g^?1 were obtained as limit of detection (LOD, 3Sb/m) and maximum adsorption capacity, respectively. The relative standard deviation (RSD) for eight replicates detections of 0.2 μg mL^?1 of Ti(IV)? was found to be 2.8%. By this method, pre-concentration factor (PF) of 100 was obtained. Successfully applying this method in the water and standard samples, reasonable results were obtained for the extraction and pre-concentration of the titanium ions.     

Radiation Induced Polymerization of N,N'-Methylenebisacrylamide in Aqueous Solution

Abstract

Gamma ray induced polymerization of N,N'-methylenebisacrylamide (MBA) in aqueous solution has been studied. Rates of polymerization have been determined as a function of dose, dose rate, and monomer concentration. Polymerization mechanism was found to be free radical with chain propagation step involving ring formation. About 90% conversion was achieved in 25 minutes of irradiation (dose rate 1.54 × 10¹⁸ eV dm^?3 s^?1) of MBA solution (36 mmol). The polymerization rates were found to vary from 1.9 × 10 4 to 5.6 × 10^?4 mol dm^?3 s^?1 when the monomer concentrations were varied between 80–164 mmols. The value of the constant k_p/k_t ^1/2 was calculated to be 9.85 for the dose rate of 1.54 × 10¹⁸ eV dm^?3 s^?1. The precipitated polymer showed mono disperse particles of diameter of about 170 nm. The polymer was found to be highly crosslinked and insoluble in any solvent.     

Electro-Catalytic Oxidation of Ascorbic Acid at a Cobalt-Salen Polymer Modified Electrode and Analytical Applications

ABSTRACT

The preparation and electrochemical characteristics of electrodes modified by cobalt complexes of N, N' - bis(salicylidene)-ethane -1, 2- diamine (salen) are described. A cobalt-salen polymer film modified electrode has strong electro-catalytic effects for the oxidation of ascorbic acid. The anodic peak potential of ascorbic acid shifted negatively for 400 m V. The catalytic reaction rate constant determined by rotating disk experiments is 7.08×10⁵ mol s^?1 cm^3. The catalytic mechanism and the effect of film thickness are discussed. A sensitive voltammetric response for ascorbic acid was obtained covering a linear range from 1.0×10^?6 to 1.0×10^?3 mol-L^?1 The modified electrode showed good stability and reproducibility. The electrode was used to the determination of ascorbic acid in fruit juices and showed promising results compared with conventional methods. The electro-catalytic effect of several metal-salen complexes and a similar Schiff base derivative for ascorbic acid was compared.     

Removal of Lead (II) Ions by Poly(2‐octadecyl butanedioic acid): Isothermal and Kinetic Studies

Poly(2‐octadecyl‐butanedioic acid), prepared from polyanhydride PA‐18, possesses novel heavy metal adsorption characteristics. The adsorption capacity of this water insoluble polymer for lead (II) was substantially higher than other heterogeneous adsorbants and is equivalent to those obtained with homogeneous sorbants. The polymer exhibited pseudo‐second‐order kinetics and nearly complete adsorption of lead occurred in 15 min with initial lead (II) concentrations greater than 100 mg · L^?1. Adsorptive behavior was accurately predicted by the Dubinin‐Radushkevich isotherm model. The mean free energy of adsorption of lead (II) onto poly(2‐octadecyl‐butanedioic acid) was determined to be 31.6 kJ · mol^?1, suggesting an ion exchange component to the adsorption mechanism. Gibb's free energy values for this process indicate that it is spontaneous. Adsorption was relatively independent of pH in the range of 3–5, due to the utilization of the sodium carboxylate form of the chelating groups, and was not influenced by high Na⁺ concentration and moderate concentrations (up to 200 mg · L^?1) of Ca⁺². Lead (II) solutions containing 2000 mg · L^?1 Ca⁺² did reduce the adsorption of 2000 mg · L^?1 lead (II) by 28%.     

Molecular Imprinting-Chemiluminescence Sensor for the Determination of Prulifloxacin

Abstract

A selective molecular imprinting-chemiluminescence sensor is developed for the determination of prulifloxacin by using a prulifloxacin-imprinted polymer as recognition material and the cerium(IV)/sodium thiosulfate/prulifloxacin chemiluminescence reaction as the detection system. The linear response range of the sensor is from 8.0 × 10^?8 to 7.0 × 10^?6 mol L^?1 with a detection limit of 2.0 × 10^?8 mol L^?1. The relative standard deviation for 5.0 × 10^?7 mol L^?1prulifloxacin solution is 1.3% (n = 7). This sensor has been applied to the determination of prulifloxacin in urine samples, and the results obtained are satisfactory.     

New 5-Octyl-thieno[3,4-c]pyrrole-4,6-dione Based Polymers: Synthesis and Photovoltaic Properties

Two donor-acceptor conjugated polymers, namely poly{4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)benzo[1,2-b:4,5-b']difuran-alt-5-octyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione}(PBDFTTPD) and poly{4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b: 4,5-b']dithiophene-alt-5-octyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione}(PBDTTTPD), were synthesized by Stille coupling polymerization reactions. Their structures were verified by ¹H-NMR and elemental analysis, the molecular weights were determined by gel permeation chromatography and the thermal properties were investigated by thermogravimetric analysis. The polymer films exhibited broad absorption bands. The hole mobility of PBDFTTPD:PC₇₁BM(1:2, w/w) blend reached up to 5.5 × 10^?2 cm² v^?1 s^?1 by the space-charge-current method. Preliminary photovoltaic cells based on the device structure of ITO/PEDOT:PSS/PBDFTTPD:PC₇₁BM(1:2, w/w)/Ca/Al showed a power conversion efficiency of 2.32% with an open-circuit voltage of 0.90 V and a short circuit current of 4.40 mA cm^?2.     

Synthesis,crystal structure and magnetic properties of 2D bi-layered coordination polymer

A new coordination polymer, [Ni(pydc)(H₂O)₂]?·?H₂O (1) (H₂pydc?=?pyridine-3,4-dicarboxylic acid), have been synthesized by treating Ni(II) nitrate with 3,4-pyridinedicarboxylic acid under hydrothermal conditions. The single-crystal X-ray structure reveals that 1 is a 2D bi-layered coordination polymer. Single-crystals are triclinic, space group P 1 , with a?=?7.065(3), b?=?7.812(4), c?=?9.031(4)?Å, α?=?75.568(8), β?=?68.970(8), γ?=?75.927(8)°, V?=?444.0(3)?ų, Z?=?2. Variable temperature magnetic susceptibility measurements demonstrate a ferromagnetic interaction in 1.     

Spectrophotometric Determination of Gold in Water and Ore with 2‐Carboxyl‐1‐Naphthalthiorhodanine

Abstract

This paper reports on the synthesis of a new chromogenic reagent, 2‐carboxyl‐1‐naphthalthiorhodanine (CNTR). A high sensitive, selective, and rapid method for the determination of gold based on the rapid reaction of gold with CNTR and the solid phase extraction of the colored chelate with a reversed phase polymer‐based C₁₈ cartridge was developed. In the presence of 0.05–0.5 mol L^?1 of phosphoric acid solution and emulsifier‐OP medium, CNTR reacts with gold to form a red chelate of a molar ratio 1∶3 (gold to CNTR). This chelate was enriched by the solid phase extraction with a polymer‐based C₁₈ cartridge and the retained chelate was eluted from the cartridge with dimethyl formamide (DMF). The enrichment factor of 100 was achieved. In the DMF medium, the molar absorptivity of the chelate is 1.35×10⁵ L · mol^?1 · cm^?1 at 540 nm. Beer's law is obeyed in the range of 0.01～2 µg mL^?1 in the measured solution. The relative standard deviation for 11 replicates sample of 0.5 µg L^?1 level is 2.05%. The detection limit, based on three times the standard deviation is 0.02 µg L^?1 in the original sample. This method was applied to the determination of gold in water and ore with good results.     

Flow Injection Chemiluminescence Sensor with Novel Rhodanine Ramification for Determination of Fenfluramine Based on Molecularly Imprinted Polymer

Abstract

Flow injection chemiluminescence (FI-CL) with molecularly imprinted polymer (MIP) was applied to determine fenfluramine. The fenfluramine-imprinted polymer was prepared with acrylamide (AM) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Methyl and sulfonic group were introduced to rhodanine matrix, and a novel rhodanine ramification 3MORASP was synthesized by the author, and it was used as chemiluminescence reagent. 3-(3′-Methoxyphenyl)-5(2′-sulfonylphenylazo)-rhodanine (3MORASP), first synthesized by the authors, was used as chemiluminescence (CL) reagent. The novel flow path of FI-CL was designed, which made three merged streams of reactants injected into MIP column move through different pathways simultaneously. Fenfluramine was detected based on the reaction of fenfluramine, 3MORASP, and potassium permanganate in an acidic medium. The CL intensity was correlated linearly with the concentration of fenfluramine over the range of 1.0 × 10^?7 to 5.0 × 10^?6 g · mL^?1, and the detection limit was 9.48 × 10^?9 g · mL^?1. The relative standard deviation (RSD) was 2.4% for determination of 1.0 × 10^?6 g · mL^?1 fenfluramine (n = 11). This method was successfully applied to the determination of fenfluramine in weight-reducing tonic.     

One Pot Synthesis Of (+−)/(S)-Atenolol And(+−)/(S)Propranolol By Employing Polymer Supported Reagent

Abstract

(+^?)/(S)-Atenolol and((+^?)/(S)- propranolol were synthesized by using reaction of((+^?)/(S) -epichlorohydrin with polymer supported phenoxide anion followed by reaction with isopropylamine.     

Synthesis and Properties of Poly(Organophosphazenes) Electrolyte

Abstract

To prepare electrolytes using poly(organophosphazenes), poly(bisanilinophosphazene) selected was carried out with the various concentration of sulfonic chloride in tetra-chloroethane solvent using vigorously sterring at room temperature for 4 hr. The products prepared were determined with IR and chemical analysis. It was found that the -SO₃H groups in the product appeared at 1,1050 cm^?1, 1,030 cm^?1 and 550 cm^?1, and the reaction rate of sulfonic chloride was about 34%-55% under this experimental conditions. Also, the products had two kind of glass transition temperatures such as 63°C and -18°C, respectively, and the values were lower in comparison with that of starting polymer. Furthermore, the conductivity of the product at room temperature was determined and the conductivity was increased the concentration of -SO₃H groups. It was found that the product having -SO₃H groups was able to ion exchange with Li⁺ or Cu²⁺ ions under aqueous solution. Also, the ion exchange rate was determined with the titration of alkaline aqueous solution with a standard solution of HCl. The products formed after the ion exchange reaction had higher conductivity in comparison with that of the polymer.     

Highly selective probe of a copper(II) complex based on a coumarin derivative for hydrogen sulfide detection

Abstract

A fluorescent probe 1 containing copper(II) had been designed and synthesized based on a coumarin derivative. The molecular structure of probe 1 was characterized by ¹H NMR, HRMS, IR, and elemental analysis. The interactions of 1 with biologically important anions and amino acid were determined by UV–Vis, fluorescence, and HRMS titration experiments. Results indicated that probe 1 showed the highest binding ability for HS^? among studied anions (AcO^?, H₂PO₄^?, F^?, Cl^?, Br^?, and I^?) and cysteine in pure dimethyl sulfoxide (DMSO) and HEPES buffer solution. As we expected, the response of UV–Vis spectra in aqueous solution was stronger than that of pure DMSO solvent. In addition, the binding ability for HS^? was not hindered by the existence of other anions. HRMS titration experiment showed that the interacted mechanism was that the copper(II) ion in 1 was captured by HS^? and then free ligand released. Furthermore, the detection limit of probe 1 with HS^? was carried out through UV–Vis titration showing 1 to be highly sensitive for HS^?.     

Solid-phase extraction using a molecularly imprinted polymer for the selective purification and preconcentration of norfloxacin from seawater

Abstract

A highly selective and effective method for the purification and preconcentration of norfloxacin (NFX) in seawater samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The molecularly imprinted polymer was synthesized by precipitation polymerization. Methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were used as the functional monomer and crosslinker, respectively. The resulting molecularly imprinted polymer (MIP) showed high adsorption for NFX and was selective for its solid-phase extraction. An offline MISPE method followed by high performance liquid chromatography with diode array detection was established for the determination of NFX in seawater. The recoveries of spiked seawater samples using the MISPE columns were satisfactorily higher than 77.6%. The relative standard deviation was less than 5.60%, and the limit of detection was 0.027?μg L^?1. Four seawater samples obtained from the Bohai Sea were analyzed, and NFX was found only at one location at a concentration of 0.280?μg L^?1.     

Preparation and liquid-crystalline properties of toluene-4-sulphonyl urethane of hydroxypropylcellulose

Abstract

A novel liquid-crystalline polymer, the toluene-4-sulphonyl urethane of hydroxypropylcellulose (TSUHPC), was prepared through chemical modification of hydroxypropylcellulose (HPC) of M_w = 60000 g mol^?1. The resulting polymer was characterized by infrared spectroscopy, differential scanning calorimetry (DSC) and polarizing microscopy. It was found that thermotropic liquid crystal phases are formed between about 60°C and 110°C. Concentrated solutions of TSUHPC in acetone and N,N-dimethylacetamide exhibit cholesteric behaviour, at room temperature. When approaching the lyotropic mesophase to solid transition, either by cooling or by solvent evaporation, very interesting arborescent structures of a seemingly fractal nature may be observed, depending on the kinetics of the transition. A banded texture can be observed when the polymer is sheared near the transition to the isotropic phase.     

Synthesis and characterization of novel nano size electroactive poly 4,4′‐diaminodiphenyl sulphone

The modification of electrodeposited polyaniline film by subsequent electrodeposition of 4,4′‐diaminodiphenyl sulfone (DDS) leads to a new material having nanostructure. The coated polymer films were treated with various pH solutions. The film adherent characteristics and surface morphology were studied using SEM. The electrochemically synthesized polyDDS revealed good redox behavior. The DDS was also polymerized by the chemical oxidation method using potassium persulphate. The polymer was characterized by UV‐Vis and FTIR spectral studies. The formation of polymer through the N? H group was understood from the single N? H stretching vibrational frequency at 3459 cm^?1. The X‐ray diffraction studies revealed the formation of nano sized (28 nm) crystalline polymer. The conductivity of the polymer was determined to be 1.07 × 10^?4 S.cm^?1. The solubility of the chemically polymerized powder was ascertained, and polyDDS showed good solubility in DMF and DMSO. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1702–1707, 2005