Synthesis and characterization of chelate polymers containing etheric diphenyl ring in the backbone: thermal,optical, electrochemical,and morphological properties

A novel Schiff base, 4‐bromo‐2‐[(2‐[(5‐bromo‐2‐hydroxyphenyl)methylene]amino‐5‐nitrophenyl)iminomethyl]phenol (M1) was synthesized from the reaction of 5‐brom‐salicylaldehyde with 4‐nitro‐o‐phenylenediamine. Schiff base–metal complex was synthesized from the reaction of 4‐bromo‐2‐[(2‐[(5‐bromo‐2‐ hydroxyphenyl)methylene]amino‐5‐nitrophenyl)iminomethyl]phenol (M1) with copper (II) acetate monohydrate [(CH₃COO)₂ Cu · H₂O] salt. Poly‐ (M1‐Cu‐TDP) was synthesized from the reaction of M1‐Cu with 4,4′‐dithiodiphenol (TDP). Poly(M1‐Cu‐PDP) was synthesized from the reaction of M1‐Cu with 4,4′‐propane‐2,2‐diyldiphenol (PDP). Poly(M1‐Cu‐HDP) was synthesized from the reaction of M1‐Cu with 4,4′‐(1,1,1,3,3,3‐hexafluoropropane‐2,2‐di‐yl)diphenol (HDP). The structures of the synthesized monomer and chelate polymers were confirmed by FT‐IR, UV–Vis, ¹H‐ and ¹³C‐NMR, and elemental analysis. The characterization was made by TGA‐DTA, DSC, size exclusion chromatography, cyclic voltammetry, and solubility tests. Also, surface morphologies of chelate polymers were investigated by scanning electron microscope. Copyright © 2009 John Wiley & Sons, Ltd.     

Trace Analysis of Al (III) Ions Based on the Redox Current of a Conducting Polymer

A conducting polymer was electrochemically prepared on a Pt electrode with newly synthesized 3′‐(4‐formyl‐3‐hydroxy‐1‐phenyl)‐5,2′ : 5′,2″‐terthiophene (FHPT) in a 0.1 M TBAP/CH₂Cl₂ solution. The polymer‐modified electrode exhibited a response to proton and metal ions, especially Al(III) ions. The poly[FHPT] was characterized with cyclic voltammetry, EQCM, and applied to the analysis of trace levels of Al(III) ions. Experimental parameters affecting the response of the poly[FHPT] were investigated and optimized. Other metal ions in low concentration did not interfere with the analysis of Al(III) ions in a buffer solution at pH 7.4. The response was linear over the concentration range of 5.0×10^?8–7.0×10^?10 M, and the detection limit was 5.0×10^?10 M using the linear sweep voltammetry (LSV). Employing the differential pulse voltammetry (DPV), the response was linear over the 1.0×10^?9–5.0×10^?11 M range and the detection limit was 3.0×10^?11 M. The relative standard deviation at 5.0×10^?11 M was 7.2% (n=5) in DPV. This analytical method was successfully verified for the analysis of trace amounts of Al(III) ions in a human urine sample.     

Highly Efficient Dye‐Sensitized Solar Cells Based on Panchromatic Ruthenium Sensitizers with Quinolinylbipyridine Anchors

Panchromatic Ru^II sensitizers TF‐30–TF‐33 bearing a new class of 6‐quinolin‐8‐yl‐2,2′‐bipyridine anchor were synthesized and tested under AM1.5 G simulated solar irradiation. Their increased π conjugation relative to that of the traditional 2,2′:6′,2′′‐terpyridine‐based anchor led to a remarkable improvement in absorptivity across the whole UV–Vis–NIR spectral regime. Furthermore, the introduction of a bulky tert‐butyl substituent on the quinolinyl fragment not only led to an increase in the J_SC value owing to the suppression of dye aggregation, but remarkably also resulted in no loss in V_OC in comparison with the reference sensitizer containing a tricarboxyterpyridine anchor. The champion sensitizer in DSC devices was found to be TF‐32 with a performance of J_SC=19.2 mA cm^?2, V_OC=740 mV, FF=0.72, and η=10.19 %. This 6‐quinolin‐8‐yl‐2,2′‐bipyridine anchor thus serves as a prototype for the next generation of Ru^II sensitizers with any tridentate ancillary.     

Structural and physicochemical characterization of zinc(II) and cadmium(II) complexes with 1,4‐dimethy‐lhomopiperazine

In order to know the relationship between structures and physicochemical properties of Group 12 metal(II) ions, the complexes with ‘simple’ ligands, such as alkyl cyclic diamine ligand and halide ions, were synthesized by the reaction of 1,4‐dimethylhomopiperazine (hp′) with MX₂ as metal sources (M = Zn, Cd; X = Cl, Br, I). The five structural types, [ZnX₂(hp′)] (X = Cl ( 1 ), Br ( 2 ) and I ( 3 )), [ZnX₃(Hhp′)] (X = Cl ( 1′ ) and Br ( 2′ )), [CdCl₂(hp′)]_n ( 4 ), [{CdCl₂(Hhp′)}₂(µ‐Cl)₂] ( 4′ ) and [{CdX(hp′)}₂(µ‐X)₂] (X = Br ( 5 ), I ( 6 )), were determined by X‐ray analysis. The sizes of both metal(II) and halide ions and the difference in each other's polarizability influence each structure. All complexes were characterized by IR, far‐IR, Raman and UV–Vis absorption spectroscopies. In the far‐IR and Raman spectra, the typical ν(M N) and ν(M X) peaks clearly depend on the five structural types around 540–410 cm⁻¹ and 350–160 cm⁻¹ respectively. The UV–Vis absorption band energy around 204–250 nm also reflects each structural type. Copyright © 2005 John Wiley & Sons, Ltd.     

Multidentate ligand exchange kinetics: Substitution reaction of polyaminocarboxylatoferrate (III) complex, [FeHPDTA(OH)]2− with 4‐(2‐pyridylazo)resorcinol

The kinetic study of ligand substitution reaction of 2‐hydroxy 1,3‐diamino propane N,N′N′‐tetraacetatoiron(III) ([FeHPDTA(OH)]^2?) complex with 4‐(2‐pyridylazo)resorcinol (Par) has been followed spectrophotometrically at pH = 9.00 ± 0.02, I = 0.1 M (NaClO₄), and temperature = 25.0 ± 0.1°C. The forward and reverse reactions have been studied at 496 nm, the λ_max of [Fe(Par)₂]^? which is identified as the final product of above reaction. The second‐order rate constants for the reaction of [FeHPDTA(OH)]^2? with Par were determined in a wide pH range viz. 8.0–11.5. It is observed from pH dependence of reaction that rate of reaction increases initially with pH and then levels off. In the case of reverse reaction between [Fe(Par)₂]^? and HPDTA^4?, the pseudo‐first‐order rate constant does not change with concentration at extremely low concentration of [HPDTA]^4? and shows zero‐order dependence in [HPDTA]^4?. At relatively higher concentration of [HPDTA]^4?, the order of reaction with respect to [HPDTA]^4? is found to be 1. An inverse first‐order dependence is also observed with respect to added [Par]^2?. The activation parameters were evaluated for forward and reverse reactions, which further supported the proposed mechanistic scheme. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 333–340, 2005     

Polyesters containing sulfur. VII. New aliphatic‐aromatic polyesters for synthesis of polyester‐sulfur compositions and polyurethanes

New linear polyesters containing sulfur in the main chain were obtained by melt polycondensation of diphenylmethane‐4,4′‐bis(methylthioacetic acid) (DBMTAA) or diphenylmethane‐4,4′‐bis(methythiopropionic acid) (DBMTPA) and diphenylmethane‐4,4′‐bis(methylthioethanol) (DBMTE) at equimolar ratio of reagents (polyesters E‐A and E‐P) as well as at 0.15 molar excess of diol (polyesters E‐A_OH and E‐P_OH). The kinetics of these reactions was studied at 150, 160, and 170°C. Reaction rate constants (k₂) and activation parameters (ΔG^≠, ΔH^≠, ΔS^≠) from carboxyl group loss were determined using classical kinetic methods. E‐A and E‐P (M̄_n = 4400, 4600) were used for synthesis of new rubber‐like polyester‐sulfur compositions, by heating with elemental sulfur, whereas oligoesterols E‐A_OH and E‐P_OH (M̄_n = 2500, 2900) were converted to thermoplastic polyurethane elastomers by reaction with hexamethylene diisocyanate (HDI) or methylene bis(4‐phenyl isocyanate) (MDI). The structure of the polymers was determined by elemental analysis, FT‐IR and liquid or solid‐state ¹H‐, ¹³C‐NMR spectroscopy, and X‐ray diffraction analysis. Thermal properties were measured by DTA, TGA, and DSC. Hardness and tensile properties of polyurethanes and polyester‐sulfur compositions were also determined. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 835–848, 1999     

Alkene–Tetrazine Ligation for Imaging Cellular DNA

5‐Vinyl‐2′‐deoxyuridine (VdU) is the first reported metabolic probe for cellular DNA synthesis that can be visualized by using an inverse electron demand Diels–Alder reaction with a fluorescent tetrazine. VdU is incorporated by endogenous enzymes into the genomes of replicating cells, where it exhibits reduced genotoxicity compared to 5‐ethynyl‐2′‐deoxyuridine (EdU). The VdU–tetrazine ligation reaction is rapid (k≈0.02 M ^?1 s^?1) and chemically orthogonal to the alkyne–azide “click” reaction of EdU‐modified DNA. Alkene–tetrazine ligation reactions provide the first alternative to azide–alkyne click reactions for the bioorthogonal chemical labeling of nucleic acids in cells and facilitate time‐resolved, multicolor labeling of DNA synthesis.     

含联吡啶，Eu(III)或Gd(III)的手性高分子配合物的合成及荧光性质研究

手性高分子P–1由(R)-5,5′-二溴-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘(R–M–1)和5,5′-二乙烯基-2,2′-联吡啶(M–2)通过Pd催化的Heck偶合反应合成得到,高分子配合物P-2和P-3由高分子P-1与Eu(TTA)3·2H2O和Gd(TTA)3·2H2O (TTA– = 2-噻吩甲酰三氟丙酮)反应生成。手性高分子P-1能发射强的蓝色荧光,这是由于手性重复单元(R)-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘和单元2,2′-联吡啶通过亚乙烯基桥连形成共轭高分子结构造成的。在不同的激发波长激发下,含Eu(III)的高分子配合物P–2不仅显示高分子荧光,还可显示Eu(III) (5D0→7F2)特征荧光。含Gd(III)的高分子配合物P–3仅发射高分子荧光。基于高分子及含RE(III)的高分子配合物的荧光性质研究发现,共轭高分子并没有把能量转移到Eu(III)或Gd(III) 配合物部分,只发射它自身的荧光,含Eu(III)的高分子配合物P–2发射Eu(III) (5D0→7F2)特征荧光能量主要来源于配阴离子TTA–。     

Graphene Functionalized Graphite Electrode with Diphenylacetylene for Sensitive Electrochemical Determination of Adenosine‐5′‐triphosphate

In this paper a molecular wire modified carbon paste electrode (MW‐CPE) was firstly prepared by mixing graphite powder with diphenylacetylene (DPA). Then a graphene (GR) and chitosan (CTS) composite film was further modified on the surface of MW‐CPE to receive the graphene functionalized electrode (CTS‐GR/MW‐CPE), which was used for the sensitive electrochemical detection of adenosine‐5′‐triphosphate (ATP). The CTS‐GR/MW‐CPE exhibited excellent electrochemical performance and the electrochemical behavior of ATP on the CTS‐GR/MW‐CPE was carefully studied by cyclic voltammetry with an irreversible oxidation peak appearing at 1.369 V (vs. SCE). The electrochemical parameters such as charge transfer coefficient (α) and electrode reaction standard rate constant (k_s) were calculated with the results of 0.53 and 5.28×10^?6 s^?1, respectively. By using differential pulse voltammetry (DPV) as detection technique, the oxidation peak current showed good linear relationship with ATP concentration in the range from 1.0 nM to 700.0 µM with a detection limit of 0.342 nM (3σ). The common coexisting substances, such as uric acid, ascorbic acid and guanosine‐5′‐triphosphate (GTP), showed no interferences and the modified electrode was successfully applied to injection sample detection.     

Nanostructured Base Electrochemical Sensor for Simultaneous Quantification and Voltammetric Studies of Levodopa and Carbidopa in Pharmaceutical Products and Biological Samples

A novel carbon paste electrode modified with carbon nanotubes and 5‐amino‐2′‐ethyl‐biphenyl‐2‐ol (5AEB) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for electrocatalytic oxidation of levodopa (LD) and carbidopa (CD), is described. Cyclic voltammetry (CV) was used to investigate the redox properties of this modified electrode at various scan rates. The apparent charge transfer rate constant, k_s, and transfer coefficient, a, for electron transfer between 5AEB and CPE were calculated as 17.3 s^?1 and 0.5, respectively. Square wave voltammetry (SWV) exhibits a linear dynamic range from 2.5×10^?7 to 2.0×10^?4 M and a detection limit of 9.0×10^?8 M for LD.     

Synthesis and characterization of polythiophene derivatives with nitrogen heterocycles on the side chain

The Grignard metathesis reaction of 2,5‐dibromo‐3‐(5′‐hexylpyridine‐2′‐yl)thiophene ( M1 ) with i‐PrMgCl afforded 5‐bromo‐2‐chloromagnesio‐3‐(5′‐hexylpyridine‐2′‐yl)thiophene ( GM1 ) in the 86% selectivity. The Kumada coupling polymerization by Ni(dppp)Cl₂ gave poly M1 having the roughly controlled molecular weight between 6700 and 23,400. The characterization using the gel permeation chromatographic and matrix‐assisted laser desorption/ionization‐time of flight mass spectra indicated the diffusion of the nickel catalyst from the propagating end. Based on the GC and ¹H NMR spectra, the head‐to‐tail content of poly M1 was calculated to be 89%. The regioselective Grignard metathesis reactions of 5,5′‐dibromo‐4‐(5″‐hexylpyridine‐2″‐yl)‐2,2′‐bithiophene ( M2 ) and 5,5′‐dibromo‐4‐(5″‐hexylpyrimidine‐2″‐yl)‐2,2′‐bithiophene ( M3 ) also occurred at the ortho‐position of the nitrogen heterocycle. The Kumada coupling polymerizations gave poly M2 and poly M3 having the head‐to‐tail content of 75% and 85%, respectively. The UV–vis spectra of polymers suggested that the polymer conformation becomes more planar in the order of poly M1 < poly M3 < poly M2 , which was investigated by the theoretical calculation of the model oligomers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2166–2174     

Development of a Carbon Paste Electrode Modified with Reduced Graphene Oxide and an Imidazole Derivative for Simultaneous Determination of Biological Species of N‐acetyl‐L‐cysteine,Uric Acid and Dopamine

In this work, the modified carbon paste electrode (CPE) with an imidazole derivative 2‐(2,3 dihydroxy phenyl) 4‐methyl benzimidazole (DHPMB) and reduced graphene oxide (RGO) was used as an electrochemical sensor for electrocatalytic oxidation of N‐acetyl‐L‐cysteine (NAC). The electrocatalytic oxidation of N‐acetyl‐L‐cysteine on the modified electrode surface was then investigated, indicating a reduction in oxidative over voltage and an intensive increase in the current of analyte. The scan rate potential, the percentages of DHPMB and RGO, and the pH solution were optimized. Under the optimum conditions, some parameters such as the electron transfer coefficient (α) between electrode and modifier, and the electron transfer rate constant) k_s) in a 0.1 M phosphate buffer solution (pH=7.0) were obtained by cyclic voltammetry method. The diffusion coefficient of species (D) 3.96×10^?5 cm² s^?1 was calculated by chronoamperometeric technique and the Tafel plot was used to calculate α (0.46) for N‐ acetyl‐L‐cysteine. Also, by using differential pulse voltammetric (DPV) technique, two linear dynamic ranges of 2–18 µM and 18–1000 µM with the detection limit of 61.0 nM for N‐acetyl‐L‐cysteine (NAC) were achieved. In the co‐existence system of N‐acetyl‐L‐cysteine (NAC), uric acid (UA) and dopamine (DA), the linear response ranges for NAC, UA, and DA are 6.0–400.0 µM, 5.0–50.0 µM and 2.0–20.0 µM, respectively and the detection limits based on (C=3s_b/m) are 0.067 µM, 0.246 µM and 0.136 µM, respectively. The obtained results indicated that DHPMB/RGO/CPE is applicable to separate NAC, uric acid (UA) and dopamine (DA) oxidative peaks, simultaneously. For analytic performance, the mentioned modified electrode was used for determination of NAC in the drug samples with acceptable results, and the simultaneous determination of NAC, UA and DA oxidative peaks was investigated in the serum solutions, too.     

3D Cadmium(II)‐Based Coordination Polymer Constructed from V‐Shaped Semirigid Ligand: Selective Detection of Oxoanion Pollutants CrO42–, Cr2O72–, MnO4– in Water

A new coordination polymer (CP), namely, [Cd(HL)(4,4′‐bipy)] ( 1 ) (H₃L = 4‐(5‐carboxy‐pyridine‐3‐yloxy)‐phthalic acid, 4,4′‐bipy = 4,4′‐bipyridine), was synthesized employing a V‐shaped asymmetric tricarboxylic acid ligand under hydrothermal condition. Single‐crystal X‐ray diffraction analysis indicates that compound 1 exhibits a novel three‐dimensional (3D) framework with (3, 5)‐connected (6³)(6⁹ · 8) topology. Meanwhile, it shows high selectivity and sensitivity for oxoanion pollutants CrO₄^2–, Cr₂O₇^2–, and MnO₄^– anions in aqueous solutions with detection limits of 4.12 × 10^–6 M, 1.75 × 10^–6 M, and 6.47 × 10^–7 M, respectively. The high selectivity and low detection limit indicate that the compound is promising functional luminescence probe for CrO₄^2–, Cr₂O₇^2–, and MnO₄^–. The mechanisms of the quenching effect and sensing properties were discussed in detail.     

Nanomolar Determination of Methyldopa in the Presence of Large Amounts of Hydrochlorothiazide Using a Carbon Paste Electrode Modified with Graphene Oxide Nanosheets and 3‐(4′‐Amino‐3′‐hydroxy‐biphenyl‐4‐yl)‐acrylic Acid

A novel electrochemical sensor for sensitive detection of methyldopa at physiological pH was developed by the bulk modification of carbon paste electrode (CPE) with graphene oxide nanosheets and 3‐(4′‐amino‐3′‐hydroxy‐biphenyl‐4‐yl)‐acrylic acid (3,′AA). Applying square wave voltammetry (SWV), in phosphate buffer solution (PBS) of pH 7.0, the oxidation current increased linearly with two concentration intervals of methyldopa, one is 1.0×10^?8–1.0×10^?6 M and the other is 1.0×10^?6–4.5×10^?5 M. The detection limit (3σ) obtained by SWV was 9.0 nM. The modified electrode was successfully applied for simultaneous determination of methyldopa and hydrochlorothiazide. Finally, the proposed method was applied to the determination of methyldopa and hydrochlorothiazide in some real samples.     

Regeneration of the Oxidation Catalysts Based on the Aqueous Solutions of Non‐Keggin Mo‐V‐P Heteropoly Acids by Molecular Oxygen

Kinetic peculiarities of regeneration of the aqueous solutions of non‐Keggin‐type Mo‐V‐P heteropoly acids H_aP_zMo_yV_x′O_b (HPA‐x′) and their acidic salts by O₂ are studied. The HPA‐x′ solutions have heightened thermal stability that permits to consider them as highly efficient catalysts for different oxidation processes. In the HPA‐x′ and their salts solutions, these peculiarities prove to be similar. The studied reaction is of the first order with respect to O₂ and V(IV), if [V(IV)] is higher than 0.8 M. As [V(IV)] decreases during the reaction, its order with respect to V(IV) increases to the third. The apparent activation energy of the reaction at temperatures 150–170°С is 37.5 kJ mol^?1. The obtained kinetic equation was used to calculate a new effective air reactor for the regeneration of the homogeneous HPA‐x′ catalyst in a pilot process of methylethylketone synthesis.     

Polymer‐based fluorescence sensors incorporating chiral binaphthyl and benzo[2,1,3]thiadiazole moieties for Hg2+ detection

Three chiral polymers P‐1 , P‐2 , and P‐3 could be obtained by the polymerization of (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2, 2′‐binaphthol (R‐M‐1) , (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2,2′‐bisoctoxy‐1,1′‐binaphthyl ( R‐M‐2 ), and (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2,2′‐bis (diethylaminoethoxy)‐1,1′‐binaphthyl ( R‐M‐3 ) with 4,7‐diethynyl‐benzo[2,1,3]‐thiadiazole ( M‐1) via Pd‐catalyzed Sonogashira reaction, respectively. P‐1 , P‐2 , and P‐3 can show pale red, blue–green, and orange fluorescence. The responsive optical properties of these polymers on various metal ions were investigated by fluorescence spectra. Compared with other cations, such as Co²⁺, Ni²⁺, Ag⁺, Cd²⁺, Cu²⁺, and Zn²⁺, Hg²⁺ can exhibit the most pronounced fluorescence response of these polymers. P‐1 and P‐2 show obvious fluorescence quenching effect upon addition of Hg²⁺, on the contrary, P‐3 shows fluorescence enhancement. Three polymer‐based fluorescent sensors also show excellent fluorescence response for Hg²⁺ detection without interference from other metal ions. The results indicate that these kinds of tunable chiral polybinaphthyls can be used as fluorescence sensors for Hg²⁺ detection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 997–1006, 2010     

A Series of Transition Metal Coordination Polymers Bearing 1,4‐Phenylenediacetate

The reactions of transition metal salts or hydroxide with 1,4‐phenylenediacetic acid (H₂PDA) in the presence of ancillary ligands 4,4′‐bipyridine (4,4′‐bpy) or imidazole (Im) produced five coordination polymers with the empirical formula [M(PDA)(4,4′‐bpy)(H₂O)₂]_n [M = Mn ( 1 ), Ni ( 2 )], [Cu(PDA)(4,4′‐bpy)]_n · 2nH₂O ( 3 ), [Ni(PDA)(Im)₂(H₂O)₂]_n · nH₂O ( 4 ), and [Cu(PDA)(Im)₂]_n · 2nH₂O ( 5 ). Their structures were determined by single‐crystal X‐ray diffraction analyses. The isomorphous 1 and 2 present a two‐dimensional sheet constructed by two kinds of one‐dimensional chains of –Ni^II–PDA^2––Ni^II– and –Ni^II–4,4′‐bpy–Ni^II–. Compound 3 features dinuclear subunits, which are further connected by two PDA^2– ligands and two 4,4′‐bpy ligands along (001) and (011) directions, respectively, to build a two‐dimensional sheet with the topology (4².6⁷.8)(4².6) different from those of 1 and 2 . Both 4 and 5 show one‐dimensional chain structure. The difference of compound 4 and 5 is that the two carboxylato groups of PDA^2– in 4 adopt monodentate coordination modes, whereas the two carboxylato groups of PDA^2– in 5 chelate to the metal ions. Magnetic susceptibility data of 1 were measured. Magnetically, 1 presents a one‐dimensional chain with a weak antiferromagnetic interaction (J =–0.064 cm^–1) between the intrachain Mn^II atoms mediated by 4,4′‐bpy.     

Comparative Study of Lead(II) Selective Poly(vinyl chloride) Membrane Electrodes Based on Podand Derivatives as Ionophores

The two podand chelates based on diethylsulfide, 1,5‐bis(2′‐hydroxy‐4′‐nitrophenoxy)‐3‐thiapentane (L₁) and 1,5‐bis(8′‐oxybenzopyridine)‐3‐thia pentane (L₂), have been synthesized and explored as neutral ionophores for preparing poly(vinyl chloride) based membrane electrodes selective to Pb²⁺. The addition of anionic additives and various plasticizers has been found to substantially improve the performance of the electrode. The best performance was obtained with the electrode No. 1 having a membrane of ionophore (L₁) with the composition PVC:o‐NPOE:ionophore (L₁):NaTFPB (%w/w) of 33 : 62 : 3 : 2. The electrode exhibits Nernstian response with a slope of 31.57±0.3 mV decade^?1 of activity in the concentration range from 2.0×10^?9 to 1.0×10^?1 M Pb²⁺, performs satisfactorily over a wide pH range (1.6–7.0), with a fast response time (5 s).     

Direct Electrochemistry of Glucose Oxidase Immobilized on Titanium Carbide‐Au Nanoparticles‐Fullerene C60 Composite Film and Its Biosensing for Glucose

The direct electrochemistry of glucose oxidase (GOD) immobilized on the designed titanium carbide‐Au nanoparticles‐fullerene C₆₀ composite film modified glassy carbon electrode (TiC‐AuNPs‐C₆₀/GCE) and its biosensing for glucose were investigated. UV‐visible and Fourier‐transform infrared spectra of the resulting GOD/TiC‐AuNPs‐C₆₀ composite film suggested that the immobilized GOD retained its original structure. The direct electron transfer behaviors of immobilized GOD at the GOD/TiC‐AuNPs‐C₆₀/GCE were investigated by cyclic voltammetry in which a pair of well‐defined, quasi‐reversible redox peaks with the formal potential (E^0′) of ‐0.484 V (vs. SCE) in phosphate buffer solution (0.05 M, pH 7.0) at the scan rate of 100 mV·s^?1 were obtained. The proposed GOD modified electrode exhibited an excellent electrocatalytic activity to the reduction of glucose, and the currents of glucose reduction peak were linearly related to glucose concentration in a wider linearity range from 5.0 × 10^?6 to 1.6 × 10^?4 M with a correlation coefficient of 0.9965 and a detection limit of 2.0 × 10^?6 M (S/N = 3). The sensitivity and the apparent Michaelis‐Menten constant (K_M^app) were determined to be 149.3 μA·mM^?1·cm^?2 and 6.2 × 10^?5 M, respectively. Thus, the protocol will have potential application in studying the electron transfer of enzyme and the design of novel electrochemical biosensors.     

Sensitive amperometric pyridoxine sensor based on self‐assembled Prussian blue nanoparticle‐modified poly(o‐phenylenediamine)/glassy carbon electrode

Prussian blue nanoparticles (PBNPs) were prepared by a self‐assembly process on a glassy carbon electrode (GCE) modified with poly(o‐phenylenediamine) (PoPD) film. The stepwise fabrication process of PBNP‐modified PoPD/GCE was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The prepared PBNPs showed an average size of 70 nm and a homogeneous distribution on the surface of the modified electrode. The PBNPs/PoPD/GCE showed electrocatalytic activity towards the oxidation of pyridoxine (PN) and was used as an amperometric sensor. The modified electrode exhibited a linear response for PN oxidation over the concentration range 3–38.5 μM with a detection limit of ca 6.10 × 10^?7 M (S/N = 3) and sensitivity of 2.79936 × 10³ mA M^?1 cm^?2 using an amperometric method. The mechanism and kinetics of the catalytic oxidation reaction of PN were investigated using cyclic voltammetry and chronoamperometry. The values of α, k_cat and D were estimated as 0.36, 1.089 × 10² M^?1 s^?1 and 8.9 × 10^?5 cm² s^?1, respectively. This sensor also exhibited good anti‐interference and selectivity. Copyright © 2016 John Wiley & Sons, Ltd.