Solid Substrate Room Temperature Phosphorimetry for the Determination of Trace Mercury Based on the Reaction between Alkaline Phosphatase and Mercury Using Triton X-100 as a Sensitizer

A new solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace mercury has been established, using Triton X‐100 as a sensitizer. The regression equation of working curve was ΔI_p=11.40m(Hg²⁺)+1.569 (ag·spot^?1, n=6, ΔI_p=I_p1?I_p2, I_p1 and I_p2 referred to the phosphorescence intensity of the blank reagent and the test solution, respectively), and correlation coefficient (r) was 0.9984. The RSD valus of the determination of 0.016 and 8.0 ag·spot^?1 Hg²⁺ were 4.1% and 1.7% (n=8), respectively, indicating that the method had good repeatability. The limit of detection (LOD) calculated by 3Sb/k was 7.0 zg·spot^?1 Hg²⁺ (corresponding concentration: 1.8×10^?17 g·mL^?1, Sb=0.025, n=11). This method has high sensitivity, selectivity and precision, which was applied to determination of trace mercury in water samples with the result being agreed very well with that of dithizone extraction spectrophotometry.     

№Determination of Trace Arsenic by Solid Substrate-Room Temperature Phosphorescence Quenching Method Based on the Catalyzed Reaction of H2O2 Oxidizing 9-Hyd roxy-2,3,4,9-tet rahyd ro-1,10-anth raquinone

A new solid substrate-room temperature phosphorescence （SS-RTP） quenching method for the determination of trace As（V） has been developed, based on the facts that 9-hydroxy-2,3,4,9-tetrahydro-1,10-anthraquinone （R） can emit intense and stable SS-RTP on solid substrate, and α,α＇-dipyridyl can activate As（V） catalysis of the reaction of H2O2 oxidizing R to non-phosphorescence compound R＇, which can cause the sharp quenching of SS-RTP. Under the optimum condition, the relationship between the ΔIp of the emitting intensity and 1.60-160 fg·spot^-1 As（V） （corresponding concentration： 0.0040-0.40 ng·mL^-1, sample volume： 0.4 μL·spot^-1） conformed to Beer＇ law. The regression equation of working curve can be expressed as ΔIp= 20.46＋0.5492CAs（v） fig·spot^-1） （r= 0.9995, n = 6）. The limit detection （LD） is 0.27 fg·spot^-1 [As（V） corresponding concentration： 6.8 × 10^-13 g·mL^-1, n=11]. The samples containing 0.0040 and 0.40 ng·mL^-1 As（V） were repeatedly determined for 11 times. RSD are 3.0% and 2.7% respectively. The SS-RTP mechanism was also discussed. R was synthesized in this paper. Meanwhile, the structure was determined by NMR, IR, mass spectra and elemental analysis.     

A New Fluorescein Isothiocyanate-Piperidine Self-ordered Ring Phosphorescent Probe for the Determination of Trace Protein

The ? COOH in fluorescein isothiocyanate (FITC) reacted with ? NH? in piperidine (P) to form FITC‐P on the center of indentation of polyamide membrane (PAM) when drying for 2 min at (92±1)°C. Then, the FITC‐P diffused outward from the indentation center and formed the round SOR‐P‐FITC (containing the FITC‐P self‐ordered rings). Thus, multi‐FITC accumulated on SOR‐P‐FITC, leading to the enhancement of RTP signal on bio‐target, whose I_p increased 2.0 times compared with non‐generated SOR. When bovine serum albumin (BSA) was added to the center of SOR‐P‐FITC, ? NCS of FITC in SOR‐P‐FITC reacted with ? NH₂ of BSA to form SOR‐P‐FITC‐BSA, which caused the RTP signal of FITC to enhance sharply. The ΔI_p of the system was 3.4 times higher than that without β‐CD and 4.0 times higher than that without SOR‐P‐FITC formed. Its ΔI_p was linear to the content of BSA. Therefore, a new solid substrate‐room temperature phosphorimetry (SS‐RTP) for the determination of trace protein was established using SOR‐P‐FITC as a phosphorescent probe. Under the optimum condition, the linear range of this method was 0.040–16.0 ag·spot^?1 with a detection limit (LD) of 8.5 zg·spot^?1 (0.40 µL sample solution per spot, the corresponding concentration was 2.1×10^?17 g·mL^?1), and the regression equation of working curve was ΔI_p=3.848+4.240m_BSA (ag·spot^‐1), n=6, correlation coefficient (r) was 0.9993. This method with high sensitivity had been applied to determining the content of trace protein in the water samples, and the results coincided well with those obtained with pyrocatechol violet‐Mo(VI) method (P.V.M.M.). At the same time, the mechanism of SS‐RTP using SOR‐P‐FITC as a phosphorescent probe (SOR‐P‐FITC‐SS‐RTP) was discussed.     

Catalytic solid substrate-room temperature phosphorimetry for the determination of trace As(V) based on oxidising reaction between hydrogen peroxide and fullerenol using tween-80 as sensitizer

A new catalytic solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace arsenic(V) has been established. It is based on the fact that fullerenol (F-ol) emitted strong and stable room temperature phosphorescence (RTP) on nitric acid cellulose membrane (NCM) substrate. H₂O₂ could oxidise F-ol to cause the quenching of RTP. As(V) could catalyse H₂O₂ to oxidise F-ol and decrease the RTP signal of F-ol sharply. After adding tween-80 in the system, its ΔI _p enhanced 7.7 times compared with the without-tween-80 levels. Under the optimum conditions, the linear dynamic range of this method was 0.016?11.2 ag spot^?1 with a detection limit (LD) of 9.3 zg spot^?1 (corresponding concentration: 2.3 × 10^?17 g mL^?1). This sensitive, simple and selective method has been successfully applied to the determination of trace As(V) in human hair and tea samples. The reaction mechanism for SS-RTP is also discussed.     

Determination of Glucose by Affinity Adsorption Solid Substrate‐room Temperature Phosphorimetry Based on Triticum Vulgare Lectin Labeled with Silicon Dioxide Nanoparticle Containing Fluorescein Isothiocyanate

In the presence of heavy atom perturber Pb2＋, silicon dioxide nanoparticle containing fluorescein isothiocyanate (FITC-SiO2) could emit a strong and stable room temperature phosphorescence (RTP) signal on the surface of acetyl cellulose membrane (ACM). It was found in the research that a quantitative specific affinity adsorption (AA) reaction between triticum vulgare lectin (WGA) labeled with luminescent nanoparticle and glucose (G) could be carried on the surface of ACM. The product (WGA-G-WGA-FITC-SiO2) of the reaction could emit a stronger RTP signal, and the ΔIp had linear correlation to the content of G. According to the facts above, a new method to determine G by affinity adsorption solid substrate room temperature phosphorimetry (AA-SS-RTP) was established, based on WGA labeled with FITC-SiO2. The detection limit (LD) of this method calculated by 3Sb/k was 0.47 pg•spot－1 (corresponding to a concentration value 1.2×10－9 g•mL－1, namely 5.3×10－9 mol•L－1), the sensitivity was high. Meanwhile, the mechanism for the determination of G by AA-SS-RTP was discussed.     

A New 4.0-Generation Dendrimer Phosphorescence Labeling Reagent and Its Application to Determination of Trace Alkaline Phosphatase by Affinity Adsorption Solid Substrate-room Temperature Phosphorimetry

A Triton X-100-4.0G-D （4.0G-D refers to a 4.0-generation dendrimer） was brought forward as a new phosphorescence labeling reagent. Two types of specific affinity adsorption （AA） reactions （direct method and sandwich method） were carried out between the labeling product of Triton X-100-4：0G-D-Wheat germ agglutinin （WGA） and alkaline phosphatase （ALP）, the product of AA reaction preserved the good characteristics of room temperature phosphorescence （RTP） of 4.0G-D and △Ip of the product was proportional to the content of ALP. According to the fact stated above, a new method for the determination of trace ALP by affinity adsorption solid substrate-room temperature phosphorimetry （AA-SS-RTP） was established on the basis of WGA labeled with the Triton X-100-4.0G-D. The detection limits were 0.20 ag·spot^-1 （corresponding concentration： 5.0×10^-16 g·mL^-1, namely 5.0×10^-18 mol·L^-1） for a direct method and 0.14 ag·spot^-1 （corresponding concentration： 3.5×10^-16 g·mL^-1, namely 3.5×10^-18 mol·L^-1） for a sandwich method, respectively. For their high sensitivity, good repeatability and high accuracy, the direct method and sandwich method have been successfully appfied to determine the content of ALP in human serum, and the results were coincided with the clinical detection results of the enzyme-linked immunosorbent assay method by the Zhangzhou Hospital of Traditional Chinese Medicine. Meanwhile, the mechanism for the determination of trace ALP by AA-SS-RTP was discussed.     

Affinity Adsorption Solid Substrate‐Room Temperature Phosphorimetry for the Determination of Alkaline Phosphatase

Abstract

In the presence of Pb(Ac)₂, the silicon dioxide nanoparticle containing rhodamine 6G (R‐SiO₂) can emit strong and stable solid substrate‐room temperature phosphorescence (SS‐RTP) signal on the surface of acetyl cellulose membrane (ACM) at λ_ex/λ_em=482/649 nm. It was found in the research that specific affinity adsorption reaction between triticum vulgare lectin (WGA) (which was labeled with luminescent silicon dioxide nanoparticle) and alkaline phosphatase (AP) can be carried out on the surface of ACM. The product of the reaction can emit stronger SS‐RTP signal. A new method of SS‐RTP for the determination of AP was established, based on an affinity adsorption reaction between AP and WGA labeled with nanoparticles containing rhodanime 6G luminescent molecules. The linear range of this WGA‐AP‐WGA‐R‐SiO₂ method is 1.00–360.00 ag AP spot^?1 (sample volume: 0.40 µL spot^?1, corresponding concentration range: 2.50–900.00 fg mL^?1). The regression equation of working curve is ΔIp=16.24+0.8856 m_AP (ag spot^?1), r=0.9993. Detection limit of this method calculated by 3S_b/k is 0.14 ag spot^?1. After 11‐fold replicate measurements, RSD are 3.9% and 3.1% for the systems containing 1.00 and 360.00 ag AP spot^?1, respectively. Compared with R‐SiO₂‐WGA‐AP method (detection limit: 0.45 ag spot^?1, corresponding concentration range: 2.00–320.00 ag spot^?1), the sensitivity of WGA‐AP‐WGA‐R‐SiO₂ method was obviously improved and the linear range was wider. The sensitivity, accuracy, and precision of this method are high. It has been successfully applied to determine AP in human serum.     

Solid substrate-room temperature phosphorimetry for the determination of residual clenbuterol hydrochloride based on the catalysis of sodium periodate oxidizing eosine Y

Clenbuterol hydrochloride (CLB) could catalyze NaIO₄ oxidation of eosine Y (R), which caused the room temperature phosphorescence (RTP) signal of R to quench sharply. The ΔI_P (=I_P2 − I_P1, I_P2 was RTP intensities of reagent blank and I_P1 was RTP intensities of test solution) of the system was directly proportional to the content of CLB. According to that academic thought, a new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace CLB has been established. This method has high sensitivity (detection limit (LD): 0.021 zg spot⁻¹, corresponding concentration: 5.2 × 10⁻²⁰ g mL⁻¹) and good selectivity (Er = ±5%, interfering species were of no interference). It has been applied to the determination of residual CLB in the practical samples. The results were verified using HPLC and GC/MS methods. The reaction mechanism of catalytic SS-RTP for the determination of residual CLB was also discussed.     

An insight into the disorder properties of the α-cyclodextrin polyiodide inclusion complex with Sr2+ ion: dielectric,DSC and FT-Raman spectroscopy studies

At T < 250 K, the polyiodide inclusion complex (α-cyclodextrin)₂·Sr_0.5·I₅·17H₂O displays two separate relaxation processes due to both the frozen-in proton motions in an otherwise ordered H-bonding network and the order–disorder transition of some normal H-bonds to flip-flop ones. At T>250 K, the AC-conductivity is dominated by the combinational contributions of the disordered water network, the mobile Sr²⁺ ions, the polyiodide charge-transfer interactions and the dehydration process. The evolution of the Raman spectroscopic data with temperature reveals the coexistence of four discrete pentaiodide forms. In form (I) (I^?  ₃·I₂ ? I₂·I^?  ₃), the occupancy ratio (x/y) of the central I^?  ion differs from 50/50. In form (IIa) (I₂·I^? ·I₂) x/y = 50/50, whereas in its equivalent form (IIb) (I₂·I^? ·I₂) ^* as well as in form (III) (I^?  ₃·I₂), x/y = 100/0 (indicative of full occupancy). Through slow cooling and heating, the inverse transformations (I) → (IIa) and (IIa) → (I) occur, respectively.

     

Synthesis of Novel Anionic Receptors with （Thio）urea and Amide Binding Sites and the Recognition Properties for Anions

IntroductionSincemoreandmoreanionsplayanimportantroleinbiologicalandchemicalprocesses ,thedesignandsynthe sisofreceptorsforon lineandrealtimedetectionofbio logicallyimportantanions ,andforenvironmentalmonitor ingofharmfulanionpollutantshaveattractedparticularat tentioninsupramolecularchemistry .1Thebasicstrategyfortheconstructionofanion bindingreceptorsistoexploitthereceptorsthathaveelectrostatic ,2 hydrogenbonding ,3orLewisacidiccentralinteraction .4 Amongavarietyofnon covalentinteractions ,h…     

Formation and Crystal Structure of the Salt (IC(PPh3)2)2I[I3]·(I2)2 with a new Polyiodide Chain

The reaction of the carbodiphosphorane Ph₃P=C=PPh₃ ( 1 ) with MeI in the presence of iodine gives the oxidation product (IC(PPh₃)₂)₂I[I₃]·(I₂)₂ ( 2 ). In the solid state dimeric units linked by indefinite ···I^?···I₂···I₃^?···I₂···I^?··· chains are found. An additional I···I contact between the cation and the I₂ molecule is formed, amounting to 359.23(5) pm. 2 crystallizes in the monoclinic space group P2/c, with the unit cell dimensions a = 2053.9(1), b = 1011.4(1), c = 1889.8(1) pm; β = 105.21(1)° and Z = 4.     

Determination of Trace Copper by Fluorescence Spectrophotometry Based on Cu(DP)2+ and Cu‐4.0‐Generations Polyamidoamine Dendrimers Catalyze Cu2+ to Oxidize Fluorescein

Abstract

Fluorescein can emit strong and stable fluorescence. Cu²⁺ can oxidize fluorescein, which causes the fluorescence signal to diminish. Cu(DP)²⁺ (DP refers to α,α′‐dipyridyl) and Cu‐GPD‐4.0 (GPD‐4.0 refers to 4.0‐generations polyamidoamine dendrimers) both can catalyze Cu²⁺ to oxidize fluorescein, which causes the fluorescence signal to diminish sharply. The ΔF is directly proportional to the content of copper. Based on the facts above, a new catalytic fluorescence spectrophotometry for the determination of trace copper using Cu(DP)²⁺ and Cu‐GPD‐4.0 was established. The linear range of this method is 0.040–28 pg mL^?1. The regression equation for working curve is ΔF=209.5+14.39 C_Cu ²⁺ (pg mL^?1), n=7; correlation coefficient is 0.991. The detection limit of this method is 1.0×10^?14 g mL^?1. After replicate measurement times, RSDs are 3.1% and 4.2% for samples containing 0.040 and 28 pg mL^?1 Cu²⁺, respectively. This method is rapid and precise with high sensitivity and good repeatability. The method has been applied to the determination of trace copper in tea and human hair with satisfactory results. Meanwhile, the mechanism for the determination of trace copper by catalytic fluorescence spectrophotometry using Cu(DP)²⁺ and Cu‐GPD‐4.0 was also discussed.     

The structure of di-μ-chloro- bis - {chloro( N,N -diethylethane-1,2-diamine-κ 2)copper(II)}

Dichloro(N,N-diethyl-ethane-1,2-diamine)copper(II) has copper(II) ions in square pyramidal coordination. The two nitrogen atoms of the diamine {Cu–N_primary?=?1.979(3), Cu–N_tertiary?=?2.108(2)?Å} and two chloride ions are in the basal plane {Cu–Cl1?=?2.2680(9), Cu–Cl2?=?2.2989(8)?Å}. A centrosymmetrical dimer di-μ-chloro-bis{chloro(N,N-diethylethane-1,2-diamine-κ²)copper(II)}, C₆H1₆Cl₂CuN₂, is formed by axial coordination by Cl2, trans to the tertiary nitrogen, to a second copper(II) ion, with Cu?···?Cuⁱ?=?3.4855(9) and Cl2–Cuⁱ?=?2.7860(8)?Å. The dimer is also linked by H-bond N1–H?···?Cl1ⁱ.     

Syntheses and structural determinations of the nine-coordinate rare earth metal: Na4[DyIII(dtpa)(H2O)]2·16H2O,Na[DyIII(edta)(H2O)3]·3.25H2O and Na3[DyIII(nta)2(H2O)]·5.5H2O

Three complexes, Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and Na₃[Dy^III (nta)₂(H₂O)]?·?5.5H₂O, have been synthesized in aqueous solution and characterized by FT–IR, elemental analyses, TG–DTA and single-crystal X-ray diffraction. Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O crystallizes in the monoclinic system with P2₁/n space group, a?=?18.158(10)?Å, b?=?14.968(9)?Å, c?=?20.769(12)?Å, β?=?108.552(9)°, V?=?5351(5)?ų, Z?=?4, M?=?1517.87?g?mol^?1, D _c?=?1.879?g?cm^?3, μ?=?2.914?mm^?1, F(000)?=?3032, and its structure is refined to R ₁(F)?=?0.0500 for 9384 observed reflections [I?>?2σ(I)]. Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O crystallizes in the orthorhombic system with Fdd2 space group, a?=?19.338(7)?Å, b?=?35.378(13)?Å, c?=?12.137(5)?Å, β?=?90°, V?=?8303(5)?ų, Z?=?16, M?=?586.31?g?mol^?1, D _c?=?1.876?g?cm^?3, μ?=?3.690?mm^?1, F(000)?=?4632, and its structure is refined to R ₁(F)?=?0.0307 for 4027 observed reflections [I?>?2σ(I)]. Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O crystallizes in the orthorhombic system with Pccn space group, a?=?15.964(12)?Å, b?=?19.665(15)?Å, c?=?14.552(11)?Å, β?=?90°, V?=?4568(6)?ų, Z?=?8, M?=?724.81?g?mol^?1, D _c?=?2.102?g?cm^?3, μ?=?3.422?mm^?1, F(000)?=?2848, and its structure is refined to R ₁(F)?=?0.0449 for 4033 observed reflections [I?>?2?σ(I)]. The coordination polyhedra are tricapped trigonal prism for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O and Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O, but monocapped square antiprism for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O. The crystal structures of these three complexes are completely different from one another. The three-dimensional geometries of three polymers are 3-D layer-shaped structure for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, 1-D zigzag type structure for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and a 2-D parallelogram for Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O. According to thermal analyses, the collapsing temperatures are 356°C for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, 371°C for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and 387°C for Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O, which indicates that their crystal structures are very stable.     

Highly Selective Salicylate Membrane Electrode Based on N,N＇- （Aminoethyl）ethylenediamide Bis（2-salicylideneimine） Binuclear Copper（Ⅱ） Complex as Neutral Carrier

A new ion selective electrode for salicylate based on N,N＇-（aminoethyl）ethylenediamide bis（2-salicylideneimine） binuclear copper（Ⅱ） complex [Cu（Ⅱ）2-AEBS] as an ionophore was developed. The electrode has a linear range from 1.0 × 10^-1 to 5.0 ×10^-7 mol·L^- 1 with a near-Nemstian slope of （ - 55 ±1 ） mV/decade and a detection limit of 2.0 × 10-7 mol·L^-1 in phosphorate buffer solution of pH 5.0 at 25 ℃. It shows good selectivity for Sal^- and displays anti-Hofmeister selectivity sequence： Sal^-〉SCN^-〉 ClO4^- 〉I^-〉 NO2^- 〉Br^-〉 NO3^- 〉Cl^-〉 SO3^2- 〉 SO4^2- The proposed sensor based on binuclear copper（Ⅱ）complex has a fast response time of 5-10 s and can be used for at least 2 months without any major deviation. The response mechanism is discussed in view of the alternating current （AC） impedance technique and the UV-vis spectroscopy technique. The effect of the electrode membrane compositions and the experimental conditions were studied. The electrode has been successfully used for the determination of salicylate ion in drug pharmaceutical preparations.     

Crystal Structure of Tetrakis (phenacetin) Dihydrogentetraiodide Dihydrate {[H5C2OC6H4N (H)C(CH3)O]4·H2I4·2H2O}

(Phenacetin)₄·₂I₄·2H₂O is triclinic, a = 13.641 (7), b = 12.807 (6), c = 7.201 (3) Å, α = 99.8 (4), b? = 86.5 (4), γ = 104.0 (5)°, P1 , Z = 1. The ordered crystal structure has been refined to R_F = 0.050, using 4173 independent reflections measured on a four-circle diffractometer with MoKa (graphite monochromator) radiation. The crystals are composed of alternating positively and negatively charged slices; each positive slice contains a double layer of stacks of hemi-protonated phenacetin molecules which are H-bonded through their carbonyl groups (d(O - - - O) = 2.432 (4) Å) while each negative slice contains a single layer of I^2?₄-ions linked in chains along [100] through H-bonds to pairs of water molecules. The axes of the phenacetin stacks are parallel to the planes of the (I^2?₄·2H₂O)-layers. The I^2?₄-ion is centro-symmetric and can be approximately represented as I^?- - - I–I- - - I^? (d(I^? - - - I) = 3.404 (1) Å; d(I–I) = 2.774 (1) Å). The compound is a pseudo-type A basic salt.     

Equilibrium,kinetics, and mechanism of the malonic acid–iodine reaction

The equilibrium constant for the reaction CH₂(COOH)₂ + I₃^? ? CHI(COOH)₂ + 2I^? + H⁺, measured spectrophotometrically at 25°C and ionic strength 1.00M (NaClO₄), is (2.79 ± 0.48) × 10^?4M². Stopped-flow kinetic measurements at 25°C and ionic strength 1.00M with [H⁺] = (2.09-95.0) × 10^?3M and [I^?] = (1.23-26.1) × 10^?3M indicate that the rate of the forward reaction is given by (k₁[I₂] + k₃[I₃^?]) [HOOCCH₂COO^?] + (k₂[I₂] + k₄[I₃^?]) [CH(COOH)₂] + k₅[H⁺] [I₃^?] [CH₂(COOH)₂]. The values of the rate constants k₁-k₅ are (1.21 ± 0.31) × 10², (2.41 ± 0.15) × 10¹, (1.16 ± 0.33) × 10¹, (8.7 ± 4.5) × 10^?1M^?1·sec^?1, and (3.20 ± 0.56) × 10¹M^?2·sec^?1, respectively. The rate of enolization of malonic acid, measured by the bromine scavenging technique, is given by k_en[CH₂(COOH)₂], with k_en = 2.0 × 10^?3 + 1.0 × 10^?2 [CH₂(COOH)₂]. An intramolecular mechanism, featuring a six-member cyclic transition state, is postulated to account for the results on the enolization of malonic acid. The reactions of the enol, enolate ion, and protonated enol with iodine and/or triodide ion are proposed to account for the various rate terms.     

Preparation, Electrochemical Behavior and Electrocatalytic Activity of a Copper Hexacyanoferrate Modified Ceramic Carbon Electrode

A copper hexacyanoferrate modified ceramic carbon electrode （CuHCF/CCE） had been prepared by two-step sol-gel technique and characterized using electrochemical methods. The resulting modified electrode showed a pair of well-defined surface waves in the potential range of 0.40 to 1.0 V with the formal potential of 0.682 V （vs. SCE） in 0.050 mol·dm^-3 HOAc-NaOAc buffer containing 0.30 mol·dm^-3 KCl. The charge transfer coefficient （a） and charge transfer rate constant （ks） for the modified electrode were calculated. The electrocatalytic activity of this modified electrode to hydrazine was also investigated, and chronoamperometry was exploited to conveniently determine the diffusion coefficient （D） of hydrazine in solution and the catalytic rate constant （kcat）. Finally, hydrazine was determined with amperometry using the resulting modified electrode. The calibration plot for hydrazine determination was linear in 3.0 × 10^-6--7.5 × 10^-4 mol·dm^-3 with the detection limit of 8.0 × 10^-7 molodm^-3. This modified electrode had some advantages over the modified film electrodes constructed by the conventional methods, such as renewable surface, good long-term stability, excellent catalytic activity and short response time to hydrazine.     

A 3D interpenetrating supramolecular compound based on Cu ··· N weak coordination: synthesis,crystal structure and DFT investigation

A metal-organic hybrid compound, Cu[(pyc)₂(4,4′-bipy)] ·?H₂O (pyc =?pyridine-2-carboxylate, 4,4′-bipy =?4,4′-bipyridine), has been hydrothermally synthesized and characterized by X-ray determination, IR and elemental analysis. The compound crystallizes in tetragonal, space group I4₁/acd with a =?24.797(2) Å, b =?24.797(2) Å, c =?14.811(2) Å, β =?90°, V =?9106.7(18) ų, C₂₂ H₁₈N₄O₅Cu, Mr =?481.94, Dc =?1.406 g cm^?3, μ(Mo-Kα) =?0.999 mm^?3, F(000) =?3952, Z =?16, the final R =?0.0712 and wR =?0.1886 for 21727 observed reflections (I >?2σ). Compound 1 exhibits a three-dimensional interpenetrating network induced by weak Cu ··· N noncovalent interaction, C–H ··· π?and π–π interactions. Based on crystal data, quantum chemistry calculation at the DFT/B3LPY level was used to reveal the electronic structure of 1.     

Preparation for nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting and its application to determine trace copper by room temperature phosphorimetry

Nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting (NCM-PVA-I-I) was prepared using Cu²⁺ as template. The cavity in NCM-PVA-I-I matched Cu²⁺ very well and the selectivity was high. Cu²⁺ entered the cavity and then could form ionic association ([Cu²⁺]·[(Fin⁻)₂]) with the anion of fluorescein (Fin⁻) outside the cavity by electrostatic effect. [Cu²⁺]·[(Fin⁻)₂] could emit strong and stable room temperature phosphorescence on NCM-PVA-I-I. Its ΔI_p was proportional to the content of Cu²⁺. Based on the above facts, a new method for the determination of trace copper by solid substrate-room temperature phosphorimetry (NCM-PVA-I-I-SS-RTP, SS-RTP is the abbreviation of solid substrate-room temperature phosphorimetry) using NCM-PVA-I-I technique has been established. The linear range of this method was 2.00-144.00 fg Cu²⁺ spot⁻¹ (sample volume: 0.40 μL spot⁻¹, corresponding concentration: 5.00-360.00 pg mL⁻¹), and the detection limit calculated by 3Sb/k was 0.43 fg Cu²⁺ spot⁻¹ (corresponding concentration: 1.1 × 10⁻¹² g mL⁻¹, n = 11). Samples containing 2.00 and 144.00 fg Cu²⁺spot⁻¹ were measured, respectively, for seven times and R.S.D.s were 3.5% and 4.7%. NCM-PVA-I-I-SS-RTP could combine very well the characteristics of both the high sensitivity of SS-RTP and the high match and selectivity of NCM-PVA-I-I, and it was rapid, accurate, sensitive and with good repeatability. It has been successfully applied to determine trace copper in human hair and tea samples.