Electroanalysis and simultaneous determination of dopamine and epinephrine at poly(isonicotinic acid)-modified carbon paste electrode in the presence of ascorbic acid

A carbon paste electrode modified with electropolymerized fills of isonicotinic acid was developed. The modified electrode shows excellent electrocatalytic activity toward the oxidation of both dopamine （DA） and epinephrine （EP）. Separation of the reduction peak potentials for dopamine and epinephrine was about 357 mV in pH 5.3 phosphate buffer solution （PBS） and the character was used for the detection DA and EP simultaneously. The peak currents increase linearly with DA and EP concentration over the range of 8.0×10^-5 to 7.0×10^-4 mol/L and 5.0×10^-6 to 1.0×10^-4 mol/L with detection limits of 2×10^-5 and 1×10^-6 mol/L, respectively. The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of ascorbic acid （AA）.

Synthesis, Structure and Fluorescence Properties of Tb(Ⅲ) Complex with Isonicotinic Acid and Biphenyl-2,2′-Dicarboxylic Acid

Terbium perchlorate reacted with isonicotinic acid （Hpya） and biphenyl-2,2＇-dicarboxylic acid （H2dpa） under hydrothermal condition, a new ternary terbium complex [ Tb （pya） （dpa） （H2O） n （ 1 ） was synthesized. The structure of the ternary complex was determined by X-ray single crystal diffraction and characterized by elemental analysis, fluorescence measurement. The fluorescence spectrum shows the title complex emits strong green light. The crystal data for the com- plex： monoclinic, P21/n space group, a =0.8908（5）nm, b = 1.0569（6）nm, c =2.0969（11）nm, β = 98.446（8）°, V = 1.9528（18） nm^3, Z = 4, R = 0.0241, wR2 = 0.0534. The center Tb3＋ ion is eight coordinated. The coordination polyhedron around Tb3 ＋ ion can be described as a distorted square antiprism. The complex forms an infinite one-dimenand sional alternating chain polymer by bridging carboxyl groups of pyadpa.

Synthesis and Crystal Structure of a New Silver(I) Isonicotinate Coordination Polymer:[(Ag_3L_2)(ClO_4)]_n(HL=Isonicotinic Acid)

The title complex [(Ag3L2)(ClO4)]n 1, where HL = isonicotinic acid, has been prepared from the reaction of isonicotinic acid with AgClO4?H2O at room temperature and its struc- ture was determined by single-crystal X-ray diffraction. The crystal of 1 is of triclinic, space group P1 with a = 8.429(3), b = 10.694(4), c = 10.840(4) ?, α = 119.063(4), β = 100.474(5), γ = 99.901(5)°, V = 800.4(5) ?3, Mr = 1334.53, Dc = 2.769 g/cm3, Z = 2, μ(MoKα) = 3.848 mm-1, F(000) = 632, R = 0.0250 and wR = 0.0582 for 2872 observed reflections with I > 2σ(I). Complex 1 is a two-dimensional network consisting of adjacent one-dimensional chains through Ag–Ag inter- actions.

Excellent electrocatalytic activity of benzil for direct reduction of CO2 as well as indirect reduction of pyridine:A kinetic view of the electrocarboxylation process

Benzil,1,2-diphenylethane-1,2-dione, was used as an excellent electrocatalyst for reduction of carbon dioxide, CO. The reduction overpotential of COwas reduced about 900 m V in the presence of a benzil mediator. The chemical reaction of the product of the electrocatalytic reduction of CO,(activated CO,CO) with pyridine at a glassy carbon electrode, GCE, surface and in an acetonitrile-ButNClOsolution was investigated by cyclic voltammetry, chronoamperometry and controlled potential coulometry.By chronoamperometry, the catalytic rate constant, k, for the electron transfer between benzil and COwas obtained as 8.1 ± 0.4 Ms. The results indicate that pyridine has a strong interaction with the activated CO. The coulometry method was used to obtain the product of the pyridine chemical reaction with CO. The spectral characterizations of FTIR,H andC NMR of the coulometry experiment product proved that the pyridine anion radical, Py, was carboxylated by CO, and isonicotinic acid is the final major product.

Synthesis,Crystal Structure,and Photoluminescent and Semiconductive Properties of [La(C_6NO_2H_5)_3-(H_2O)_2]_(2n)·(nH_5O_2)(nHgCl_5)(2nHgCl_4)·(2nH_2O)

A new heterometallic 4f-5d inorganic-organic metal-isonicotinic acid complex [La（C6NO2Hs）3-（H2O）2]2n·（nH5O2）（nHgCl5）（2nHgCl4）·（2nH2O） 1 has been synthesized via hydro- thermal reaction and structurally characterized. Complex 1 crystallizes in the space group C21c of monoclinic system with four formula units in a cell： a = 24.140（7）, b = 20.884（7）, c = 15.462（2）A, fl = 127.46（1）°, V = 6187（3）A3, C36HaTCl13Hg3La2N6020, Mr = 2224.24, Dc = 2.388 g/cm3, Z = 4, T = 293（2） K, μ（MoKa） = 9.401 mm-1, F（000） = 4160 and RIwR = 0.0376/0.0636 for 4130 observed reflections （I 〉 20（/）） and 5617 unique reflections. Complex 1 is characteristic of a one-dimensional polycationic chain-like structure. Photoluminescent investigation reveals that the title complex displays interesting emissions in violet and orange regions. The luminescence spectra show stronger orange emission than violet emission. Optical absorption spectra of 1 reveal the presence of a wide optical bandgap of 3.41 eV.

Synthesis,Crystal Structure and Photoluminescence of [Gd(C_6NO_2H_5)_3-(H_2O)_2]_(2n)·(nH_5O_2)(nHgCl_5)(2nHgCl_4)·(2nH_2O)

A heterometallic 4f-5d inorganic-organic metaMsonicotinato hybrid [Gd（C6NO2H5）3- （H2O）2]2n·（nH5O2）（nHgCl5）（2nHgCl4）·（2nH2O） 1 has been synthesized via hydrothermal reaction and structurally characterized. Complex 1 crystallizes in the space group C2/c of monoclinic system with four formula units in a cell： a = 24.234（8）, b = 20.816（7）, c = 15.333（3）A , β= 128.091（8）°, V = 6088（3）A^3, C36H47Cl13Gd2Hg3N6O20, Mr = 2260.92, Dc = 2.467 g/cm^3, S = 0.896, μ（MoKα） = 10.331 mm^-1, F（000） = 4216, R = 0.0344 and wR = 0.0629. The crystal structure analysis reveals that the title complex is characteristic of a one-dimensional chain-like structure. Photoluminescent investigation reveals that the title complex displays a broad and intense emission in the green region.

Synthesis and Crystal Structure of Bis(N’-(Pyridine-3-Carboxaldehyde) Isonicotinoylhydrazone) Zinc(II)

Zinc complexes of Schiff base ligands exhibit interesting properties which could be exploited for potential applications as catalysts and models for biochemical systems. In this study, we report of the synthesis of a new zinc Schiff base complex, bis(N’-(pyridine-3-carboxaldehyde) isonicotinoylhydrazone) zinc(II), which has been characterized by physico-chemical methods. The X-ray single crystal structure of the complex has also been determined. The Schiff base ligand is bonded to the metal in a monodentate manner, coordinating through the pyridine N-atom, as shown from spectral studies. The crystal structure shows the zinc atom bonded to two Schiff bases and four aqua ligands, with each Schiff base ligand coordinating through its pyridine N-atom forming a distorted octahedral ZnN2O4 complex. Two water molecules and two nitrate ions found in the crystal structure link the different monomers through hydrogen bonding to form a layered supramolecular structure.

Design, Synthesis, Crystal Structure and Photophysical Properties of New Oxadiazole Extended Viologen Fluorophore

Viologens (N,N'-dimethyl-4,4-bipyridinium) are advanced functional materials, found important applications in electrochromic devices, molecular machines, organic batteries, and carbohydrate oxidation catalysts in alkaline fuel. In this article, we investigated the design, synthesis and photophysical properties of N,N'-dimethyl-2,5-Bis(pyridinium)oxadiazole 4 and its precursor 2,5- Bis(pyridine)oxadiazole 2. The crystal structure and photophysical properties of viologen 4 and precursor 2 have been determined. The viologen molecule 4 crystallized in monoclinic form, space group P21/n with four molecules in unit cell. Precursor molecule 2 also crystalized in monoclinic form, space group C2/c with four molecules in unit cell. From X-rd data, we found three cations in the molecular structure of viologen molecule 4, which is unusual in viologens. In the three-dimensional molecular packing diagram of molecule 4, the three cations and iodate anions are stabilized by C···C, C···I, N···I, N···H, H···I, N—H···I and C—H···I. The dihedral angle between planes having oxadiazole and two benzene rings are 5°and 8°, suggesting the molecule 4 is a slightly strained one. The molecular structure of precursor molecule 2 stabilized by C···C and N···H short contacts between the molecules. The molecule 4 displayed strong absorbance at 315 nm and emissions between 390 - 410 nm.

Relationship between Coordination Structure and Biological Activity of Copper(II) Nicotinate

The copper（Ⅱ） complexes of pyridine-3-carboxylic acid （nicotinic acid） and pyridine-2-carboxylic acid （isonicotinic acid） were synthesized, and their structures were characterized by elemental analysis, infrared spectrum, powder X-ray diffraction and so on. The results show that under experimental conditions, the ligands of synthesized copper nicotinate and copper isonicotinate are coordinated simultaneity with copper（Ⅱ） via the nitrogen of pyridine group and an oxygen of carboxylic acid group to form bidentate chelates. The crystal of copper nicotinate with two six-membered chelate rings belongs to monoclinic system, while that of copper isonicotinate having two five-membered chelate rings is of triclinic system. The tests show that the biological activities, such as the improvement of feed utilization, growth, anti-oxidation ability of organism and disease-resistant power, are different when copper nicotinate, copper inicotinate, copper-lysine chelate, copper-methionine chelate and copper sulphate are added in pig＇s feed, respectively. Due to its higher biological activity, less pollution and lower toxicity, copper nicotinate has wide potential applications as a feed additive.