Application of Thermogravimetry to Study the Kinetics and Stability of Porphyrin Copper-sodium of Ephedra

Thermogravimetry was used to study the non-isothermal decomposition kinetics and the stability of porphyrin copper-sodium from ephedra. The kinetic equation for the second step can be expressed as . The kinetic compensation effect is found to be: InA=0. 2468E a ?8. 0513.Ea is 206. 61 kJ/mol. The results show that porphyrin copper-sodium has a high activation energy and good stability.

Determination of Hypoxanthine in the Presence of Copper by Adsorptive Stripping Voltammetry

A stripping method for the determination of hypoxanthine in the presence of copper at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation of hypoxanthine-copper at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10﹣3 mol·L﹣1 NaOH solution as electrolyte supporting, an accumulation potential of ﹣0.50 V and a linear scan rate of 200 mV·s﹣1. The response of hypoxanthine-copper is linear over the concentration ranges of 10 - 60 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 250 ppt (1.8 × 10﹣9 mol·L﹣1). Adequate conditions for measuring the hypoxanthine in the presence of metal ions, xanthine, uric acid and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of hypoxanthine associated in ATP or ssDNA.

PHOTOELECTROCHEMICAL STUDY OF PASSIVE LAYERS ON COPPER ELECTRODES IN SOME ALKALINE MEDIA

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Electrochemical Behavior of Novel Bis(Aliphatic Amine) Ruthenium(Ⅱ)and Osmium (Ⅱ) Porphyrins

Bis (aliphatic amine ) ruthenium (Ⅱ) and osmium (Ⅱ) porphyrins, M (Por )-(H2NR)2 andM(Por) (HNR'2)2, [M = Ru and Os; Por=meso-tetrakis (p-tolyl)porphyrinato (TTP), meso-tetrakis (4-chlorophenyl )porphyrinato (4-Cl-TPP ), meso-tetrakis (3, 5-dichlorophenyl) porphyrinato (3, 5-Cl-TPP ) andmeso-tetraphenyl porphyrinato(TPP); R=methyl, ethyl, iso-propyl and t-butyl; R'=methyl and ethyl]were synthesized by us. The electrochemical behavior of these complexes in 1,2-dichloroethane with TBABF4as supporting electrolyte, has been studied by cyclic voltammetry and controlled potential electrolysis. Bis(aliphatic amine)ruthenium (Ⅱ)porphyrins under go reversible one-electron oxidation and one-electron reduction processes in 1,2-dichloroethane solution. The osmium(Ⅱ) analogues is shown two oxidation couplesⅢ and Ⅴ, an additional small wave Ⅳ. The redox potentials of these complexes are markedly dependent onthe nature of the substituent bound to the phenyl group of the porphyrin ring. It is obvious that redox potentials increases the electron-withdrawing power of the substituents increases. The couple I was found at-0. 34, -0. 23 and -0. 15 V vs CP2 Fe+/o (Cp2Fe = ferrocene) for Ru (TPP ) (H2NBu-t)2, Ru (4-Cl-TPP)(H2NBu-t)2 and Ru (3, 5-Cl-TPP) (H2NBu-t)2 respectively.

Voltammetric Detection of Nanomolar Levels of Hypoxanthine in the Presence of Copper(Ⅱ) at Glassy Carbon Electrode

Nanomolar levels of the hypoxanthine in NaOH electrolyte cantaining copper(Ⅱ) can be determined by anodic stripping voltammetry at a glassy carbon electrode. In the present article hypoxanthine Cu + is shown to be adsorbed on the electrode surface in the presence of an excess of copper(Ⅱ). After accumulation period, hypoxanthine Cu + was stripped from the electrode surface and the anodic current coming near to the oxidation of Cu(Ⅰ) to Cu(Ⅱ) was measured. A linear calibration curve in the range of 5 nmol/L 1.5 mmol/L hypoxanthine, with a detection limit of 0.5 nmol/L hypoxanthine were obtained.

Electrochemical and Spectroscopic Studies on Interaction between Complex of Copper(Ⅱ) with Schiff Base Ligand and DNA

The crystal structure of ([CuL(H_2O)_2](ClO_4)_2·2H_2O, CuL)(L=N-(5-sulfosalicylidene)-4′-bromoaniline) was determined by means of X-ray crystallography. The interaction between CuL and salmon sperm DNA in a 0.1 mol/L HOAc-NaOAc buffer solution(pH 5.10) was investigated by cyclic voltammetry and UV-Vis spectroscopy. A couple of redox peaks of CuL in the cyclic voltammograms(CV) can be seen at the glassy carbon electrode. It was found that the peak current of CuL decreased significantly with a negative shift of the peak potential in the presence of DNA compared with that in the absence of DNA. In addition, the decreased absorbance of CuL was observed with increasing the concentration of DNA; the absorption spectrum of an ethidium bromide(EB)-DNA system in the presence of CuL confirms that the binding mode of CuL to DNA is different from the intercalation of EB with DNA. All the experimental results indicate that CuL can bind to DNA by electrostatic binding and form a 1∶1 association complex with a binding constant of 2.72×10 4 L/mol.

Crystal Structure and Electrochemical Behavior of Copper Complex with 6-Hydroxymethyl-substituted Tris(2-pyridylmethyl) Amine, [CuCl(C_(19)H_(20)N_4O)]ClO_4

A Cu(II) complex [CuCl(C19H20N4O)]ClO4 1 containing hydroxymethyl substituted TPA (TPA = tris(2-pyridylmethyl)amine) was prepared. It crystallizes in monoclinic, space group P21/c with a = 11.7628(2), b = 13.0083(3), c = 15.11280(10) ?, β = 108.724(2)°, V = 2190.09(7) ?3, Mr = 518.83, Z = 4, T = 293(2) K, Dc = 1.574 g/cm3, μ = 1.280 mm-1, F(000) = 1060 and S = 1.085. The final R = 0.0543 and wR = 0.1433 for 2693 observed reflections with I >2σ(I). The penta- coordinated copper (II) complex assumes an approximate square pyramidal geometry. Cyclic volta- mmetry measurement of the complex showed a quasi-reversible CuII/CuI redox couple with E1/2 = –0.467 v and ?E = 68 mv.

Synthesis, Spectroscopic, Structural Characterization, Conductivity and Electrochemical Studies of a Schiff Base Ligand and Its Copper Complexes

Schiff base ligand (L) derived from glyoxal and 4-aminoantipyrine was synthesized. The ligand (L) has been characterized by IR, NMR, electronic spectral studies and electrochemical studies. Cu(II) complexes of a Schiff base ligand (L) from 4-aminoantpyrine and glyoxal having the composition [CuL1]X2 where X = Cl¯?or NO3¯? have been prepared and characterized by elemental analysis, electrical conductivity in non-aqueous solvent, infrared and electronic, as well as cyclic voltammetric studies. L acts as a neutral tetradentate ligand coordinating through both the carbonyl oxygen and azomethine nitrogen. On both the complexes both the anions are not coordinated. A square planar geometry is assigned for complexes. The electrochemical studies of ligand show a typical cyclic voltammogram for an irreversible process. While copper(II) complexes show the typical cyclic voltammograms for quasi reversible process.

Synthesis,spectroscopic and electrochemical property of an unsymmetrical porphyrin and its Zn compound

In this article,a new 5-（p-maleicaminophenyl）-10,15,20-triphenylporphyrin（H_2P） and relative zinc compound（ZnP） were synthesized and characterized by means of elemental analyses,UV-vis,IR,MS and 1H NMR spectroscopies.Furthermore,we have investigated the fluorescence spectroscopy of these compounds.The oxidation and reduction properties of the compounds were studied by the cyclic voltarnmetry,the oxidation-reduction potentials were obtained.

The Application of Novel Electrochemical Approach to Antioxidant Activity Assay of Metal Porphyrins with Bulky 3,5-Diisobornyl-4-hydroxyphenyl Moieties

The complexes of biogenic metals (Zn2+,Cu2+,Co2+,Mn3+,Fe3+) based on meso-tetra(3,5-diisobor- nyl-4-hydroxyphenyl)porphyrin 1 were synthesized. The electrochemical behavior of these com-pounds was studied using cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques. The antioxidant activity of complexes was estimated by means of the electrochemical assay based on the hydrogen atom transfer reaction to the stable radical 2,2’-diphenyl-1-picrylhydrazyl (DPPH). The RDE method was applied for this process monitoring. It was shown that the efficiency of the metal complexes (Cu2+,Co2+,Mn2+,Ni2+,Fe3+) is practically the same order as that of free base porphyrin 1. However the Zn2+ complex demonstrates significantly higher antioxidant activity, and the stoichiometry of the reaction was determined as σ = 4. The results demonstrate that porphyrin macrocycle can directly affect the antioxidant properties of 2,6-diisobornylphenol.

Photophysical, Electrochemical and Photovoltaic Properties of Porphyrin-Based Dye Sensitized Solar Cell

Porphyrins occur in a number of important biomolecules and are also synthetically made for use as probe component of chemical and biological sensors. The performance of dye sensitized solar cells with two different porphyrin dyes was investigated in this work. The two porphyrin complexes comprised of a metal-free 5, 10, 15, 20-meso-tetrakis-(9H-2-fluorene-yl) porphyrin (H2TFP) and its Zinc complex (ZnTFP). UV-Vis, Fluorescence, and Fourier transformed infrared measurements of the two dyes were carried out to evaluate their absorption, emission and binding characteristics. Both dyes absorbed light in the UV-visible region all the way to the near-infrared. The surface morphology and elemental analysis of the porphyrin dye sensitized photoanodes were determined using Field Emission Scanning Electron Microscopy Imaging and Transmission Electron Microscopy Imaging. Cyclic voltammetry studies, current-voltage characteristics and the electrochemical impedance spectroscopic studies were also carried out. Solar-to-electric energy efficiency of H2TFP dye sensitized solar cell was higher (0.11%) than that of the zinc complex (0.08%). Thus the metal free porphyrin generated more power than the zinc complex under similar conditions. The impedance measurement also displayed less overall resistance for the free porphyrin (50 Ω) compared with the zinc complex (130 Ω). The LUMO levels of H2TFP and ZnTFP sensitizers were -0.87 eV and -0.77 eV respectively. Both of these LUMO values are higher than the lower bound level of the conduction band of TiO2 (-4.0 eV), ensuring the efficient injection of an electron from the excited porphyrin dye to the conduction band of the titanium dioxide.

Lead and Iodide Fixation by Thiol Copper(Ⅱ)Porphyrin for Stable and Environmental-Friendly Perovskite Solar Cells

The formation of undersaturated lead or iodide ions and I_(2) on the perovskite surface can decrease the performance and stability of perovskite solar cells(PSCs).Additionally,the leakage of noxious lead limits the application of PSCs.Here,we develop a strategy for molecular modulation of a perovskite surface using thiol copper(Ⅱ)porphyrin(CuP)to post-treat the perovskite film.

Preparation and Cyclic Voltammetry Characterization Of Cu-dipyridyl Imprinted Polymer

Polymer capable of specific binding to Cu-dipyridyl complex was prepared by molecular imprinting technology. The binding specificity of the polymer to the template (Cu-dipyridyl complex) was investigated by cyclic voltametric scanning using the carbon paste electrode modified by polymer particles in phosphate buffer solution. Factors that influence rebinding of the imprinted polymer were explored. The result demonstrated that the cyclic voltammetry was an efficient approach to explore interactions between template and imprinted polymers.

Synthesis and Crystal Structure of the Copper Complex of 7,16-Bis(2-hydroxy-5-methylbenzyl)-1,4,10,13- tetraoxa-7,16-diazacyclooctadecane

A lariat crown ether ligand 7,16-bis (2-hydroxy-5-methylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (L1) has been prepared via one-pot Mannich reaction. Its copper(II) complex Cu-L1 was synthesized and charac-terized by elemental analysis, IR and UV-visible spectroscopy. The crystal structure of the complex has been deter-mined by X-ray diffraction analysis. The result shows that the copper(II) ion is six-coordinated by two nitrogen and four oxygen atoms, two from the crown ether and the other two from the deprotonated phenolate anions, forming an elongated octahedral complex. Electrochemical study indicates that the complex undergoes reversible reduction in DMF solution.

Electrochemical reduction characteristics and the mechanism of chlorinated hydrocarbons at the copper electrode

The electrochemical reduction characteristics of chlorinated hydrocarbons were investigated by cyclic voltam-metry technique.The reduction mechanism and activity of the chlorinated hydrocarbons at the copper electrode were explored.The relationship between the structure of chlori-nated hydrocarbons and their reductive activity were dis-cussed.The experimental results showed that chlorinated alkanes and a portion of chlorinated aromatic hydrocarbons could be reduced directly at the copper electrode.However,chlorinated aromatic hydrocarbons were not easy to reduce at the copper electrode.The results provided a theoretical basis for the catalyzed iron inner electrolysis method.

A Novel Catenarian Cyano（triphenyl phosphite） Copper（I） Complex： Synthesis, Crystal Structure, Thermal, Voltammetric and Spectral Properties

Quantitative reaction between copper（I） cyanide and triphenyl phosphite forms copper（I） complex [（P（OPh）3）gCug（CN）4] （1）. X-Ray crystal structure shows a catenarian polymer of tandem interconnected copper cyanide, with C and N connecting to proximal Cu atoms. The Cu atoms adopt two different conformations： one exhibits linear construction, while the other exhibits distorted tetrahedral geometry through coordinating to two cyano groups and the P donors of triphenyl phosphite molecules. The feature of 1 is the propagation pattern of two- and four-coordination along with the chain. IR and electronic absorption spectra also confirm the established single crystal structure. Thermal analysis indicates that 1 has a high thermal stability. 3-D fluorescence result shows the middle absorption peaks with the maximum excitement and emission wavelength 342 and 350 nm, respectively. Cyclic voltammogram in DMSO, DMF and MeCN gives a midpoint voltage of --0.003, 0.061 and 0.137 V versus SCE, respectively, showing the different solvent virtue on reduction potential.

Size-dependent catalytic activity of copper nanoclusters for oxygen electroreduction in alkaline solution

By using 2-mercapto-5-n-propylpyrimidine(MPP)as capping ligands,copper nanoclusters with different core sizes were prepared using a chemical reduction method.The as-prepared copper nanoclusters were loaded onto a glassy carbon electrode and their size effect on the electrocatalytic activity towards the oxygen reduction reaction(ORR)was investigated with electrochemical techniques in alkaline electrolyte.Cyclic voltammetric(CV)studies showed that the onset potential of ORR on smaller copper nanoclusters is more positive than that on larger copper nanoclusters.Compared to the larger clusters,higher current density of ORR was obtained using the smaller copper nanoclusters.These CV results indicate that the smaller Cu nanoclusters exhibit higher catalytic performance for ORR.In rotating-disk voltammetric studies,ORR on the synthesized MPP monolayer-protected copper nanoclusters is mainly dominated by a two-electron transfer pathway to produce H_(2)O_(2).

Copper Nitroprusside-Based Electrochemical Sensor for Detection of Tryptophan

This work presents a novel electrochemical approach for detecting tryptophan through its interaction with copper nitroprusside,which is synthesized using a simple chemical co-precipitation method.The utilization of the reduction reaction inherent to copper nitroprusside effectively exhibits high selectivity against common interferences present in urine,such as melatonin,lactate,cytosine,cytidine,urea,ascorbic acid,creatine,creatinine,tyrosine,glycine,alanine,arginine,and lysine.The method demonstrates two linear ranges:0.0-0.15 mmol/L and 0.15-2.0 mmol/L with the sensitivities of 119.7±0.2μA/(mmol/L)and 9.9±0.4μA/(mmol/L),respectively.The limit of detection(3S_(B)/m)was determined to be 5.5μmol/L.Application of the sensor in synthetic urine yielded the recovery of 103%±5%.

Properties of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin liquid crystal Co and Ni complexes

Six series of meso-tetrakis (4-n-alkanoyloxyphenyl) porphyrin Co and Ni complexes (12 kinds) were reported. Nine of the compounds were found to exhibit liquid crystal properties and display a hexagonal columnar discotic columnar (Colh) phase. Molecular structure of all synthesized compounds was confirmed by IR, UV, MS, 1H NIVR, and elemental analysis. These liquid crystalline compounds have been studied by cyclic voltammetry, luminescence, and surface photovoltage spectroscopy.

Interaction of DNA with a water-soluble porphyrin

The investigation of interactions of DNA with other molecules, whose results may be helpful to understanding some diseases and the mechanisms, by which some medicines (especially antitumor drugs) act, is of great importance in elucidating the structures of DNA and their function. Many studies of interactions of DNA with porphyrins have