Facile cyclic ammonium salt with the smallest size for high performance electric double layer capacitors

A novel cyclic ammonium salt, N,N-dimethylpyrrolidinium tetrafluoroborate (P₁₁-BF₄), was successfully synthesized for the first time. The smallest cyclic structure of P₁₁-BF₄ induced high solubility and conductivity in PC, which can easier enter the micropores of activated carbon and occupy more surface area during charge/discharge process.     

Naturally occurring antitubercular cyclic peptides

The antibiotic pipeline has failed to keep pace with the rise of multidrug resistant tuberculosis and extensively drug-resistant tuberculosis pathogens. Naturally occurring peptides provide a rich source of lead compounds for developing novel pharmaceuticals with high selectivity and potency. Given the vast number of naturally-occurring bioactive cyclic peptides identified so far, the following digest highlights several cyclic peptides, discovered in the preceding decade, that exhibit promising activity against Mycobacterium tuberculosis.     

Platinum electrode modified with polyterthiophene doped with metallic nanoparticles,as sensitive sensor for the electroanalysis of ascorbic acid (AA)

A novel electrochemical sensor for ascorbic acid (AA) detection based on platinum electrode modified with polyterthiophene (P3T) and doped with metallic particles (Cu, Co, Ag, Au, Pd) was constructed. The electrocatalytic performances of the modified electrode with polyterthiophene-metallic particles related to the detection of AA, showed a better catalytic activity compared to the modified electrode with polyterthiophene film. The obtained results demonstrate also that the use of P3T–Ag nanocomposite allows a good sensitivity; which gives a high response in oxidation peak of AA. In order to have a good performance using this sensor, several parameters such as polymerization time of the film and immersion time of the film in AgNO₃ solution were optimized.     

Rapid Electrochemical Detection of Vanillin in Natural Vanilla

A commercially available and disposable multiwalled carbon nanotube screen‐printed electrode (CNT‐SPE) was employed to detect and determine vanillin compounds in natural vanilla. The voltammetric behaviour of vanillin at the CNT‐SPE is examined and shown to be a sensitive method for quantifying vanillin. Linear calibration for vanillin in the range of 2.5–750 μM was obtained with a detection limit of 1.03 μM and a quantification limit of 3.44 μM. The developed method comprises a simple sample preparation method and a sensitive electrochemical detection for the quantification of vanillin in vanilla pods and is an easy and simple procedure for manufacturers and consumers.     

Electrochemical Characteristics of a Triphenylamine Derivative by Microelectrode Voltammetry

With the objective of understanding the kinetic redox properties of triphenylamine derivatives in association with chemical reactions, for their future application in functional organic semiconductor devices, the electrochemical characteristics of 4‐(2,2‐diphenylethenyl)‐N,N‐bis(4‐methylphenyl)‐benzenamine (TPA) were evaluated. Based on cyclic voltammograms of TPA on Pt disk electrodes with diameters of 300 μm and 10 μm at slow and fast scan rates in an acetonitrile solution, the TPA^.+ is stable, while the TPA²⁺ is unstable. Importantly, the unstable TPA²⁺ appears to break down by a subsequent chemical reaction. A Cottrell plot analysis from chronoamperometry of a solution containing TPA reveals that both the first and second oxidations are one‐electron reactions. Concerning the stabilization mechanism of the first oxidation state of TPA, the results of molecular orbital calculations indicate that the electrons of the HOMO level are distributed in the triphenylamine group, which induces a resonance‐stabilized TPA^.+. Based on these results, TPA/TPA^.+ is suggested to have a sufficient stability for further application in organic semiconductor devices.     

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

<正>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.     

Synthesis,characterization, electrochemical behaviour and X-ray crystal structures of nickel(II) complexes with a N2O4 donor set macrocyclic Schiff base ligand

Two nickel(II) complexes of [1 + 1] macrocyclic Schiff base ligand (L) have been prepared by cyclocondensation reactions between 1,3-diamino-2-propanol and 2-[3-(2-formylphenoxy)-2-hydroxypropoxy] benzaldehyde, using NiX₂ (X = Br, and I) salts as template agents, and characterized by elemental analyses, IR, molar conductivity and electronic spectra in both solid and solution states. The single-crystal X-ray diffractions of the complexes are also reported that contain nickel(II) ion in a distorted octahedral geometry coordination of N₂O₃X (X = Br, I and NO₃). In all complexes the ligand behaves as a pentadentate ligand. Cyclic voltammetric studies of nickel(II) complexes indicate a quasi-reversible redox wave in the negative potential range.     

Benign synthesis of carboxamide ligands,H2Me2bqb and H2Me2bpb. Preparation,characterization and electrochemistry of Ni(II) complexes: The crystal structure of [Ni(Me2bqb)]

A novel and highly efficient approach for the synthesis of H₂Me₂bqb and H₂Me₂bpb using ionic liquid as an environmentally benign reaction medium has been developed, eliminating the need for the pyridine as a toxic solvent. The Ni(II) complex of the dianionic ligand Me₂bqb²⁻, [Me₂bqb²⁻ = 1,2-bis(quinoline-2-carboxamide)-4,5-dimethyl-benzene dianion], has been synthesized and characterized by elemental analyses and spectroscopic methods, and the crystal and molecular structure of [Ni(Me₂bqb)] (1), has been determined by X-ray crystallography. The complex exhibits distorted square-planar NiN₄ coordination geometry with two short and two long Ni–N bonds (Ni–N ∼1.85 and ∼1.96 Å, respectively). The electrochemical behavior of [Ni(Me₂bqb)] (1), has been studied by cyclic voltammetry and compared with the analogous complex, [Ni(Me₂bpb)] (2).     

The electrochemistry and determination of Ligustrazine hydrochloride

Ligustrazine is one of the active ingredients contained in Ligusticum chuanxiong Hort. (Umbelliferae), which is widely used in traditional Chinese medicine for the treatment of cardiovascular problems. In this work, the electrochemistry of Ligustrazine hydrochloride (LZC) and its determination are investigated. The detection limit is estimated to be 8.0×10^–8 M, with three linear ranges from 1.0×10^–6 to 1.0×10^–4 M, 1.0×10^–4 to 5.0×10^–4 M, and 6.5×10^–4 to 1.6×10^–3 M. The method has been proved to be highly sensitive, selective, and stable, and has been successfully applied to determining LZC in LZC injections.     

Study of the Behavior of an EC Mechanism Using Cyclic and Derivative Chronopotentiometric Techniques with Spherical Electrodes

The theory for an EC mechanism in chronopotentiometric techniques – reversal chronopotentiometry, cyclic chronopotentiometry and reciprocal derivative chronopotentiometry – is developed. The equations of this article are valid for spherical electrodes of any size and present a compact and easy‐to‐manage form. Methods for determining kinetic parameters of the chemical reaction are proposed and the influence of the electrode radius is discussed. We conclude that large errors in the determination of these parameters are committed if electrode sphericity is neglected. Reciprocal derivative chronopotentiometry has been applied in its traditional form (dt/dE vs. E), and in a more recently proposed modality consisting of plotting dt^1/2/dE vs. E. These techniques are very convenient for studying an EC mechanism since the response is obtained in the form of peaks which are quantitatively related to the kinetic parameters of the chemical reaction. A comparison of the chronopotentiometric methods analyzed leads us to conclude that working curves based on the dt^1/2/dE vs. E curves are more suitable to obtain accurate values of the rate constants of the chemical reaction.