Nitrate and ammonium ion-selective electrodes as sensors : Part II. Assay of nitrate ion and nitrate and nitrite reductases in stationary solutions and under flow-stream conditions

Nitrate ion-selective electrodes were successfully applied both in stationary solutions and in flow streams as new analytical techniques for the assay of nitrate reductase activity. An ammonium-selective electrode was similarly used to measure the increase in ammonium ion concentration during the enzymatic reduction of nitrate to ammonium. Preliminary studies on a true enzyme electrode for assay of nitrate ion are discussed.     

Copper(I) complexes withN-methylbenzothiazole-2-thione and -2-selone

Summary N-methylbenzothiazole-2-thione (bttme) and -2-selone (btseme) form complexes with CuX₂ (X=Cl, Br, NO₃, 1/2SO₄ or BF₄). The reaction, carried out in MeOH, produces complexes of copper(I), whose stoichiometry mainly depends on the ligand. Infrared evidence shows that the coordination occurs through the exo-sulphur and selenium atoms.     

Electrochemistry of the bis(1,4,7-triazacyclodecane) cobalt(III) complex and its role in the catalytic reduction of hydrogen

The electrochemistry of the bis(1,4,7-triazacyclodecane) cobalt(III) complex at a mercury electrode, HMDE, in aqueous Britton–Robinson buffer solutions was investigated using cyclic voltammetry, double-potential-step chronoamperometry and chronocoulometry. The cyclic voltammetric data were analyzed by digital simulation to confirm and to measure the heterogeneous and homogeneous parameters for the suggested electrode mechanism. Generally, the complex is electrochemically reduced giving rise to two cyclic voltammetric waves. The first wave is a diffusion-controlled reversible wave. It is assigned to the stable Co(III)/Co(II) redox couple. The second one is found to be irreversible and corresponding to a reduction of Co(II) to Co(I) species. The monovalent cobalt, highly unstable, is rapidly protonated, and then forms cobalt hydride. The hydride decomposes to hydrogen molecules and regenerates Co(II) species following a disproportionation pathway. The overall reduction mechanism is concluded to be an EECC kinetics.     

Stability constants of At(I)-complexes with thiourea,iodide and mixed ligands in ethanol and water

The ion mobilities of [²¹¹At] At(I) in dependence on thiourea (tu) concentration, iodide concentration and a mixture of both ligands were measured by the electromigration method in free electrolytes. An equilibrium model was developed for the characterization of electromigration curves which permitted the calculation of stability constants and ion mobilities of the complexes [AtI], [AtI₂]^–, [Attu]⁺, [Attu₂]⁺ and [AtItu] existing in these solutions. Ethanol and water served as solvents. The temperature was 298 K and the ionic strength was about 0.05 mol/dm³.     

Pyrazoles and Pyrazolo[4,3-<Emphasis Type="Italic">e</Emphasis>]pyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrazines,I. Synthesis and Antimicrobial Activity

Summary. The synthesis of the title compounds was achieved using 1-phenyl-5-(pyrrol-1-yl)-1H-pyrazole-3-carboxylic acid azide as starting material. The latter compound was allowed to react with alcohols and amines to afford the corresponding carbamates and urea derivatives. Alkaline hydrolysis of the carbamates gave the corresponding amine, which was acylated and/or aroylated to give amide derivatives. These and the urea derivatives were subjected to cyclodehydration to give the title compounds. Antibacterial and antifungal activities were observed for several derivatives.     

[1]Benzothienopyrimidines. I. Etude de la 3H-benzothieno[3,2-d]pyrimidone-4

3H-benzothieno[3,2-d]pyrimidin-4-one (3) was synthesized by bimolecular cyclising the 3-amino-2-carbethoxybenzothiophene (1) with formamide. The electrophilic substituion of 3 afforded N-methylated lactam derivavtives, the structure of which was assigned by 'H nmr and unequivocal synthesis. The sysnthesis of benzothieno[3,2-d]pyrimidine (7) was achieved by desulphurization of the 3H-benzothieno[3,2-d]-[3,2-d]pyrimisine-4-thione (6) or by oxydation of the 4-hydrazinobenzothieno[3,2-d]primidine (5).     

Structure and stability of complexes of thiohydantoin derivative

The formation constant of 4-phenylhydrazono-2-thiohydantoin with 3d transition metal ions has been determined. The factors affecting the stability of the metal chelates have been studied. Complexes of Ag(I), Cu(II), Cd(II) and Pd(II) with the ligand have been isolated and characterized by physico-chemical techniques. The ligand forms a 1∶1 complex with Ag(I) and 1∶2 complexes with the other metal ions.     

Utilization of thiazolylacetonitriles in the synthesis of thiophene,thiazole, pyrazolo[1,5‐a]pyrimidine and pyrazolo [5,1‐c]triazine derivatives

Thiazolylcyanothioacetanilides react with α‐haloketones and haloesters to give the corresponding thiophene or thiazole derivatives according to the reaction conditions. Pyrazolo[1,5‐a]pyrimidines and pyrazolo[5,1‐c]triazines were synthesized by reaction of 3‐amino‐4‐(4′‐arylthiazol‐2′‐yl)‐5‐phenylaminopyrazole with different reagents. Structures of the new compounds were confirmed by elemental analyses, spectral data, and alternative methods of synthesis whenever possible. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 508–516, 1999     

Molecular Docking,DFT Calculations,Effect of High Energetic Ionizing Radiation,and Biological Evaluation of Some Novel Metal (II) Heteroleptic Complexes Bearing the Thiosemicarbazone Ligand

New Pb(II), Mn(II), Hg(II), and Zn(II) complexes, derived from 4-(4-chlorophenyl)-1-(2-(phenylamino)acetyl)thiosemicarbazone, were synthesized. The compounds with general formulas, [Pb(H₂L)₂(OAc)₂]ETOH.H₂O, [Mn(H₂L)(HL)]Cl, [Hg₂(H₂L)(OH)SO₄], and [Zn(H₂L)(HL)]Cl, were characterized by physicochemical and theoretical studies. X-ray diffraction studies showed a decrease in the crystalline size of compounds that were exposed to gamma irradiation (γ-irradiation). Thermal studies of the synthesized complexes showed thermal stability of the Mn(II) and Pb(II) complexes after γ-irradiation compared to those before γ–irradiation, while no changes in the Zn(II) and Hg(II) complexes were observed. The optimized geometric structures of the ligand and metal complexes are discussed regarding density functional theory calculations (DFT). The antimicrobial activities of the ligand and metal complexes against several bacterial and fungal stains were screened before and after irradiation. The Hg(II) complex has shown excellent antibacterial activity before and after γ-irradiation. In vitro cytotoxicity screening of the ligand and the Mn(II) and Zn(II) complexes before and after γ-irradiation disclosed that both the ligand and Mn(II) complex exhibited higher activity against human liver (Hep-G2) than Zn(II). Molecular docking was performed on the active site of MK-2 and showed good results.     

Lysinibacillus Isolate MK212927: A Natural Producer of Allylamine Antifungal ‘Terbinafine’

Resistance to antifungal agents represents a major clinical challenge, leading to high morbidity and mortality rates, especially in immunocompromised patients. In this study, we screened soil bacterial isolates for the capability of producing metabolites with antifungal activities via the cross-streak and agar cup-plate methods. One isolate, coded S6, showed observable antifungal activity against Candida (C.) albicans ATCC 10231 and Aspergillus (A.) niger clinical isolate. This strain was identified using a combined approach of phenotypic and molecular techniques as Lysinibacillus sp. {"type":"entrez-nucleotide","attrs":{"text":"MK212927","term_id":"1520090447"}}MK212927. The purified metabolite displayed fungicidal activity, reserved its activity in a relatively wide range of temperatures (up to 60 °C) and pH values (6–7.8) and was stable in the presence of various enzymes and detergents. As compared to fluconazole, miconazole and Lamisil, the minimum inhibitory concentration of the metabolite that showed 90% inhibition of the growth (MIC₉₀) was equivalent to that of Lamisil, half of miconazole and one fourth of fluconazole. Using different spectroscopic techniques such as FTIR, UV spectroscopy, 1D NMR and 2D NMR techniques, the purified metabolite was identified as terbinafine, an allylamine antifungal agent. It is deemed necessary to note that this is the first report of terbinafine production by Lysinibacillus sp. {"type":"entrez-nucleotide","attrs":{"text":"MK212927","term_id":"1520090447"}}MK212927, a fast-growing microbial source, with relatively high yield and that is subject to potential optimization for industrial production capabilities.