Electrochemical synthesis of benzoylglycine and ethylphthaloyl-glycine complexes of transition metal ions

Summary The direct electrochemical oxidation of metallic iron, cobalt, nickel and copper in Me₂CO solution of benzoylglycine and/or ethylphthaloylglycine gave products with high yields. For each of the complexes, the electrochemical efficiency is commensurate with the metals being divalent. Conventional physical and chemical studies were used to characterize the isolated complexes and octahedral geometry was suggested for them on the basis of magnetic and electronic spectral studies. The i.r. spectra show that the ligands coordinate in a bidentate fashion; the carboxylate ion is monodentate. The molar conductances agree with the complexes being non-electrolytes.     

New approach for the identification of power system economic dispatch parameters

It is well known that the coefficients of the input-output characteristics of the thermal steam-turbine model as well as the network model parameters have a great effect on the optimal economic operation of all thermal-electric power systems. Until today, these coefficients, the loss formula coefficients, theB-coefficients, and the active-reactive power loss models have been estimated using the well-known least-square estimation algorithm.In this paper, we present a new algorithm to estimate the power system parameters for economic dispatch calculation (EDC); this algorithm is based on the least absolute-value approximation (LAV)l ₁-norm. We compare the results obtained using the proposed algorithms with those obtained using the least-square error algorithm (LS). Optimal costs as well as overall network performance resulting from the implementation of each technique provide the basis of our conclusion.This work was supported by the Natural Science and Engineering Research Council of Canada, Grant No. A4146.     

Kinetic determination of morphine in illicit powders,using a fluoride selective electrode,based on reaction with 1-fluoro-2,4-dinitrobenzene

A simple, accurate and selective method is described for the determination of morphine in illicit powders, based on monitoring the initial rate of fluoride ion liberation from the reaction of morphine with 1-fluoro-2,4-dinitrobenzene at pH 9 and 35 °C, using a solid-state fluoride ion-selective electrode. Under optimized reaction conditions, as little as 15 g/ml of morphine is determined with an average recovery of 99.5% and a mean relative standard deviation of 1.2%. Determination of morphine in real illicit powders containing 6–18% morphine gives results comparing favorably with those obtained from isocratic reverse-phase high-performance liquid chromatography. No interferences are caused by many structurally related and associated compounds such as codeine, acetylcodeine, ethylmorphine, acetylmorphine and diacetylmorphine (heroin).     

Noncovalent attachment of psoralen derivatives with DNA: Hartree-Fock and density functional studies on the probes

Two psoralen derivatives (probes) were prepared. Their geometries were optimized at the Hartree-Fock (HF) and Density Functional (B3LYP) levels employing 6-31G** and cc-pVDZ basis sets. Their interaction with DNA was investigated using spectrophotometric and computational techniques. Both of them have shown strong binding to calf thymus DNA. The red-shift and hypochromism that detected in the spectrum were taken as an evidence for the strong interaction between these probes and DNA. The spectrophotometric DNA titration data were treated by two different methodologies to calculate the intercalation affinity. Half-reciprocal plots gave binding constants of 5.5065 x 10(4) and 6.4727 x 10(4) for 8-butoxypsoralen (8-BOP) and 8-hexoxypsoralen (8-HOP), respectively. Schatchard plots gave a comparable intercalation binding constants and also the surface binding constants along with the number of intercalated probe molecules per base pair. The interaction between these probes and DNA were studied theoretically. The energy of interaction was computed using molecular mechanics method. Strength of interaction of these probes with different types of DNA was computed and compared. Calculated energies of interaction were compared with the observed intercalation affinities. HOMO and LUMO energies were computed and used to account for the strength of interaction.     

Kinetics of the oxidation of [N-(2-hydroxyethyl)-ethylene-diamine-N,N′,N′-triacetato]cobalt(II) by N-bromosuccinimide

The kinetics of the oxidation of [N-(2-hydroxyethyl)-ethylene-diamine-N,N,N-triacetato] cobalt(II), [Co^II-(HEDTA)]^–, by N-bromosuccinimide, NBS, have been studied in aqueous solutions and water-methanol solvent mixtures under various conditions. The reaction stoichiometry indicates that one mole of NBS reacts with one mole of [Co^II(HEDTA)]^–. In aqueous solutions the reaction obeys the following rate law:

Electrochemical synthesis,magnetic, spectral and cyclic voltammetric studies on lactic acid complexes

Summary Complexes of iron, cobalt, nickel and copper with lactic acid (H₂LA) were prepared by electrochemical oxidation of the metal in non-aqueous solution; this new method gives a high yield (73–87%). The reaction mechanism and the electrochemical efficiency show that cobalt, nickel and copper give divalent complexes and the iron complex is trivalent. The isolated complexes were characterized by physicochemical techniques. C.v.s of the complexes indicate the irreversibility of the electrode processes and confirm the oxidation state of the metals.     

Novel synthesis of 2‐amino[1,4,5]benzoxadiazepine derivatives via a mild one‐pot reaction

The diazonium salt of 2‐aminophenol 2 was coupled in situ with malononitrile derivatives 3a‐d , 2‐cyanomethylthiazolin‐4‐one 9 , 2‐cyanomethylbenzimidazole 11a , and 2‐cyanomethylbenzothiazole 11b to give 2‐amino[1,4,5]benzoxadiazepine derivatives 6a‐d, 10 and 12a,b via a one‐pot reaction.     

Kinetics and mechanism of the oxidation of a ternary complex involving nitrilotriacetatocobaltate(II) and malonic acid by N-bromosuccinimide

The kinetics of oxidation of [Co^IINM(H₂O)]^3– (N = nitrilotriacetate, M = malonate) by N-bromosuccinimide (NBS) in aqueous solution have been found to obey the equation: d[Co^III]/dt = k ₁ K ₂[NBS][Co^II]_T/{1 + K₂[NBS] + (H⁺/K₁)} where k ₁ is the rate constant for the electron transfer process, K ₁ the equilibrium constant for dissociation of [Co^IINM(H₂O)]^3– to [Co^IINM(OH)]^4– + H⁺, and K ₂ the pre-equilibrium formation constant. Values of k ₁ = 1.07 × 10^–3 s^–1, K ₁ = 4.74 × 10^–8 mol dm^–3 and K ₂ = 472 dm³ mol^–1 have been obtained at 30 °C and I = 0.2 mol dm^–3. The thermodynamic activation parameters have been calculated. The experimental rate law is consistent with a mechanism in which the deprotonated [Co^IINM(OH)]^4– is considered to be the most reactive species compared to its conjugate acid. It is assumed that electron transfer takes place via an inner-sphere mechanism.     

Thermal and spectral studies of 5-(phenylazo)-2-thiohydantoin and 5-(2- hydroxyphenylazo)-2-thiohydantoin complexes of cobalt(II), nickel(II) and copper(II)

Complexes of 5-(phenylazo)-2-thiohydantoin (L¹) and 5-(2-hydroxyphenylazo)-2-thiohydantoin (HL²) with Co(II), Ni(II) and Cu(II) salts have been synthesised and characterized by elemental analysis, conductivity, magnetic susceptibility, UV-Vis, IR, ESR and TG studies. The magnetic and spectral data suggested octahedral geometry for [L¹M(OAc)₂(H₂O)₂]·xH₂O {M=Ni^ll and Cu^ll} and [L¹CuCl₂(H₂O)]·H₂O (dimeric form for the latter), trigonal bipyramidal geometry for [L²Co(OAc)(H₂O)]·2H₂O, square pyramidal geometry for [L²Ni(OAc)(H₂O)]·H₂O and square planar geometry for [L²CuCl]·2H₂O. TG studies confirmed the chemical formulations of these complexes and showed that their thermal degradation takes place in three to five steps, depending on the type of the ligand and the geometry of the complex. The kinetic parameters (n, E^#, A, ΔH^#, ΔS^# and ΔG^#) of the thermal decomposition stages were computed using the Coats-Redfern and other standard equations and are discussed.     

N-2-[3-methylpyridyl]-N′-phenylthiourea transition metal complexes

New complexes of N-2-[3-methylpyridyl]-N-phenylthiourea (HMPyPT) have been prepared from Ni^II, Cu^II, Zn^II, Pd^II, Pt^IV and Au^III chlorides. Three types, containing 1:1, 1:2 and 1:3 metal–ligand ratios, were isolated and characterized. In every case the ligand behaves in a monodentate manner coordinating via the pyridyl nitrogen. Attempts to isolate complexes containing the deprotonated ligand by raising the pH of the reaction mixture from 1.6–5.5 to 8.5 were unsuccessful. The bonding modes and the stereochemistry of the metal complexes have been determined from spectral (i.r., u.v.–vis., ¹H-n.m.r.) and magnetic measurements. The results suggest a square-planar structure for the Pd^II and Au^III complexes, but octahedral geometry for the other metal complexes. Thermal analysis (d.t.a., t.g.a.) measurements on the solid complexes have also been conducted.