Thermal, vibrational and EPR studies of Cu(II) bromide bis(p-methylaniline) and bis(m-methylaniline) complexes

[CuBr(2)(pMA)(2)] and [CuBr(2)(mMA)(2)] complexes (pMA: p-methylaniline, mMA: m-methylaniline) have been prepared and characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, and IR, Raman and EPR spectroscopic studies. Coordination effects on the vibrational spectra of the ligands have been investigated. The room temperature EPR spectra of the complexes and their simulated spectra are also discussed in detail. The vibrational and EPR spectral studies suggest that the coordination sphere around Cu(II) consist of a distorted tetragonal structure.     

Principal active species of horseradish peroxidase, compound I: a hybrid quantum mechanical/molecular mechanical study

The active species, Compound I, of horseradish peroxidase (HRP) has been investigated by quantum mechanical/molecular mechanical (QM/MM) calculations using 10 different QM regions. In accord with experimental data, the lowest doublet and quartet states are found to be virtually degenerate, with two unpaired electrons on the FeO moiety and one localized on the porphyrin in an a(2u)-dominant orbital with a minor, but nonnegligible, a(1u) component. The proximal ligand appears to be imidazole rather than imidazolate. The hydrogen-bonding network around the FeO moiety (i.e., Arg38 and His42) has significant influence on the axial bonds and the spin density distribution in the FeO moiety. Including this network in the QM region was found to be essential for reproducing the experimental M?ssbauer parameters. The protein environment shapes most of the subtle features of Compound I of HRP.     

Study of Solvent Effects on the Protonation of Functional Group of Disubstituted Anilines: Factor Analysis Applied to the Correlation between Protonation Constants and Solvatochromic Parameters in Ethanol–Water Mixtures

The stoichiometric protonation constants (log β) of some disubstituted aniline derivatives in ethanol–water mixtures (0–90% ethanol by volume) at 25.0 ± 0.1°C were firstly submitted to factor analysis in order to obtain the number factors which affect the variation of the whole data sets and, afterwards, submitted to target factor analysis to identify these factors. The influence of solvatochromic parameters in the interactions between aniline derivatives and the solvent studied was identified and quantified. The general equation of Kamlet and Taft was reduced for these mixtures to two terms using combined factor analysis (FA) and target factor analysis (TFA): the independent term and the hydrogen-bond donating ability, α (HBD), solvatochromic parameters. Further, the quasi-lattice quasi-chemical (QLQC) theory of preferential solvation has been applied to quantify the preferential solvation by water of electrolytes in ethanol–water mixtures. The effects of the substituents on the protonation constants, the additivities of these effects, and the applicability of the Hammett equation to the behavior of substituents are also discussed. Further, Hammett’s reaction constant for the protonation of disubstituted anilines has been obtained for all the solvent mixtures and correlates well with α (HBD) of the solvent.     

Use of a Packed Minicolumn Connected to a Syringe for Determination of Trace Elements in Biological and Water Samples by Flame Atomic Absorption Spectrometry

In this study, a syringe-connected minicolumn resin was used for the separation and enrichment of cadmium, copper, nickel and zinc prior to their determination by flame atomic absorption spectrometry. The proposed technique was compared with classical batch and column techniques in terms of rapidness, simplicity, enrichment and risk of contamination. The minicolumn was filled with Chromosorb-103 resin and connected to a syringe. If the samples were treated with ammonium pyrrolidine dithiocarbamate or 8-hydroxyquinoline, the analytes were quantitatively retained at pH2 and pH5 on the resin, respectively. On the other hand, if no chelating agent was added, the analytes were quantitatively retained at pH10. The analytes retained by the resin were quantitatively eluted by drawing and discharging nitric acid in acetone. The analytes in spiked river-water samples and in certified standard reference Bovine-Liver (NIST SRM 1577 b) were quantitatively (94%) recovered. The relative standard deviations for the determinations were found to be 1.0–10%.     

Analytical approach to Boussinesq equation with space‐ and time‐fractional derivatives

In this paper, the homotopy perturbation method (HPM) is developed to obtain approximate analytical solutions of a fractional Boussinesq equation with initial condition. The fractional derivatives are described in the Caputo sense. Some examples are given and comparisons are made, the comparisons show that the HPM is very effective and convenient and overcomes the difficulty of traditional methods. The numerical results show that the approaches are easy to implement and accurate when applied to space‐ and time‐fractional equations. Copyright © 2010 John Wiley & Sons, Ltd.     

The synthesis and electrochemical behaviour of carbazole-substituted phthalocyanines

The syntheses of new cobalt and zinc phthalocyanine complexes containing carbazole (Cz) substituents at the peripheral positions are reported (CzCoPc and CzZnPc). The reaction of Cz with 4-iodophthalonitrile in the presence of a catalytic amount of copper(I) oxide and potassium carbonate led to the formation of 4-(9H-carbazol-9-yl) phthalonitrile. Furthermore, by heating the dinitrile and anhydrous metal salts (CoCl₂, Zn(CH₃COO)₂) at 160 °C in n-hexanol in the presence of DBU, the phthalocyanines were obtained. They were characterised by ¹H NMR, FT-IR, UV-Vis and MS spectroscopic data. Aggregation behaviours of Pcs were investigated in THF. Electrochemical redox behaviour of CzCoPc was investigated by cyclic voltammetry depending on the potential range, and the oxidation and reduction products were followed by UV-Visible absorption measurements. Polymerisation of CzCoPc was carried out by potentiodynamic methods on glassy carbon electrode, and the catalytic activity of resulting polymer (P[CzCoPc]) was tested comparatively with polycarbazole (PCz)-coated electrode for dopamine and better response was obtained for P[CzCoPc] modified electrode.     

In Situ Electrochemical Production of Metal-organic Hybrid Composite Film from Nickel Containing Polyoxometalate and 3,4-Ethylenedioxy-thiophene for Sensor Application

In situ electrochemical synthesis of an organic-inorganic hybrid material composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and nickel-based Keggin type polyoxometalate, K₇[Ni^IIINi^II(H₂O)W₁₁O₃₉].15H₂O(NiPOM), has been proposed here. The remarkable optical and electrical properties of the PEDOT and the unique redox properties of NiPOM have synergistically combined to make the hybrid structure highly desired multi-functional materials for a myriad of applications. The driving force for the formation of hybrid structure is thought to be electrostatic interactions between POM anions and cationic polaron/bipolaron structures that in the PEDOT. PEDOT/NiPOM based hybrid composite modified graphite electrode has been used for non-enzymatic glucose sensor platform as a sample of applications. Furthermore, PEDOT/NiPOM based sensor platform was successfully utilized for detection of glucose content with the lowest detection limit in real samples like honey and milk. These results suggest that PEDOT/NiPOM metal-organic hybrid composite could be utilized as multi-functional material for a myriad of applications.     

Modelling with the Novel INAR(1)-PTE Process

Methodology and Computing in Applied Probability - In this paper, the first-order non-negative integer-valued autoregressive process with Poisson-transmuted exponential innovations is introduced....     

Fixed point and common fixed point theorems on ordered cone metric spaces

In the present work, some fixed point and common fixed point theorems for self-maps on ordered cone metric spaces, where the cone is not necessarily normal, are proved.