Metal complexes of a homopolymer system containing diethanolamine side group: synthesis and dielectrical behaviors

In this work, 4-diethanolaminomethyl styrene (DEAMSt) monomer was prepared by modification of 4-chloromethyl styrene with diethanolamine. The homopolymerization of styrene modificated was carried out by free radical polymerization method at 60?°C in presence of 1,4-dioxane and AIBN. The metal complexes were prepared by reaction of the homopolymer used as ligand P(DEAMSt)L^l and Ni(II), Co(II) metal ions in presence of ethanol and dilute NaOH at 65?°C for 48?h in pH 6.

The structure of modificated monomer, homopolymer used as ligand and polymer-metal complexes were characterized by (FT-IR), ¹H-NMR, ¹³C-NMR, Raman spectroscopy tecniques, elemental analysis, SEM, XRD and magnetic measurements. Their geometric structures according to magnetic measurements of Co(II) and Ni(II) complexes were estimated that have a tetrahedral structure. P(DEAMSt)L^l polymer has a transition state between amorphous and crystalline, whereas metal complexes (Co(II) and Ni(II) are with a large crystal structure. The molecular weight of P(DEAMSt)L¹ homopolymer was determined by gel permeation chromatography (GPC). The glass transition temperature (Tg) of homopolymer was measured by differantial scanning calorimeter (DSC). The thermal behaviors of both ligand and polymer-metal complexes were investigated by thermogravimetric analysis (TGA) and (DTA). The results obtained were compared with each other. Then, the dielectrical measurements (dielectric constant, dielectric loss and conductivity) of the ligand and polymer-metal complexes were investigated as a function of temperature and frequency. The activation energies (Ea) of the ligand and metal complexes were determined from the conductivity measurements.     

Synthesis and structural studies of (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}pyridin-2-yl)imino]butan-2-one oxime, ligand and its mono-, di- and trinuclear copper(II) complexes

A new dioxime ligand, (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}-pyridin-2-yl)imino]butan-2-one oxime, (H₂Pymdo) (3) has been synthesized in H₂O by reacting 2,3-butenedione monoxime (2) with 2,6-diaminopyridine. Mono-, di- and tri-nuclear copper(II) complexes of the dioxime ligand (H₂Pymdo) and/or 1,10-phenanthroline have been prepared. The dioxime ligand (H₂Pymdo) and its copper(II) complexes were characterized by ¹H-n.m.r., ¹³C-n.m.r. and elemental analyses, magnetic moments, i.r. and mass spectral studies. The mononuclear copper(II) complex of H₂Pymdo was found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). In the dinuclear complexes, in which the first Cu(II) ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu(II) ion is ligated with dianionic oxygen atoms of the oxime groups and are linked to the 1,10-phenanthroline nitrogen atoms. The trinuclear copper(II) complex (6) was formed by coordination of the third Cu(II) ion with dianionic oxygen atoms of each of two molecules of the mononuclear copper(II) complexes. The data support the proposed structure of H₂Pymdo and its Cu(II) complexes.     

Sensitivity optimization of PRESAGE polyurethane based dosimeter

A new class of three-dimensional dosimeter (PRESAGE) has recently emerged, that consists of an optically clear polyurethane matrix containing a leuco dye and a free radical initiator. The dye exhibits a radiochromic response when exposed to ionizing radiation, changing color in proportion to the radiation dose. In this work we investigate and characterize the sensitivity of this new dosimeter by changing the portion of these two materials in the feature. Our results show considerable improvement in both dosimeter sensitivity and dose response stability by changing the percents of leuco dye and free radical initiator to approach to an optimum value.     

Synthesis, spectroscopy, electrochemistry and thermal study of vanadyl tridentate Schiff base complexes: theoretical study of the structures of compounds by ab initio calculations

The VO(IV) complexes of tridentate ONN Schiff ligands were synthesized and characterized by IR, UV–Vis and elemental analysis. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron-withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO < H < Br < NO₂. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the VO(IV) complexes were carried out in the range of 20–700 °C. The VOL¹(OH₂) and VOL²(OH₂) decomposed in three steps, whereas the VOL³(OH₂) and VOL⁴(OH₂) complexes decomposed in two steps. The thermal decomposition of these complexes is closely related to the nature of the Schiff base ligands and proceeds via first-order kinetics. The structures of compounds were determined by ab initio calculations. The optimized molecular geometry and atomic charges were calculated using MP2 method with 6-31G(d) basis. The results suggested that, in the complexes, V(IV) ion is in square-pyramid N₂O₃ coordination geometry. Also the bond lengths and angles were studied and compared.     

Synthesis and Thermolysis of the Homoleptic Iron(II) Complex [Fe{cyclo‐(P5tBu4)}2]

Na[cyclo‐(P₅tBu₄)] ( 1 ) reacts with [FeBr₂(CO)₄] (2:1) to give the first homoleptic iron(II) complex [Fe{cyclo‐(P₅tBu₄)}₂] ( 2 ) containing two tridentate cyclo‐(P₅tBu₄)^– ligands. Thermolysis of 2 up to 500 °C produces a new phosphorus‐rich iron phosphide, calculated as FeP₆ according to the mass change.     

Selenium heterocycles. XXXV . Synthesis and pyrrolysis of aryloxy-, arylthio-, and arylseleno-1,2,3-selenadiazoles

A series of 4-substituted-5-arylthio-1,2,3-selenadiazoles, 4-substituted-5-arylseleno-1,2,3-selenadiazoles and 4-aryloxymethyl-1,2,3-selenadiazoles were synthesized. Pyrrolysis of these compounds afforded the corresponding acetylenes XI, XIII (X = S, Se) and XII, respectively. Oxidation of 4-substituted-5-arylthio-1,2,3-selenadiazoles (XIV) with m-chloroperbenzoic acid gave 4-substituted-5-arylsulfinyl-1,2,3-selenadiazoles (XV) and 4-substituted-5-arylsulfonyl-1,2,3-selenadiazoles (XVI).     

On the fractional-order extended Kalman filter and its application to chaotic cryptography in noisy environment

In this paper via a novel method of discretized continuous-time Kalman filter, the problem of synchronization and cryptography in fractional-order systems has been investigated in presence of noisy environment for process and output signals. The fractional-order Kalman filter equation, applicable for linear systems, and its extension called the extended Kalman filter, which can be used for nonlinear systems, are derived. The result is utilized for chaos synchronization with the aim of cryptography while the transmitter system is fractional-order, and both the transmitter and transmission channel are noisy. The fractional-order stochastic chaotic Chen system is then presented to apply the proposed method for chaotic signal cryptography. The results show the effectiveness of the proposed method.     

Exact boundary controllability of vibrating non-classical Euler–Bernoulli micro-scale beams

This study investigates the exact controllability problem for a vibrating non-classical Euler–Bernoulli micro-beam whose governing partial differential equation (PDE) of motion is derived based on the non-classical continuum mechanics. In this paper, it is proved that via boundary controls, it is possible to obtain exact controllability which consists of driving the vibrating system to rest in finite time. This control objective is achieved based on the PDE model of the system which causes that spillover instabilities do not occur.     

Application of Monte Carlo simulation method to polymerization kinetics over Ziegler–Natta catalysts

In the current work, the Monte Carlo simulation method was applied to ethylene polymerization over Ziegler–Natta catalysts. As expected, polymerization over each center of a Ziegler–Natta catalyst leads to a polymer having a Schultz–Flory molecular weight distribution. Notwithstanding, the total molecular weight distribution obtained by all catalyst centers together is at least twice as broad as that of each center. As another interesting finding, the introduction of hydrogen to the reaction deactivates the catalyst active centers and thereby reduces the catalyst activity. Nevertheless, it does not mainly affect the polymerization kinetics. In addition, the polymer molecular weight falls as hydrogen is added to the reaction since it acts as a strong transfer agent. The same effect is seen when cocatalyst concentration increases. Hydrogen also widens the polymer molecular weight distribution. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 45–56, 2009