Influence of substrate nature on the growth of copper oxide thin films

Cu thin films were deposited on Si(111), glass, and quartz substrates by magnetron sputtering. X‐ray diffraction, SEM, and photoemission electron microscope studies were carried out to characterize the films. An influence of the nature of substrate on the Cu₂O and CuO phases formed was observed. Copper silicide formation in case of silicon substrates aided in formation of Cu₂O rather than CuO unlike glass and quartz substrates. Formation of nanocrystallites was observed by SEM and X‐ray diffraction. Copyright © 2016 John Wiley & Sons, Ltd.     

Whirling agitated single drop microextraction technique for the simultaneous analysis of Paraquat and Maneb in tissue samples of treated mice

A new microextraction technique, whirling agitated single drop microextraction, has been proposed for the simultaneous analysis of Paraquat and Maneb in tissue samples before liquid chromatography with tandem mass spectrometry. This technique is based on the idea that the escalatory motion of the sample solution along with the extraction solvent increases the movement of molecules into the extraction solvent. In this technique, a simple handheld rotator was utilized to rapidly agitate the biphasic extraction system for the instantaneous extraction of targeted analytes. After extraction, the extracted phase was directly solidified by cooling in crushed ice and easily collected using a micro‐spatula. The method showed good performance by achieving sensitive detection limits at 4.81 ng g^?1 (Paraquat) and 9.12 ng g^?1 (Maneb). Mean recoveries and enrichment factors were obtained >91.21% and up to 114 that ensured the preconcentration capacity of the method. The method precision was verified by evaluating intraday variation (n = 10) ≤4.57 (Paraquat) and ≤4.68 (Maneb) in terms of percent relative standard deviation. Additionally, method efficacy was assured by obtaining very little matrix interferences (≤3.11%). Moreover, the method suitability was also checked with its application on tissue samples of intraperitoneally treated mice with Paraquat and Maneb.     

Selective complexometric determination of mercury with thiocyanate as masking agent

A method is proposed for selective complexometrie determination of mercury, thiocyanate being used as masking agent. An excess of EDTA is added and the surplus is back-titrated at pH 5-6 with lead nitrate, Xylenol Orange or Methylthymol Blue being used as indicator. Thiocyanate is then added to decompose the mercury-EDTA complex and the liberated EDTA is titrated with lead nitrate. The interference of various cations has been studied.     

Synthesis,characterization, and catalytic oxidation of styrene,cyclohexene, allylbenzene,and cis-cyclooctene by recyclable polymer-grafted Schiff base complexes of vanadium(IV)

Schiff base-functionalized chloromethylated polystyrenes, PS-[Ae-Eol] (I), PS-[Hy-Eda] (II) and PS-[HyP-Eda] (III), were synthesized by reacting 2-(2-aminoethoxy)ethanol (Ae-Eol), N-(2-hydroxyethyl)ethylenediamine (Hy-Eda), and N-(2-hydroxpropyl)ethylenediamine (HyP-Eda) with oxidized chloromethylated polystyrene. Oxidized chloromethylated polystyrene (PS-CHO) was prepared by oxidation of chloromethylated polystyrene (PS) with sodium bicarbonate in DMSO. By reacting DMSO solution of [VO(acac)₂] with polymer-anchored Schiff base ligands I, II, and III, vanadium(IV) complexes PS-[V^IVO(Ae-Eol)] (1), PS-[V^IVO(Hy-Eda)] (2), and PS-[V^IVO(HyP-Eda)] (3) were prepared. Structure and bonding of I, II, and III as well as corresponding vanadium complexes 1, 2, and 3 were confirmed by FT-IR, UV–vis spectroscopy, SEM, EDX, AAS, TGA, EPR, etc. Polymer-anchored vanadium(IV) complexes 1, 2, and 3 show, efficient catalysis toward oxidation of styrene, cyclohexene, allylbenzene, and cis-cyclooctene in the presence of hydrogen peroxide. Optimized reaction conditions for the oxidation of these alkenes was achieved by changing various reaction parameters (like amount of catalyst, amount of oxidizing agent, volume of solvent, etc.). Polymer-grafted 1, 2, and 3 can be reused multiple times without depletion of their activity.     

Theoretical study of nematic to smectic transition in cylindrical porous media

Experimental observations show that the nematic–isotropic (N–I) transition temperature (T_NI) and nematic to smectic transition temperature (T_NA) for liquid crystal (LC) embedded in solid porous materials is lower compared to that of the bulk LC. To explain this, various theoretical studies have been proposed. We propose to use the mean field approach considering cylindrical pores. We have earlier modified the Maier–Saupe (M–S) mean field theory to include the disordering effects of porosity as a disordering surface potential. A molecule near the surface is assumed to feel the mean field potential (M–S type) and also the surface induced potential. Our earlier calculations of extension of M–S theory on the variation of T_NI with pore diameter agree with experimental data. In the present article, we propose the extension of McMillan theory to include the disordering effects of porosity as a disordering surface potential. Our calculations on the variation of TNA with different pore diameters agree qualitatively with experimental data.     

Biomimetic oxidation of metribuzin with hydrogen peroxide catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides

The biomimetic oxidation of metribuzin, a pre- and post-emergence herbicide with hydrogen peroxide catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides [TAPFe(III)Cl], has been studied yielding 6-t-butyl-3-methylthio-1,2,4-triazine-5(4H)-one, 4-amino-6-t-butyl-3,5(2H,4H)-dione and 6-t-butyl-1,2,4-triazin-3,5(2H,4H)-dione under various reaction conditions.     

Structure and thermal characterisation of poly(arylene ether sulphone)s

Structurally different poly(arylene ether sulphone) (PES) copolymers were synthesized by reacting stoichiometric amount of dichlorodiphenyl sulphone (DCDPS) with bisphenols. The molar ratio of bisphenol-A and phenolphthalein (ESP)/hydroquinone (ESH)/resorcinol (ESR) was varied to prepare nine copolymer samples. Structural characterization was done by FT-IR and ¹H-NMR studies. The initial decomposition temperature as well as temperature of maximum rate of mass loss in ESR and ESH copolymers were similar and a marginal decrease in these decomposition temperatures were observed by increasing the isopropylidine units in the backbone. High char residue at 800°C was observed in polymers having high content of phthalein units.The paper was presented at Thermans 2004 held at Baroda, January 20–22, 2004.Reliance Industries Limited is gratefully acknowledged for creating a Chair at IIT Delhi (I. K. Varma) and Council of Scientific and Industrial Research for providing scholarship to one of the authors (R. T. S. Muthu Lakshmi).     

Titrimetric determination of mercaptans with potassium persulphate

Summary 2- and 3-Mercaptopropionic acids, thiomalic acid, 2-mercaptoethanol and propyl mercaptan have been determined by direct titration with potassium persulphate in the presence of iodide in acidic aqueous medium. These mercaptans react with the oxidant in 2 1 molar ratio forming corresponding disulphides. The reaction of thio-p-cresol, thioglycollic acid and thioacetic acid with persulphate is too slow to be followed titrimetrically. However, they are oxidised to disulphide when allowed to stand with excess persulphate for 2.0, 1.75 and 0.75 hours respectively. The reaction stoichiometry is not a function of time. 2- and 3-Mercaptopropionic acids, cysteamine hydrochloride, thiomalic acid, thioacetic acid and thioglycollic acid react with potassium persulphate in acidic medium in the presence of iodine cyanide which acts as preoxidiser and catalyst, in the molar ratio 1 3 forming corresponding sulphonic acids. As little as 0.50 mg of the mercaptan can be determined in 50 ml solution with ± 0.25 % error.

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Zusammenfassung Durch direkte Titration mit Kaliumpersulfat in Gegenwart von Jodid kann man in saurem Medium 2- und 3-Mercaptopropionsäure, Thiomalonsäure, 2-Mercaptoäthanol und Propylmercaptan bestimmen. Diese Thiole reagieren mit dem Oxydationsmittel im Molverhältnis 2 1 unter Disulfidbildung. Die Umsetzung von Thio-p-kresol, Thioglykolsäure und Thioessigsaure mit Persulfat verläuft für maßanalytische Zwecke zu langsam. Die genannten Verbindungen werden von überschüssigem Persulfat in 2,0, 1,75 bzw. 0,75 Stunden zu Disulfiden oxydiert. Die Stöchiometrie der Reaktionen ist zeitunabhängig. 2- und 3-Mercaptopropionsäure, Cysteaminchlorhydrat, Thiomalonsäure, Thioessigsäure und Thioglykolsäure reagieren mit Kaliumpersulfat in saurer Lösung in Gegenwart von Jodcyan, das als Voroxydationsmittel und Katalysator füngiert, im Molverhältnis 1 3 unter Bildung von Sulfonsäuren. Nur 0,25 mg Mercaptan in 50 ml Lösung sind mit ± 0,25% Fehler bestimmbar.

     

Pentacoordinated Cu(II)/Zn(II) complexes bearing macrocyclic skeleton: synthesis, spectroscopic and molecular structure optimization studies

2,6-Diacetylpyridine and 1,2-diaminoethane in the presence of copper(II) and zinc(II) chlorides containing a few drops of acetic acid were condensed into compositions [CuLH2]2.2HCl.H2O (1), [Cu2LPyz]2.2HCl.4CH3COCH3 (2) [CuZnLPyz]2.2HCl.2CH3COCH3.10H2O (3) and [ZnL'Cl]3.3HCl.3H2O (4) substantiated by elemental analyses, IR, UV-vis, 1H NMR and FAB mass spectral data. Demetallation of a Ni(II) complex (isolated as above) afforded macrocyclic skeleton LH4, whereas L' symbolizes a skeleton of the ligand containing only ethylenediamine and 2,6-diacetylpyridine. Molecular structure optimization using MM2 force field calculations for the complexes revealed distorted square pyramidal geometry around Cu(II) centers in complexes 1 and 2 and tetrahedral geometry around Cu(II) and Zn(II) centers with different degrees of distortion in complex 3 whereas three Zn(II) atoms (each in distorted square pyramidal geometry) attached via Cl bridges form a cyclic structure in complex 4. In complexes 1 and 2,Cu-Cu = 2.63-2.66 angstroms indicated the possibility of coupling between the two Cu(II) centers which has been supported by lower magnetic moment as well as ESR spectra showing half-field signal.