Synthesis,characterization, crystal structure and chemical behavior of [1,1-bis(diphenylphosphinomethyl)ethene]ruthenium(II) complex toward primary alkylamine addition

Reaction of the ruthenium phosphine complex [RuCl₂(PPh₃)₃] 1 with an unsaturated functionalized diphosphine ligand, namely 1,1-bis(diphenyl-phosphinomethyl)ethene, H₂C=C(CH₂PPh₂)₂, (dppme) gave trans-Cl₂Ru(dppme)₂ 2. Complex 2 served as a precursor for the synthesis of trans-Cl₂Ru(dppme)(alkylamine)₂ complexes 3–5 by reaction with RNH₂. All these complexes were characterized by spectroscopic techniques and by elemental analysis. The solid-state structure of complex 2 was determined by X-ray crystallography.     

Kinetics and mechanism of the dehydration reaction of sarcosine to a bislactame through diacyclperoxide intermediate in strong acidic medium

The influence of substitution on the amine functional group of glycine in the permanganic oxidation of such an α‐amino acid in moderately concentrated sulfuric acid medium has been investigated. Reaction products analysis has revealed that contrary to the usual α‐amino acid oxidation product, which is an aldehyde species, a valuable compound, namely 1,4‐dimethylpiperazine‐2,5‐dione, has been obtained as the main product via a cheap, simple, efficient, and novel method. Sarcosine has been chosen as a substituted derivative of glycine, and the kinetics and mechanism of its permanganic oxidation have been investigated using a spectrophotometric technique. Conclusive evidence has proven delayed autocatalytic activity for Mn(II) in this reaction, analogous to some α‐amino acids. It has been revealed that such activity can show up when a certain concentration ratio of Mn(II) to sarcosine is built up in the medium, which we call the “critical ratio.” The magnitude of the latter ratio depends on the sulfuric acid concentration. Considering the “delayed autocatalytic behavior” of Mn(II) ions, rate equations satisfying observations for both catalytic and noncatalytic routes have been presented. The reaction shows first‐order dependence on permanganate ions and sarcosine concentrations in both catalytic and noncatalytic pathways, and apparent first‐order dependence on Mn²⁺ ions in catalytic pathways. The correspondence of pseudo‐order rate constants of the catalytic and noncatalytic pathways to Arrhenius and Eyring laws has verified “critical ratio” as well as “delayed autocatalytic behavior” concepts. The activation parameters associated with both pathways have been computed and discussed. Mechanisms for both catalytic and noncatalytic routes involving radical intermediates as well as a product having a diketopiperazine skeleton have been reported for the first time. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 689–703, 2009     

A needle trap device packed with a sol–gel derived,multi-walled carbon nanotubes/silica composite for sampling and analysis of volatile organohalogen compounds in air

A needle trap device (NTD) packed with silica composite of multi-walled carbon nanotubes (MWCNTs) prepared based on sol–gel technique was utilized for sampling and analysis of volatile organohalogen compounds (HVOCs) in air. The performance of the NTD packed with MWCNTs/silica composite as sorbent was examined in a variety of sampling conditions and was compared with NTDs packed with PDMS as well as SPME with Carboxen/PDMS-coated fibers. The limit of detection of NTDs for the GC/MS detection system was 0.01–0.05 ng mL⁻¹ and the limit of quantitation was 0.04–0.18 ng mL⁻¹. The RSD were 1.1–7.8% for intra-NTD comparison intended for repeatability of technique. The NTD-MWCNTs/silica composite showed better analytical performances compared to the NTD-PDMS composite and had the same analytical performances when compared to the SPME-Carboxen/PDMS fibers. The results show that NTD-MWCNTs-GC/MS is a powerful technique for active sampling of occupational/environmental pollutants in air.     

Synthesis and Study of Plasmon‐Induced Carrier Behavior at Ag/TiO2 Nanowires

Nanocomposites of Ag/TiO₂ nanowires with enhanced photoelectrochemical performance have been prepared by a facile solvothermal synthesis of TiO₂ nanowires and subsequent photoreduction of Ag⁺ ions to Ag nanoparticles (AgNPs) on the TiO₂ nanowires. The as‐prepared nanocomposites exhibited significantly improved cathodic photocurrent responses under visible‐light illumination, which is attributed to the local electric field enhancement of plasmon resonance effect near the TiO₂ surface rather than by the direct transfer of charge between the two materials. The visible‐light‐driven photocatalytic performance of these nanocomposites in the degradation of methylene blue dye was also studied, and the observed improvement in photocatalytic activity is associated with the extended light absorption range and efficient charge separation due to surface plasmon resonance effect of AgNPs.     

Decoherence effects on superpositions of chiral states in a chiral molecule

The superposition of chiral states of chiral molecules, as delocalized quantum states of a many-particle system, can be used for the experimental investigations of decoherence theory. In this regard, a great challenge is the precise quantification of the robustness of these superpositions against environmental effects. The methods so far proposed need the detailed specification of the internal states of the molecule, usually requiring heavy numerical calculations. Here, by using the linearized quantum Boltzmann equation and by borrowing ideas employed for analyzing other quantum systems, we present a general and simple approach, of wide applicability, which can be used to compute the dominant contribution to the decoherence rate for the superpositions of chiral states of chiral molecules, due to environmental scattering.     

High-performance liquid chromatographic-mass spectrometric assay of high-value compounds for pharmaceutical use from plant cell tissue culture: Cinchona alkaloids

The use of high-performance liquid chromatography (HPLC) interfaced with thermospray (TSP) mass spectrometry is described for the separation and identification of various alkaloids from Cinchona ledgeriana extracts. The use of water-acetonitrile-acetic acid (71:25:4) with 0.01 M ammonium acetate (pH 3.0) as the mobile phase gave good HPLC separation and good TSP sensitivity. The specificity obtained by single-ion monitoring allowed the analysis of commercially important alkaloids such as quinine and quinidine in plant material, transformed roots and in cells from tissue culture, with relatively simple extraction and work-up procedures. TSP gave protonated species with few fragment ions but collision-induced dissociation offers the promise of increased analytically specificity from the fragment ion data. This work has important implications for the biotechnological production of pharmaceuticals normally obtained from plant sources.     

Adsorption of cadmium and lead from palm oil mill effluent using bone-composite: optimisation and isotherm studies

The adsorption of Cd and Pb ions from palm oil mill effluent on a mesoporous-activated cow bone composite powder has been investigated. Adsorbent was developed from cow bones, coconut shells and zeolite. The composite examined in the present work has a BET surface area of 248.398 m²/g. The optimisation of the removal efficiency of the heavy metals was investigated using central composite design and analysed using response surface methodology. The analysis of variance of the quadratic model signified that the model suitably predicted the uptake of the heavy metal ions at a 95% confidence level. The optimal operating condition was recorded at pH 4, 50 rpm, within 24 h and 1 mm of particle size and 12.5 gL^?1 of adsorbent dosage. The characteristics of the composite were investigated using the Fourier transform irradiation. The morphology and chemical composition of composite was examined using the scanning electron microscopy equipped with energy dispersive x-ray. Characterisation study was conducted before and after the adsorption process. The results obtained illustrated that the removal of cadmium and lead from POME was influenced by the functional groups available on the surface of the composite. The carboxyl and hydroxyl groups are mainly responsible for the removal of cadmium and lead through chelating process. The point of zero charge (pH_pzc) revealed that the adsorbent contained acidic sites with negatively charge surface which influenced the adsorption process. The experimental data of the heavy metals of Cd and Pb investigated were fitted to the Langmuir and Freundlich models. The result revealed that the adsorption equilibrium data fitted better to the Langmuir model for the adsorption Cd and to the Freundlich model for the adsorption of Pb.     

Unusual coupling constants n J(195Pt—1H) and Pt↼H—C interactions in new Schiff base complexes of N-alkyl-1-(ferrocen-1-yl)methanimine

A series of novel ferrocenylimine complexes of platinum(II) ethene of general formula trans-[PtCl₂( ²-C₂H₄) (imine)], imine = N-alkyl-1-(ferrocen-1-yl)methanimine, (alkyl = Me; i-Pr, i-Bu, s-Bu, t-Bu, ±CH(Me)Ph, CH₂Ph and Ph) have been prepared and characterized by elemental analysis, i.r, ¹H-, ¹³C-n.m.r. spectra (¹⁵N- and ¹⁹⁵Pt-n.m.r. in part). Unusual coupling constants ³ J(¹⁹⁵Pt—¹H), 92–98 Hz were observed between the imino proton H₆ and platinum(II) which are too large for three bond coupling constants, thereby suggesting a PtH—C interaction.     

Synthesis,characterization, inequivalency of methylene proton and proton lability in the amino ligand of trans-[dichloro[(N-ferrocenyl methyl)amine](eta2-ethene)platinum] complexes

A series of complexes of the type trans-[PtCl(2)(eta(2)-ethene)(N-ferrocenyl methyl)amine)] complexes, N-ferrocenylmethylamine=[(eta(5)-C(5)-H(5))Fe(eta(5)-C(5)-H(4)CH(2)NHR], R=(Me, Pr(i), Bu(s), Bu(t), CH(2)Ph, (p-OCH(3))Ph, (o-(OCH(3))Ph, (p-CH(3))Ph, (o-CH(3))Ph, (m-CH(3))Ph, (p-Cl)Ph) have been synthesized and characterized on the basis of elemental analysis, IR, 1H and 13C NMR spectroscopic methods. The CpCH(2)NHR (Cp=(eta(5)-C(5)H(5))Fe(eta(5)-C(5)H(4)), region of the 1H NMR spectrum of the complexes has been investigated and shown to contain inequivalent methylene protons, NH-CH and 195Pt-N-CH coupling take place.