Amido binding to ReO3+ core: Synthesis, structure and intermolecular interactions

The light green coloured complexes of general formula [(ReO)-O-V(L)CI(OH2)]Cl have been synthesised in good yields by reacting [RcvOCl(3)(AsPh3)21 with HL in dichloromethane in dinitrogen atmosphere. Here, L- is the deprotonated form of N',N'-bis(2-pyridylmethyl)amine (HL1); N-(2-pyridylmethyl)-N',N'-dimethylethylenediamine (HL2) and N-(2-pyridylmethyl)-N',N-diethylethylenediamine (HL3). Single crystal X-ray structure determination of [(ReO)-O-V(L-1)Cl(OH2)Cl confirms the amido binding of ReO3+ species. In the solid state of [(ReO)-O-V(L-1)Cl(OH2)]Cl, the coordinated and counter chloride ions are engaged in Re-Cl... H-C(ring), Cl...H-C(ring) and Re(OH2)...Cl hydrogen bonding and forming of a supramolecular network in the solid state. The subunit of the supramolecular network consists of one eight-membered and two nine-membered hydrogen bonded rings. The average diameters of eight-membered and nine-membered rings are similar to 3.70 and similar to 5.26 angstrom, respectively.

One pot synthesis of polycyclic oxygen aromatics. Part III mechanism of formation

Reaction of 6-Image -butyl-1-bromomethyl-2-(2-tetrahydropyranyloxy)-naphthalene2c with tetrachlorocatechol (TCC) in acetone in presence of K2CO3 gave diastereomers 6c and 7c. A mechanism (Scheme-1) invoking the base induced cleavage of the pyranyl ether 2 to 1,2-naphthoquinone-1-methide 8 as the first step has been postulated. The cleavage of the pyranyl ether linkage in 2 to give dimers 4 and 5 of 1,2-naphthoquinone-1-methide has been demonstrated with different bases. 1,2-Naphthoquinone-1-methide 8, thus generated, undergoes Michael addition with TCC followed by elimination of chloride ions to give a diketone, which further undergoes aldolisation with acetone to give diastereomers 6 and 7. Michael reaction of 8, generated Image from pyranyl ethers 2a-c, with tetrabromocatechol (TBC) under similar-reaction conditions gave the expected monobromo compounds 6h, 6i, 6k, 7n, 7n and 7q. The last step in the proposed mechanism, Image ., aldolisation has also been demonstrated using different ketonic solvents. Thus, reaction of 2a-c with TCC/TBC in diethyl ketone/methyl ethyl ketone under similar reaction conditions gave the expected compounds 6 and 7.

Crystal structure of cadaverine dihydrochloride monohydrate

The structure of cadaverine dihydrochloride monohydrate has been determined by X-ray crystallography with the following features: NH3+(CH2)5NH3+.2Cl-.H2O, formula weight 191.1, monoclinic, P2, a = 11.814(2) angstrom, b = 4.517(2) angstrom, c = 20.370(3) angstrom, beta = 106.56-degrees(1): V = 1041.9(2) angstrom3, lambda = 1.541 angstrom; mu = 53.4 1; T = 296-degrees; Z = 4, D(x) = 1.218 g.cm-3, R = 0.101 for 1383 observed reflections. The crystal is highly pseudosymmetric with 2 molecules of cadaverine, 4 chloride ions and 2 partially disordered water molecules present in the asymmetric unit. Though both the cadaverine molecules in the asymmetric unit have an all trans conformation, the carbon backbones are slightly bent. Between the concave surfaces of two bent cadaverine molecules exists water channels all along the short b axis. The water molecules present in the channels are partially disordered

The first structurally characterized diruthenium(II,III) complex with four bridging arylcarboxylato ligands

The diruthenium(II,III) compound [Ru2Cl(O2CC6H4-p-OMe)4](H2O)0.25 (1) has been prepared and its crystal structure determined by X-ray studies. The crystals belong to the triclinic space group, PImage , and the asymmetric unit consists of one full dimer and two half dimers. The {Ru2(O2CC6H4-p-OMe)4+} units are bridged by chloride ions into an infinite zigzag chain, with an average Ru---Cl distance and Ru---Cl---Ru angle of 2.567(2) Å and 121.0(1)°, respectively. The average Ru---Ru distance of 2.286(1) Å in 1 is comparable with that in analogous tetra-alkylcarboxylates, Ru2Cl(O2CR)4 and tetra-amidates, Ru2Cl(ArCONH)4.

The influence of chemical additives on surface charge and hardness of hematite

The zeta potential of high-purity hematite at pH 6 and in a 10−3N NaCl solution has been determined at different concentrations of acetone using the streaming potential technique and the results correlated with the microhardness of the mineral. The zeta potential has been found to decrease as the hardness increases reaching a minimum at 10 cc per litre concentration of acetone when the hardness reaches a maximum. The results have been explained on the basis of competitive adsorption of chloride ions and acetone molecules at low concentrations of acetone and coadsorption of both species above 10 cc per litre concentration. Acetone in distilled water and 10−3N NaCl in distilled water decrease the microhardness of hematite individually between pH 5 to 7 and in combination increase the microhardness reaching a maximum at pH 6.

Kinetic studies on the interaction of gold(III) with nucleic acids. I. Native DNA-Au(III) system-spectrophotometric studies

Kinetics of the interaction of Au(III) with native calf thymus DNA has been studied spectrophotometrically to determine the kinetic parameters and to examine their dependency on the concentrations of DNA and Au(III), temperature, ionic strength and pH. The reaction is of the first order with respect to both the nucleotide unit of DNA and Au(III) in the stoichiometry of 2∶1 respectively. The rate constants vary with the initial ratio of DNA to Au(III) and is attributed to the effect of free chloride ions and the existence of a number of reaction sites with slight difference in the rate constants. The activation energies of this interaction have been found to be 14–16 kcal/mol. From the effect of ionic strength the reaction is found to occur between a positive and a negative ion in the rate-limiting step. The logarithm of rate constants are the linear function of pH and the slopes are dependent on ther-values. A plausible mechanism has been proposed which involves a primary dissociation of the major existing species (AuCl2(OH)2)−, to give (AuCl2)+ which then reacts with a site in the nucleotide unit of DNA in the rate-liminting step followed by a rapid binding to another site on the complementary strand of the DNA double helix. There exist a number of binding sites with slight difference in reactivity.

(+/-)-cis-Dichloro[P-(isopropylamino)-dinaphtho[2,1-d:1',2'-f][1,3,2]dioxaphosphepine](triethylphosphine)platinum(II) dichloromethane solvate

In the racemic title compound, [PtCl2(C23H20NO2P)-(C6H15P)].CH2Cl2, the platinum(II) ion, which has approximately square-planar coordination geometry, is coordinated to two different monophosphorus ligands in a cis arrangement along with two chloride ions. A significant shortening of the P-N bond [1.604(7) Angstrom] relative to that in phosphinoamines and their complexes was observed.

Metallo-beta-lactamase and phosphotriesterase activities of some zinc(II) complexes

Metallo-beta-lactamases (m beta l) and phosphotriesterase (PTE) are zinc(II) enzymes, which hydrolyze the beta-lactam antibiotics and toxic organophosphotriesters, respectively. In the present work, we have synthesized a few asymmetric phenolate-based ligands by sequential Mannich reaction and their corresponding zinc(II) complexes. These zinc(II) complexes were studied for their m beta l and PTE activities. It is shown that the zinc(II) complexes can hydrolyze oxacillin, the beta-lactam antibiotic, at much higher rates as compared to the hydrolysis of p-nitrophenyl diphenylphosphate (PNPDPP), the phosphotriester. Among the complexes studied, the binuclear asymmetric complex 1 having a water molecule coordinated to one of the zinc(II) ions exhibits much better mbl activity than the mononuclear complexes. However, the mononuclear zinc(II) complexes having labile chloride ions exhibit significant PTE activity, which can be ascribed to the replacement of chloride ions by hydroxide ions during hydrolysis reactions. (C) 2011 Elsevier B.V. All rights reserved.

Structural and functional analysis of two universal stress proteins YdaA and YnaF from Salmonella typhimurium: possible roles in microbial stress tolerance

In many organisms ``Universal Stress Proteins'' CUSPS) are induced in response to a variety of environmental stresses. Here we report the structures of two USPs, YnaF and YdaA from Salmonella typhimurium determined at 1.8 angstrom and 2.4 angstrom resolutions, respectively. YnaF consists of a single USP domain and forms a tetrameric organization stabilized by interactions mediated through chloride ions. YdaA is a larger protein consisting of two tandem USP domains. Two protomers of YdaA associate to form a structure similar to the YnaF tetramer. YdaA showed ATPase activity and an ATP binding motif G-2X-G-9X-G(S/T/N) was found in its C-terminal domain. The residues corresponding to this motif were not conserved in YnaF although YnaF could bind ATP. However, unlike YdaA, YnaF did not hydrolyse ATP in vitro. Disruption of interactions mediated through chloride ions by selected mutations converted YnaF into an ATPase. Residues that might be important for ATP hydrolysis could be identified by comparing the active sites of native and mutant structures. Only the C-terminal domain of YdaA appears to be involved in ATP hydrolysis. The structurally similar N-terminal domain was found to bind a zinc ion near the segment equivalent to the phosphate binding loop of the C-terminal domain. Mass spectrometric analysis showed that YdaA might bind a ligand of approximate molecular weight 800 daltons. Structural comparisons suggest that the ligand, probably related to an intermediate in lipid A biosynthesis, might bind at a site close to the zinc ion. Therefore, the N-terminal domain of YdaA binds zinc and might play a role in lipid metabolism. Thus, USPs appear to perform several distinct functions such as ATP hydrolysis, altering membrane properties and chloride sensing. (C) 2015 Elsevier Inc. All rights reserved.

Analysis of stream waters in the catchment of Lake Windermere (1975-1978), England [Dataset]

This dataset provides raw data of chemical analyses made during studies on seasonal variations of some major ions in the stream water of the catchment of Lake Windermere in Cumbria. Measurements of sodium, calcium, potassium, magnesium, chloride ions and pH were taken at 37 stations in the catchment between 1975 and 1978.

Analyses of treated sewage effluent from Grasmere Treatment Unit (1974-1976), England [Dataset]

This dataset provides raw data of chemical analyses made during studies on seasonal variations of treated sewage effluent from Grasmere Treatment Unit in Cumbria. Measurements of sodium, calcium, potassium, magnesium and chloride ions were taken between 1974 and 1976.

Corrosão dos aços UNS S30400 e 31600 em meios simuladores de poros de concreto

Com o objetivo de investigar a influência que o molibdênio exerce nas propriedades das camadas passivas das armaduras de aços austeníticos, barras redondas dos aços UNS S30400 e 31600 foram submetidas à ação de soluções que simulam as que são encontradas nos poros de concreto. Para caracterizar o efeito do molibdênio na resistência daqueles aços à corrosão por pites, foram conduzidos ensaios de circuito aberto, polarização anódica, espectroscopia de impedância eletroquímica, análise de Mott-Schottky, tração em baixa taxa de deformação e análise das superfícies por microscopias óptica e eletrônica de varredura. Os resultados obtidos demonstram que, de uma forma geral, o aço UNS S30400 (sem molibdênio) apresentou maior resistência à corrosão localizada que o UNS S31600 (2% de Mo) nas soluções alcalinas cloretadas naturalmente aeradas, comportamento este inverso ao que se observa nos mesmos materiais quando submetidos a soluções cloretadas neutras ou ácidas.

Nonenzymatic glucose sensor based on renewable electrospun Ni nanoparticle-loaded carbon nanofiber paste electrode

A novel nonenzymatic glucose sensor was developed based on the renewable Ni nanoparticle-loaded carbon nanofiber paste (NiCFP) electrode. The NiCF nanocomposite was prepared by combination of electrospinning technique with thermal treatment method. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that large amounts of spherical nanoparticles were well dispersed on the surface or embedded in the carbon nanofibers. And the nanoparticles were composed of Ni and NiO, as revealed by energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD). In application to nonenzymatic glucose determination, the renewable NiCFP electrodes, which were constructed by simply mixing the electrospun nanocomposite with mineral oil, exhibited strong and fast amperometric response without being poisoned by chloride ions. Low detection limit of 1 mu M with wide linear range from 2 mu M to 2.5 mM (R = 0.9997) could be obtained.

Efficient preparation of silver nanoplates assisted by non-polar solvents

In the paper, we report an efficient method to prepare high yield (up to 97%) of silver nanoplates. Synthesis of silver nanoplates was carried Out in a binary solvent system of N,N-dimethylformamide (DMF) and toluene, in which DMF served as the reductant and polyvinylpyrrolidone (PVP) as the capping agent. By increasing the ratio of toluene to DMF to 7:6, silver nanoplates can be Successfully synthesized; otherwise other shaped nanoparticles would be the major products. The nanoplate sample was characterized by TEM, HRTEM, SAED, XRD, AFM and UV-visible spectroscopy, proving the high nanoplate purity of this sample. The influence of toluene content, other solvents, AgNO3 concentration, preparation temperature and chloride ions was also examined, which suggests that the function of nonpolar solvents in this system is to enhance the PVP coverage on silver surface and, furthermore, to facilitate the preferential adsorption of PVP on two (I I I) facets of silver nanoplates.

Surface enhanced Raman scattering of brilliant green on ag nanoparticles and applications in living cells as optical probes

In this article, surface enhanced Raman scattering (SERS) of different concentrations of brilliant green (13G) on Ag nanoparticles (AgNPs) has been investigated. The results indicate that only 10(-12) M BG can be detected on AgNPs while as low as 10(-11) M BG can be detected upon the activation of AgNPs by chloride ions. The additional improvement of the detection of BG mainly derives from the increase of the electromagnetic field around AgNPs and partially from the reorientation of BG on AgNPs induced by chloride ions, which was proved by the different spectra feature in the two systems. Adsorption of BG on AgNPs has also been demonstrated in applications of living cells as optical probes based on SERS, indicating that dye-AgNPs can probe the local environment in the living cells. The related cytotoxicity measurements demonstrated that BG-AgNPs produced little cytotoxicity to the cells, which shows great potential in biornedical applications of BG labeled-AgNPs for SERS nanosensors in cells as optical probes. Meanwhile, SERS spectra of BG on AgNPs in the presence chloride ions are expected to be used in living cells as more sensitive optical probes.