Influence of carbon nanotubes on surfactants supramolecular structures

The surfactant-base membrane mimetic supramolecular structures and their reaction on the presence of carbon nanotubes were studied. On an example of cetyltrimethylammonium bromide (CTAB) it was shown that CTAB molecules can form structures which in texture, shape and sizes imitate the morphology of biological membranes, - the sheets with a typical size of several tens of micrometers. It has been established that the presence of carbon nanotubes leads both to the change in the characteristic size of the sheets in the direction of their increase, and the appearance of new structural state - the sheets which form the «flower structures» (nanoflowers). This means that the presence of the carbon nanoparticles may change the geometry of the membrane structure, thereby altering membrane properties and thus causing disturbances in the activity of biological organisms

Anthracene mediated electrochemical synthesis of metallic cobalt nanoparticles in solution

© 2015 Elsevier Ltd. All rights reserved. The metallic cobalt nanoparticles in the bulk solution were obtained by antracene mediated reduction of [CoCl4]2- in the potentiostatic electrolysis in an undivided cell at the potential of the anthracene reduction to radical anion at room temperature in DMF/0.1 M Bu4NCl media. [CoCl4]2- ions are generated by the sacrificial cobalt anode dissolution during the electrolysis. The metal particles are oxidized upon contact with the air to form the oxidized cobalt nanoparticles with a low dispersity (20-30 nm)

Dimeric d- and dl-dysprosium(iii) tartrates: paramagnetic birefringence, molecular mechanics, stereoselectivity

The molar constants of paramagnetic birefringence (PBR) for the dimeric dysprosium(iii)d- and dl-tartrates, Dy2(d-Tart)(l-Tart)2- (1) and Dy2(d-Tart)2 2- (2) have been determined by means of pH-metric and PBR measurements. The simulation of the structure of the ligand and solvate environment has been carried out using the method of molecular mechanics (Dashevsky-Plyamovaty model, the MIND program). In addition to the four oxygen atoms from the ligand, each DyIII ion coordinates four molecules of water and a Na+ ion. © 1995 Plenum Publishing Corporation

Solution state and complexing ability of 1,4-bis(amidomethylsulfinyl)butane toward iron(III), copper(II), cobalt(II), nickel(II), and manganese(II)

© 2017, Springer Science+Business Media, LLC. The solution state and thermodynamic stability of complexes of the new antituberculosis agent 1,4-bis(amidomethylsulfinyl)butane (L) with iron(III), copper(II), cobalt(II), nickel(II), and manganese(II) in an aqueous solution in the presence and in the absence of the nonionic surfactant Brij 35 were studied by spectrophotometry, pH potentiometry, NMR relaxation technique (T = 25 °C; variable ionic strength), and mathematical simulation. The geometry optimization of all structures was carried out by the molecular mechanics method MM2 in order to obtain data on coordination modes. In addition, the structure of 1,4-bis(amidomethylsulfinyl)butane was refined by the DFT/B3LYP/6-311++G(d,p) quantum chemical method using the IEFPCM model to take into account solvent effects. In an aqueous solution (in the concentration range of 1.3•10 –5 —1•10 –3 mol L–1) and in the presence of Brij 35, 1,4-bis(amidomethylsulfinyl)butane exists as a neutral monomer. The Beer—Lambert—Bouguer law is obeyed in a wide concentration range for compound L in an aqueous solution, as well as in the pres ence of the surfactant, which can be used for the quantification of compound L. Iron(III), cobalt(II), and nickel(II) were shown to form 1: 1 mononuclear complexes with L; and copper(II) forms, 1: 1 and 2: 2 complexes. The presence of Brij 35 in the Cu 2+ —L system at a micellar concentration promotes the formation of a dinuclear complex

2,4-diamino-6-(acetohydrazidomethylsulfinylmethyl)-1,3,5-triazine. State in solution, acid-base and complexing properties

Solutions of a new drug, 2,4-diamino-6- (acetylhydrazidomethylsulfonylmethyl)-1,3,5-triazine, exhibiting tuberculocidal activity were studied using the methods of pH-metry, spectrophotometry, mathematical simulation of equilibria (CPESSP software), and molecular mechanics. Protolytic properties of the compound in the medium of aqueous dimethylsulfoxide (40 vol % of DMSO) were characterized. The composition of the copper(II) complex of this compound was determined and its stability constants were calculated. Based on the absorption spectra in the UV and visible regions the complexing ability of 2,4-diamino-6-(acetylhydrazidomethylsulfonylmethyl)-1, 3,5-triazine toward nickel(II) and cobalt(II) were characterized in comparison with copper(II) under the same conditions. © 2013 Pleiades Publishing, Ltd

High catalytic activity of palladium nanoparticle clusters supported on a spherical polymer network

© The Royal Society of Chemistry 2015. In this communication we report the synthesis of Pd nanoparticle clusters achieved via the assembly of Pd nanoparticles on the surface of a spherical polymer network. The network exhibits flexibility and adapts to the cluster formation. The nanoclusters display high catalytic activity toward p-nitrophenol reduction and the Suzuki-Miyaura coupling reaction

Reduction-controlled substrate release from a polymer nanosphere based on a viologen-cavitand

© 2016 The Royal Society of Chemistry.In this article, we present a new polymeric nanosphere (p(MVCA-co-SS)) for redox-controlled substrate release. The nanosphere consists of a hydrophobic core with disulfide bridges stabilized by the viologen-resorcinarene cavitand shell. The nanosphere is sensitive to thiol-containing reducing agents: glutathione (GSH) and dithiothreitol (DTT). GSH destructs the hydrophobic core of p(MVCA-co-SS) while DTT integrates into the core increasing its size. The nanosphere as shown can be used as nanocarriers for the redox-controlled substrate release for the fluorescent dyes (pyrene, rhodamine b and fluorescein)

A Ni(III) complex stabilized by silica nanoparticles as an efficient nanoheterogeneous catalyst for oxidative C-H fluoroalkylation

© The Royal Society of Chemistry 2016.We have developed NiIII-doped silica nanoparticles ([(bpy)xNiIII]@SiO2) as a recyclable, low-leaching, and efficient oxidative functionalization nanocatalyst for aromatic C-H bonds. The catalyst is obtained by doping the complex [(bpy)3NiII] on silica nanoparticles along with its subsequent electrooxidation to [(bpy)xNiIII] without an additional oxidant. The coupling reaction of arenes with perfluoroheptanoic acid occurs with 100% conversion of reactants in a single step at room temperature under nanoheterogeneous conditions. The catalyst content is only 1% with respect to the substrates under electrochemical regeneration conditions. The catalyst can be easily separated from the reaction mixture and reused a minimum of five times. The results emphasize immobilization on the silica support and the electrochemical regeneration of NiIII complexes as a facile route for developing an efficient nanocatalyst for oxidative functionalization

Pathogen-induced conditioning of the primary xylem vessels – a prerequisite for the formation of bacterial emboli by Pectobacterium atrosepticum

© 2016 German Botanical Society and The Royal Botanical Society of the NetherlandsRepresentatives of Pectobacterium genus are some of the most harmful phytopathogens in the world. In the present study, we have elucidated novel aspects of plant–Pectobacterium atrosepticum interactions. This bacterium was recently demonstrated to form specific ‘multicellular’ structures – bacterial emboli in the xylem vessels of infected plants. In our work, we showed that the process of formation of these structures includes the pathogen-induced reactions of the plant. The colonisation of the plant by P. atrosepticum is coupled with the release of a pectic polysaccharide, rhamnogalacturonan I, into the vessel lumen from the plant cell wall. This polysaccharide gives rise to a gel that serves as a matrix for bacterial emboli. P. atrosepticum-caused infection involves an increase of reactive oxygen species (ROS) levels in the vessels, creating the conditions for the scission of polysaccharides and modification of plant cell wall composition. Both the release of rhamnogalacturonan I and the increase in ROS precede colonisation of the vessels by bacteria and occur only in the primary xylem vessels, the same as the subsequent formation of bacterial emboli. Since the appearance of rhamnogalacturonan I and increase in ROS levels do not hamper the bacterial cells and form a basis for the assembly of bacterial emboli, these reactions may be regarded as part of the susceptible response of the plant. Bacterial emboli thus represent the products of host–pathogen integration, since the formation of these structures requires the action of both partners

Influence of Nature of Functional Groups on Interaction of Tetrasubstituted at Lower Rim p-tert-Butyl Thiacalix[4]arenes in 1,3-Alternate Configuration with Model Lipid Membranes

The influence of p-tert-butyl thiacalix[4]arenes (1,3-alternate) functionalized by N-propyl morpholine, N,N-dipropyliden-amine and aminodiacetate fragments on dynamic structure of liposomal membranes prepared from dipalmitoyl phosphatidylcholine was investigated by means of electron spin resonance spin-probe technique and Fourier transform infrared spectroscopy. Nuclear magnetic resonance and transmission electron microscopy techniques were applied to characterize the interacting systems. The obtained results have shown that all studied calixarenes interact with polar domains of bilayer. Depending on functional groups and hydrophobic/hydrophilic properties of calixarenes they can dip into bilayer, locate close to the surface of bilayer or form bridges between positively charged groups of adjacent lipid molecules, thus assisting to disordering or putting in order the lipid molecules. © 2011 Springer-Verlag