Cyclic voltammetry of tris(2,2-bipyridine)zinc(II) diperchlorate detected by electron spin resonance

Electrochemical transformations of the tris(2,2-bipyridine) complex of zinc(II) perchlor- ate were studied by cyclic voltammetry detected by electron spin resonance (DESR CV), which made it possible to indentify the intermediates formed and to monitor the unpaired electron localization in them. © 2013 Springer Science+Business Media, Inc

Langmuir monolayers and thin films of amphifilic thiacalix[4]arenes. properties and matrix for the immobilization of cytochrome c

© 2014 American Chemical Society. Formation and properties of Langmuir films of thiacalix[4]arene (TCA) derivatives containing N-donor groups on the lower rim (Y=O(CH2)3CN; OCH2CN; NH2; OCH2ArCN-p) in 1,3-alternate conformation on aqueous subphase and solid substrates have been studied. Only tetra-cyanopropoxy-p-tert-butylthiacalix[4]arene 1 forms a typical monomolecular layer with perpendicular orientation of the macrocycle relative to the water-air interface that is able to immobilize cytochrome c in the entire range of the surface pressure. Obtained monolayers were transferred by Langmuir-Schaefer technique onto quartz, indium-tin oxide (ITO), and silicon. It was demonstrated that protein activity is retained after immobilization on the substrate

Spectroelectrochemistry: ESR of Paramagnetic Intermediates in the Electron Transfer Series [Cr(bpy)<inf>3</inf>]ⁿ (n = 3+, 2+, 1+, 0, 1-)

© 2015 Elsevier Ltd. All rights reserved. A new method of cyclic voltammetry with simultaneous ESR spectra multiple recording (CV-MRESR) has been proposed and implemented. Along with cyclic voltammetry (CV) and electron spin resonance (ESR), the combined method involving cyclic voltammetry and ESR (CV-ESR) has been used for the study of electron transfer in a series of complexes [Cr(bpy)3]n (n = 3+, 2+, 1+, 0, 1-)

EPR imaging study of paramagnetic centre distribution in thiokol-epoxy hermetics

The distribution of paramagnetic centres in carbon black filler in the interphase layer of the thiokol-epoxy hermetics on the border of brass or glass substrate was studied using EPR-imaging method. It was shown that the relative content of radicals decreases near the hermetic-"rigid" surface contact border. The thickness of the layer with a low concentration of radicals is estimated as 0.5±0.3 mm. The inhomogeneous distribution of radicals is more obvious in the case of hermetic hardening on a brass surface. These results are explained by a catalytic acceleration of the thiokol-epoxy polymerization reaction in the region of hermetic-metal surface contact. © 1996 Springer

One-step synthesis of gold colloids using amidoaminocalix[4]resorcinarenes as reducing and stabilizing agents. Investigation of naproxen binding

© 2017 Elsevier B.V.Amido(dimethylamino) calix[4]resorcinarenes with different substituents on the lower rim (-CH3 (С1), −C5H11 (C5), −C11H23 (C11)) both as reducing and stabilizing agent in an aqueous solution were used for the fabrication of stable gold colloids. Gold colloids are characterized by spectrophotometry, FTIR − spectroscopy, transmission electron microscopy, dynamic light scattering. It is found that increase of the macrocycle's concentration towards HAuCl4 concentration during the synthesis leads to the decrease in the size of formed particles. It is shown that the size of gold nanoparticles (AuNPs) decreases with the increase of the hydrophobicity of the substituents on the macrocycles lower rim (C1@Au − 4–14 nm, C5@Au - 10–11 nm, C11@Au − 7–8 nm). The monolayer packing of the macrocycle molecules on the surface of the metal particle for C1@Au and bilayer − for C5@Au and C11@Au, providing both the stabilization of AuNPs and their solubility in water, are proposed. Temperature and pH variation during the synthesis showed that the optimal synthesis conditions for all kinds of particles C1@Au, C5@Au, C11@Au are spontaneous installed during the synthesis pH (for C1@Au − pH 8.10, C5@Au − pH 8.56, C11@Au − pH 8.63) and the synthesis temperature of the 25 °C. High binding fraction of drug substrate naproxen on the surface of AuNPs modified by C5 and C11 macrocyclic aggregates due to the ordering of the macrocycles on the particle surface and enhancing their receptor ability towards naproxen is defined by fluorescence method

Supramolecular nanoscale systems based on amphiphilic tetramethylensulfonatocalix[4]resorcinarenes and cationic polyelectrolyte with controlled guest molecule binding

© 2016 Informa UK Limited, trading as Taylor & Francis GroupThe water-soluble tetramethylensulfonatocalix[4]resorcinarene with methyl (C1) and pentyl (C5) substitutes on the lower rim forms colloid nanoscale aggregates with poly(diallyldimethylammonium chloride) (PDDA) in aqueous solutions. The size and stability of nanoparticles depend on concentrations of the components and their ratio in the ‘calixarene-polymer’ system. Ternary supramolecular complexes «polymer–macrocycle–guest molecule L-tryptophan (Trp) in conditions of spontaneous pH (3.80 and 4.78 for C1-PDDA and C5-PDDA systems, respectively) in an aqueous solution and in phosphate buffer (pH 7) were investigated by fluorescence method. The addition of the third component – PDDA – to the «non-aggregated C1–Trp» associates leads to the release of Trp in all studied conditions. The possibility of the «binding–release» process of L-tryptophan in «C5–Trp» associates after PDDA addition in the ternary complex is achieved and controlled by the structure of the macrocyclic self-associates and pH conditions

Photoinduced toxicity of PrF<inf>3</inf> and LaF<inf>3</inf> nanoparticles

© 2016, Pleiades Publishing, Ltd.PrF3 and LaF3 nanoparticles were synthesized by the hydrothermal method. The size distribution of these nanoparticles in the colloidal solution produced was studied by photon correlation spectroscopy. The mean diameter of the nanoparticles was 42 ± 1 nm. During the study of the toxicity of the nanoparticles, the mixture of a colloidal solution of the nanoparticles with cells to be studied was irradiated by 30-mW continuous lasers at wavelengths of 532 and 473 nm. The concentration of salmonella cells in normal saline was 106 cell/mL, while that of nanoparticles was 0.1 g/L. The cell survival percentage was 39, 34, and 20% for the irradiation times of 5, 10, and 15 min, respectively, at an optimal laser radiation power density of 0.4 W/cm at a wavelength of 532 nm. It was ascertained that LaF3 nanoparticles do not possess the property of photoinduced toxicity and the apoptosing effect. Moreover, the property of photoinduced toxicity is not shared by microparticles, in contrast to nanoparticles

Novel thermoresponsive water-soluble oligomers based on amphiphilic calixresorcinarenes

© 2017 Informa UK Limited, trading as Taylor & Francis Group.Novel water-soluble thermoresponsive oligomers TO1 and TO2 were obtained by reaction of amidoamine tetramethylcalixresorcinarenes (C1) and tetrapentylcalixresorcinarenes (C5) with ethylene glycol diglycidyl ether. The compounds were characterised by 1H and FT-PGSE NMR, FTIR, static light scattering and elemental analysis. The thermoresponsive properties of oligomers were investigated by spectrophotometry, DLS, FT-PGSE NMR and TEM. The cloud points of oligomers (43 °C for TO1 (5 mg/ml) and 41 °C for TO2 (1.2 mg/ml), respectively) were determined. The influence of salts effect on TO2 cloud points was investigated. The binding of anti-inflammatory drug naproxen (Nap) at 20 °C by TO1 and TO2 and its partial release at cloud points of oligomers in aqueous solution are observed using fluorescence and FT-PGSE NMR methods. New example of creating of thermoresponsive macrocyclic systems on the basis of amidoamine calixresorcinarenes with possibility of substrate binding and release under the influence of termo-stimuli in an aqueous solution was shown

Supramolecular nanoscale systems based on amphiphilic tetramethylensulfonatocalix[4]resorcinarenes and cationic polyelectrolyte with controlled guest molecule binding

© 2016 Informa UK Limited, trading as Taylor & Francis Group.The water-soluble tetramethylensulfonatocalix[4]resorcinarene with methyl (C1) and pentyl (C5) substitutes on the lower rim forms colloid nanoscale aggregates with poly(diallyldimethylammonium chloride) (PDDA) in aqueous solutions. The size and stability of nanoparticles depend on concentrations of the components and their ratio in the ‘calixarene-polymer’ system. Ternary supramolecular complexes «polymer–macrocycle–guest molecule L-tryptophan (Trp) in conditions of spontaneous pH (3.80 and 4.78 for C1-PDDA and C5-PDDA systems, respectively) in an aqueous solution and in phosphate buffer (pH 7) were investigated by fluorescence method. The addition of the third component–PDDA–to the «non-aggregated C1–Trp» associates leads to the release of Trp in all studied conditions. The possibility of the «binding–release» process of L-tryptophan in «C5–Trp» associates after PDDA addition in the ternary complex is achieved and controlled by the structure of the macrocyclic self-associates and pH conditions

Thiacalix[4]monocrowns substituted by sulfur-containing anchoring groups: New ligands for gold surface modification

Crown containing calix[4]arenes 2a-f with thioacetate-functionalized carbon chains on lower rim in 1,3-alternate conformation were synthesized starting from corresponding bromo-derivatives. The use of thiacalixcrowns monolayer films improves adhesion between gold and biomolecules (cytochrome c and catalase). The structures of these monolayers were analyzed using contact angle measurements and AFM visualization by discontinuous contact mode. © ISUCT Publishing