Search results for "ionic"
showing 10 items of 2016 documents
Characterization of isomeric 1,2,4-oxadiazolyl-N-methylpyridinium salts by electrospray ionization tandem mass spectrometry.
2007
The mass spectrometric behavior of 1,2,4-oxadiazolyl- N-methylpyridinium salts has been investigated. These substances are of current interest as perspective ionic liquids, compounds used as green solvents for synthesis, and for their catalytic properties. The studies have been developed through electrospray ionization tandem mass spectrometry (ESI-MS/MS) experiments. The obtained results demonstrate a ready distinction between the two isomeric classes, 3- N-methylpyridinium- and 5- N-methylpyridinium-1,2,4-oxadiazoles, is possible through ESI-MS/MS experiments. A deeper investigation on the principal fragmentation pathways of characteristic ions has been also developed.
Recognition of G-quadruplex DNA by triangular star-shaped compounds: with or without side chains?
2011
International audience; We report the synthesis of two new series of triangular aromatic platforms, either with three aminoalkyl side chains (triazatrinaphthylene series, TrisK: six compounds), or without side chains (triazoniatrinaphthylene, TrisQ). The quadruplex-DNA binding behavior of the two series, which differ essentially by the localization of the cationic charges, was evaluated by means of FRET-melting and G4-FID assays. For the trisubstituted triazatrinaphthylenes (TrisK), the length of the substituents and the presence of terminal hydrogen-bond-donor groups (NH(2)) were shown to be crucial for ensuring a high quadruplex affinity (ΔT(1/2) values of up to 20 °C at 1 μM for the best…
Pyrophosphate-mediated magnetic interactions in Cu(II) coordination complexes.
2010
The reaction in water of Cu(NO(3))(2)·2.5H(2)O with 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), or 1,10-phenanthroline-5-amine (phenam), and sodium pyrophosphate (Na(4)P(2)O(7)), at various pHs, afforded three new copper(II)-pyrophosphate complexes, namely, {[Cu(bipy)(cis-H(2)P(2)O(7))](2)}·3H(2)O (1a), {[Cu(phen)(H(2)O)](4)(HP(2)O(7))(2)}(ClO(4))(2)·4H(2)O (2), and {[Cu(2)(phenam)(2)(P(2)O(7))](2)·25H(2)O}(n) (3). A solvent free crystalline phase of 1a was also isolated with formula {[Cu(bipy)(trans-H(2)P(2)O(7))](2)} (1b), which can be regarded as a pseudo-polymorph of 1a. Single crystal X-ray analyses revealed these compounds to have uncommon molecular architectures, with 3 being…
Development of Bimetallic Titanocene−Ruthenium−Arene Complexes As Anticancer Agents: Relationships between Structural and Biological Properties
2010
A series of bimetallic titanium-ruthenium complexes of general formula [(η(5)-C(5)H(5))(μ-η(5):κ(1)-C(5)H(4)(CR(2))(n)PR'R'')TiCl(2)](η(6)-p-cymene)RuCl(2) (n = 0, 1, 2 or 4; R = H or Me; R' = H, Ph, or Cy; R'' = Ph or Cy) have been synthesized, including two novel compounds as well as two cationic derivatives of formula [(η(5)-C(5)H(5))(μ-η(5):κ(1)-C(5)H(4)(CH(2))(n)PPh(2))TiCl(2)] [(η(6)-p-cymene)RuCl](BF(4)) (n = 0 or 2). The solid state structure of two of these compounds was also established by X-ray crystallography. The complexes showed a cytotoxic effect on human ovarian cancer cells and were markedly more active than their Ti or Ru monometallic analogues titanocene dichloride and RA…
Volumetric properties of binary mixtures of ionic liquid 1-butyl-3-methylimidazolium octylsulfate with water or propanol in the temperature range of …
2006
Abstract Densities of 1-butyl-3-methylimidazolium octylsulfate ([bmim][OcOSO3]) solutions in water and 1-propanol have been measured with an oscillating-tube densimeter at temperatures from 278.15 K to 328.15 K. From these densities, apparent molar volumes Vϕ of [bmim][OcOSO3] in both solvents have been calculated, and its dependence on the molality has been treated with the Redlich and Meyer equation. Debye–Huckel limiting slopes for 1-propanol at working temperatures have been calculated, and apparent molar volumes of [bmim][OcOSO3] at infinite dilution V ϕ ∘ in both solvents have been evaluated. The partial molar volume at infinite dilution of [bmim][OcOSO3] in water is higher than in 1-…
Thermodynamic studies of actinide complexes. 1. A reappraisal of the solution equilibria between plutonium(IV) and ethylenediaminetetraacetic acid (E…
2007
Abstract A detailed reevaluation of the complexation equilibria of plutonium(IV) with the polyaminocarboxylic sequestering agent EDTA4− has been performed in 1 M (H,K)NO3 media at 298 K by means of visible absorption spectrophotometry and glass-electrode potentiometry at millimolar concentration levels. The high binding affinity even under strongly acidic conditions supports the exclusive formation of the neutral Pu(EDTA) complex over the range 0.01 ≤ [H+] ≤ 0.9 M with an apparent formation constant of log β110 = 25.8(1) at 0.9 M HNO3. Extrapolation to zero ionic strength using the SIT approach provides the first ever-reported NEA–TDB compliant estimate of β 110 0 ( log β 110 0 = 32.2 ( 3 )…
Molecular characterization of α,β-poly[( N -hydroxyethyl)- dl –aspartamide] by light scattering and viscometry studies
2000
Abstract α,β-poly[(N-hydroxyethyl)- dl -aspartamide] (PHEA) is a new synthetic polymer which is of interest in biomedical applications. In this paper, the molecular characterization of PHEA by multi-angle laser light scattering and viscometry off-line and on-line to a size exclusion chromatography system is reported. These techniques furnish an exhaustive and consistent characterization of the PHEA polymer. The fractionation of the PHEA macromolecules was relatively simple. Using an aqueous mobile phase of medium ionic strength, the elution was substantially regular and the macromolecules were not aggregate. The molar mass M of four PHEA samples approximately ranges from 46 to 53 K g/mol, t…
Synthesis, characterization and properties of functional star and dendritic block copolymers of ethylene oxide and glycidol with oligoglycidol branch…
2009
Abstract Well-defined, four-arm star block copolymers of ethylene oxide and glycidol were prepared via controlled anionic polymerization using protected glycidol. The length of the poly(ethylene oxide) block was varied from DP = 10 to 50, while the length of the short polyglycidol block remained nearly constant, at DP = 4–6. Star block copolymers with hydroxyl groups at the ends of the arms after conversion to the corresponding alkoxides were used as multifunctional macroinitiators for the sequential polymerization of ethylene oxide and protected glycidol. After deprotection, the branched block copolymers of ethylene oxide and glycidol had narrow molar mass distributions and multiple hydrox…
Apparent Molar Mass of a Polyelectrolyte in an Organic Solvent in the Low Ionic Strength Limit As Revealed by Light Scattering
2013
The apparent molar mass of a partially quaternized poly-2-vinylpyridines (degree of quaternization 4.3% < Q < 35%) in 1-propanol is measured by light scattering at low ionic strength (10–6 M < cs < 10–3 M) as a function of polyion repeat unit concentration (7 × 10–5 monomol/L < cm,p < 4 × 10–2 monomol/L). No dialysis was applied prior to measurements. The apparent molar mass under “salt-free” conditions is smaller than the true molar mass by an order of magnitude, while approaching the true value at higher ionic strength. Concomitant data on the dependence of scattering intensity on scattering wave vector show that the dilute polyelectrolyte solutions are strongly correlated. A recent theor…
Molecular Association of a Nonionic and an Ionic-Induced Surfactant: Cryptand (221D) NaCl in Water
2003
The cryptand 5-decyl-4,7,13,16,21-pentaoxa-1,10-diazabicyclo-[8.8.5] tricosane [221D] strongly resembles a surfactant in its characteristics: it contains a hydrophilic headgroup, the cryptand unit, and a hydrophobic unit, the decyl chain. It is insoluble in water, but in the presence of an appropriate amount of NaCl, as a consequence of the complex formation between 221D and Na+, it becomes soluble and forms aggregates. The aggregates, depending on the NaCl-221D molar ratio, can be considered as mixed ionic nonionic micelles or ionic micelles. The evolution of the aggregate dimensions and their shape has already been studied at two NaCl-221D molar ratios as a function of the 221D concentra…