Search results for "aqueous solution"
showing 10 items of 1610 documents
Hydrolysis and chemical speciation of (C2H5)2Sn2+, (C2H5)3Sn+ and (C3H7)3Sn+ in aqueous media simulating the major composition of natural waters
2001
The hydrolysis of (C 2 H 5 ) 2 Sn 2+ , (C 2 H 5 ) 3 Sn + and (n-C 3 H 7 ) 3 Sn + has been studied, by potentiometric measurements ([H + ]-glass electrode), in NaNO 3 , NaCl, NaCl/Na 2 SO 4 mixtures and in a synthetic seawater (SSWE), as an ionic medium simulating the major composition of natural seawater, at different ionic strengths (0 ≤ I ≤ 5 mol dm -3 ) and salinities (15 ≤ S ≤ 45), and at t = 25 °C. Five hydrolytic species for (C 2 H 5 ) 2 Sn 2+ , three for (C 2 H 5 ) 3 Sn + and two for (C 3 H 7 ) 3 Sn + are found. Interactions with the anion components of SSWE, considered as single-salt seawater, are determined by means of a complex formation model. A predictive equation for the calcul…
Lactate complexes of molybdenum(VI)
1983
Spectrophotometric and cryoscopic studies of the molybdenum(VI)-lactic acid (C3O3H6) system show the existence of three different oxoanion complexes in aqueous solution which have been isolated as [Co(en)3]3+ salts. These are one molybdodilactate {[MoO2(C3O3H42]2−} and two dinuclear 1/1 species: [Mo2O5(C3O3H4)2(H2O)2]2− and [Mo2O3(OH)3-(C3O3H4)2]−. The pH of the medium is the main variable, controlling the formation equilibria which are similar to those previously described for other α-hydroxy-acid ligands.
Novel Three-Dimensional Cage Assembly of amgr;(4)-Carbonato-Bridged Cobalt(II) Compound [Co(2)(bpm)(H(2)O)(2)(CO(3))(OH)]NO(3).4H(2)O.
2001
The new three-dimensional cobalt(II) complex of formula [Co2(bpm)(H2O)2(CO3)(OH)]NO3·4H2O (1) is obtained from aqueous solutions containing cobalt(II) nitrate hexahydrate, 2,2‘-bipyrimidine (bpm), ...
Cu2+-cyclam complex functionalised with naphthylmethyl fluorescent signalling subunits as fluorescent chemosensors for sulfate in aqueous environment.
2000
Abstract The fluorescent behaviour of the polyazacycloalkane containing naphthyl groups 1,4,8,11-tetrakis(naphthylmethyl)-1,4,8,11-tetraazacyclotetradecane (L 1 ) and its Cu 2+ complex in the presence of anions are compared in aqueous environment (THF:water 70:30 v/v, 0.1 mol dm −3 tetrabutylammonium perchlorate, 25°C). The emission fluorescent intensity of the L 1 –Cu 2+ system is selectively enhanced in the presence of sulfate at acid pH.
Heptacoordinated MnIIin oxalate-based bimetallic 2D magnets: synthesis and characterisation of [Mn(L)6][Mn(CH3OH)MIII(ox)3]2(MIII= Cr, Rh; ox = oxala…
2006
Oxalate-based magnets have been known with several different crystallographic structures, from 1D to 3D, but with all of them based in metal ions with octahedral coordination. In this article we report a new bidimensional oxalate-bridged bimetallic magnet where the divalent metal appears heptacoordinated, which has strong effects in the structure and properties of this materials.
Dimensionality Variation in Polymeric Metallo‐Organic Frameworks
2003
Single crystal X-ray crystallography was used to determine the structures of four metallo-organic complexes derived from pyridyl ligands and the metal ions, Cu2+, Zn2+ and Ag+. Two metallo-organic layer framework structures (1 and 3), a strand (2) and a dimer (4) structure were formed when the tetradentate ligands, tetrakis(nicotinoxymethyl)methane (TNM) and tetrakis(isonicotinoxymethyl)methane (TINM), were reacted with the first and second row transition metal cations, copper, silver, and zinc. The choice of anion and ligand was found to affect the outcome of the structure. Contrary to our previous results with the same ligands and similar transition metal cations, no genuine 3D metallo-or…
Aqueous solution chemistry of alkyltin(IV) compounds for speciation studies in biological fluids and natural waters
2012
Abstract Organotin(IV) cations behave as Lewis acids of different strength depending on the charge, according to the following acidity scale: RSn3+ > R2Sn2+ > R3Sn+. For this reason they can react with Lewis bases containing –O, –N, –S donor groups to form complex species of different stability. Complex formation of organotin(IV) moieties with a great number of inorganic and organic ligands in aqueous solution is reviewed here in the light of their environmental and biological impact. To this end, complex species formation was considered in different ionic media and at different ionic strengths, with reference to the composition of natural waters and biological fluids. In particular, the in…
Acid Titrations of poly(dG-dC).poly(dG-dC) in Aqueous Solution and in a w/o Microemulsion
2005
The model polynucleotide poly(dG-dC).poly(dG-dC) (polyGC) was titrated with a strong acid (HCl) in aqueous unbuffered solutions and in the quaternary w/o microemulsion CTAB/n-pentanol/n-hexane/water. The titrations, performed at several concentrations of NaCl in the range 0.005 to 0.600 M, were followed by recording the modifications of the electronic absorption and of the CD spectra (210or = lambdaor =350 nm) upon addition of the acid. In solution, the polynucleotide undergoes two acid-induced transitions, neither of which corresponds to denaturation of the duplex to single coil. The first transition leads to the Hoogsteen type synG.C+ duplex, while the second leads to the C+.C duplex. The…
Sequestering ability of some chelating agents towards methylmercury(II).
2013
A study on the interactions between CH3Hg+ and some S, N and O donor ligands (2-mercaptopropanoic acid (thiolactic acid (H2 TLA)), 3-mercaptopropanoic acid (H2 MPA), 2-mercaptosuccinic acid (thiomalic acid (H3 TMA)), d,l-penicillamine (H2 PSH), l-cysteine (H2 CYS), glutathione (H3 GSH), N,N′-bis(3-aminopropyl)-1-4-diaminobutane (spermine (SPER)), 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid (H6 MLT)) and ethylenediaminetetraacetic acid (H4 EDTA)) is reported. The speciation models in aqueous solution and the possible structures of the complexes formed are discussed on the basis of potentiometric, calorimetric, UV spectrophotometric and electrospray mass spectrometric results. For t…
Ionic and Free Solvent Motion in Poly(azure A) Studied by ac-Electrogravimetry
2011
International audience; This work is focused on the mechanistic aspects of the redox behavior of poly(azure A) taking advantage of the controlled modulation of their oxidation states by ac-electrogravimetry. The originality of this technique is its ability to discriminate between cation and anion involved in the charge compensation process and the accompanying free solvent transfer, directly or indirectly. Two processes were proposed where the faster ionic exchange is considered to be the participation of the anion species acting as counterions whereas the slower one is related to the proton transfer. The proton is implied as reactants for the two electroactive sites identified in the polym…