Search results for "Titration"
showing 10 items of 312 documents
A highly enantioselective abiotic receptor for malate dianion in aqueous solution
2006
The highly enantioselective molecular recognition of the malate dianion by a synthetic receptor in aqueous solution has been studied by potentiometric titrations, mass spectrometry (ESI-MS), diffusion measurements (PGSE NMR) and molecular modeling. Garcia-España Monsonis, Enrique, Enrique.Garcia-Es@uv.es
Digestion-free determination of heavy metals (Pb, Cd, Cu) in honey using anodic stripping differential pulse voltammetry and potentiometric stripping…
1995
Experiments have been carried out to assess the potential of differential pulse voltammetry and potential stripping analysis for determining Pb, Cu and Cd directly in dissolved honey samples using a flow-through cell. With the hanging mercury drop electrode Pb alone can be determined only if the electrode is first modified in-situ with Triton X 100 to increase the separation between the Pb peak and a broad, interfering adsorption peak which overlaps the Cu peak. If the (more sensitive) thin film mercury electrode is used the interference encountered is less so also Cu and Cd can be determined. With potentiometric stripping analysis Cu and Pb can be determined using normal procedures. The de…
Potentiometric, NMR, and Fluorescence-Emission Studies on the Binding of Adenosine 5′-Triphosphate (ATP) by Open-Chain Polyamine Receptors Containing…
2003
The interaction in aqueous solution of adenosine 5′-triphosphate (ATP) with a series of open-chain polyamines linked at one or both ends to anthrylmethyl or naphthylmethyl fragments was followed by potentiometric titration, 1H-, 13C-, and 31P-NMR spectroscopy, and by steady-state fluorescence measurements. The results revealed greater stabilities for the compounds containing one anthracene moiety than for those with one naphthalene moiety, the stabilities of the compounds with both ends N-substituted with naphthylmethyl groups being close to those containing just one anthrylmethyl unit. The 1H-NMR spectra showed that in all systems, there is involvement of π-π stacking interactions in the s…
Synthesis, solid state and solution studies of cobalt(II) complexes with 2-hydroxyiminopropanoic acid
2013
Abstract This paper describes the synthesis of the Zn(II) complex with H2L = 2-hydroxyiminopropanoic acid. The final structure incorporated two linear dimeric anions with two Zn2+ atoms, which are linked by a carbonate anion into a tetranuclear unit. In each dinuclear unit, the two Zn(II) ions are coordinated by three molecules of the doubly deprotonated ligand in two different coordination modes. This result is confirmed both by X-ray crystallography and by ESI-MS investigations of the crystals dissolved in water. Equilibrium studies of the zinc(II) complexes formed by H2L in aqueous solution based on independent pH-metric titrations and zinc ion-selective electrode (ISE) titrations indica…
Thermodynamic study of the interaction of long open-chain polyazaalkanes with cobalt(II) and nickel(II) ions
1993
Complexation equilibria between the open-chain terminally methylated polyamines 1,14-bis(methylamino)-3,6,9,12- tetraazatetradecane (L1), 1,17-bis(methylamino)-3,6,9,12,15-pentaazaheptadecane (L2), 1,20-bis(methylamino)- 3,6,9,12,15,18-hexaazaicosane (L3) and 1,23-bis(methylamino)-3,6,9,12,15,18,21-heptaazatricosane (L4) with Co2+ and Ni2+ have been studied by means of potentiometric and spectrophotometric methods in 0.15 mol dm−3 NaClO4 aqueous solution at 298.15 K The stability constants for the complexes formed have been determined from e.m.f, data. All these ligands form mononuclear ML2+ complexes of similar stability with Co2+ and Ni2+. Binuclear Co2L44+, Ni2L34+ and Ni2L44+ are also f…
Complex formation of copper( ), nickel( ) and zinc( ) with ethylophosphonoacetohydroxamic acid: solution speciation, synthesis and structural charac…
2019
We present herein the thermodynamic and X-ray characterisation of a novel ethyl phosphonohydroxamic acid-based Cu( ) metallacrown, predominating in solution in a broad pH range.
A novel thermodynamic approach for the complexation study of toxic metal cations by a landfill leachate
2018
Landfill leachates can contaminate nearby aquifers. The hazards deriving from this contamination also depend on the chemical speciation of various contaminants. A novel approach is proposed here to face this problem from a chemical thermodynamics point of view. The complexing ability of the soluble fraction of a landfill leachate (collected from Bellolampo, Palermo, Italy) towards Pb2+, Cd2+ and Cu2+ has been investigated at T = 298.15 K in NaClaq at I = 0.1 mol dm−3. The soluble fraction of the landfill leachate was first characterized by different analytical techniques. Then, its acid–base properties were studied by ISE-H+ potentiometric titrations and modelled by the so-called diprotic-l…
Exploring new water soluble bridged dicopper(II) assemblies: Synthesis, structure, spectroscopic characterization, properties, and their interactions…
2021
Abstract Three new water soluble dimetallic copper(II) complexes, [Cu(H2O)5][Cu2(cpdp)(µ-O2As(CH3)2)]2Br2·13.83H2O·0.67CH3OH (1), [Cu2(Hcpdp)(µ-SO4)]·5H2O (2) and [Cu2(cpdp)(µ-pz)]·16H2O (3) (H3cpdp = N,N′-Bis[2-carboxybenzomethyl]-N,N′-Bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol; (CH3)2AsO2− = cacodylate; SO42− = sulfate; pz− = pyrazolate) have been successfully synthesized and characterized for the investigation of coordination/binding aspects with biologically significant monosaccharide, d -glucosamine. Preparation of 1, 2 and 3 has been achieved by carrying out reaction of H3cpdp with stoichiometric quantities of CuCl2·2H2O/NaO2As(CH3)2·3H2O, CuSO4·5H2O and CuCl2·2H2O/1H-pyrazole, respe…
Coordination properties of the ACE inhibitor captopril towards Me2Sn(IV)2+ in aqueous solution, and biological aspects of some dialkyltin(IV) derivat…
2003
Abstract The coordination of Me 2 Sn(IV) 2+ (M) to captopril { N -[( S )-3-mercapto-2-methylpropionyl]- l -proline, H 2 (cap), H 2 L} in aqueous solution was studied by means of potentiometric titration, electrospray mass spectrometry, 1 H-NMR spectroscopy and Mossbauer spectroscopy in the pH range 2–11 ( I =0.1 mol dm −3 NaClO 4 , 298 K). The results obtained with these methods proved that only monomeric complexes are formed in solution. In the acidic pH range, species with a metal-to-ligand ratio of 1:1 exist. The neutral complex ML, similarly to the complex Me 2 Sn(cap) crystallized in the same pH range, adopts a tbp structure with eq S − and ax COO − , while, instead of the coordina…
Solubilization of an Organic Solute in Aqueous Solutions of Unimeric Block Copolymers and Their Mixtures with Monomeric Surfactant: Volume, Surface T…
2008
The ability of aqueous systems, formed by unimeric copolymers and their mixtures with a monomeric surfactant, in solubilizing large quantities of 1-nitropropane (PrNO2) was explored. The copolymers are F68 and L64, which differ for the hydrophilicity, and the surfactant is sodium dodecanoate. For a better understanding of the mechanism of solubilization, thermodynamic (volume and differential scanning calorimetry), spectroscopy (steady-state fluorescence), viscosity, and interfacial investigations were carried out. PrNO2 causes the micellization of the unimeric copolymer, and the required amount of PrNO2 depends on the composition, the copolymer nature, and the temperature. Large quantities…