Crystal structures of zinc(II) complexes with β-hydroxypyridinecarboxylate ligands: examples of structure-directing effects used in inorganic crystal engineering.

The coordination properties of four hydroxypyridinecarboxylates, designed for the treatment of iron-overloading conditions as bidentate O,O'-donor ligands, have been studied with Zn in the solid state. The coordination compounds [Zn(A1)(HO)] (1), [Zn(A2)(HO)] (2), [Zn(A3)(HO)]·2HO (3) and [Zn(B1)(HO)]·4HO (4), where the ligands are 1-methyl-4-oxidopyridinium-3-carboxylate (A1, CHNO), 1,6-dimethyl-4-oxidopyridinium-3-carboxylate (A2, CHNO), 1,5-dimethyl-4-oxido-pyridinium-3-carboxylate (A3, CHNO) and 1-methyl-3-oxidopyridinium-4-carboxylate (B1, CHNO), have been synthesized and analysed by single-crystal X-ray diffraction. The ligands were chosen to probe (i) the electronic effects of inverting the positions of the O-atom donor groups (i.

Ultratrace determination of total and available cyanides in industrial wastewaters through a rapid headspace-based sample preparation and gas chromatography with nitrogen phosphorous detection analysis.

A new analytical method for the determination of both available (free and weak acid dissociable, WAD) and total cyanides in industrial wastewaters has been developed. It is based on the static headspace (HS) sampling procedure followed by a GC separation and the selective nitrogen-phosphorous detection (NPD), in which different thermal treatment allows the speciation of total and available cyanides. Detection limits (0.

Perturbations produced by electrospray ionization mass spectrometry in the speciation of aluminium(III)/1,6-dimethyl-4-hydroxy-3-pyridinecarboxylate aqueous solutions.

Electrospray ionization mass spectrometry (ESI-MS) is very often employed to study metal/ligand equilibria in aqueous solution. However, the ionization process can introduce perturbations which affect the speciation results in an unpredictable way. It is necessary to identify these perturbations in order to correctly interpret the ESI-MS speciation results.

Metal-ligand solution equilibria studied by electrospray ionization mass spectrometry: effect of instrumental parameters.

Electrospray ionization mass spectrometry (ESI-MS) is being increasingly employed in the study of metal-ligand equilibria in aqueous solution. In the present work, the ESI-MS spectral changes due to different settings of the following instrumental parameters are analyzed: the solution flow rate (F(S)), the nebulizer gas flow rate (F(G)), the sprayer potential (E), and the temperature of the entrance capillary (T). Twenty-eight spectra were obtained for each of six samples containing aluminum(III) and 2,3-dihydroxypyridine at various pH, in the absence or in the presence of a buffer and of sodium ions.

Evaluation of 2-methyl-3-hydroxy-4-pyridinecarboxylic acid as a possible chelating agent for iron and aluminium.

In view of a possible application to Fe and Al chelation therapy, 2-methyl-3-hydroxy-4-pyridinecarboxylic acid (DT2) was synthesised, and its complex formation, electrochemical and cytotoxic properties were studied. The complexing properties of DT2 towards Fe(III) and Al(III) were investigated in aqueous 0.6 m (Na)Cl at 25 degrees C by means of potentiometric titrations, UV-vis spectrophotometry, and 1H NMR spectroscopy.

Metal-ligand solution equilibria studied by electrospray ionization mass spectrometry: correlation between ion intensity and acid-base equilibria in solution.

Electrospray ionization mass spectrometry (ESI-MS) is increasingly used in the study of metal-ligand equilibria in aqueous solutions. However, the correlation between conditions in solution and mass spectra in the gas phase is far from being completely established. In the present work the equation i = kC(0)f was used to correlate relative ion intensity (i) in an ESI mass spectrum, the stoichiometric concentration (C(0)) in solution of the complex which produced this ion, and the fraction (f) of complex having the same protonation state as that of the ion detected in the spectrum.

Electrospray mass spectrometry (ESI-MS) in the study of metal-ligand solution equilibria.

In the 20 years, since the introduction of electrospray mass spectrometry (ESI-MS), the use of this technique in various fields of inorganic, organometallic, and analytical chemistry has been steadily increasing. In this study, the application of ESI-MS to the study of metal-ligand solution equilibria is reviewed (till 2004 included). In a first section, advantages and drawbacks of ESI-MS in this type of application are described.

Electrospray ionization mass spectrometry in studies of aluminium(III)-ligand solution equilibria.

Electrospray ionization mass spectrometry (ESI-MS) has been applied to the study of solution equilibria between Al(III) and the two ligands 4-hydroxy-3-pyridinecarboxylic acid (4H3P) and 3-hydroxy-4-pyridinecarboxylic acid (3H4P). The results compare well with the speciation data obtained from potentiometric, UV-visible spectroscopy, and NMR measurements. This agreement suggests the applicability of ES-MS to the study of more complicated aluminium-ligand systems.

Chemical characterisation, plant remain analysis and radiocarbon dating of the Venetian "Manna di San Nicola".

A sample of oil coming from the case containing the relics of St. Nicholas the Great, preserved in the church of "San Nicolò al Lido" (Venice, Italy), has been characterised by the determination of its chemical composition, its age (radiocarbon dating) and the presence of particles of biological origin. Experimental results show that the sample is a vegetal oil, with a fatty acids composition modified by natural oxidation processes, containing pollen grains of plants from Northern Italy, and dating around 1300 A.