Determinazione dei residui di Deltametrina nelle ciliegie

This paper describes the determination of residues of the insecticide Deltamethrin in cherries growing in the Bonnanaro area near Sassari (Sardinia - Italy). The analytical procedure for the isolation of the insecticide was developed. The quantitative determinations were carried out by HPLC, with UV detector at 220 nm, on a Perkin-Elmer C18-HS3 column with acetonitrile - water (75: 25) as the mobile phase. A rapid decrease of the concentration of the insecticide with ti me was ascertained; three days after from the treatment the values were significantly lower than those required by the italian law

Hyperpolarization-activated and cyclic nucleotide-gated channels are differentially expressed in juxtaglomerular cells in the olfactory bulb of mice

In the olfactory bulb, input from olfactory receptor neurons is processed by neuronal networks before it is relayed to higher brain regions. In many neurons, hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels generate and control oscillations of the membrane potential. Oscillations also appear crucial for information processing in the olfactory bulb. Four channel isoforms exist (HCN1–HCN4) that can form homo- or heteromers. Here, we describe the expression pattern of HCN isoforms in the olfactory bulb of mice by using a novel and comprehensive set of antibodies against all four isoforms. HCN isoforms are abundantly expressed in the olfactory bulb. HCN channels can be detected in most cell populations identified by commonly used marker antibodies. The combination of staining with marker and HCN antibodies has revealed at least 17 different staining patterns in juxtaglomerular cells. Furthermore, HCN isoforms give rise to an unexpected wealth of co-expression patterns but are rarely expressed in the same combination and at the same level in two given cell populations. Therefore, heteromeric HCN channels may exist in several cell populations in vivo. Our results suggest that HCN channels play an important role in olfactory information processing. The staining patterns are consistent with the possibility that both homomeric and heteromeric HCN channels are involved in oscillations of the membrane potential of juxtaglomerular cells

Electronic structure of oxovanadium(IV) complexes of alpha-hydroxycarboxylic acids

A series of VIVO bis chelated complexes of α-hydroxycarboxylic acids with a 2(COO-, O-) coordination set was analyzed by electronic absorption and EPR spectroscopy in aqueous solution. All the complexes exhibit a square-pyramidal geometry distorted toward trigonal bipyramid. The influence of the distortion of the geometry, as deduced from the steric hindrance produced by the substituents at the α-carbon atom of the ligands, on the spectroscopic parameters has been studied. The observed trends were related to the electronic structure of the metal ion in the distorted geometry

L-mimosine: an amino acid with maltol-type binding properties toward copper(II), oxovanadium(IV) and other metal ions

The complex formation between -mimosine, α-amino-β-(3-hydroxy-4-oxo-1,4-dihydropyridin-1-yl)-propanoic acid, a rare α-amino acid provided with a 3-hydroxypyridin-4(1H)one moiety, and some metal ions — Cu(II), VO(IV), Ni(II) and Zn(II) — was studied by spectroscopic (EPR and electron absorption) and potentiometric techniques in aqueous solution. It was found that -mimosine prefers the maltol-like donor set of the 3-hydroxypyridin-4(1H)one fragment for binding copper(II) and oxovanadium(IV). However, the presence of two alternative donor centres in the ligand, (COO-, NH2) and (CO, O-), both suitable for chelating behaviour, makes possible the formation of very stable polynuclear species in which the -mimosine ligand coordinates at both the (CO, O-) maltol-like and the (COO-, NH2) α-aminocarboxylate sites. Nickel(II) interacts with the ligand, but prefers a mixed bonding mode in the bis chelated species. Zn(II) only forms complexes with the 3-hydroxypyridin-4(1H)one fragment

Tetrahydrogendecavanadate(V) and its binding to glycylglycine

An adduct between the tetrahydrogen form of decavanadate H4V10O282− and glycylglycine, with the stoichiometry Rb2H4V10O28·2Gly-Gly·2H2O, has been isolated and fully characterized. The crystal structure has been determined by X-ray diffraction data. The four hydrogen atoms of the polyvanadate framework could not be located directly, but structural features suggest strongly that they are associated with two triply bridging and two doubly bridging oxygens atoms. Two dipeptide molecules interact with the decavanadate polyanion via a hydrogen bond between O atoms of the carboxylic groups and a couple of doubly bridging surface atoms, which act as acceptors. In addition, there are hydrogen bonding contacts in which the nitrogen atoms and the carbonyl oxygen of the dipeptide molecules take part. IR spectroscopy proved useful in establishing the protonation state of Gly-Gly

Co-ordination ability of Cu²⁺ ion toward the nucleobase-amino acid willardiine

The complex formation between CuII and DL-willardiine [1-(2-amino-2-carboxyethyl)uracil], an analog of phenylalanine containing the uracil residue, was investigated by potentiometric and spectral studies. The results indicate that the primary metal binding site of the ligand is the α-amino-carboxylate chelating set. The uracil moiety, however, can coordinate the metal ion in basic solution giving rise to intermolecular bridging

Molecular structure of a mono-peroxo vanadium(V) complex formed by _D _,_L-lactic acid

The peroxo complex formed by vanadium(V) in the presence of D ,L-lactic acid (H2lact) as heteroligand, K2[{VO(O2)(lact)}2], is described. A single-crystal X-ray diffraction study indicates that the ligand behaves as a bidentate chelator adopting the (O-, COO-) donor set. The complex has a dinuclear core based on the V2O2 cyclic arrangement arising from two vanadium(V) atoms sharing the hydroxyl oxygens of two ligands. The coordination sphere of each vanadium includes two hydroxyl oxygens, an oxygen atom from a carboxylate group, an oxo ligand and two peroxo oxygens. The geometry at the metal ion is severely distorted and, in the ideal limit, it could be described as a trigonal bipyramid, in which one of the equatorial bonds corresponds to the axis joining the vanadium atom and the centre of the peroxo group. A strikingly short interatomic O---O distance, 1.35 Å, is measured for the peroxo group, suggesting both σ- and π-donor ability in the bonding to the metal ion

Binding of oxovanadium(IV) to dipeptides containing histidine and cysteine residues

The complexation of the oxovanadium(IV) ion with five dipeptides containing L-histidine or L-cysteine (GlyHis, HisHis, HisGly, CysGly, GlyCys) was studied. L-histidinamide (HisNH2) was assumed as a model system for dipeptides with L-histidine in the N-terminal position. The study was performed in aqueous solution through the combined application of potentiometric and spectroscopic (electronic absorption and EPR) techniques. The results indicate that simple dipeptides lacking a strong anchoring group can form mono- and bischelated complexes with the VIVO ion if a suitable donor is present in the chain. The ligands behave like amino acids in the acidic and neutral pH range, inhibit the precipitation of hydroxides and suppress the formation of hydrolytic species if at least a fivefold molar excess of ligand is used. In alkaline media all the ligands, except CysGly, promote the deprotonation and N-coordination of the amide group. CysGly forms a bischelated complex with a [2 (NH2, S-)] donor set. The contribution of the deprotonated amide group to the 51V hyperfine coupling constant, Az, as a function of the total equatorial charge of oxovanadium(IV) ion, is discussed. The results have general validity and are useful to predict the geometry and donor set of complexes involving the bonding of the VIVO ion to the deprotonated amide group

Copper(II) complexes of (<i>R</i>,<i>S</i>)-alpha-hydroxymethylornithine and its N^delta-benzoyl derivative

Complex formation between copper(II) and (R,S)-α-hydroxymethylornithine of (R,S)-Nα-benzoyl-α-hydroxymethylornithine was studied in aqueous solution by potentiometric and spectroscopic (electron paramagnetic resonance and electronic absorption) techniques. The results show that the α-hydroxymethyl derivatives of ornithine are coordinated through the alcoholic group to the copper(II) ion in basic solution. Deprotonation and coordination of the α-hydroxymethyl group occurs and yields species with the amino and/or carboxylato groups also bound to the metal ion

Gold Clusters: From the Dispute on a Gold Chair to the Golden Future of Nanostructures

The present work opens with an acknowledgement to the research activity performed by Luciana Naldini while affiliated at the Università degli Studi di Sassari (Italy), in particular towards gold complexes and clusters, as a tribute to her outstanding figure in a time and a society where being a woman in science was rather difficult, hoping her achievements could be of inspiration to young female chemists in pursuing their careers against the many hurdles they may encounter. Naldini’s findings will be a key to introduce the most recent results in this field, showing how the chemistry of gold compounds has changed throughout the years, to reach levels of complexity and elegance that were once unimagined. The study of gold complexes and clusters with various phosphine ligands was Naldini’s main field of research because of the potential application of these species in diverse research areas including electronics, catalysis, and medicine. As the conclusion of a vital period of study, here we report Naldini’s last results on a hexanuclear cationic gold cluster, [(PPh3)6Au6(OH)2]2+, having a chair conformation, and on the assumption, supported by experimental data, that it comprises two hydroxyl groups. This contribution, within the fascinating field of inorganic chemistry, provides the intuition of how a simple electron counting may lead to predictable species of yet unknown molecular architectures and formulation, nowadays suggesting interesting opportunities to tune the electronic structures of similar and higher nuclearity species thanks to new spectroscopic and analytical approaches and software facilities. After several decades since Naldini’s exceptional work, the chemistry of the gold cluster has reached a considerable degree of complexity, dealing with new, single-atom precise, materials possessing interesting physico-chemical properties, such as luminescence, chirality, or paramagnetic behavior. Here we will describe some of the most significant contributions