Synthesis and X-ray structure of tetrakis[μ-(3,4-dimethoxy-α-β-dihydrocinnamato)] dimethanoldicopper(II)

The synthesis, magnetic, and structural properties of the title compound are reported. The crystals are triclinic, space groupP¯1, witha=15.084(2),b=11.820(1),c=7.5253(7) Å, =71.50(1),=77.61(1), =68.68(1)° andZ=1; the structure was solved by Patterson and Fourier methods and refined toR 0.0351 for 4147 observed reflections. The content of the unit cell consists of a centrosymmetrical copper acetate-like molecule in which each copper can be described as square-pyramidally surrounded by four carboxylic oxygens in the basal plane [1.955(2)–1.970(2) Å], one methanolic oxygen in the apical site [2.206(2) Å] and a CuCu interaction of 2.612(5) Å at a sixth position of a distorted octahedron. The dimers are packed by means of hydrogen bonds formed between the methanolic OH group and the carboxylic O(2) atom of one adjacent complex and by normal Van der Waals contacts. The subnormal magnetic moment, characteristic of exchange interactions between the two copper(II) ions, and the energy of the d-d band observed are consistent with the reported dinuclear copper(II) acetate-like structure.     

Insight into the hard-soft acid-base properties of differently substituted phenylhydrazines in reactions with dimethyl carbonate

Following the preliminary studies on the reactivity of the ambident nucleophile phenylhydrazine with dimethyl carbonate, investigations involving para-substituted phenylhydrazines were carried out in order to probe differences in the reactivity within this class of nucleophile. Phenylhydrazines substituted by electron withdrawing or donating substituents showed an increase in reactivity of the phenylhydrazine toward dimethyl carbonate. Under the basic conditions used, all phenylhydrazines displayed hard nucleophilicity, signifying that para-substitution on the phenyl ring has little effect on the hard-soft behavior of this class of nucleophile. This conclusion fits well within the results previously obtained using other para-substituted nucleophiles, i.e., phenols.     

Congruences of lines in {{\mathbb P}^5}, quadratic normality, and completely exceptional Monge–Ampère equations

The existence is proved of two new families of sextic threefolds in , which are not quadratically normal. These threefolds arise naturally in the realm of first order congruences of lines as focal loci and in the study of the completely exceptional Monge–Ampère equations. One of these families comes from a smooth congruence of multidegree (1, 3, 3) which is a smooth Fano fourfold of index two and genus 9.      

Mapping the stability diagram of a digital ion trap (DIT) mass spectrometer varying the duty cycle of the trapping rectangular waveform

In a digital ion trap the beta(r) and beta(z) boundary lines of the stability diagram are determined experimentally using an innovative approach. In the rectangular waveform-driven digital ion trap (DIT) manipulation of the waveform duty cycle allows introduction of a precisely defined DC quadrupole component into the main trapping field. Variation of the duty cycle can be controlled at software level without any hardware modification. The data generated use peptide ions, which produce stability diagrams in good agreement with the theoretical stability diagrams previously determined by simulation studies.     

Differentiation of Vitis vinifera varieties by MALDI-MS analysis of the grape seed proteins

Until now the study of pathogenic related proteins in grape juice and wine, performed by ESI-MS, LC/ESI-MS, and MALDI/MS, has been proposed for differentiation of varieties. In fact, chitinases and thaumatin-like proteins persist through the vinification process and cause hazes and sediments in bottled wines. An additional instrument, potentially suitable for the grape varieties differentiation, has been developed by MALDI/MS for the grape seed protein analysis. The hydrosoluble protein profiles of seeds extract from three different Vitis vinifera grape (red and white) varieties were analyzed and compared. In order to evaluate the environmental conditions and harvest effects, the seed protein profiles of one grape variety from different locations and harvests were studied.     

Synthesis,characterization and antitumor activity of palladium(II) complexes of monoethyl 8-quinolylmethylphosphonate

The complex-forming properties of monoethyl 8-quinolylmethylphosphonate (8-Hmqmp) towards palladium(II) ion have been investigated by reactions of the hydrochloride, 8-Hmqmp · HCl · H₂O, and sodium salt, Na(8-mqmp) · 2H₂O, of this monoester with palladium(II) halide compounds in aqueous solution over a wide pH range. Depending on pH and initial quinolinium and palladium salts, four types of complexes have been formed. Under acidic solution the ion-pair salt complexes [8-H₂mqmp]₂[PdX₄] (1 and 2, pH < 3) and [8-H₂mqmp]₂[Pd₂X₆] (3 and 4, pH ∼ 3), with protonated quinoline ligand as cation and tetrahalopalladate or hexahalodipalladate complex as anion (X = Cl, Br), were isolated. By heating in methanol the chloro complexes 1 and 3 as well as bromo complexes 2 and 4 were converted into the quinolinium salt complexes, [8-H₂mqmp][Pd(8-Hmqmp)X₃], 5 and 6, respectively, containing as anion the quinoliniummethylphosphonatetrihalopalladate complex with palladium bonded at the phosphonic acid moiety. The chelate complex 7, [Pd(8-mqmp)₂], with ligand bonded through the quinoline nitrogen and the deprotonated phosphonic acid oxygen and forming two seven-membered {N,O} chelate rings, was obtained in neutral and basic media. The complexes were identified and characterized by elemental analysis, magnetic and conductance measurements, spectroscopic studies (IR, ¹H NMR, UV–Vis, positive/negative ion FAB MS) and thermal analysis (TG, DTA). As a preliminary screening for their biological activity, complexes were investigated for their ability to inhibit the cancer growth in vitro in the human KB and murine L1210 cell lines. The results obtained were compared with those obtained for the complexes of diethyl 8-quinolylmethylphosphonate (8-dqmp) and monoethyl 2-quinolylmethylphosphonate (2-Hmqmp), and structural factors that determine the complex activity were discussed.     

Mass spectrometry in the characterization of ambers. I. Studies of amber samples of different origin and ages by laser desorption ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization mass spectrometry

Amber is a fossil resin constituted of organic polymers derived through complex maturation processes of the original plant resin. A classification of eight samples of amber of different geological age (Miocene to Triassic) and geographical origin is here proposed using direct mass spectrometric techniques, i.e. laser desorption ionization (LDI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI), in order to obtain a fingerprint related to the amber origin. Differences and similarities were detected among the spectra with the four methods, showing quite complex spectra, full of ionic species in the mass range investigated (up to m/z 2000). The evaluation required statistical analysis involving multivariate techniques. Cluster analysis or principal component analysis (PCA) generally did not show a clear clustering with respect to the age of samples, except for the APPI method, which allowed a satisfying clustering. Using the total ion current (TIC) obtained by the different analytical approaches on equal quantities of the different amber samples and plotted against the age, the only significant correlation appeared to be that involving APPI. To validate the method, four amber samples from Cretaceous of Spain were analyzed. Also in this case a significant correlation with age was found only with APPI data. PCA obtained with TIC values from all the MS methods showed a fair grouping of samples, according to their age. Three main clusters could be detected, belonging to younger, intermediate and older fossil resins, respectively. This MS analysis on crude amber, either solid or extract, followed by appropriate multivariate statistical evaluation, can provide useful information on amber age. The best results are those obtained by APPI, indicating that the quantity of amber soluble components that can be photoionized decreases with increasing age, in agreement with the formation of highly stable, insoluble polymers.