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Robert McElroy C.,University of Venice | Arico F.,University of Venice | Benetollo F.,CNR Institute of Inorganic and Surface Chemistry | Tundo P.,University of Venice
Pure and Applied Chemistry | Year: 2012

A number of six-membered cyclic carbamates (oxazinanones) were synthesized from the reaction of a primary amine or hydrazine with a dicarbonate derivative of 1,3-diols in a one-pot reaction, in good yield, short time span, and in the absence of a solvent. The reaction proceeds in two steps: an intermolecular reaction to give a linear intermediate and an intramolecular cyclization to yield the cyclic carbamate. This is the first example of a carbonate reacting selectively and sequentially, firstly at the carbonyl center to form a linear carbamate and then as a leaving group to yield a cyclic carbamate. © 2011 IUPAC.

Battistel D.,University of Venice | Daniele S.,University of Venice | Gerbasi R.,CNR Institute of Inorganic and Surface Chemistry | Baldo M.A.,University of Venice
Thin Solid Films | Year: 2010

In this paper, physiochemical properties of amorphous alumina thin films, grown by the metal organic chemical vapour deposition process on the surface of platinum (Pt/Al2O3) and stainless steel (SS/Al2O3), were investigated in aqueous media. The study was performed by the use of scanning electrochemical microscopy (SECM), which allowed obtaining information on uniformity, topography and chemical stability/reactivity of the alumina coatings with high spatial resolution. In particular, the effects due to local acid, base and fluoride ions attack on alumina layers of thickness of about 250 nm (in the Pt/Al2O3 sample) and 1000 nm (in the SS/Al2O3 sample) were investigated. In the acid and base attack, high concentrations of H2SO4 and KOH were electrogenerated locally by the use of a 25 μm diameter platinum microelectrode. The latter was also used as SECM tip to monitor the chemical effect on the alumina layers. It was found that, regardless of the thickness of the film, alumina provided good resistance against local attack of concentrated H2SO4; instead, the film dissolved when subjected to KOH attack. The dissolution rate depended on several experimental parameters, such as SECM-tip to substrate distance, electrolysis time and alumina film thickness. The alumina layer proved also relatively poor resistance to etching in 0.1 M NaF solutions. © 2009 Elsevier B.V. All rights reserved.

Tisato F.,CNR Institute of Inorganic and Surface Chemistry | Marzano C.,University of Padua | Porchia M.,CNR Institute of Inorganic and Surface Chemistry | Pellei M.,University of Camerino | Santini C.,University of Camerino
Medicinal Research Reviews | Year: 2010

Copper is found in all living organisms and is a crucial trace element in redox chemistry, growth and development. It is important for the function of several enzymes and proteins involved in energy metabolism, respiration, and DNA synthesis, notably cytochrome oxidase, superoxide dismutase, ascorbate oxidase, and tyrosinase. The major functions of copper - biological molecules involve oxidation-reduction reactions in which they react directly with molecular oxygen to produce free radicals. Therefore, copper requires tightly regulated homeostatic mechanisms to ensure adequate supplies without any toxic effects. Overload or deficiency of copper is associated, respectively, with Wilson disease (WD) and Menkes disease (MD), which are of genetic origin. Researches on Menkes and Wilson disorders have provided useful insights in the field of copper homeostasis and in particular into the understanding of intracellular trafficking and distribution of copper at molecular levels. Therapies based on metal supplementation with copper histidine or removal of copper excess by means of specific copper chelators are currently effective in treating MD and WD, respectively. Copper chelation therapy is now attracting much attention for the investigation and treatment of various neurodegenerative disorders such as Alzheimer, Parkinson and CreutzfeldtJakob. An excess of copper appears to be an essential co-factor for angiogenesis. Moreover, elevated levels of copper have been found in many types of human cancers, including prostate, breast, colon, lung, and brain. On these basis, the employment of copper chelators has been reported to be of therapeutic value in the treatment of several types of cancers as anti-angiogenic molecules. More recently, mixtures of copper chelators with copper salts have been found to act as efficient proteasome inhibitors and apoptosis inducers, specifically in cancer cells. Moreover, following the worldwide success of platinum(II) compounds in cancer chemotherapy, several families of individual copper complexes have been studied as potential antitumor agents. These investigations, revealing the occurrence of mechanisms of action quite different from platinum drugs, head toward the development of new anticancer metallodrugs with improved specificity and decreased toxic side effects. © 2009 Wiley Periodicals, Inc.

Donoli A.,University of Padua | Bisello A.,University of Padua | Cardena R.,University of Padua | Benetollo F.,CNR Institute of Inorganic and Surface Chemistry | And 2 more authors.
Organometallics | Year: 2011

Novel biferrocenyl complexes of s- and as-dihydroindacenes have been prepared and the charge transfer properties of their mono- and dicationic derivatives, selectively generated by one-electron and two-electron oxidation, have been investigated. Mixed-valence cations are generated by chemical oxidation using acetylferricinium as an oxidant agent and monitored in the visible, IR, and near-IR regions. The IT bands in the near-IR spectra are rationalized in the framework of Marcus-Hush theory. The rigid and planar indacene platform bonded to two terminal redox groups displays a redox chemistry that can be switched from single two-electron transfers to two successive one-electron transfers by changing the supporting electrolyte from nBu 4NPF6 to nBu4NB(C6F 5)4. © 2011 American Chemical Society.

Bolzati C.,CNR Institute of Inorganic and Surface Chemistry | Carta D.,University of Padua | Salvarese N.,University of Padua | Refosco F.,CNR Institute of Inorganic and Surface Chemistry
Anti-Cancer Agents in Medicinal Chemistry | Year: 2012

Currently, receptor based radiopharmaceuticals have received great attention in molecular imaging and radiotherapy of cancer, and provide a unique tool for target-specific delivery of radionuclides to pathological tissues. In this context, receptor binding peptides represent an attractive class of target vectors for Nuclear Medicine purposes. The rich chemistry of the group 7 elements elaborated in past years, has allowed the development of different procedures for the preparation of radiolabeled peptides in high yield. This, joint to the use of solid-phase peptide synthesis, has opened the possibility to explore new strategies for approaching the design of new class of radiolabeled receptor-targeted peptides, and to create new versatilities in targeting vehicle design e.g. in synthesis of metal-cyclized peptides or of multivalent targeting agents. This review provides an overview on several aspects of the development of new 99mTc/ 188Re-peptide based target specific radiopharmaceuticals, in particular on the synthetic strategies employed for modifying molecular vectors, and the application of the different metal-cores and/or building block for preparing high specific activity agents. © 2012 Bentham Science Publishers.

Favaro M.,CNR Institute of Inorganic and Surface Chemistry | Guastoni A.,University of Padua | Marini F.,University of Rome La Sapienza | Bianchin S.,CNR Institute of Inorganic and Surface Chemistry | Gambirasi A.,CNR Institute of Inorganic and Surface Chemistry
Analytical and Bioanalytical Chemistry | Year: 2012

In this paper, we propose an analytical methodology for attributing provenance to natural lapis lazuli pigments employed in works of art, and for distinguishing whether they are of natural or synthetic origin. A multitechnique characterization of lazurite and accessory phases in lapis lazuli stones from Afghan, Siberian and Chilean quarries, on the pigments obtained by their purification, and on synthetic ultramarine pigments was performed. According to the results obtained, infrared spectroscopy is not a suitable technique for distinguishing the provenance of lapis lazuli, but a particular absorbance band makes it relatively easy to determine whether it is of natural or synthetic origin. On the other hand, EDS elemental composition and XRD patterns show the presence of specific mineral phases associated with specific lapis lazuli sources, and can be used to distinguish the provenance of the stones as well as-albeit to a lesser extent-the corresponding purified blue pigments. In contrast, FEG-SEM observations clearly show different stone textures depending on their provenance, although these distinctive features do not persist in the corresponding pigments. PCA analyses of EDS data allow Afghan lapis lazuli stone to be distinguished from Chilean and Siberian ones, and can distinguish between the pigments resulting from their purification as well as synthetic blue ones. Although this methodology was developed using a limited number of samples, it was tested on lapis lazuli pigments collected from three paintings (from the fourteenth to sixteenth centuries) in order to perform a preliminary validation of the technique, and based on the results, the provenance of the blue pigments employed in those artworks is proposed. Finally, upon analytically monitoring the process of purifying lapis lazuli to obtain the corresponding pigments, it was found that ion-exchange reactions occur between the alkali modifiers of silicate/aluminosilicate phases and free carboxylic acids present in the doughy mixture of natural terpenes and ground stone, namely pastello. These reactions favor (i) the retention of silicate phases in the organic mixture and (ii) the selective extraction of lazurite due to the formation of Brønsted acidic sites [Al(OH)Si], which are responsible for its high hydrophilicity in comparison to the one of the other species present in the lapis lazuli stone. [Figure not available: see fulltext.] © 2011 Springer-Verlag.

Passarelli V.,Centro Universitario Of La Defensa | Benetollo F.,CNR Institute of Inorganic and Surface Chemistry
Inorganic Chemistry | Year: 2011

The coordination abilities of the novel N,N′-diphosphino- silanediamine ligand of formula SiMe2(NtolPPh2) 2 (SiNP, 1) have been investigated toward rhodium, and the derivatives [RhCl(SiNP)]2 (2), [Rh(SiNP)(COD)][BF4] (3), and Rh(acac)(SiNP) (4) have been synthesized. The stability of the dinuclear frame of [RhCl(SiNP)]2 (2) toward incoming nucleophiles has been shown to be dependent on their π-acceptor ability. Indeed, the mononuclear complexes RhCl(SiNP)(L) (L = CO, 5; CNtBu, 6) have been isolated purely and quantitatively upon reaction of 2 with CO and CNtBu, respectively. Otherwise, PPh3 and RhCl(SiNP) equilibrate with Rh(Cl)(SiNP)(PPh3) (7). Carbon electrophiles such as MeI and 3-chloro-1-proprene afforded the oxidation of rhodium(I) to rhodium(III) and the formation of RhCl2(η3-C3H 5)(SiNP) (8) and Rh(Me)(I)(SiNP)(acac) (10), respectively. The methyl derivative 10 is thermally stable and does not react either with CO or with CNtBu even in excess. Otherwise, RhCl2(η3- C3H5)(SiNP) (8) is thermally stable but reacts with CO, affording 3-chloro-1-proprene and RhCl(SiNP)(CO) (5). Finally, upon reaction of Rh(acac)(SiNP) (4) and 3-chloro-1-proprene, RhCl(acac)(η1-C 3H5)(SiNP) (9a) and [Rh(acac)(η3-C 3H5)(SiNP)]Cl (9b) could be detected at 233 K. At higher temperatures, 9a and 9b smoothly decompose, affording the dinuclear derivative [RhCl(SiNP)]2 (2) and the CC coupling product 3-allylpentane-2,4- dione. © 2011 American Chemical Society.

Vigato P.A.,CNR Institute of Inorganic and Surface Chemistry | Peruzzo V.,CNR Institute of Inorganic and Surface Chemistry | Tamburini S.,CNR Institute of Inorganic and Surface Chemistry
Coordination Chemistry Reviews | Year: 2012

The most relevant results published from 2006 up to 2010 are reported; they especially regard the synthetic pathway and the structural and physico-chemical aspects of planar or tridimensional cyclic and acyclic compartmental Schiff bases, their polyamine homologs and related polynuclear complexes.Particular emphasis is placed on the role of the shape of the coordinating ligands and of the different metal ions in directing the synthesis totally or preferentially toward specific entities. The multiple self-condensation of appropriately designed polyformyl- with polyamine-precursors or the templating capability of different metal ions in directing the synthesis pathway toward specific compounds are evaluated together with the possibilities offered by the transmetalation reactions in the obtainment of not otherwise accessible complexes.The ability of compartmental ligands to bind two or more metal ions in close proximity into two identical or different compartments, the presence of different bridging groups inside these coordination moieties, the insertion of peripheral functionalities and their relevance in modulating the type and the extent of mutual interaction between the metal ions inside the adjacent chambers and in producing quite sophisticated architectures is reviewed.The selective generation of helically folden strands, which can modify their structure into a linear one upon complexation and to return to the helical form by demetalation cycling between contracted and extended structures, is also reported.Also the ability of acyclic and macrocyclic ligands without endogenous bridging groups to incapsulate two or more metal ions and to act as building blocks in the construction of oligomeric or polymeric systems is also analyzed.The magneto-structural correlation of the homo- and hetero-dinuclear or -polynuclear complexes, together with the photochemical and photophysical properties resulting from these specific recognition processes, were also considered. The insertion of specific linkers, capable of evolving dinuclear complexes into oligomeric or polymeric ones or into unusual structures with the consequent modification of their properties, is also reported. Also, the design and diversification of the two adjacent sites, aimed at enhancing the ability of these ligands to act as selective transfers of specific cations, anions or salts across liquid membranes are discussed. Finally, the specific reactivity and catalytic properties arising from di- or polynuclear aggregations are considered. © 2012 Elsevier B.V.

Mattarozzi L.,CNR Institute for Energetics and Interphases | Cattarin S.,CNR Institute for Energetics and Interphases | Comisso N.,CNR Institute for Energetics and Interphases | Guerriero P.,CNR Institute of Inorganic and Surface Chemistry | And 3 more authors.
Electrochimica Acta | Year: 2013

The performances of electrodeposited CuNi alloys in the electrochemical reduction of nitrates and nitrites in alkaline electrolyte have been studied and compared with those of the individual metals. CuNi alloys have been deposited from a citrate bath and characterized by SEM-EDS: A large range of compositions (30-95 Cu at.%) was prepared by varying the deposition potential. Application to the electrochemical reduction of nitrate (and nitrite) shows that Cu-rich alloys (Cu = 70-95 at.%) work better than Cu: voltammetric waves show a lower overpotential in the order of 120-150 mV at fresh electrodes; chronoamperometries show higher initial currents and less severe current decay during prolonged polarization; electrolyses reduce more rapidly and with a better selectivity nitrate to ammonia. © 2012 Elsevier Ltd. All Rights Reserved.

Benetollo F.,CNR Institute of Inorganic and Surface Chemistry | Peruzzo V.,CNR Institute of Inorganic and Surface Chemistry | Tamburini S.,CNR Institute of Inorganic and Surface Chemistry | Vigato P.A.,CNR Institute of Inorganic and Surface Chemistry
Inorganic Chemistry Communications | Year: 2012

The end-off acyclic compartmental ligands H5-LA and H6-LB have been prepared by [2 + 1] or [3 + 1] condensation of the appropriate amounts of pyridoxal hydrochloride with 1,3-diamine-2-propanol and 3-formylsalicylic acid with tris-2-(aminoethyl)amine, respectively. The ligand H5-LA, which contains two adjacent N2O chambers, bears an endogenous hydroxo potentially bridging group and H6-LB, which contains an inner N 4O3 and an outer O3O3 compartment, bears three potentially bridging phenolic groups. The complexes [Mn 2(H2-LA)(CH3COO)2](Cl) •5H2O and [Mn(H3-LB)]•0.25H 2O•CH3OH have been obtained by the template condensation of the appropriate amine and formyl precursors in the presence of Mn(CH3COO)2•4H2O in methanol. When recrystallized [Mn2(H2-LA)(CH 3COO)2](Cl)•5H2O undergoes demetalation reaction giving rise to [Mn(H3-LA)(H2O) 2](Cl)(H2O) where the octahedral manganese(III) ion is surrounded by two axial water molecules trans with respect to the equatorial plane formed by the two imine nitrogen atoms and the two phenolate oxygen atoms of the Schiff base [H3-LA]2-. The central -OH group of [H3-LA]2-does not participate in the coordination. In [Mn(H3-LB)]•0.25H 2O•CH3OH the octahedral environment about the manganese(III) ion is reached by the coordination of three carboxylate and three phenolate oxygen atoms of the external O3O3 site and the three imine nitrogen atoms are protonated. © 2011 Elsevier B.V. All rights reserved.

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