Synthesis and characterization of COPPER(II) 4´-phenyl-terpyridine compounds and catalytic application for aerobic oxidation of benzylic alcohols

The reactions between 4'-phenyl-terpyridine (L) and nitrate, acetate or chloride Cu(II) salts led to the formation of [Cu(NO3)(2)L] (1), [Cu(OCOCH3)(2)L]center dot CH2Cl2 (2 center dot CH2Cl2)and [CuCl2L]center dot[Cu(Cl)(mu-Cl)L](2) (3), respectively. Upon dissolving 1 in mixtures of DMSO-MeOH or EtOH-DMF the compounds [Cu(H2O){OS(CH3)(2)}L]-(NO3)(2) (4) and [Cu(HO)(CH3CH2OH)L](NO3) (5) were obtained, in this order. Reaction of 3 with AgSO3CF3 led to [CuCl(OSO2CF3)L] (6). The compounds were characterized by ESI-MS, IR, elemental analysis, electrochemical techniques and, for 2-6, also by single crystal X-ray diffraction. They undergo, by cyclic voltammetry, two single-electron irreversible reductions assigned to Cu(II) -> Cu(I)and Cu(I) -> Cu(0) and, for those of the same structural type, the reduction potential appears to correlate with the summation of the values of the Lever electrochemical EL ligand parameter, which is reported for the first time for copper complexes. Complexes 1-6 in combination with TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl radical) can exhibit a high catalytic activity, under mild conditions and in alkaline aqueous solution, for the aerobic oxidation of benzylic alcohols. Molar yields up to 94% (based on the alcohol) with TON values up to 320 were achieved after 22 h.

Tetranuclear COPPER(II) complexes with macrocyclic and open-chain disiloxane ligands as catalyst precursors for hydrocarboxylation and oxidation of alkanes and 1-phenylethanol

Two new tetranuclear complexes [Cu-4(mu-O)(L-1)-Cl-4] and [Cu-4(mu(4)-O)(L-2)(2)Cl-4] (2), where H2L1 is a macrocyclic ligand resulting from [2+2] condensation of 2,6-diformy1-4-methylphanol (DFF) and 1,3-bis(aminopropy1)tetramethyldisiloxane, and HL2 is a 1:2 condensation product: of DFF with trimethylsilyl p-aminobenzoate, have been prepared. The structures of the products were established by Xray diffraction. The complexes have been characterised by FTIR, UV/Vis spectroscopy, ES1 mass-spectrometry and magnetic susceptibility measurements. The latter revealed that the letrftriuclear complexes can be descr bed as two ferromagnetically coupled dinuclear units, in which the two copper(II) ions interact antiferromacinetically. The ccimpi.iunds act as homogeneous catalyst precursors for a number of single-pot reactions, including (I) hydrocarbaxylation, with CO, H2O and K2S2O8, of a variety of linear and cyclic (n = 5-8) alkanes into the corresponding Cn+1 carboxylic acids, (ii) peroxidative oxidation of cyclohexane, and (iii) solvent-free microwave-assisted oxidation of 1-phenyletha.nol.

The solvation and electrochemical behaviour of Copper acetylacetonate complexes in ionic liquids

The behavior of copper(II) complexes of pentane-2,4-dione and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, [Cu(acac)(2) (1) and [Cu(HFacac)(2)(H2O)] (2), in ionic liquids and molecular organic solvents, was studied by spectroscopic and electrochemical techniques. The electron paramagnetic resonance characterization (EPR) showed well-resolved spectra in most solvents. In general the EPR spectra of [Cu(acac)(2)] show higher g(z) values and lower hyperfine coupling constants, A(z), in ionic liquids than in organic solvents, in agreement with longer Cu-O bond lengths and higher electron charge in the copper ion in the ionic liquids, suggesting coordination of the ionic liquid anions. For [Cu(HFacac)(2)(H2O)] the opposite was observed suggesting that in ionic liquids there is no coordination of the anions and that the complex is tetrahedrically distorted. The redox properties of the Cu(II) complexes were investigated by cyclic voltammetry (CV) at a Pt electrode (d = 1 mm), in bmimBF(4) and bmimNTf(2) ionic liquids and, for comparative purposes, in neat organic solvents. The neutral copper(II) complexes undergo irreversible reductions to Cu(I) and Cu(0) species in both ILs and common organic solvents (CH2Cl2 or acetonitrile), but, in ILs, they are usually more easier to reduce (less cathodic reduction potential) than in the organic solvents. Moreover, 1 and 2 are easier to reduce in bmimNTf(2) than in bmimBF(4) ionic liquid. (C) 2013 Elsevier B.V. All rights reserved.

The solvation and redox behaviour of mixed ligand COPPER(II) complexes of acetylacetonate and aromatic dimines in ionic liquids

The behavior of two cationic copper complexes of acetylacetonate and 2,2'-bipyridine or 1,10-phenanthroline, [Cu(acac)(bipy)]Cl (1) and [Cu(acac)(phen)]Cl (2), in organic solvents and ionic liquids, was studied by spectroscopic and electrochemical techniques. Both complexes showed solvatochromism in ionic liquids although no correlation with solvent parameters could be obtained. By EPR spectroscopy rhombic spectra with well-resolved superhyperfine structure were obtained in most ionic liquids. The spin Hamiltonian parameters suggest a square pyramidal geometry with coordination of the ionic liquid anion. The redox properties of the complexes were investigated by cyclic voltammetry at a Pt electrode (d = 1 mm) in bmimBF(4) and bmimNTf(2) ionic liquids. Both complexes 1 and 2 are electrochemically reduced in these ionic media at more negative potentials than when using organic solvents. This is in agreement with the EPR characterization, which shows lower A(z) and higher g(z) values for the complexes dissolved in ionic liquids, than in organic solvents, due to higher electron density at the copper center. The anion basicity order obtained by EPR is NTf2-, N(CN)(2)(-), MeSO4- and Me2PO4-, which agrees with previous determinations. (C) 2013 Elsevier B.V. All rights reserved.

Reactivity of bulky tris(Phenylpyrazolyl) methanesulfonate copper(I) complexes towards small unsaturated molecules

Reaction of the tris(3-phenylpyrazolyl)methane sulfonate species (Tpms(Ph))Li with the copper(I) complex [Cu(MeCN)(4)][PF6] affords [Cu(Tpms(Ph))(MeCN)] 1. The latter, upon reaction with equimolar amounts of cyclohexyl-(CyNC) or 2,6-dimethylphenyl (XylNC) isocyanides, or excess CO, furnishes the corresponding Cu(I)complexes [Cu(Tpms(Ph))(CNR)] (R = Cy 2, Xyl 3) or [Cu(Tpms(Ph))(CO)] 4. The ligated isocyanide in 2 or 3 (or the acetonitrile ligand in 1)is displaced by 3-iminoisoindolin-1-one to afford 5, the first copper(I) complex containing an 3-iminoisoindolin-1-one ligand. The ligated acetonitrile in 1 undergoes nucleophilic attack by methylamine to give the amidine complex [Cu(Tpms(Ph)){MeC(NH)NHMe}] 6, whereas only the starting materials were recovered from the attempted corresponding reactions of 2 and 3 with methylamine. Complexes 1 or 6 form the trinuclear hydroxo-copper(II)species [(mu-Cu){Cu(mu-OH) (2)(Tpms(Ph))}(2)] 7 upon air oxidation in moist methanol. In all the complexes the scorpionate ligand facially caps the metal in the N,N,O-coordination mode.

Greener Selective Cycloalkane Oxidations with Hydrogen Peroxide Catalyzed by Copper-5-(4-pyridyl)tetrazolate Metal-Organic Frameworks

Microwave assisted synthesis of the Cu(I) compound [Cu(µ4-4-ptz)]n [1, 4-ptz = 5-(4-pyridyl)tetrazolate] has been performed by employing a relatively easy method and within a shorter period of time compared to its sister compounds. The syntheses of the Cu(II) compounds [Cu3(µ3-4-ptz)4(µ2-N3)2(DMF)2]n∙(DMF)2n (2) and [Cu(µ2-4-ptz)2(H2O)2]n (3) using a similar method were reported previously by us. MOFs 1-3 revealed high catalytic activity toward oxidation of cyclic alkanes (cyclopentane, -hexane and -octane) with aqueous hydrogen peroxide, under very mild conditions (at room temperature), without any added solvent or additive. The most efficient system (2/H2O2) showed, for the oxidation of cyclohexane, a turnover number (TON) of 396 (TOF of 40 h−1), with an overall product yield (cyclohexanol and cyclohexanone) of 40% relative to the substrate. Moreover, the heterogeneous catalytic systems 1–3 allowed an easy catalyst recovery and reuse, at least for four consecutive cycles, maintaining ca. 90% of the initial high activity and concomitant high selectivity.

Electrorheological characterization of dispersions in silicone oil of encapsulated liquid crystal 4-n-penthyl-4 '-cyanobiphenyl in polyvinyl alcohol and in silica

The electrorheological (ER) effect is known as the change in the apparent viscosity upon the application of an external electric field perpendicular to the flow direction. In this work we present the electrorheological behaviour of suspensions in silicone oil of two different dispersed phases: foams of liquid crystal 4-n-penthyl-4'-cyanobiphenyl (5CB) encapsulated in polyvinyl alcohol (PVA) and nano/microspheres of 5CB encapsulated in silica. We will present the viscosity curves under the application of an electric field ranging between 0 and 3 kV mm(-1). The ER effect was observed for the suspensions of 5CB/PVA but not in the case of 5CB/silica. For the case of the suspensions of 5CB/PVA, the effect of the viscosity of the continuum phase and the concentration of the dispersed phase was analysed, showing that the enhancement of the viscosity of the suspension increases with the concentration, as expected, however the continuum phase viscosity has no significant effect, at least in the investigated viscosity range.

Chemical analysis of 17th century Millefiori glasses excavated in the Monastery of Sta. Clara‐a‐Velha: comparison with Venetian and façon‐de‐Venise production

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro,Área de especialização Cerâmica e Vidro

Sulfonated Schiff base copper(ii) complexes as efficient and selective catalysts in alcohol oxidation: syntheses and crystal structures

The reaction between 2-aminobenzenesulfonic acid and 2-hydroxy-3-methoxybenzaldehyde produces the acyclic Schiff base 2-[(2-hydroxy-3-methoxyphenyl) methylideneamino] benzenesulfonic acid (H2L center dot 3H(2)O) (1). In situ reactions of this compound with Cu(II) salts and, eventually, in the presence of pyridine (py) or 2,2'-bipyridine (2,2'-bipy) lead to the formation of the mononuclear complexes [CuL(H2O)(2)] (2) and [CuL(2,2'-bipy)]center dot DMF center dot H2O (3) and the diphenoxo-bridged dicopper compounds [CuL(py)](2) (4) and [CuL(EtOH)](2)center dot 2H(2)O (5). In 2-5 the L-2-ligand acts as a tridentate chelating species by means of one of the O-sulfonate atoms, the O-phenoxo and the N-atoms. The remaining coordination sites are then occupied by H2O (in 2), 2,2'-bipyridine (in 3), pyridine (in 4) or EtOH (in 5). Hydrogen bond interactions resulted in R-2(2) (14) and in R-4(4)(12) graph sets leading to dimeric species (in 2 and 3, respectively), 1D chain associations (in 2 and 5) or a 2D network (1). Complexes 2-5 are applied as selective catalysts for the homogeneous peroxidative (with tert-butylhydroperoxide, TBHP) oxidation of primary and secondary alcohols, under solvent-and additive-free conditions and under low power microwave (MW) irradiation. A quantitative yield of acetophenone was obtained by oxidation of 1-phenylethanol with compound 4 [TOFs up to 7.6 x 10(3) h(-1)] after 20 min of MW irradiation, whereas the oxidation of benzyl alcohol to benzaldehyde is less effective (TOF 992 h(-1)). The selectivity of 4 to oxidize the alcohol relative to the ene function is demonstrated when using cinnamyl alcohol as substrate.

A study on metallurgy and corrosion of ancient copper-based artefacts from the portuguese territory

Dissertação apresentada para a obtenção do Grau de Doutor em Conservação e Restauro, especialidade Ciências da Conservação, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Heavy-metal resistance in Marinobacter aquaeolei 617 insights into copper resistance

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Biotecnologia

Haemoglobin smart plastic antibody material tailored with charged binding sites on silica nanoparticles: its application as an ionophore in potentiometric transduction

This work uses surface imprinting to design a novel smart plastic antibodymaterial (SPAM) for Haemoglobin (Hb). Charged binding sites are described here for the first time to tailor plastic antibody nanostructures for a large size protein such as Hb. Its application to design small, portable and low cost potentiometric devices is presented. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its ionic interaction with charged vinyl monomers. A neutral polymeric matrix was created around these and the imprinted protein removed. Additional materials were designed in parallel acting as a control: a neutral imprinted material (NSPAM), obtained by removing the charged monomers from the procedure, and the Non-Imprinted (NI) versions of SPAM and NSPAM by removing the template. SEM analysis confirmed the surface modification of the silica nanoparticles. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Electromotive force (emf) variations were detected only for selective membranes having a lipophilic anionic additive in the membrane. The presence of Hb inside these membranes was evident and confirmed by FTIR, optical microscopy and Raman spectroscopy. The best performance was found for SPAM-based selective membranes with an anionic lipophilic additive, at pH 5. The limits of detection were 43.8 mg mL 1 and linear responses were obtained down to 83.8 mg mL 1, with an average cationic slope of +40 mV per decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results.

Protein–polyphenol interaction on silica beads for astringency tests based on eye, photography or reflectance detection modes

Astringency is an organoleptic property of beverages and food products resulting mainly from the interaction of salivary proteins with dietary polyphenols. It is of great importance to consumers, but the only effective way of measuring it involves trained sensorial panellists, providing subjective and expensive responses. Concurrent chemical evaluations try to screen food astringency, by means of polyphenol and protein precipitation procedures, but these are far from the real human astringency sensation where not all polyphenol–protein interactions lead to the occurrence of precipitate. Here, a novel chemical approach that tries to mimic protein–polyphenol interactions in the mouth is presented to evaluate astringency. A protein, acting as a salivary protein, is attached to a solid support to which the polyphenol binds (just as happens when drinking wine), with subsequent colour alteration that is fully independent from the occurrence of precipitate. Employing this simple concept, Bovine Serum Albumin (BSA) was selected as the model salivary protein and used to cover the surface of silica beads. Tannic Acid (TA), employed as the model polyphenol, was allowed to interact with the BSA on the silica support and its adsorption to the protein was detected by reaction with Fe(III) and subsequent colour development. Quantitative data of TA in the samples were extracted by colorimetric or reflectance studies over the solid materials. The analysis was done by taking a regular picture with a digital camera, opening the image file in common software and extracting the colour coordinates from HSL (Hue, Saturation, Lightness) and RGB (Red, Green, Blue) colour model systems; linear ranges were observed from 10.6 to 106.0 μmol L−1. The latter was based on the Kubelka–Munk response, showing a linear gain with concentrations from 0.3 to 10.5 μmol L−1. In either of these two approaches, semi-quantitative estimation of TA was enabled by direct eye comparison. The correlation between the levels of adsorbed TA and the astringency of beverages was tested by using the assay to check the astringency of wines and comparing these to the response of sensorial panellists. Results of the two methods correlated well. The proposed sensor has significant potential as a robust tool for the quantitative/semi-quantitative evaluation of astringency in wine.

Myoglobin-biomimetic electroactive materials made by surface molecular imprinting on silica beads and their use as ionophores in polymeric membranes for potentiometric transduction

Myoglobin (Mb) is among the cardiac biomarkers playing a major role in urgent diagnosis of cardiovascular diseases. Its monitoring in point-of-care is therefore fundamental. Pursuing this goal, a novel biomimetic ionophore for the potentiometric transduction of Mb is presented. It was synthesized by surface molecular imprinting (SMI) with the purpose of developing highly efficient sensor layers for near-stereochemical recognition of Mb. The template (Mb) was imprinted on a silane surface that was covalently attached to silica beads by means of self-assembled monolayers. First the silica was modified with an external layer of aldehyde groups. Then, Mb was attached by reaction with its amine groups (on the external surface) and subsequent formation of imine bonds. The vacant places surrounding Mb were filled by polymerization of the silane monomers 3-aminopropyltrimethoxysilane (APTMS) and propyltrimethoxysilane (PTMS). Finally, the template was removed by imine cleavage after treatment with oxalic acid. The results materials were finely dispersed in plasticized PVC selective membranes and used as ionophores in potentiometric transduction. The best analytical features were found in HEPES buffer of pH 4. Under this condition, the limits of detection were of 1.3 × 10−6 mol/L for a linear response after 8.0 × 10−7 mol/L with an anionic slope of −65.9 mV/decade. The imprinting effect was tested by preparing non-imprinted (NI) particles and employing these materials as ionophores. The resulting membranes showed no ability to detect Mb. Good selectivity was observed towards creatinine, sacarose, fructose, galactose, sodium glutamate, and alanine. The analytical application was conducted successfully and showed accurate and precise results.

Smart Plastic Antibody Material for Hemoglobin Tailored by Silica Surface Imprinting and with Charged Binding Sites: Its use as Ionophore in Potentiometric Transduction

JORNADAS DE ELECTROQUÍMICA E INOVAÇÃO 2013