XII Iberian Meeting of Electrochemistry XVI Meeting of the ...

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XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society O E 03 Potentiometric Determination of Copper with a New Selective Electrode Maximilian N. Kopylovich, a K amran T. Mahmudov, a Matti Haukka, b Konstantin V. Luzyanin, a Armando J. L. Pombeiro a a Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, TU Lisbon, Av. Rovisco Pais, 1049001 Lisbon, Portugal b University of Joensuu, Department of Chemistry, P.O. Box 111, FIN-80101, Joensuu, Finland kamran_chem@mail.ru A new azoderivative of benzoylacetone, namely 1-phenyl-2-(2- hydroxyphenylhydrazo)butane-1,3-dione (H 2 L), was synthesized and shown to exist in solution as a mixture of enol-azo and hydrazo tautomeric forms, the latter being promoted by a decrease in temperature and an increase in solvent polarity. A copper(II) complex with H 2 L was isolated in the solid state and found to be the polymer [Cu 2 (- L) 2 ] n with a binuclear core. The dissociation constants of H 2 L (pK 1 =5.98±0.04, pK 2 =9.72±0.03) and the stability constants of its copper(II) complex (log 1 =11.010.07, log 2 =20.190.08) were determined. A new copper-selective PVC membrane electrode with H 2 L as a carrier was elaborated and its composition was optimized. This electrode has a detection limit of 6.30×10 M Cu(II) at pH 4.0 with response time 10 s and displays a linear EMF vs. log[Cu 2+ ] response over the concentration range 2.0×10 M Cu(II) with a 0, and good selectivity over a wide range of metal ions (e.g. Na + , K + , Ba 2+ , Ca 2+ , Zn 2+ , Cd 2+ , Co 2+ , Mn 2+ , Ni 2+ , Fe 2+ , Al 3+ ). The proposed sensor shows better characteristics than most of its, response time and selectivity over other metal ions. A procedure for the determination of copper(II) in zinc, aluminum and nickel based alloys was also developed showing its high selectivity, sensitivity and reproducibility. Thus, the established method can be used in routine determination of copper in a diversity of objects with environmental, biological, medical or industrial significance without need for preconcentration or pretreatment. Acknowledgements: This work has been partially supported by the Foundation for Science and References [1] Z. Bazooka, Analyst, 1988, 113, 1803. [2] A. Abbaspur, M.A. Kamyabi, Anal. Chim. Acta, 2002, 455, 225. [3] L.P. Singh, J.M. Bhatnagar, Talanta 64, 2004, 313. September, 811, 2010. ISEL - Lisbon 52
XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society O E 04 Redox Properties of Cu(I) Camphor Hydrazone Complexes M. Fernanda N.N. Carvalho, Tiago. A. Fernandes, Adelino M. Galvão CQE, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais 1049-001 Lisboa, Portugal fcarvalho@ist.utl.pt Aiming at get an insight into the redox properties of Cu(I) camphor hydrazone compounds we studied the electrochemical behavior of the one-dimensional coordination polymers [{CuX} 2 (YNC 10 H 14 O)] n (X=Cl: Y=NMe 2 1a; Y=NHMe 1b, Y=NH 2 1c; X=Br: Y=NH 2 2c) [1] and dimers [Cu(YNC 10 H 14 -X)] (X=Cl: Y=NMe 2 3a; Y=NHMe 3b; X=Br: Y=NMe 2 4a; Y=NHMe 4b) [2] by cyclic voltammetry and controlled potential electrolysis (CPE). As a general trend the camphor hydrazone Cu(I) complexes display one cathodic and one anodic processes (Table 1). The cathodic processes occur at potential values in the range of the corresponding free ligand suggesting a ligand based process. Table 1 - Cyclic voltammetry data a for complexes [{CuX} 2 (YNC 10 H 14 O)] n and [Cu(YNC 10 H 14 -X)] E ½ red (V) E ½ ox (V) X Y Polymer Dimer Polymer Dimer Cl NMe 2 -2,04 -2,07 0.61 0.60 Cl NHMe -2.12 b, d -2.18 b,d 0.58 0.62 Cl NH 2 c 0.63 Br NMe 2 -2,09 0.65 Br NHMe -2.23 b,d 0.67 Br NH 2 -1,96 d 0.62 a Pt wire as electrode and [NBu 4 ](BF 4 ] (0.2M) in THF using as electrolyte. Values measured in Volt (± 10 mV). b Irreversible wave. c Not observed within the potential range available. d Another cathodic wave is observed at lower potential. The anodic processes are metal based involving transfer of two electrons per mole in the dimer species. CPE performed at the potential of the anodic process in coordination polymers is masked by chemical reactivity. Acknowledgments: To Fundação para a Ciência e Tecnologia (F CT) for financial support to Project PPCDT 58119/QUI/2004 and a PhD grant to T.A. Fernandes (SFRH/BD/48331/2008). References [1] M.F.N.N. Carvalho, T.A. Fernandes, A.M. Galvão, H.-A. Krug von Nidda, M.A.P. Sampaio, Inorganica Chimica Acta, 2010, 363, 7176. [2] M.F.N.N. Carvalho, M.T. Duarte, T.A. Fernandes, A.M. Galvão, A. M. Botelho do Rego, unpublished work. September, 811, 2010. ISEL - Lisbon 53
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