Examinando por Autor "Toledo, Dominique"
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Ítem Comparitive study on structural, magnetic and spectroscopic properties of four new copper(II) coordination polymers with 4′-substituted terpyridine ligands(Academic Press Inc., 2017-09) Toledo, Dominique; Vega, Andrés; Pizarro, Nancy; Baggio, Ricardo; Peña, Octavio; Roisnel, Thierry; Pivan, Jean-Yves; Moreno, YankoThe synthesis and characterization of four copper(II) complexes with different terpyridyl ligands have been carried out, their crystal and molecular structures determined and their magnetic and luminescent properties analyzed. The ligands used in the coordination reactions were 4′-(3-methyl-2-thienyl)-4,2′:6′,4''-terpyridine (4-stpy), -4′-(4-quinolinyl)-4,2′:6′,4''-terpyridine (4-qtpy), 4′-(4-quinolinyl)-3,2′:6′,3''-terpyridine (3-qtpy, unreported so far) and 4′-(4-cyanophenyl)-4,2′:6′,4''-terpyridine (4-cntpy); the reaction of these ligands with Cu(II)-hexafluoroacetylacetone (Cu(hfacac)2) gives rise to coordination polymers Cu(4-stpy)(hfacac)2 (I), Cu(4-qtpy)(hfacac)2 (II), Cu(3-qtpy)(hfacac)2 (III) and Cu(4-cntpy)(hfacac)2 (IV). The different location of the nitrogen atom of the outer ring is responsible for the different coordination modes. The emission spectra of dichloromethane solutions are consistent with dissociation of the complexes; the emission maxima simulate those of the free ligands. The emission of I, III and IV in the solid state is essentially quenched upon complexation with Cu(II), whereas for compound II an emission at 420 nm is observed. The interaction between copper centers has been related with the coplanarity of terpyridine rings. Complexes I–III exhibit a paramagnetic behavior, while compound IV, with the smallest torsion angle between pyridine moieties, shows an antiferromagnetic behavior described by a dimeric model, with J=−4.38 cm−1, g =2.06 and ρ=0.07. © 2017 Elsevier Inc.Ítem Influence of structural changes on photophysical properties of terpyridine derivates: Experimental studies and theoretical calculations(Elsevier B.V., 2018-02) Toledo, Dominique; Brovelli, Francisco; Soto-Delgado, Jorge; Peña, Octavio; Pivan, Jean-Yves; Moreno, YankoFour terpyridine ligands containing different aryl substituents 4'-(4-quinolinyl)-3,2':6′,3″-terpyridine (3-qtpy), 4'-(4-quinolinyl)-2,2':6′,2″-terpyridine (2-qtpy), 4'-(3-methyl-2-thienyl)-4,2':6′,4″-terpyridine (4-stpy) and 4'-(3-methyl-2-thienyl)-2,2':6′,2″-terpyridine (2-stpy) were synthesized in a one-pot procedure and characterized by elemental analysis, FT-IR and 1H- and 13C NMR spectroscopy. Additionally, the 2-stpy structure was confirmed by single crystal X-ray diffraction analysis. The influence of the N-position in the tpy and aryl substituents on the photophysical properties was systematically investigated by spectroscopic methods and simulated by density functional theory (DFT and TD-DFT) calculations. Thermal stability was observed until about 280 °C, making these kind of ligands interesting candidates for their use as complex ligands, which are obtained by solvothermal synthesis under temperatures of about 180 °C. The electrochemical behavior was also investigated. All molecules show irreversible anodic and cathodic voltammetric peaks in organic medium. © 2017Ítem Magnetic analysis of two [cobalt-imidazole-carboxylate] complexes: Orbital contribution(Sociedad Chilena de Quimica, 2018) Arrué, Ramón; Toledo, Dominique; Peña, Octavio; Pivan, Jean-Yves; Reis, Mario; Moreno, YankoTwo coordination complexes, Co(HIMC)2(H2O)2 (1) and Co(H2IMDC)2(H2O)2 (2), were synthesized by mixing the complex precursor Cobalt(II) hexafluoroacetylacetonate (Co(hfacac)2) with 1H-imidazole-4-carboxylic acid (H2IMC) and 1H-imidazole-4,5-imidazoledicarboxylic acid (H3IMDC) ligands. These compounds have been isolated as neutral, air and thermal stable solid and have been characterized by FT-IR and powder X-Ray diffraction analysis. The thermal stability and magnetic properties were studied in the solid state. Compounds (1) and (2) are mononuclear complexes, where the cobalt ions adopt an distorted octahedral geometry. At low temperature they exhibit a weak antiferromagnetic interaction. The contribution of the angular momentum to the magnetic moment as well as intermolecular interactions were taken into consideration for the quantitative modeling of their magnetic properties. © 2018 Sociedad Chilena de Quimica. All Rights Reserved.Ítem Unusual trinuclear complex of copper(II) containing a 4′-(3-methyl-2-thienyl)-4,2′:6′,4″-terpyridine ligand. Structural, spectroscopic, electrochemical and magnetic properties(Elsevier B.V., 2017-11) Toledo, Dominique; Ahumada, Guillermo; Manzur, Carolina; Roisnel, Thierry; Peña, Octavio; Hamon, Jean-René; Pivan, Jean-Yves; Moreno, YankoWe report the synthesis, characterization, crystal and molecular structure as well as the spectroscopic, electrochemical and magnetic properties of an unexpected trinuclear copper(II) complex (1), made of three Cu(2-TTA)2 units (2-TTA = 2-thenoyltrifluoroacetone) bridged by two 4'-(3-methyl-2-thienyl)-4,2′:6′,4″-terpyridine (4-stpy) ligands. The central Cu(II) atom shows an octahedral geometry, while the lateral metal centers present a slightly distorted square pyramidal coordination sphere. It is suggested that the introduction of the relatively bulky substituent groups (2-thienyl and [sbnd]CF3) in the 2-TTA ligand are responsible of this uncommon coordination mode. The magnetic behavior of 1 is reported in terms of a combination of monomer and dimer units, leading to weak antiferromagnetic interaction (J = −1.93 cm−1). The cyclovoltammogram of 1 exhibits, in the cathodic potential region, three redox events due to Cu2+/Cu+ and Cu+/Cu0 redox couples and to the mono-electronic reduction of the 4-stpy ligand. © 2017 Elsevier B.V.