Browsing by Author "Chavez, Ivonne"

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    A new series of zirconium metallocenes derived from partially alkylated s-indacene with potential applications in the polymerization of ethylene
    (2015) Felipe Araneda, Juan; Morales-Verdejo, Cesar; Adams, Christopher; Martinez-Diaz, Ivan; Chavez, Ivonne; Teresa Garland, Maria; Rojas, Rene S.; Molins, Elies; Manuel Manriquez, Juan
    This contribution describes the synthesis and characterization of a series of zirconium metallocenes derived from partially alkylated s-indacene. The complexes [Cp*ZrCl2-s-Ic '' H] 1, [Cp/ZrCl2-s-Ic '' H] 3 and [CpZrCl2-s-Ic '' H] 4 (s-Ic'H = 2,6-diethyl-4,8-dimethyl-1-hydro-s-indacene; s-Ic '' H = 2,6-dibutyl-4,8-dimethyl-1-hydro-s-indacene) were synthesized from the monolithiated salts of s-indacene (s-Ic'H or s-Ic '' H) with one equivalent of C5R5ZrCl3 (R = H, CH3). All complexes here reported were characterized by means of H-1 and C-13 NMR, mass spectrometry, elemental analysis. Complexes [Cp*ZrCl2-s-Ic'H] 1 and [CpZrCl2-s-Ic'H] 2 (previously reported by NMR analysis) were characterized by X-ray diffraction. In order to gain further knowledge about their catalytic behavior, the complexes were tested in the catalysis of ethylene polymerization showing a highest activity. Complex 4 presents the highest ethylene polymerization activity than complexes 1 and 2, and 3 under the same working conditions. (C) 2015 Elsevier B.V. All rights reserved.
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    A PRELIMINARY STUDY ON ELECTROCATALYTIC REDUCTION OF CO2 USING FAC-ReI(CO)3(4,4′-DIMETHYL-2,2′-BIPYRIDYL)((E)-2-((3-AMINO-PYRIDIN-4-YLIMINO)-METHYL)-4,6-DI-TERT-BUTYLPHENOL))+COMPLEX
    (2017) Carlos Canales, Juan; Carreno, Alexander; Oyarzun, Diego; Manuel Manriquez, Juan; Chavez, Ivonne
    Several research to explore the possible conversion of CO2 using rhenium(I) tricarbonyl complexes have been reported the last years. In the present work, we investigated a potential use of fac-Re(CO)(3)(4,4'-di-methyl-2,2'-bipyridyl)L+ complex (C2), where L is an electron-withdrawing ancillary ligands which present an intramolecular hydrogen bond (IHB), in a preliminary electrocatalytic reduction of CO2 . The C2 complex was synthesized and characterized according to reported methods earlier. The cyclic voltammogram profile for the C2 complex were studied in dichloromethane under inert atmosphere, and it shows a typical behavior for an electrocatalytic process, the C2 complex illustrate the electrochemical reaction mechanism corresponds to an electrochemical chemical electrochemical pathway (ECE). Also, a Vitreous Carbon plate used as working electrode was employed and modified by cycling the anodic region of C2 in CH2Cl2 which involve the oxidative redox response for the -NH2 and -OH groups. The voltammogram profile involve shows a polymeric deposit on the plate surface in a CO2 saturated solution (pH=7.0). A strong electrocatalytic discharge of current is obtained with a wave foot of -1.3 V showing that C2 have the potential to be used in electrocatalyst CO2 reduction.
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    An Improved Synthesis of 3,6-Dihydro-as-indacene
    (2021) RDibdalli, Yuvaraja; Faundez, Rodrigo; Preite, Marcelo; Molins, Elies; Chavez, Ivonne; Amshumali, Mungalimane K.; Morales-Verdejo, Cesar; Manriquez, Juan M.
    This contribution describes an updated synthetic route to 3,6-dihydro-as-indacene along with full characterization of all intermediates. The title compound is prepared by Mannich condensation of 2-methylfuran with formaldehyde and dimethylamine hydrochloride, quaternization of the resulting amine with methyl iodide, and conversion into the ammonium hydroxide salt by treatment with silver oxide in water. Subsequent Hoffmann elimination and [6,6]-cycloaddition through pyrolysis produces a furanocyclophane, which after photooxidation, intramolecular cycloaddition, and dehydration with sodium carbonate affords 2,3,6,7-tetrahydro-1,8-dione-as-indacene. Reduction of this diketone gives a mixture of alcohols, which after dehydration under slightly basic or acidic conditions produces 3,6-dihydro-as-indacene. The structure is confirmed by X-ray diffraction, and all intermediates are characterized by means of H-1 and C-13 NMR spectroscopy.
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    Catalytic effects of p-phenylene-bridged methylated binuclear ferrocenes on thermal decomposition of the main component of composite solid propellants
    (2018) Povea, Paula; Arroyo, Juan Luis ; Carreno, Gustavo; Norambuena, Angel; Rios, Paulina L.; Belen Camarada, Maria; Chavez, Ivonne; Manriquez, Juan Manuel ; Morales-Verdejo, Cesar
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    Experimental and Theoretical Studies of the ancillary ligand (E)-2-((3-amino- pyridin-4-ylimino)-methyl)-4,6-di-tert-butylphenol in Rhenium(I) core
    (2015) Carreno, Alexander; Gacitua, Manuel; Schott Verdugo, Eduardo Enrique; Zarate, Ximena; Manriquez, Juan Manuel; Preite, Marcelo Daniel; Ladeira, Sonia; Castel, Annie; Pizarro, Nancy; Vega, Andres; Chavez, Ivonne; Arratia-Perez, Ramiro
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    New Cationic fac-[Re(CO)3(deeb)B2]+ Complex, Where B2 Is a Benzimidazole Derivative, as a Potential New Luminescent Dye for Proteins Separated by SDS-PAGE
    (2021) Carreno, Alexander; Gacitua, Manuel; Solis-Cespedes, Eduardo; Paez-Hernandez, Dayan; Swords, Wesley B.; Meyer, Gerald J.; Preite, Marcelo D.; Chavez, Ivonne; Vega, Andres; Fuentes, Juan A.
    Sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) can be used to separate proteins based mainly on their size such as in denaturing gels. Different staining methods have been reported to observe proteins in the gel matrix, where the most used dyes are generally anionic. Anionic dyes allow for interactions with protonated amino acids, retaining the dye in the proteins. Fluorescent staining is an alternative technique considered to be sensitive, safe, and versatile. Some anionic complexes based on d(6) transition metals have been used for this purpose, where cationic dyes have been less explored in this context. In this work, we synthesized and characterized a new monocationic rhenium complex fac-[Re(CO)(3)(deeb)B2](+) (where deeb is 4,4 '-bis(ethoxycarbonyl)-2,2 '-bpy and B2 is 2,4-di-tert-butyl-6-(3H-imidazo[4,5-c]pyridine-2-yl)phenol). We carried out a structural characterization of this complex by MS+, FTIR, H-1 NMR, D2O exchange, and HHCOSY. Moreover, we carried out UV-Vis, luminescence, and cyclic voltammetry experiments to understand the effect of ligands on the complex's electronic structure. We also performed relativistic theoretical calculations using the B3LYP/TZ2P level of theory and R-TDDFT within a dielectric continuum model (COSMO) to better understand electronic transitions and optical properties. We finally assessed the potential of fac-[Re(CO)(3)(deeb)B2](+) (as well as the precursor fac-Re(CO)(3)(deeb)Br and the free ligand B2) to stain proteins separated by SDS-PAGE. We found that only fac-[Re(CO)(3)(deeb)B2](+) proved viable to be directly used as a luminescent dye for proteins, presumably due to its interaction with negatively charged residues in proteins and by weak interactions provided by B2. In addition, fac-[Re(CO)(3)(deeb)B2](+) seems to interact preferentially with proteins and not with the gel matrix despite the presence of sodium dodecyl sulfate (SDS). In future applications, these alternative cationic complexes might be used alone or in combination with more traditional anionic compounds to generate counterion dye stains to improve the process.
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    New mono and bimetallic iron complexes derived from partially methylated s-indacene. Evidence of a trinuclear iron s-indacene complex
    (2014) Morales-Verdejo, Cesar; Martinez-Diaz, Ivan; Adams, Christopher; Araneda, Juan Felipe; Oehninger, Luciano; Carey, Desmond Mac-Leod; Munoz-Castro, Alvaro; Arratia-Perez, Ramiro; Chavez, Ivonne; Manuel Manriquez, Juan
    The preparation and characterization of new mono- and multinuclear iron complexes derived from s-indacene partially alkylated has been achieved by the development of rational synthetic routes. The synthesis of the new multimetallic complexes are based on the employment of 1,5-dihydro-2,4,6, 8-tetramethyl-s-indacene (Ic'H-2) as ligand to obtain two monometallic complexes, namely, [Cp*-Fe-(eta(5)-2,4,6,8-tetramethyl-5-hydro-s-indacenide)] (1), and [Fe-bis(eta(5)-2,4,6,8-tetramethyl-5-hydro-s-indacenide)] (2) (Cp* = pentamethylcyclopentadiene), as well as, the new bimetallic [Cp*Fe-(mu:eta(5):eta(5)-2,4,6,8-tetramethyl-s-indaceneiide)-FeCp*] (3) and trimetallic [Fe-bis{Cp*Fe-(mu:eta(5):eta(5)-2,4,6,8-tetramethyl-s-indaceneiide)}] (4) complexes. All complexes here reported were characterized by means of H-1, C-13 NMR, mass spectrometry, elemental analysis, together with cyclic voltammetry. In addition, these complexes have been studied by DFT methods in order to gain further knowledge about its electronic structure. In addition, the possibility to generate organometallic polymers employing the complexes here reported, is proposed theoretically with the study of an oligomer titled as [Cp*(Fe(Ic')}(4)FeCp*], 6(t). (C) 2013 Elsevier Ltd. All rights reserved.
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    New Rh derivatives of s-indacene active in dehydrogenative silylation of styrene
    (ELSEVIER SCIENCE SA, 2006) Esponda, Edgardo; Adams, Christopher; Burgos, Francisco; Chavez, Ivonne; Manriquez, Juan M.; Delpech, Fabien; Castel, Annie; Gornitzka, Heinz; Riviere Baudet, Monique; Riviere, Pierre
    The mono- and bimetallic complexes [(2,6-diethyl-4,8-dimethyl-s-indacenide){Rh(COD)}] (1), anti-[(2,6-diethyl-4,8-dimethyl-s-indacenediide) {Rh(COD)}(2)] (2a), syn-[(2,6-diethyl-4,8-dimethyl-s-indacenediide){Rh(COD)}(2)] (2b) were synthesized and characterized spectroscopically and in the case of complex 2b, by means of X-ray diffraction. The C-13 and Rh-103 NMR studies suggest that the bonding mode of the indacenediide ligand can be described as intermediate between eta(3)- and eta(5)-coordination. This result was confirmed by the crystal structure of 2b as evidenced by the slippage of the rhodium atom towards the periphery of the ligand. Cyclic voltammetry studies revealed a strong intermetallic communication through the fused ring ligand. This property was further illustrated by higher activity and selectivity of binuclear complexes 2 for the catalytic dehydrogenative silylation of styrene. (c) 2006 Elsevier B.V. All rights reserved.
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    Novel and Convenient Synthesis of 2,7-Dialkyl-1,8-dihydro- as -indacenes
    (2019) Faúndez Gutiérrez, Rodrigo Esteban; Castillo, Francisco; Preite, Marcelo Daniel; Schott Verdugo, Eduardo Enrique; Zarate, Ximena; Manríquez M., Juan Manuel; Molins, Elies; Morales-Verdejo, César; Chavez, Ivonne
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    Synthesis and structure of some heterobimetallic complexes having a polyalkyl-s-indacenyl spacer
    (ELSEVIER SCIENCE SA, 2013) Morales Verdejo, Cesar; Martinez, Ivan; Mac Leod Carey, Desmond; Chavez, Ivonne; Manuel Manriquez, Juan; Matioszek, Dimitri; Saffon, Nathalie; Castel, Annie; Riviere, Pierre; Molins, Elies
    Three heterobimetallic complexes LmM(s-Ic')M'Ln (M = Fe, Ru or Mn; M' = Ni) having the same Cp* nickel moiety and based on a polyalkyl-s-indacenyl spacer (s-Ic' = 2,6-diethyl-4,8-dimethyl-s-indacenyl) were synthesized by reacting Cp* Ni(acac) with the lithium derivative of the parent monometalated complex. All three compounds were fully characterized and shown to adopt a trans geometry by X-ray crystallography. (C) 2012 Elsevier B. V. All rights reserved.
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    Toward the Synthetic Control of the HOMO-LUMO Gap in Binuclear Systems: Insights from Density Functional Calculations
    (AMER CHEMICAL SOC, 2010) Munoz Castro, Alvaro; Mac Leod Carey, Desmond; Morales Verdejo, Cesar; Chavez, Ivonne; Manuel Mariquez, Juan; Arratia Perez, Ramiro
    Computational methods based on density functional theory have been applied to address the design of tailored HOMO-LUMO gap bimetallic complexes. We focus our attention on the [Cp*Fe-(L)-FeCp*] system, where two ferrocenyl units are linked through the dianion of fused ring ligands such as pentalene, s-indacene, dicyclopenta-[b,g]-naphthalene, dicyclopenta-[b,l]-anthracene and dicyclopenta-[b,l]-tetracene Our DFT calculations on the title organometallic complexes suggest a controlled decrease in the HOMO-LUMO gap, which is desirable for studies on electron-transfer phenomena, as well as the design potential devices for molecular electronic purposes.