Flavone complexes of Ti and Zr active in ethylene polymerization

Gheno, Grasiela; Basso, Nara Regina de Souza; Ceschi, Marco Antonio; Livotto, Paolo Roberto; Nascimento, Alanjone Azevedo; Rocha, Zildete; Galland, Griselda B.

doi:10.1016/j.apcata.2013.08.015

Cited by 4 publications

(2 citation statements)

References 26 publications

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“…Similar results were obtained by Galland and co-workers, who prepared a [Ti(3HF) 2 ]Cl 2 complex using TiCl 4 as a source of the Ti IV core. 43 The emission spectra of the examined species (Fig. 8c–e) further support the formation of the metal–3HF complex.…”

Section: Resultssupporting

confidence: 59%

Tunable physics through coordination chemistry: formation on oxide surface of Ti and Al chelates with 3-hydroxyflavone capable of electron injection and light emission

et al. 2022

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Section: Resultssupporting

confidence: 59%

Tunable physics through coordination chemistry: formation on oxide surface of Ti and Al chelates with 3-hydroxyflavone capable of electron injection and light emission

et al. 2022

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“…Organometallic complexes of Ti and Zr were obtained from bidentate chelator ligands as naphthoquinone, methylpyrone, ethylpyrone and 3-hydroxyflavone. [1][2][3][4][5] All the synthesized complexes were active in homogeneous ethylene polymerization at different reaction conditions. 3-Hydroxy-2-methyl-4-pyrone (methylpyrone or maltol) is a non-toxic compound of natural occurrence in many plants, 6 while 3-hydroxy-2-ethyl-4-pyrone (ethylmaltol) is a synthetic commercial product.…”

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A New Post-Metallocene-Ti Catalyst with Maltolate Bidentade Ligand: an Investigation in Heterogeneous Polymerization Reactions in Different Mesoporous Supports

Gheno¹,

Basso²,

Livotto³

et al. 2016

Journal of the Brazilian Chemical Society

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A new titanium catalyst easily synthesized from ethylmaltol bidentate chelator ligand was studied in homogeneous and heterogeneous ethylene polymerization. The dichlorobis(3-hydroxy-2-ethyl-4-pyrone)titanium(IV) complex was characterized by 1 H and 13 C NMR (nuclear magnetic resonance), UV-Vis and elemental analysis. Theoretical study by density functional theory (DFT) showed that the complex chlorines exhibit cis configuration, which is important for the activity in olefin polymerization. The complex was supported by two methods, direct impregnation or methylaluminoxane (MAO) pre-treatment, in five mesoporous supports: MCM-41 (micro and nano), SBA-15 and also the corresponding modified Al species. All the catalytic systems were active in ethylene polymerization and the catalytic activity was strongly influenced by the method of immobilization of the catalyst and the type of support. Keywords: catalysis, synthesis, mesoporous support, immobilization, polyethylene IntroductionPolyethylene (PE) has a broad application in different segments of the everyday life, from food packaging to resistant pieces for engineering. Due to the polymer industrial demands, continuous development of new technologies and synthetic methods for obtaining this material are necessary. Existing processes, involving polyethylene synthesis in industrial and/or research scale, use Ziegler-Natta, metallocene, and more recently, postmetallocene catalysts. Our research group has studied the synthesis of different post-metallocene catalysts and tested these complexes in ethylene polymerization. Organometallic complexes of Ti and Zr were obtained from bidentate chelator ligands as naphthoquinone, methylpyrone, ethylpyrone and 3-hydroxyflavone. [1][2][3][4][5] All the synthesized complexes were active in homogeneous ethylene polymerization at different reaction conditions. 3-Hydroxy-2-methyl-4-pyrone (methylpyrone or maltol) is a non-toxic compound of natural occurrence in many plants, 6 while 3-hydroxy-2-ethyl-4-pyrone (ethylmaltol) is a synthetic commercial product. These organic compounds are commonly used in food industries as flavor ingredients. Both hydroxypyrones are characterized by their synthetic versatility and they easily coordinate with transition metals of group IV to give L 2 MCl 2 complexes.7 Bis(maltolate) metal(IV) complexes are extensively used in medical studies to assess their therapeutic value as active agents against diabetes, as agents for controlling metal levels in the body and as contrast agents in imaging applications. [8][9][10][11][12] Maltolate complexes appear attractive to catalyze olefin polymerization reaction as well. In 2001, Sobota et al. 13 synthesized and characterized titanium complexes of methylmaltol and verified their catalytic activity in ethylene and propylene polymerization. Subsequently, our research group has synthesized several Ti and Zr complexes Gheno et al. 2083 Vol. 27, No. 11, 2016 analogous based in maltolate ligands. The synthesized complexes were shown to be active in the ethylene...

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Polyethylene-polyaniline Nanofiber Composites: Evaluation of Experimental Conditions of in situ Polymerization

et al. 2015

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The difficult processability of polyaniline (PAni) can be overcome by preparing composites with high density polyethylene (HDPE), resulting in a conducting material with improved mechanical properties. PAni nanofibers were synthesized in this research using a rapid mixing method, while HDPE/PAni composites were prepared by in situ polymerization using Cp 2 ZrCl 2 /MAO as a catalyst system. Different experimental conditions for polymerization and an electrochemical study were performed. The findings confirmed that the addition of small amounts of Pani (up to 7%) and longer impregnation (120 min) with methylaluminoxane (MAO) before polymerization are important factors contributing to increased catalytic activity. Analysis by cyclic and differential pulse voltammetry indicates that MAO reacts with the PAni in the ethylene polymerization process, and forms active species in the presence of the catalyst. Changes in catalytic activity may be due to the kinetic consumption of the active species, which become less important in the presence of PAni.

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Flavone complexes of Ti and Zr active in ethylene polymerization

Cited by 4 publications

References 26 publications

Tunable physics through coordination chemistry: formation on oxide surface of Ti and Al chelates with 3-hydroxyflavone capable of electron injection and light emission

Tunable physics through coordination chemistry: formation on oxide surface of Ti and Al chelates with 3-hydroxyflavone capable of electron injection and light emission

A New Post-Metallocene-Ti Catalyst with Maltolate Bidentade Ligand: an Investigation in Heterogeneous Polymerization Reactions in Different Mesoporous Supports

Polyethylene-polyaniline Nanofiber Composites: Evaluation of Experimental Conditions of in situ Polymerization

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