Introdución á química de coordinación

Titulación: Grao en Enxeñaría Técnica Industrial. Especialidade en Química Industrial -- Materia: Química Inorgánica IIEsta unidade didáctica pecha un conxunto de temas destinados a conceptos básicos da materia, encadrados no Bloque I, e abórdase despois de estudar algunhas xeneralidades dos metais de transición e de ver cales son os métodos de beneficio dos metais a escala industrial. Nesta unidade iníciase o estudo da química de coordinación, que é unha parte fundamental da química dos metais de transición. Deste xeito, en todos os temas seguintes do programa do curso farase uso dos coñecementos aprendidos nesta unidade. Ademais, debemos sinalar que moitos procesos industriais e analíticos utilizan compostos de coordinación. Así, estes teñen grande interese en moi diversas áreas, entre as cales se pode destacar a modo de exemplo a medicina, dado que moitos tratamentos anticanceríxenos son en realidade terapias con compostos de coordinación. En canto á temporización desta unidade didáctica, está deseñada para ser desenvolvida nunhas 12-13 horas.Universidade de Santiago de Compostela. Servizo de Normalización Lingüístic

Neuroprotective effects of fluorophore-labelled manganese complexes: Determination of ROS production, mitochondrial membrane potential and confocal fluorescence microscopy studies in neuroblastoma cells

In this work, four manganese(II) complexes derived from the ligands H2L1-H2L4, that incorporate dansyl or tosyl fluorescent dyes, have been investigated in term of their antioxidant properties. Two of the manganese(II) complexes have been newly prepared using the asymmetric half-salen ligand H2L2 and the thiosemicarbazone ligand H2L3. The four organic strands and the manganese complexes have been characterized by different analytical and spectroscopic techniques. The study of the antioxidant behaviour of these two new complexes and other two fluorophore-labelled analogues was tested in SH-SY5Y neuroblastoma cells. These four model complexes 1–4 were found to protect cells from oxidative damage in this human neuronal model, by reducing the release of reactive oxygen species. Complexes 1–4 significantly improved cell survival, with levels between 79.1 ±0.8% and 130.9 ±4.1%. Moreover, complexes 3 and 4 were able to restore the mitochondrial membrane potential at 1 μM, with 4 reaching levels higher than 85%, similar to the percentages obtained by the positive control agent cyclosporin A. The incorporation of the fluorescent label in the complexes allowed the study of their ability to enter the human neuroblastoma cells by confocal microscopy.The research leading to these results has received funding from the following FEDER cofunded-grants. From Consellería de Cultura, Educaci´ on e Ordenaci´ on Universitaria, Xunta de Galicia, 2017 GRC GI-1682 (ED431C 2017/01), 2018 GRC GI-1584 (ED431C 2018/13), MetalBIO Network (ED431D 2017/01). From CDTI and Technological Funds, supported by Ministerio de Economía, Industria y Competitividad IISCIII/PI19/001248. From Ministerio de Ciencia, Innovaci´ on y Universidades, MULTIMETDRUGS (RED2018-102471-T). From European Union, Interreg AlertoxNet EAPA-317-2016, Interreg Agritox EAPA- 998-2018, and H2020 778069-EMERTOX.S

Study of the conformational rearrangement of a tetradentate hydrazone ligand

We report herein the first example of a tetradentate hydrazone structurally studied. The analysis of the conformations of this molecule together with the hydrogen bonding interactions allowed us to investigate the changes experienced by this ligand upon coordination to metal center

Synthesis and X-ray Crystal Structure of the Thiosemicarbazone L bis(4-N-Methyl-Thiosemicarbazone)-4,4'-Diacetylphenylmethane

The 18th International Electronic Conference on Synthetic Organic Chemistry session Polymer and Supramolecular ChemistryWe report herein the synthesis of the tetradentate thiosemicarbazone ligand bis(4-N-methyl-thiosemicarbazone)-4,4'-diacetylphenylmethane, which is a suitable precursor in supramolecular chemistry for the preparation of helical metal complexes. This molecule has been characterized by microanalysis, mass spectrometry, IR and 1H and 13C NMR spectroscopies. Its crystal structure has also been analyse

Electrochemical Conversion of the Lignin Model Veratryl Alcohol to Veratryl Aldehyde Using Manganese(III)-Schiff Base Homogeneous Catalysts

Lignin and other colored structures need to be bleached after the Kraft process in the pulp industry. Development of environmentally-safe bleaching catalysts or electrocatalysts constitutes an attractive strategy for selective removal of lignin. Seven manganese(III)-complexes with Schiff base ligands 1–7 were synthetized and characterized by different analytical and spectroscopic techniques. The tetragonally elongated octahedral geometry for the manganese coordination sphere and the global µ-aquo dimeric structure were revealed by X-ray diffraction (XRD) studies for 1, Mn2L12(H2O)2(N(CN)2)2 (N(CN)2 = dicyanamide). Complexes 1–4 behave as more efficient peroxidase mimics as compared to 5–7. Electrochemical oxidation of the lignin model veratrylalcohol (VA) to veratrylaldehyde (VAH) is efficiently catalyzed by a type of dimanganese(III) complexes in a chlorine-free medium. The electrocatalytic reaction proceeds through the oxidation of chloride into hypochlorite at alkaline pH along with the formation of hydrogen from water as a subproductThis research was funded by Xunta de Galicia (GRC GI-1584-ED431C2018/13 Suprabioin Research Group, and MetalBIO Network ED431D 2017/01)S

Synthetic Route to Novel Asymmetric Tetradentate Ligands Containing Both Amino and Imino Groups

The 18th International Electronic Conference on Synthetic Organic Chemistry session General Organic SynthesisThe synthesis of a new asymmetric ligand (E)-4-bromo-2-(((2-((5-bromo-2-hydroxybenzyl)(methyl)amino)ethyl)imino)methyl)phenol, which was conceived to model the asymmetry in the active site of peroxidase/catalase mimics, is reported. The new synthetic route involves seven steps: 1) obtention of phthalimido-acetal; 2) Acetal deprotection; 3) Synthesis of the salicylamine; 4) Obtention of the benzoxacine; 5) Reduction of the benzoxacine with NaBH3CN; 6) Reduction with hydrazine to form salycilamine; 7) Synthesis of the final ligand by condensation of salicylamine with salycilaldehyde. All organic products were characterised by microanalysis and 1H NMR, IR and mass spectroscopie

Neuroprotective effects of fluorophore-labelled manganese complexes: determination of ROS production, mitochondrial membrane potential and confocal fluorescence microscopy studies in neuroblastoma cells

In this work, four manganese(II) complexes derived from the ligands H2L1-H2L4, that incorporate dansyl or tosyl fluorescent dyes, have been investigated in term of their antioxidant properties. Two of the manganese(II) complexes have been newly prepared using the asymmetric half-salen ligand H2L2 and the thiosemicarbazone ligand H2L3. The four organic strands and the manganese complexes have been characterized by different analytical and spectroscopic techniques. The study of the antioxidant behaviour of these two new complexes and other two fluorophore-labelled analogues was tested in SH-SY5Y neuroblastoma cells. These four model complexes 1–4 were found to protect cells from oxidative damage in this human neuronal model, by reducing the release of reactive oxygen species. Complexes 1–4 significantly improved cell survival, with levels between 79.1 ± 0.8% and 130.9 ± 4.1%. Moreover, complexes 3 and 4 were able to restore the mitochondrial membrane potential at 1 μM, with 4 reaching levels higher than 85%, similar to the percentages obtained by the positive control agent cyclosporin A. The incorporation of the fluorescent label in the complexes allowed the study of their ability to enter the human neuroblastoma cells by confocal microscopyThe research leading to these results has received funding from the following FEDER cofunded-grants. From Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia, 2017 GRC GI-1682 (ED431C 2017/01), 2018 GRC GI-1584 (ED431C 2018/13), MetalBIO Network (ED431D 2017/01). From CDTI and Technological Funds, supported by Ministerio de Economía, Industria y Competitividad IISCIII/PI19/001248. From Ministerio de Ciencia, Innovación y Universidades, MULTIMETDRUGS (RED2018-102471-T). From European Union, Interreg AlertoxNet EAPA-317-2016, Interreg Agritox EAPA-998-2018, and H2020 778069-EMERTOXS

Crystal Structure of H2L (N,N'-BIS(3-METHOXYSALICYLIDENE)-1,4-Diaminobutane

The 11th International Electronic Conference on Synthetic Organic Chemistry session General Organic SynthesisThree multidentate Schiff-base ligands were obtained by condensation of different diamines (1,3-diaminopropane, 1,3-diamino-2,2-dimethylpropane, 1,4-diaminobutane) and 3-methoxy-2-hydroxybenzaldehyde to yield H 2 L n (H 2 L 1 , H 2 L 2 and H 2 L 3 , respectively). The ligands have been characterised by elemental analysis, IR, and 1 H and 13 C NMR spectroscopies, mass spectrometry (ES) and X-ray diffractio

Crystal structure of (n-n'-bis(3-ethoxysalicylidene)-1,2-diaminopropane

The 13th International Electronic Conference on Synthetic Organic Chemistry session General Organic SynthesisThree hexadentate Schiff base ligands were obtained by condensation of 3-ethoxy-2-hydroxybenzaldehyde and different diamines (1,2-diaminoethane, 1,2-diaminopropane, 1,2-diamino-2-metylpropane) to yield H2Ln (H2L1, H2L2 and H2L3, respectively). The ligands have been characterised by elemental analysis, IR, and 1H and 13C NMR spectroscopic techniques, mass spectrometry (ES) and X-ray diffractio

Understanding the Effect of the Electron Spin Relaxation on the Relaxivities of Mn(II) Complexes with Triazacyclononane Derivatives

[Abstract] Investigating the relaxation of water ¹H nuclei induced by paramagnetic Mn(II) complexes is important to understand the mechanisms that control the efficiency of contrast agents used in diagnostic magnetic resonance imaging (MRI). Herein, a series of potentially hexadentate triazacyclononane (TACN) derivatives containing different pendant arms were designed to explore the relaxation of the electron spin in the corresponding Mn(II) complexes by using a combination of ¹H NMR relaxometry and theoretical calculations. These ligands include 1,4,7-triazacyclononane-1,4,7-triacetic acid (H₃NOTA) and three derivatives in which an acetate group is replaced by sulfonamide (H₃NOƨASAm), amide (H₂NOƨAM), or pyridyl (H₂NOƨAPy) pendants. The analogue of H₃NOTA containing three propionate pendant arms (H₃NOTPrA) was also investigated. The X-ray structure of the derivative containing two acetate groups and a sulfonamide pendant arm [Mn(NOƨASAm)]⁻ evidenced six-coordination of the ligand to the metal ion, with the coordination polyhedron being close to a trigonal prism. The relaxivities of all complexes at 20 MHz and 25 °C (1.1–1.3 mM⁻¹ s⁻¹) are typical of systems that lack water molecules coordinated to the metal ion. The nuclear magnetic relaxation profiles evidence significant differences in the relaxivities of the complexes at low fields (<1 MHz), which are associated with different spin relaxation rates. The zero field splitting (ZFS) parameters calculated by using DFT and CASSCF methods show that electronic relaxation is relatively insensitive to the nature of the donor atoms. However, the twist angle of the two tripodal faces that delineate the coordination polyhedron, defined by the N atoms of the TACN unit (lower face) and the donor atoms of the pendant arms (upper face), has an important effect in the ZFS parameters. A twist angle close to the ideal value for an octahedral coordination (60°), such as that in [Mn(NOTPrA)]⁻, leads to a small ZFS energy, whereas this value increases as the coordination polyhedron approaches to a trigonal prism.C.P.-I., D.E.-G., and A.R.-R. thank Ministerio de Ciencia e Innovación (Grants CTQ2016-76756-P and PID2019-108352RJ-I00) and Xunta de Galicia (Grants ED431B 2017/59 and ED431D 2017/01) for generous financial support. R.U.-V. thanks Xunta de Galicia (Grant ED481A-2018/314) for funding her PhD contractXunta de Galicia; ED431B 2017/59Xunta de Galicia; ED431D 2017/01Xunta de Galicia; ED481A-2018/31