Bibliografías temáticas / CATIONIC LIGANDS

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Literatura académica sobre el tema "CATIONIC LIGANDS"

Autor: Grafiati
Publicado: 11 de septiembre de 2023

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Artículos de revistas sobre el tema "CATIONIC LIGANDS"

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Lamberts, Kevin, Andreas Möller y Ulli Englert. "Enantiopure and racemic alanine as bridging ligands in Ca and Mn chain polymers". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 70, n.º 6 (1 de diciembre de 2014): 989–98. http://dx.doi.org/10.1107/s2052520614021398.

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Under accelerated and controlled evaporation, chain polymers crystallize from aqueous solutions of CaIIand MnIIhalides with enantiopure L-alanine or racemic DL-alanine. In all ten solids thus obtained zwitterionic amino acid ligands bridge neighbouring cations. The exclusively O-donor-based coordination sphere around the metal cations is completed by aqua ligands; the halides remain uncoordinated and act as counter-anions for the cationic strands. Despite the differences in ionic radii and electronic structure between the main group and the transition metal cation, their derivatives with L-alanine share a common structure type. In contrast, the solids derived from DL-alanine differ and adopt structures depending on the metal cation and the halide. Homochiral chains of either chirality or heterochiral chains with different arrangements of crystallographic inversion centres along the polymer strands are encountered. On average, the six-coordinated CaIIcations, devoid of any ligand field effect, show more pronounced deviation from idealized octahedral geometry than thed-block cation MnII.
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Ogura, Yusaku, Masahiro Nakano, Hajime Maeda, Masahito Segi y Taniyuki Furuyama. "Cationic Axial Ligand Effects on Sulfur-Substituted Subphthalocyanines". Molecules 27, n.º 9 (26 de abril de 2022): 2766. http://dx.doi.org/10.3390/molecules27092766.

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Herein, we report the synthesis of sulfur-substituted boron(III) subphthalocyanines (SubPcs) with cationic axial ligands. Subphthalocyanines were synthesized by a condensation reaction using the corresponding phthalonitriles and boron trichloride as a template. An aminoalkyl group was introduced on the central boron atom; this process was followed by N-methylation to introduce a cationic axial ligand. The peripheral sulfur groups shifted the Q band of SubPcs to a longer wavelength. The cationic axial ligands increased the polarity and enhanced the hydrophilicity of SubPcs. The effect of axial ligands on absorption and fluorescence properties is generally small. However, a further red shift was observed by introducing cationic axial ligands into the sulfur-substituted SubPcs. This change is similar to that in sulfur-substituted silicon(IV) phthalocyanines. The unique effect of the cationic axial ligand was extensively investigated by theoretical calculations and electrochemistry. In particular, the precise oxidation potential was determined using ionization potential measurements. Thus, the results of the present study provide a novel strategy for developing functional dyes and pigments based on SubPcs.
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Wright, Stephen H. "Molecular and cellular physiology of organic cation transporter 2". American Journal of Physiology-Renal Physiology 317, n.º 6 (1 de diciembre de 2019): F1669—F1679. http://dx.doi.org/10.1152/ajprenal.00422.2019.

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Organic cation transporters play a critical role in mediating the distribution of cationic pharmaceuticals. Indeed, organic cation transporter (OCT)2 is the initial step in the renal secretion of organic cations and consequently plays a defining role in establishing the pharmacokinetics of many cationic drugs. Although a hallmark of OCTs is their broad selectivity, this characteristic also makes them targets for unwanted, adverse drug-drug interactions (DDIs), making them a focus for efforts to develop models of ligand interaction that could predict and preempt these adverse interactions. This review discusses the molecular characteristics of these transporters as well as the evidence that established the OCTs as key players in the distribution of organic cations. However, the primary focus is the present understanding of the complexity of ligand interaction with OCTs, particularly OCT2, including evidence for the presence of multiple ligand-binding sites and the influence of substrate structure on the affinity of the transporter for inhibitory ligands. This leads to a discussion of the complexities associated with the development of protocols for assessing the inhibitory potential of new molecular entities to perpetrate unwanted DDIs, the criteria that should be considered in the interpretation of the results of such protocols, and the challenges associated with development of models capable of predicting unwanted DDIs.
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Babukutty, Leslie, Ethan Moskovic, Davina Wadler, Thomas Strekas y Robert Engel. "Polycations XX: New Monodentate Cationic Ligands and Their Coordination with Ruthenium for the Construction of Complexes Expressing Enhanced Interaction with DNA". Organic Chemistry International 2012 (15 de octubre de 2012): 1–7. http://dx.doi.org/10.1155/2012/282137.

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Prior investigations from this laboratory concerned with the preparation of new types of organic cations for a variety of biological and nonbiological applications have been extended to the preparation of cation-bearing ligands with nitrogen coordinating sites for use in complexation reactions with ruthenium cores. The syntheses of new cationic ligands as well as ruthenium complexes bearing them are reported here. The introduction of these new types of ligands is intended to provide to the complexes an enhanced ability to interact with DNA, and thereby to have the potential to be enhanced antitumor agents. Preliminary observations of their interactions with DNA are presented.
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Zeng, Juxiang, Guodong Tang y Jun Qian. "Synthesis and crystal structure of (1,10-phenanthroline-κ2 N,N′)[2-(1H-pyrazol-1-yl)phenyl-κ2 N 2,C 1]iridium(III) hexafluoridophosphate with an unknown number of solvent molecules". Acta Crystallographica Section E Crystallographic Communications 76, n.º 6 (5 de mayo de 2020): 803–6. http://dx.doi.org/10.1107/s2056989020005861.

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The cationic complex in the title compound, [Ir(C9H7N2)2(C12H8N2)]PF6, comprises two phenylpyrazole (ppz) cyclometallating ligands and one 1,10-phenanthroline (phen) ancillary ligand. The asymmetric unit consists of one [Ir(ppz)2(phen)]+ cation and one [PF6]− counter-ion. The central IrIII ion is six-coordinated by two N atoms and two C atoms from the two ppz ligands as well as by two N atoms from the phen ligand within a distorted octahedral C2N4 coordination set. In the crystal structure, the [Ir(ppz)2(phen)]+ cations and PF6 − counter-ions are connected with each other through weak intermolecular C—H...F hydrogen bonds. Additional C—H...π interactions between the rings of neighbouring cations consolidate the three-dimensional network. Electron density associated with additional disordered solvent molecules inside cavities of the structure was removed with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s). The title compound has a different space-group symmetry (C2/c) from its solvatomorph (P21/c) comprising 1.5CH2Cl2 solvent molecules per ion pair.
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Mbiangué, Yves Alain, Alfred Bijvédé, Patrice Kenfack Tsobnang, Emmanuel Wenger y Claude Lecomte. "Crystal structure of diammonium bis[tris(oxamide dioxime-κ2 N,N′)nickel(II)] bis[tris(oxalato-κ2 O,O′)chromate(III)] 6.76-hydrate". Acta Crystallographica Section E Crystallographic Communications 76, n.º 11 (9 de octubre de 2020): 1732–36. http://dx.doi.org/10.1107/s2056989020013390.

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The asymmetric unit of the title compound, (NH4)2[Ni(C2H6N4O2)3]2[Cr(C2O4)3]2·6.76H2O, comprises two NH4 + cations, two [Ni(C2H6N4O2)3]2+ cations and two [Cr(C2O4)3]3– anions, as well as eight water molecules of crystallization of which only one is fully occupied. In the cationic and anionic complexes, the central atoms (NiII and CrIII) are each surrounded by three bidentate ligands (N-chelating oxamide dioxime and O-chelating oxalate, respectively), resulting in distorted octahedral coordination spheres. In the crystal, O—H...O hydrogen bonds between the oxamide dioxime ligands as donor groups and the oxalate ligands as acceptor groups alternately connect the cationic and anionic complexes into infinite pillars extending parallel to [100]. Moreover, N—H...O hydrogen bonds between the same ligands connect neighboring pillars, thus delineating channels that accommodate the charge-balancing NH4 + cations as well as the water molecules of crystallization. Although the H atoms could not be localized for these two species, the corresponding N...O and O...O distances indicate hydrogen bonds of medium strength.
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Santiago, Tomás G., Carmen Urbaneja, Eleuterio Álvarez, Elena Ávila, Pilar Palma y Juan Cámpora. "Neutral, cationic and anionic organonickel and -palladium complexes supported by iminophosphine/phosphinoenaminato ligands". Dalton Transactions 49, n.º 2 (2020): 322–35. http://dx.doi.org/10.1039/c9dt04062e.

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Ligand exchange and oxidative addition reactions allow the synthesis of Ni(ii) and Pd(ii) complexes with deprotonable iminophosphine ligands. The acid–base behavior of iminophosphine ligands coordinated to organometallic Ni(ii) fragments is analyzed.
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Rahimi, Naser y Davit Zargarian. "Cationic tetra- and pentacoordinate complexes of nickel based on POCN- and POCOP-type pincer ligands: synthesis, characterization, and ligand exchange studies". New Journal of Chemistry 45, n.º 33 (2021): 15063–73. http://dx.doi.org/10.1039/d1nj01355f.

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The closely related pincer ligands POCN and POCOP display different electron donating properties and different degrees of resistance to ligand exchange reactions proceeding via cationic reaction intermediates.
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Wagler, Jörg, Uwe Böhme, Erica Brendler y Gerhard Roewer. "First X-Ray Structure of a Cationic Silicon Complex with Salen-Type Ligand: An Unusual Compound with Two Different Si-N Dative Bonds". Zeitschrift für Naturforschung B 59, n.º 11-12 (1 de diciembre de 2004): 1348–52. http://dx.doi.org/10.1515/znb-2004-11-1255.

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Abstract Two novel compounds containing pentacoordinate alkylsiliconium-cations with an 〈O, N, O 〉- chelating ligand of salen-type were prepared by reacting the trimethylsilyl derivatives of the ligand with alkyltrichlorosilanes. Pentacoordination of the silicon atom is found in solid state as well as in solution. Crystals of compound 2a, ethylene-N, N’ -bis(2-oxy-4-methoxybenzophenoneiminato) methylsiliconium chloride, were obtained from chloroform solution. This complex crystallizes in monoclinic space group P21/n. The chloride ion is surrounded by three chloroform molecules in the solid state. The siliconium cation has trigonal bipyramidal geometry in the solid state, although the signals of two chemically equal half-sides of the salen-type ligand were revealed in 1H and 13C NMR spectra of its chloroform solution. Therefrom two different Si-N dative bonds within the same molecule arise. The reaction of methyltrichlorosilane with two non-linked “half-ligands” of the salen-type leads also to a siliconium complex with similar cationic coordination sphere motif.
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Schenk, Wolfdieter A., Ute Karl y Michael R. Horn. "Kationische Schwefeldioxid-Komplexe des Eisens und Rutheniums vom Halbsandwich-Typ [1] / Cationic Halfsandwich-Type Sulfur Dioxide Complexes of Iron and Ruthenium [1]". Zeitschrift für Naturforschung B 44, n.º 12 (1 de diciembre de 1989): 1513–18. http://dx.doi.org/10.1515/znb-1989-1208.

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Cationic halfsandwich-type complexes of sulfur dioxide, [C5R5M(PR3)2(SO2)]+ (R = H, Me, M = Fe, Ru, (PR3)2 = mono- or bidentate phosphorus ligands) and [C5Me5Fe(CO)(PR3)(SO2)]+, are obtained by ligand exchange from labile cationic (M = Fe) or neutral (M = Ru) precursors. The new compounds are characterized by IR, 1H131H, 13C and 31P NMR spectroscopy. Their stability increases with increasing electron density at the metal.
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Tesis sobre el tema "CATIONIC LIGANDS"

1

Polywka, M. E. C. "Mechanistic organometallic chemistry". Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253399.

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Meehan, Paul R. "Complexation of neutral and cationic scandium(III) species with macrocyclic ligands". Thesis, University of Warwick, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339827.

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Gu, Lianghu [Verfasser]. "Synthesis of α-cationic phosphines and their applications as ligands / Lianghu Gu". Dortmund : Universitätsbibliothek Dortmund, 2016. http://d-nb.info/111256246X/34.

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Umuhire, Mahoro Gilbert. "Development of new cationic copper (l) complexes for white light-emitting electrochemical cells". Thesis, Normandie, 2021. http://www.theses.fr/2021NORMC202.

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De nouveaux complexes de cuivre(I) cationiques de formule générale [Cu(P^P)(N^N)][PF6] où P^P représente un ligand bis-phosphine chélatant, bis-[2- (diphenylphosphino)phenyl]ether (DPEPhos) et N^N, des ligands 2,2-bis-pyridyls ont été développés. Les complexes ont montré des émissions à l’état solide couvrant tout le spectre du visible et la présence de la fluorescence retardée activée thermiquement (TADF) a été démontrée. Ces complexes ont été évaluées dans des cellules électrochimiques luminescentes (LECs) et ont conduit aux LECs émettant dans de différentes couleurs, i.e., bleue, verte, jaune, orange, rouge, et enfin des LECs blanches
New cationic copper(I) complexes with the general formula of [Cu(P^P)(N^N)][PF6] where P^P is a chelating bis-phosphine ligand bis-[2-(diphenylphosphino)phenyl]ether (DPEPhos) and N^N 2,2-bis-pyridyl ligand derivatives were developed. The complexes featured solid-state emissions covering the entire visible spectrum and the presence of the thermally activated delayed fluorescence (TADF) was demonstrated. Furthermore, the complexes were incorporated in light-emitting electrochemical cells (LEC) and led to devices emitting in different colors, i.e., blue, green, yellow, orange, red, and ultimately white-emitting LECs
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Tinnermann, Hendrik. "Design, Synthesis and Applications of new cationic ligands of the 15th main group elements". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://hdl.handle.net/11858/00-1735-0000-0023-3FA7-F.

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Tredget, Cara Siobhan. "Polymerisation and reactivity studies of cationic group 3 complexes with neural face-capping ligands". Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442923.

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Mehrkhodavandi, Parisa 1976. "Living α-olefin polymerization by cationic zirconium and hafnium complexes containing chelating diamidopyridine ligands". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16887.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2002.
Vita.
Includes bibliographical references (leaves 196-199).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
by Parisa Mehrkhodavandi.
Ph.D.
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8

Tafazolian, Hosein. "Hydroamination and Hydrosilylation Catalyzed by Cationic Palladium- and Nickel(allyl) Complexes Supported by 3-Iminophosphine Ligands". University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1473397460390363.

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Dallanegra, Romaeo. "Cationic rhodium complexes with chelating phosphine and phosphine alkene ligands. Application in dehydrogenation and dehydrocoupling reactions". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:c6841db3-aadf-428f-bd4e-a16e9eaa3511.

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A series of cationic Rh(I) diphosphine and phosphine-alkene complexes have been isolated and fully characterised. The reactivity of these species towards hydrogenation, dehydrogenation and dehydrocoupling reactions has been investigated. The use of potentially hemilabile ligands DPEphos and XANTphos in the intramolecular dehydrogenation chemistry of tricyclopentylphosphine is reported. The comparison in reactivity of these isolated diphosphine phosphine-alkene complexes towards hydrogenation and with acetonitrile is discussed along with their ability to dehydrocouple secondary silane, Ph₂SiH₂, and amine-borane H₃B·NMe₂H. The acceptorless dehydrogenation of a tethered cyclopentane with cationic Rh(I) diphosphine complexes has also been extended to include thioethers. Isolated cationic Rh(I) phosphine-alkene complexes with labile fluorobenzene ligands are found to act as a source of the reactive 12-electron [Rh{PR₂(ƞ²-C₅H₇)}]+ (R = cyclopentyl (Cyp)/ iPr) fragment in solution and can coordinate two amine-borane ligands (either H₃B·NMe₃, H₃B·NMe₂H or H₃B·NMeH₂) in a novel and unique bis-σ-binding mode. The catalytic activity of some of these isolated complexes in the dehydrocoupling of H₃B·NMe₂H and H₃B·NMeH₂ has been determined. With a view to further understanding the mechanism of catalytic transition metal assisted amine-borane dehydrogenation and dehydrocoupling, known B-N intermediates H₃B·NMe₂BH₂·NMe₂H and [H₂B·NMeH]₃ were also coordinated to the [Rh{PCyp₂(ƞ²-C₅H₇)}]+ fragment and investigated with regard to their role in the catalytic cycle. Structure activity relationships determined from stoichiometric reactions of cationic Rh(I) diphosphine fluorobenzene complexes with amine-boranes enabled the design of a highly efficient homogeneous catalyst capable of dehydrogenating H₃B·NMe₂H to [H₂BNMe₂]₂ at 0.2 mol% loading in 30 minutes at 298 K. Rapid dehydrogenation and dehydrocoupling of H₃B·NMeH₂ to form high molecular weight poly(N-methylaminoborane) with a low PDI has also been achieved. Investigations using model aminoborane H₂B=NiPr₂ and intermediate B-N species H₃B·NMe₂BH₂·NMe₂H and [H₂B·NMeH]₃ has helped establish an overall mechanistic rationale for this process.
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Sypaseuth, Fanni Daruny [Verfasser]. "Electrocatalytic Carbon Dioxide Reduction Using Cationic Cp*-Iridium Complexes Bearing Unsymmetrically Substituted Bipyridine Ligands / Fanni Daruny Sypaseuth". Berlin : Freie Universität Berlin, 2015. http://d-nb.info/106880985X/34.

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Libros sobre el tema "CATIONIC LIGANDS"

1

Meehan, Paul R. Complexation of neutral and cationic scandium(III) species with macrocyclic ligands. [s.l.]: typescript, 1996.

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Tipping, Edward. Cation Binding by Humic Substances. Cambridge University Press, 2009.

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Cation Binding by Humic Substances. Cambridge University Press, 2002.

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Tipping, Edward. Cation Binding by Humic Substances. Cambridge University Press, 2002.

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Tipping, Edward. Cation Binding by Humic Substances. Cambridge University Press, 2002.

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Tipping, Edward, P. G. C. Campbell, R. M. Harrison y S. J. de Mora. Cation Binding by Humic Substances. Cambridge University Press, 2005.

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Capítulos de libros sobre el tema "CATIONIC LIGANDS"

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Ohmatsu, Kohsuke y Takashi Ooi. "Cationic Organic Catalysts or Ligands in Concert with Metal Catalysts". En Asymmetric Organocatalysis Combined with Metal Catalysis, 131–52. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43851-7_6.

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Graham, Harold D., Deborah M. John y Bruce W. Erickson. "Engineering of a cationic coiled-coil protein bearing RGD-like ligands on proline-II helical spacers". En Peptides Frontiers of Peptide Science, 140–41. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/0-306-46862-x_53.

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Gokel, G. W., L. Echegoyen, K. A. Arnold, T. P. Cleary, V. J. Gatto, D. A. Gustowski, C. Hanlon et al. "Cation Effects on Solvents, Ligands, and Nucleophiles". En Advances in Chemistry, 443–56. Washington, DC: American Chemical Society, 1987. http://dx.doi.org/10.1021/ba-1987-0215.ch030.

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Richardson, David E. "Intrinsic Ancillary Ligand Effects in Cationic Zirconium Polymerization Catalysts". En Advances in Chemistry, 79–90. Washington, DC: American Chemical Society, 1997. http://dx.doi.org/10.1021/ba-1997-0253.ch005.

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Raymond, Kenneth N. "Template Synthesis of Ligands for Highly Charged Metal Cations". En United States-Japan Seminar on Host-Guest Chemistry, 169–71. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0969-4_19.

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Köster, Andreas M., Patrizia Calaminici y Ana Martínez. "Reactions of Mo Atoms and Cations with NO: A Density Functional Study". En Metal-Ligand Interactions in Chemistry, Physics and Biology, 371–82. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4245-8_16.

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Beer, Paul D. "Transition Metal Redox Active Ligand Systems for Recognising Cationic and Anionic Guest Species". En Transition Metals in Supramolecular Chemistry, 33–54. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-015-8380-0_2.

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Scrimin, Paolo y Umberto Tonellato. "Ligand Surfactants: Aggregation, Cations Binding and Transport, and Catalytic Properties". En Surfactants in Solution, 349–62. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3836-3_25.

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Sachleben, Richard A. y Bruce A. Moyer. "Ligand Design for Small Cations: The Li+/14-Crown-4 System". En ACS Symposium Series, 114–32. Washington, DC: American Chemical Society, 1999. http://dx.doi.org/10.1021/bk-1999-0716.ch007.

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Beer, Paul D. "Cation and Anion Coordination Chemistry of Redox Active Calixarene Macrocyclic Ligand Systems". En Molecular Engineering for Advanced Materials, 99–118. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8575-0_6.

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Actas de conferencias sobre el tema "CATIONIC LIGANDS"

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Pokidova, Olesya Viktorovna, Nina Sergeevna Emel’yanova, Alexander Vasilievich Kulikov, Alexander Ivanovich Kotelnikov y Natalia Alekseevna Sanina. "STUDY OF THE TRANSFORMATION OF NITROSYL IRON COMPLEX WITH N-ETHYLTHIOUREA LIGANDS IN MODEL BIOLOGICAL SYSTEMS". En NEW TECHNOLOGIES IN MEDICINE, BIOLOGY, PHARMACOLOGY AND ECOLOGY. Institute of information technology, 2021. http://dx.doi.org/10.47501/978-5-6044060-1-4.52.

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The process of transformation of a mononuclear cationic complex with N-ethylthiourea ligands in Tris-HCl buffer, as well as in a reaction mixture with reduced glutathione and bovine serum albumin, has been studied. It was found that in the presence of glutathione, the complex dimer-izes, while its initial ligands are replaced by glutathione. In the presence of albumin, the decay product of the complex is coordinated with amino acid residues (Cys34 and His39) to form a protein-bound complex.
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Borodin, Evgeniy. "SEARCH FOR POTENTIAL LIGANDS FOR TRPM8 WITH THE HELP OF COMPUTER DESIGN". En XIV International Scientific Conference "System Analysis in Medicine". Far Eastern Scientific Center of Physiology and Pathology of Respiration, 2020. http://dx.doi.org/10.12737/conferencearticle_5fe01d9b2fdca3.97577371.

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A search was carried out for potential ligands to TRPM8 - a representative of the family of cationic channels with a transient receptor potential involved in the development of bronchial hypersensitivity and the occurrence of bronchospasm in response to low temperatures. We used a structural design and molecular docking using the autodock software package (http://autodock.scripps.edu/), which allows automated testing of many potential ligands for TRPM8. Docking was carried out with tyrosine 745 (Y745) amino acid residue as a critical residue for channel sensitivity to menthol, a classic TRPM8 agonist. The selection of potential candidates for the role of drugs intended for the treatment of bronchial cold hyperreactivity using in silico methods can be supplemented by testing their biological activity in vitro experiments with cell and tissue cultures and in vivo with experimental animals.
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Solling, Theis, Mohamed Mahmoud y Michael Pittelkow. "Taking a New Approach Towards Chelating Agents for Scale Removal". En International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22604-ea.

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Abstract Scale presents a significant challenge in any context where flow is involved. In the oil and gas sector scale associated problems are notorious because of the significant volumes of brine that are involved at any stage of production. In addition, the formation brines are usually extremely concentrated when it comes to electrolytes that are prone to form scale. The real problematic scales are usually considered to be barite (BaSO4) and pyrite (FeS2, or mixed iron sulfides). The approach to remove them is usually to drive the solubility equilibrium towards solution by simply stabilizing the ions that are involved. That is usually done by coordination of the ions with a ligand that favors binding to the particular cation in question. For pyrite the challenge is then to identify a ligand that strongly coordinates Fe2+ whereas in the case of barite the focus will be on Ba2+. This is the classical approach to mostly target the cation and it has mostly been dealt with in the form of various chelating agents. We show results firstly, where newly designed cation binders provide a 20 % higher dissolving power than the second best and where binding pockets are designed for anions. This new binding mode will enable the design of a structure that simultaneously binds cations and anions and this is where we are heading with the current results. The efficiency of chelating agents is significantly dependent on pH this topic will be touched upon in a computational study here the calculated structure and the associated calculated binding energy will be discussed and related to dissolving power. The result show that ab initio calculations are nice supplements to experimental endeavors.
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Franich, Andjela, Ivana Vasić, Snežana Rajković, Aleksandar Arsenijević, Marija Milovanović, Nebojša Arsenijević, Jelena Milovanović y Marija Živković. "CYTOTOXICITY OF CATIONIC DINUCLEAR PLATINUM(II) COMPLEXES IN AN EXPERIMENTAL MODEL OF MOUSE COLON CANCER". En 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.293f.

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The series of nine dinuclear platinum(II) complexes, [{Pt(L)Cl}2(μ-X)]2+ (where L is two NH3 or bidentantly coordinated diamine ligand – ethylenediamine, en; (±)-1,2-propylenediamine, 1,2-pn; isobutylenediamine, ibn; trans-(±)-1,2-diaminocyclohexane, dach; 1,3-propylenediamine, 1,3-pd; 2,2- dimethyl-1,3-propylenediamine, 2,2-diMe-1,3-pd; (±)-1,3-pentanediamine,1,3-pnd, and X is a bridging pyrazine (pz) or pyridazine (pydz) ligand) have been synthesized and characterized. The antitumor potential of these complexes against CT26 cells were determined by in vitro and in vivo assays. A murine model of heterotopic colon cancer tumor was induced in immunocompetent BALB/c mice for investigating antitumor potential of the Pt(II) complexes in vivo. It was found that complexes Pt1, Pt2 and Pt7 shows significant in vitro cytotoxic activity against mouse colon carcinoma CT26 cells, while all these complexes show moderate apoptotic effect. Complexes Pt1 and Pt7 arrested CT26 cells in G2/M phase of cell cycle, while complexes Pt5 and Pt6 exerted the highest antiproliferative effect which was evaluated by detection of Ki67 expressing cells. Complexes Pt1 and Pt2 performed significant in vivo antitumor effects reducing the growth of primary tumor and the incidence of lung and liver metastases without causing the significant hepato- and nephro- toxicity.
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Silva, Victor Hugo Malamace da y Glaucio Braga Ferreira. "Chemical interaction study between xanthate ligand and lead (II) using NBO, EDA and QTAIM analysis". En VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol2020159.

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As a useful flotation agent, the xanthate ligand, O-alkyldithiocarbonates, has been used by different countries by its easy and inexpensive synthesis. More recently papers explored many different applications using this ligand within a complex of several metals cation. In order to study the proprieties of the lead (II) complex with such ligand, the object of this work is to provide a better understanding of the Pb-S bond using different theoretical approaches as NBO, EDA and QTAIM analysis and the influence caused by the different alkyl groups of the ligand. By an optimized structure, the NBO showed that the Pb-S is mainly composed by p orbital of the lead and by the p lone pair of the sulfur atom. The calculation with different alkyl groups highlights that the presence of a larger hydrocarbon chain provides a higher contribution of the s orbital of the lead atom to the interaction. Through the EDA analysis, the interaction between ligand and metal has the predominance of an electrostatic character. The size of the alkyl group has an impact on the value of both covalent and electrostatic character, making the interaction more covalent, due to a higher presence of an electronic density on sulfur atom. This density can be evaluated by the topological study of the QTAIM analysis, which enhances the fact that the charge over the sulfur atom gets higher when using a larger alkyl group for the xanthate ligand.
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Greve, Daniel R., Tommy Geisler, Thomas Bjørnholm y Jan C. Petersen. "Third-Order Nonlinear Optical Effects in Organic Nickel Complexes and Triarylmethyl Cations". En Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.md.23.

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The second molecular hyperpolarizability, γ, has been determined at 1064 nm by Third- Harmonic Generation (THG) using the Maker fringe technique, for a family of triarylmethyl cations and for a familiy of organic Nickel complexes as guests in PMMA thin films. For the metal complexes it is a well established notion that the low-lying transition with ligand to metal charge transfer character is important for the nonlinear optical properties(1). However, ambiguity arises due to large discrepancies between different measurements(2-5), as well as difficulties in assessing the exact contribution to γ of the ligand to metal charge transfer transition(2,6). To assess the latter question by experimental means, we present here a comparison between a family of Nickel complexes, and triarylmethyl cations. The electronic structure of the triarylmethyl cations resemble that of the metal complexes in the sense that intramolecular charge transfer from the periphery to the central atom takes place upon excitation in the first electronic band. This is shown by semi-empirical PM3 calculations on the three members of the family shown in figure 1. For the amino substituted compound 1 the calculations reveal a significant charge transfer from the amino moiety to the central carbon atom. For the molecules 2 and 3 this effect decreases due to the less efficient donor substituents (2) or forced planarity (3) resulting in more delocalized electronic states both in the HOMO and the LUMO. The observed γ values (table 1) can be correlated with the PM3 calculations in the way that the greater the amount of charge moved and the longer the spatial distance over wich it is moved, the greater is γ. The calculated static γ values, using the semi-empirical PM3/Finite-Field method follow the same trend although much smaller values are obtained.
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7

Krinochkin, Alexey P., Dmitry S. Kopchuk, Sougata Santra, Grigory V. Zyryanov, Vladimir L. Rusinov y Oleg N. Chupakhin. "Preparation of ligands for lanthanide cations based on 5-aryl-2,2′-bipyridine-6′-carboxylic acids with an extended conjugation system". En PROCEEDINGS OF THE 3RD INTERNATIONAL CONFERENCE ON AUTOMOTIVE INNOVATION GREEN ENERGY VEHICLE: AIGEV 2018. Author(s), 2019. http://dx.doi.org/10.1063/1.5087364.

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Jiang, Li, Suzanne Stewart y Jonathan Abbott. "Downhole Mineral Scale Dissolution Booster". En Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/32069-ms.

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Abstract Mineral scale formation in the wellbore represents a widespread and serious threat to flow assurance and ultimately to well productivity. Scale formation is generally attributable to the incompatibility between reservoir and injection waters and the main mineral scale types include carbonate, sulfate and sulfide salts of divalent cations. Currently available scale dissolvers for the latter two types are often based on chelating ligand chemistry, restricted by a kinetically sluggish process of displacing the cations plus near static scale-fluid interface at the scale surface area in downhole scenarios. We wish to report two newly generated material developments aimed at accelerating downhole scale dissolution treatment performance by using either or both: Discrete surfactants able to encapsulate entrained gases in the form of micro- and nano-bubbles that migrate in the fluid body along the pressure differential.Gas generating reactions catalyzed by freshly produced divalent cations at the scale-fluid interface. It has been demonstrated through systematic, lab-based proof of concept tests that these minor additives can promote interfacial mass transfer of both reactant and products as such that some of the current physical and engineering challenges of downhole mineral scale treatment can be circumvented, resulting in remarkably enhanced scale dissolution rates. Further increase of scale dissolution rates can also be achieved by the inclusion of a genuinely sustainable biosurfactant which, at certain concentration range, can effectively remove any hydrocarbon coatings that might have saturated the mineral scale surface, hence eliminate the often-hazardous organic solvent based preflush. In addition to the aforementioned example, it is believed that the methodology reported in this manuscript can also be applicable to enhance other chemistry oriented downhole treatments where mechanic agitation is not viable.
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Jiang, Li, Suzanne Stewart y Jonathan Abbott. "Downhole Mineral Scale Dissolution Booster". En Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/32069-ms.

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Abstract Mineral scale formation in the wellbore represents a widespread and serious threat to flow assurance and ultimately to well productivity. Scale formation is generally attributable to the incompatibility between reservoir and injection waters and the main mineral scale types include carbonate, sulfate and sulfide salts of divalent cations. Currently available scale dissolvers for the latter two types are often based on chelating ligand chemistry, restricted by a kinetically sluggish process of displacing the cations plus near static scale-fluid interface at the scale surface area in downhole scenarios. We wish to report two newly generated material developments aimed at accelerating downhole scale dissolution treatment performance by using either or both: Discrete surfactants able to encapsulate entrained gases in the form of micro- and nano-bubbles that migrate in the fluid body along the pressure differential.Gas generating reactions catalyzed by freshly produced divalent cations at the scale-fluid interface. It has been demonstrated through systematic, lab-based proof of concept tests that these minor additives can promote interfacial mass transfer of both reactant and products as such that some of the current physical and engineering challenges of downhole mineral scale treatment can be circumvented, resulting in remarkably enhanced scale dissolution rates. Further increase of scale dissolution rates can also be achieved by the inclusion of a genuinely sustainable biosurfactant which, at certain concentration range, can effectively remove any hydrocarbon coatings that might have saturated the mineral scale surface, hence eliminate the often-hazardous organic solvent based preflush. In addition to the aforementioned example, it is believed that the methodology reported in this manuscript can also be applicable to enhance other chemistry oriented downhole treatments where mechanic agitation is not viable.
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Milenković, Dejan A., Marko N. Živanović, Milan S. Dekić, Marijana Stanojević Pirković y Jelena R. Đorović Jovanović. "CYTOTOXIC ACTIVITY AND MOLECULAR DOCKING STUDY OF 4- SUBSTITUTED FLAVYLIUM SALT". En 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac,, 2021. http://dx.doi.org/10.46793/iccbi21.466m.

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In the present manuscript, the cytotoxic activity of flavylium cation substituted at 4- position with phenyl (FC-4Ph) was tested to two cells lines (human colorectal carcinoma, HCT-116, and human fibroblast lung, MRC-5). In vitro cytotoxicity experiments were performed to elucidate the possible anticancer activity of tested substance. Investigated compound did not show cytotoxic effect on HCT-116 after 24 h, while after 72 h exerted significant effect. A significant selectivity towards colorectal carcinoma cells was observed. On the other hand, this compound did not show any effect on MRC-5 cell line. The molecular interactions between receptor tyrosine kinase (RTK) and title compound was examined. The crystal structure of investigated receptor RTK was downloaded from Protein Data Bank. The native bound ligand ((E)-[4-(3,5-difluorophenyl)-3H-pyrrolo[2,3-b]pyridin-3-ylidene](3- methoxyphenyl)methanol was extracted from receptor and binding pocket analysis was performed. Re-docking was carried out with the FC-4Ph in order to generate the same docking pose as found in co-crystallized form of receptor. The obtained results of revealed that investigated compound binds at the same binding pockets to RTK, as well as native bound ligand, by weak non-covalent interactions. The most prominent interactions are hydrogen bonds, π-alkyl, and π-π interactions. The preliminary results suggest that investigated compound showed good binding affinity against RTK, as evident from the free binding energy (ΔGbind in kJ/mol).
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Informes sobre el tema "CATIONIC LIGANDS"

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Scamehorn, John F., Richard W. Taylor y Cynthia E. Palmer. Removal of Radioactive Cations and Anions from Polluted Water using Ligand-Modified Colloid-Enhanced Ultrafiltration. Office of Scientific and Technical Information (OSTI), diciembre de 2001. http://dx.doi.org/10.2172/789796.

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Scamehorn, John F., Cynthia E. Palmer y Richard W. Taylor. Removal of Radioactive Cations and Anions from Polluted Water Using Ligand-Modified Colloid-Enhanced Ultrafiltration. Office of Scientific and Technical Information (OSTI), junio de 1999. http://dx.doi.org/10.2172/828491.

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Scamehorn, John F., Richard W. Taylor y Cynthia E. Palmer. Removal of Radioactive Cations Anions from Polluted Water Using Ligand-Modified Colloid-Enhanced Ultrafiltration (60041-OK). Office of Scientific and Technical Information (OSTI), junio de 2000. http://dx.doi.org/10.2172/828493.

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Zhu, C. Y., R. M. Izatt, J. S. Bradshaw y N. K. Dalley. A Thermodynamic and Structural Study of the Interactions of Pyridino- and Diketopyridino-18-Crown-6 Ligands with some Primary Organic Ammonium Cations. Fort Belvoir, VA: Defense Technical Information Center, marzo de 1992. http://dx.doi.org/10.21236/ada248056.

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Scamehorn, J. F., C. E. Palmer y R. W. Taylor. Removal of radioactive cations and anions from polluted water using ligand-modified colloid-enhanced ultrafiltration. 1998 annual progress report. Office of Scientific and Technical Information (OSTI), junio de 1998. http://dx.doi.org/10.2172/13751.

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Yermiyahu, Uri, Thomas Kinraide y Uri Mingelgrin. Role of Binding to the Root Surface and Electrostatic Attraction in the Uptake of Heavy Metal by Plants. United States Department of Agriculture, 2000. http://dx.doi.org/10.32747/2000.7586482.bard.

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The principal accomplishment of the research supported by BARD was progress toward a comprehensive view of cell-surface electrical effects (both in cell walls [CWs] and at plasma membrane [PM] surfaces) upon ion uptake, intoxication, and amelioration. The research confirmed that electrostatic models (e.g., Gouy-Chapman-Stern [G-C-S]), with parameter values contributed by us, successfully predict ion behavior at cell surfaces. Specific research objectives 1. To characterize the sorption of selected heavy metals (Cu, Zn, Pb, Cd) to the root PM in the presence of other cations and organic ligands (citric and humic acids). 2. To compute the parameters of a G-C-S model for heavy-metal sorption to the root PM. 3. To characterize the accumulation of selected heavy metals in various plant parts. 4. To determine whether model-computed ion binding or ion activities at root PM surfaces predict heavy-metal accumulation in whole roots, root tips, or plant shoots. 5. To determine whether measured ion binding by protoplast-free roots (i.e., root CWs) predicts heavy-metal accumulation in whole roots, root tips, or plant shoots. 6. To correlate growth inhibition, and other toxic responses, with the measured and computed factors mentioned above. 7. To determine whether genotypic differences in heavy-metal accumulation and toxic responses correlate with genotypic differences in parameters of the G-C-S model. Of the original objectives, all except for objective 7 were met. Work performed to meet the other objectives, and necessitated on the basis of experimental findings, took the time that would have been required to meet objective 7. In addition, work with Pb was unsuccessful due to experimental complications and work on Cd is still in progress. On the other hand, the uptake and toxicity of the anion, selenate was characterized with respect to electrostatic effects and the influences of metal cations. In addition, the project included more theoretical work, supported by experimentation, than was originally planned. This included transmembrane ion fluxes considered in terms of PM-surface electrical potentials and the influence of CWs upon ion concentrations at PM surfaces. A important feature of the biogeochemistry of trace elements in the rhizosphere is the interaction between plant-root surfaces and the ions present in the soil solution. The ions, especially the cations, of the soil solution may be accumulated in the aqueous phases of cell surfaces external to the PMs, sometimes referred to as the "water free space" and the "Donnan free space". In addition, ions may bind to the CW components or to the PM surface with variable binding strength. Accumulation at the cell surface often leads to accumulation in other plant parts with implications for the safety and quality of foods. A G-C-S model for PMs and a Donnan-plus-binding model for CWs were used successfully to compute electrical potentials, ion binding, and ion concentration at root-cell surfaces. With these electrical potentials, corresponding values for ion activities may be computed that are at least proportional to actual values also. The computed cell-surface ion activities predict and explain ion uptake, intoxication, and amelioration of intoxication much more accurately than ion activities in the bulk-phase rooting medium.
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Ohad, Itzhak y Himadri Pakrasi. Role of Cytochrome B559 in Photoinhibition. United States Department of Agriculture, diciembre de 1995. http://dx.doi.org/10.32747/1995.7613031.bard.

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The aim of this research project was to obtain information on the role of the cytochrome b559 in the function of Photosystem-II (PSII) with special emphasis on the light induced photo inactivation of PSII and turnover of the photochemical reaction center II protein subunit RCII-D1. The major goals of this project were: 1) Isolation and sequencing of the Chlamydomonas chloroplast psbE and psbF genes encoding the cytochrome b559 a and b subunits respectively; 2) Generation of site directed mutants and testing the effect of such mutation on the function of PSII under various light conditions; 3) To obtain further information on the mechanism of the light induced degradation and replacement of the PSII core proteins. This information shall serve as a basis for the understanding of the role of the cytochrome b559 in the process of photoinhibition and recovery of photosynthetic activity as well as during low light induced turnover of the D1 protein. Unlike in other organisms in which the psbE and psbF genes encoding the a and b subunits of cytochrome b559, are part of an operon which also includes the psbL and psbJ genes, in Chlamydomonas these genes are transcribed from different regions of the chloroplast chromosome. The charge distribution of the derived amino-acid sequences of psbE and psbF gene products differs from that of the corresponding genes in other organisms as far as the rule of "positive charge in" is concerned relative to the process of the polypeptide insertion in the thylakoid membrane. However, the sum of the charges of both subunits corresponds to the above rule possibly indicating co-insertion of both subunits in the process of cytochrome b559 assembly. A plasmid designed for the introduction of site-specific mutations into the psbF gene of C. reinhardtii. was constructed. The vector consists of a DNA fragment from the chromosome of C. reinhardtii which spans the region of the psbF gene, upstream of which the spectinomycin-resistance-conferring aadA cassette was inserted. This vector was successfully used to transform wild type C. reinhardtii cells. The spectinomycin resistant strain thus obtained can grow autotrophically and does not show significant changes as compared to the wild-type strain in PSII activity. The following mutations have been introduced in the psbF gene: H23M; H23Y; W19L and W19. The replacement of H23 involved in the heme binding to M and Y was meant to permit heme binding but eventually alter some or all of the electron transport properties of the mutated cytochrome. Tryptophane W19, a strictly conserved residue, is proximal to the heme and may interact with the tetrapyrole ring. Therefore its replacement may effect the heme properties. A change to tyrosine may have a lesser affect on the potential or electron transfer rate while a replacement of W19 by leucine is meant to introduce a more prominent disturbance in these parameters. Two of the mutants, FW19L and FH23M have segregated already and are homoplasmic. The rest are still grown under selection conditions until complete segregation will be obtained. All mutants contain assembled and functional PSII exhibiting an increased sensitivity of PSII to the light. Work is still in progress for the detailed characterization of the mutants PSII properties. A tobacco mutant, S6, obtained by Maliga and coworkers harboring the F26S mutation in the b subunit was made available to us and was characterized. Measurements of PSII charge separation and recombination, polypeptide content and electron flow indicates that this mutation indeed results in light sensitivity. Presently further work is in progress in the detailed characterization of the properties of all the above mutants. Information was obtained demonstrating that photoinactivation of PSII in vivo initiates a series of progressive changes in the properties of RCII which result in an irreversible modification of the RCII-D1 protein leading to its degradation and replacement. The cleavage process of the modified RCII-D1 protein is regulated by the occupancy of the QB site of RCII by plastoquinone. Newly synthesized D1 protein is not accumulated in a stable form unless integrated in reassembled RCII. Thus the degradation of the irreversibly modified RCII-D1 protein is essential for the recovery process. The light induced degradation of the RCII-D1 protein is rapid in mutants lacking the pD1 processing protease such as in the LF-1 mutant of the unicellular alga Scenedesmus obliquus. In this case the Mn binding site of PSII is abolished, the water oxidation process is inhibited and harmful cation radicals are formed following light induced electron flow in PSII. In such mutants photo-inactivation of PSII is rapid, it is not protected by ligands binding at the QB site and the degradation of the inactivated RCII-D1 occurs rapidly also in the dark. Furthermore the degraded D1 protein can be replaced in the dark in absence of light driven redox controlled reactions. The replacement of the RCII-D1 protein involves the de novo synthesis of the precursor protein, pD1, and its processing at the C-terminus end by an unknown processing protease. In the frame of this work, a gene previously isolated and sequenced by Dr. Pakrasi's group has been identified as encoding the RCII-pD1 C-terminus processing protease in the cyanobacterium Synechocystis sp. PCC 6803. The deduced sequence of the ctpA protein shows significant similarity to the bovine, human and insect interphotoreceptor retinoid-binding proteins. Results obtained using C. reinhardtii cells exposes to low light or series of single turnover light flashes have been also obtained indicating that the process of RCII-D1 protein turnover under non-photoinactivating conditions (low light) may be related to charge recombination in RCII due to back electron flow from the semiquinone QB- to the oxidised S2,3 states of the Mn cluster involved in the water oxidation process.
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