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Macrocyclic Complexes (macrocyclic + complex)
Selected AbstractsStructure Comparison of Early and Late Lanthanide(III) Homodinuclear Macrocyclic Complexes with the Polyamine Polycarboxylic Ligand H8OHECEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2004Ulrike A. Böttger Abstract The solid-state structures of two new homodinuclear chelate complexes with the late lanthanide(III) ions Yb and Lu, [Na2(Yb2OHEC)].14.5H2O (1), and [Na2(Lu2OHEC)].14.5H2O (2) (H8OHEC = 1,4,7,10,14,17,20,23-octaazacyclohexacosane- 1,4,7,10,14,17,20,23-octaacetic acid), have been determined by X-ray crystal structure analysis. Each lanthanide(III) ion is coordinated by eight donor atoms of the ligand and the geometry of the coordination polyhedron approaches a bicapped trigonal prism. These structures are compared with those of the homodinuclear chelate complexes with the same ligand and the mid to early lanthanide(III) ions Gd, Eu, La and also Y. A distinctive structural change occurs across the lanthanide series. The centrosymmetric mid to early lanthanide(III) complexes are all ninefold-coordinated in a capped square antiprismatic arrangement with a water molecule coordinated in a prismatic position. This structure is maintained in aqueous solution, together with an asymmetric minor isomer. The late lanthanide(III) OHEC complexes not only lack the inner-sphere water, but the change of coordination sphere also results in a loss of symmetry of the whole complex molecule. The observed change of coordination mode and number of the lanthanide ion may offer a geometric model for the isomerization process in eight- and ninefold-coordinated complex species that are isomers in a possible coordination equilibrium observed by NMR in aqueous solution. This model may also explain the intramolecular rearrangements necessary during water exchange in the inner coordination sphere of the complex [(Gd2OHEC)(H2O)2]2, through a slow dissociative mechanism. Protonation constants of the H8OHEC ligand and complex formation constants of this ligand with GdIII, CaII, CuII and ZnII have been determined by solution thermodynamic studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] NMR and Luminescence Binding Studies of Ytterbium, Thulium, and Europium Macrocyclic Complexes with Phosphorus(V) Oxy AnionsHELVETICA CHIMICA ACTA, Issue 3 2005Paul Atkinson The binding of a series of phosphate anions to coordinatively unsaturated macrocyclic complexes of Yb, Tm, and Eu was studied by 1H-NMR, emission and circularly polarized luminescence (CPL) spectroscopy. Each ternary adduct was distinguished by its spectral profile. With O -phosphorylated amino acids and peptides, chemoselective ligation of the phosphate moiety was favored by Eu over chelation involving the terminal amino group, which was competitive for Tm and Yb. A preference for binding O -phosphono- L -tyrosine sites was found with various Eu complexes, and was signalled by ratiometric changes in metal-based emission and CPL spectra. [source] Metallomacrocycles with a Difference: Macrocyclic Complexes with Exocyclic Ruthenium(II)-Containing DomainsCHEMISTRY - A EUROPEAN JOURNAL, Issue 43 2009Edwin Abstract The templated synthesis of organic macrocycles containing rings of up to 96 atoms and three 2,2,-bipyridine (bpy) units is described. Starting with the bpy-centred ligands 5,5,-bis[3-(1,4-dioxahept-6-enylphenyl)]-2,2,-bipyridine and 5,5,-bis[3-(1,4,7-trioxadec-9-enylphenyl)]-2,2,-bipyridine, we have applied Grubbs' methodology to couple the terminal alkene units of the coordinated ligands in [FeL3]2+ complexes. Hydrogenation and demetallation of the iron(II)-containing macrocyclic complexes results in the isolation of large organic macrocycles. The latter bind {Ru(bpy)2} units to give macrocyclic complexes with exocyclic ruthenium(II)-containing domains. The complex [Ru(bpy)2(L)]2+ (isolated as the hexafluorophosphate salt), in which L=5,5,-bis[3-(1,4,7,10-tetraoxatridec-12-enylphenyl)]-2,2,-bipyridine, undergoes intramolecular ring-closing metathesis to yield a macrocycle which retains the exocyclic {Ru(bpy)2} unit. The poly(ethyleneoxy) domains in the latter macrocycle readily scavenge sodium ions, as proven by single-crystal X-ray diffraction and atomic absorption spectroscopy data for the bulk sample. In addition to the new compounds, a series of model complexes have been fully characterized, and representative single-crystal X-ray structural data are presented for iron(II) and ruthenium(II) acyclic and macrocyclic species. [source] Brain temperature and pH measured by 1H chemical shift imaging of a thulium agentNMR IN BIOMEDICINE, Issue 2 2009Daniel Coman Abstract Temperature and pH are two of the most important physiological parameters and are believed to be tightly regulated because they are intricately related to energy metabolism in living organisms. Temperature and/or pH data in mammalian brain are scarce, however, mainly because of lack of precise and non-invasive methods. At 11.7,T, we demonstrate that a thulium-based macrocyclic complex infused through the bloodstream can be used to obtain temperature and pH maps of rat brain in vivo by 1H chemical shift imaging (CSI) of the sensor itself in conjunction with a multi-parametric model that depends on several proton resonances of the sensor. Accuracies of temperature and pH determination with the thulium sensor , which has a predominantly extracellular presence , depend on stable signals during the course of the CSI experiment as well as redundancy for temperature and pH sensitivities contained within the observed signals. The thulium-based method compared well with other methods for temperature (1H MRS of N -acetylaspartate and water; copper,constantan thermocouple wire) and pH (31P MRS of inorganic phosphate and phosphocreatine) assessment, as established by in vitro and in vivo studies. In vitro studies in phantoms with two compartments of different pH value observed under different ambient temperature conditions generated precise temperature and pH distribution maps. In vivo studies in , -chloralose-anesthetized and renal-ligated rats revealed temperature (33,34°C) and pH (7.3,7.4) distributions in the cerebral cortex that are in agreement with observations by other methods. These results show that the thulium sensor can be used to measure temperature and pH distributions in rat brain in vivo simultaneously and accurately with using biosensor imaging of redundant. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hydrogenolysis of glycerol with FeCo macrocyclic complex bonded to Raney Nickel support under mild reaction conditionsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010K. A. Anand Abstract The hydrogenolysis of dilute glycerol solution to 1,2-propanediol was studied in the presence of heterogeneous catalyst (FeCoL/Raney Nickel) having a heterodinuclear FeCo macrocyclic complex ionically bonded to Raney Nickel. Studies on the stability of the complex bonded to the support were carried out at different temperature as well as the effect of solvent to confirm that it was stable up to 600°C and 100,h of refluxing. In the hydrogenolysis of glycerol, the temperature has been varied from 165 to 220°C with an initial hydrogen pressure 0.35,MPa and the conversion increases from 1% to 36% with no gases evolving in this temperature range. The major product is 1,2-propanediol which is formed with 80% selectivity. The initial water content (20,60%) in the feed was also varied and it was found that the conversion and yield of 1,2-propanediol increases when the water content increases. Based on literature, a kinetic model was proposed and optimal rate constants determined using Genetic Algorithm (GA). On a étudié l'hydrogénolyse d'une solution diluée de glycérol solution en 1,2-propanediol, en présence d'un catalyseur hétérogène (FeCoL/nickel de Raney) ayant un complexe macrocyclique hétérodinucléaire de FeCo ioniquement lié au nickel de Raney. Des études sur la stabilité du complexe lié au soutien ont été effectuées à différentes températures et on a étudié aussi l'effet du solvant pour confirmer qu'il était stable jusqu'à 600 °C et 100 h de reflux. Dans l'hydrogénolyse du glycérol, la température variait de 165 à 220°C avec une pression initiale d'hydrogène de 0,35 MPa et la conversion augmente de 1% à to 36% sans évolution des gaz dans cet intervalle de température. Le produit majeur est le 1,2-propanediol, lequel est formé avec une sélectivité de 80%. Le contenu d'eau initial (20% à 60%) dans l'alimentation variait également et on a conclu que la conversion et le rendement de 1,2-propanediol augmentait avec les augmentations de contenu d'eau. En se basant sur la littérature, un modèle cinétique a été proposé et des constantes de taux optimal ont été déterminées en utilisant un algorithme génétique. [source] NMR and Luminescence Binding Studies of Ytterbium, Thulium, and Europium Macrocyclic Complexes with Phosphorus(V) Oxy AnionsHELVETICA CHIMICA ACTA, Issue 3 2005Paul Atkinson The binding of a series of phosphate anions to coordinatively unsaturated macrocyclic complexes of Yb, Tm, and Eu was studied by 1H-NMR, emission and circularly polarized luminescence (CPL) spectroscopy. Each ternary adduct was distinguished by its spectral profile. With O -phosphorylated amino acids and peptides, chemoselective ligation of the phosphate moiety was favored by Eu over chelation involving the terminal amino group, which was competitive for Tm and Yb. A preference for binding O -phosphono- L -tyrosine sites was found with various Eu complexes, and was signalled by ratiometric changes in metal-based emission and CPL spectra. [source] AgI and CuI binuclear macrocyclic complexes with 1-(3-pyridyl)ethanone oximeACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2004Ingrid Socorro Bis[,-1-(3-pyridyl)ethanone oxime-,2N:N,]bis[nitratosilver(I)], [Ag2(NO3)2(C7H8N2O)2], crystallizes as a centrosymmetric binuclear macrocylic complex containing silver(I) ions bridged by the organic 1-(3-pyridyl)ethanone oxime ligand. The ligand coordinates via the pyridine and the oxime N atoms. A similar metal,ligand arrangement was found in the copper(I) complex catena -poly[[bis[,-1-(3-pyridyl)ethanone oxime-,2N:N,]dicopper(I)]-di-,-iodo], [Cu2I2(C7H8N2O)2]n, but here the centrosymmetric macrocycles are connected by double anion bridges, resulting in the formation of a one-dimensional coordination polymer. [source] Metallomacrocycles with a Difference: Macrocyclic Complexes with Exocyclic Ruthenium(II)-Containing DomainsCHEMISTRY - A EUROPEAN JOURNAL, Issue 43 2009Edwin Abstract The templated synthesis of organic macrocycles containing rings of up to 96 atoms and three 2,2,-bipyridine (bpy) units is described. Starting with the bpy-centred ligands 5,5,-bis[3-(1,4-dioxahept-6-enylphenyl)]-2,2,-bipyridine and 5,5,-bis[3-(1,4,7-trioxadec-9-enylphenyl)]-2,2,-bipyridine, we have applied Grubbs' methodology to couple the terminal alkene units of the coordinated ligands in [FeL3]2+ complexes. Hydrogenation and demetallation of the iron(II)-containing macrocyclic complexes results in the isolation of large organic macrocycles. The latter bind {Ru(bpy)2} units to give macrocyclic complexes with exocyclic ruthenium(II)-containing domains. The complex [Ru(bpy)2(L)]2+ (isolated as the hexafluorophosphate salt), in which L=5,5,-bis[3-(1,4,7,10-tetraoxatridec-12-enylphenyl)]-2,2,-bipyridine, undergoes intramolecular ring-closing metathesis to yield a macrocycle which retains the exocyclic {Ru(bpy)2} unit. The poly(ethyleneoxy) domains in the latter macrocycle readily scavenge sodium ions, as proven by single-crystal X-ray diffraction and atomic absorption spectroscopy data for the bulk sample. In addition to the new compounds, a series of model complexes have been fully characterized, and representative single-crystal X-ray structural data are presented for iron(II) and ruthenium(II) acyclic and macrocyclic species. [source] | ||||||||||