Search results for "organometalli"
showing 10 items of 395 documents
Equilibrium, Kinetic, and Computational Studies on the Formation of Cu2+ and Zn2+ Complexes with an Indazole-Containing Azamacrocyclic Scorpiand: Evi…
2015
Cu(2+) and Zn(2+) coordination chemistry of a new member of the family of scorpiand-like macrocyclic ligands derived from tris(2-aminoethyl)amine (tren) is reported. The new ligand (L1) contains in its pendant arm not only the amine group derived from tren but also a 6-indazole ring. Potentiometric studies allow the determination of four protonation constants. UV-vis and fluorescence data support that the last protonation step occurs on the indazole group. Equilibrium measurements in the presence of Cu(2+) and Zn(2+) reveal the formation of stable [ML1](2+), [MHL1](3+), and [ML1(OH)](+) complexes. Kinetic studies on the acid-promoted decomposition of the metal complexes were carried out usi…
Solid-State Aggregation of Metallacyclophane-Based MnIICuII One-Dimensional Ladders
2012
Two distinct one-dimensional (1) and two-dimensional (2) mixed-metal-organic polymers have been synthesized by using the "complex-as-ligand" strategy. The structure of 1 consists of isolated ladderlike Mn(II)(2)Cu(II)(2) chains separated from each other by neutral Mn(II)(2) dimers, whereas 2 possesses an overall corrugated layer structure built from additional coordinative interactions between adjacent Mn(II)(2)Cu(II)(2) ladders. Interestingly, 1 and 2 show overall ferri- and antiferromagnetic behavior, respectively, as a result of their distinct crystalline aggregation in the solid state.
Novel Hexanuclear Copper(II) Complex Built from a Simple Tetrachelating Triazole Ligand: Synthesis, Structure, and Magnetism
2013
A new easy symmetric 3,5-disubstituted 1,2,4-triazole ligand (H3diV) by reaction with an excess of copper(II) salt has afforded a novel hexanuclear compound (Cu/HdiV ratio of 6:2) through a bis(trans-cis-cis-trans) binding mode, exhibiting two types of Cu(II) centers and two clearly distinguishable antiferromagnetic J1 (-234 cm(-1)) and J2 (-35 cm(-1)) coupling constants.
Bis(diethylenetriamine-κ3N)nickel(II) 5-amino-1,3,4-thiadiazole-2-sulfonamidate chloride monohydrate
2000
In the X-ray crystal structure of the title complex, [Ni(C(4)H(13)N(3))(2)](C(2)H(3)N(4)O(2)S(2))Cl.H(2)O, the coordination polyhedron is composed of non-centrosymmetric [Ni(diethylenetriamine)(2)](2+) cations in which the triamine ligands coordinate to the metal centre as tridentate ligands in a facial position. The Ni(II) ions are linked to six N atoms in an octahedral arrangement, slightly compressed in one extreme. The sulfonamide behaves as a counter-ion instead of as a ligand. Important information about the deprotonated sulfonamide group conformation has been obtained.
Effect of tin and lead chlorotriphenyl analogues on selected living cells.
2010
Three kinds of living cells, human embryonic kidney cells, Saccharomyces cerevisiae, and Escherichia coli, were tested for their sensitivity to chlorotriphenyltin and chlorotriphenyllead. The tin compound proved definitely more toxic than the lead derivative, particularly in the case of the human embryonic kidney cells devoid of any protective cell wall. Electron paramagnetic resonance (EPR) comparative studies carried out by using a natural model liposome system (egg yolk lecithin) confirmed considerable changes within the lipid bilayer upon doping by the aforementioned additives, which may be crucial to the mechanism of the observed cell cleavage. The individual dopants revealed diverse i…
Palladium(II)-Stabilized Pyridine-2-Diazotates: Synthesis, Structural Characterization, and Cytotoxicity Studies
2018
Well-defined diazotates are scarce. Here we report the synthesis of unprecedented homoleptic palladium(II) diazotate complexes. The palladium(II)-mediated nitrosylation of 2-aminopyridines with NaNO2 results in the formation of metal-stabilized diazotates, which were found to be cytotoxic to human ovarian cancer cells.
Interactions of zinc octacarboxyphthalocyanine with selected amino acids and with albumin
2015
Effect of selected amino acids (glycine, l-histidine, l-cysteine, l-serine, l-tryptophan) and albumin on the spectroscopic properties and photostability of zinc octacarboxyphthalocyanine (ZnPcOC) was explored in the phosphate buffer at a pH of 7.0. The photodegradation of ZnPcOC alone and in the presence of amino acids or albumin has been investigated in aqueous phase using UV-366 nm and daylight irradiation. Kinetic analysis showed that the interaction with amino acids or albumin enhances the photostability of ZnPcOC. To answer the question of how zinc phthalocyanine interacts with amino acids extensive DFT calculations were performed. Analysis of the optimized geometry features of ZnPcOC:…
A Trinuclear Copper(II) Cryptate and Its μ3-CO3 Cascade Complex: Thermodynamics, Structural and Magnetic Properties
2011
The 2,4,6-triethylbenzene-capped hexaamine macrobicycle with pyridyl spacers (pyr) was able to coordinate three copper(II) ions within its cavity. Potentiometric studies performed at 298.2 K in MeOH/H(2)O (50:50 v/v) and at ionic strength 0.10 mol dm(-3) in KNO(3) revealed that trinuclear species predominate in solution from pH 5.0, the hydroxo complexes being the main species, which start forming at unusual very low pH values. The single-crystal X-ray determination of the trinuclear complex showed that the three copper centres have square-planar geometry, arranged in an almost equilateral triangle, and have carbonate bridging the three metal centres. The presence of carbonate resulted from…
Reactivity of Neutral Mo(S2C6H4)3 in Aqueous Media: an Alternative Functional Model of Sulfite Oxidase.
2009
The kinetics of the reaction of neutral [Mo(S2C6H4)3] with hydrogen sulfite to produce the anionic Mo(V) complex, [Mo(S2C6H4)3]-, and sulfate have been investigated. It has been shown that [Mo(S2C6H4)3] acts as the electron-proton sink in the oxygenation reaction of HSO3(-) by water. Reaction rates, monitored by UV/vis stopped-flow spectrometry, were studied in THF/water media as a function of the concentration of HSO3(-) and molybdenum complex, pH, ionic strength, and temperature. The reaction exhibits pH-dependent HSO3(-) saturation kinetics, and it is first-order in complex concentration. The kinetic data and MS-ESI spectra are consistent with the formation of [Mo O(S2C6H4)2(S2C6H5)]- (1…
Hyper-CEST NMR of metal organic polyhedral cages reveals hidden diastereomers with diverse guest exchange kinetics.
2022
AbstractGuest capture and release are important properties of self-assembling nanostructures. Over time, a significant fraction of guests might engage in short-lived states with different symmetry and stereoselectivity and transit frequently between multiple environments, thereby escaping common spectroscopy techniques. Here, we investigate the cavity of an iron-based metal organic polyhedron (Fe-MOP) using spin-hyperpolarized 129Xe Chemical Exchange Saturation Transfer (hyper-CEST) NMR. We report strong signals unknown from previous studies that persist under different perturbations. On-the-fly delivery of hyperpolarized gas yields CEST signatures that reflect different Xe exchange kinetic…