Search results for "Coordination sphere"
showing 10 items of 99 documents
Atomic structure of manganese-doped yttrium orthoaluminate
2018
Abstract Using hybrid exchange-correlation functional within density functional theory we have performed first-principle total energy calculations of Mn-doped yttrium orthoaluminate (YAlO3). Its equilibrium atomic structure has been predicted through optimization of coordinates of all atoms using a supercell approach. In our research both Mn3+ and Mn2+ ions have been substituted for the host alumina atom at orthorhombic Pbnm unit cell of YAlO3. F-center has been implemented as charge-compensating defect in case, when Mn2+ dopant is under study. In this study we thoroughly analyze the atomic displacements in seven nearest to Mn ion coordination spheres. Insertion of isoelectronic substitutio…
The effect of a membrane-mimicking environment on the interactions of Cu2+ with an amyloidogenic fragment of chicken prion protein
2017
Prion proteins (PrP) from different species have the ability to tightly bind Cu2+ ions. Copper coordination sites are located in the disordered and flexible N-terminal region which contains several His anchoring sites. Among them, two His residues are found in the so called amyloidogenic PrP region which is believed to play a key role in the process leading to oligomer and fibril formation. Both chicken and human amyloidogenic regions have a hydrophobic C-terminal region rich in Ala and Val amino acids. Recent findings revealed that this domain undergoes random coil to α-helix structuring upon interaction with membrane models. This interaction might strongly impact metal binding abilities e…
Ferromagnetic coupled μ-phenoxo-μ-carboxylato heterodinuclear complexes based on the Cr(salen) moiety: Structural and magnetic characterization
2009
The synthesis, crystal structure, and magneto-chemical characterization of two new unprecedented μ-phenoxo-μ-carboxylato heterodinuclear complexes based on the Cr(salen) moiety (salen = N,N′-bis(salicylidene)ethylenediamine), [MII(O2C(CH3)3)(OH2)2(μ-O2C(CH3)3)(μ-salen)CrIII(O2C(CH3)3)], M = Ni (2), Co(3) are reported. The dinuclear complexes were obtained starting from the mononuclear trans-[Cr(salen)(CN)2]PPh4 (1), whose crystal structure is also reported. They show a trans arrangement of the Cr(salen) unit, bridging through the phenolate O atoms to a second metal center. An additional μ2-O2-carboxylato bridge and a further monodentating carboxylate ligand complete the roughly octahedral C…
Homoleptic heavy alkaline Earth and europium triazenides.
2009
The sigma-bond metathesis reaction between PhSiH(3) and the heteroleptic metal pentafluorophenyl compounds [Dmp(Tph)N(3)MC(6)F(5)(thf)(n)] (Dmp = 2,6-Mes(2)C(6)H(3) with Mes = 2,4,6-Me(3)C(6)H(2); Tph = 2-TripC(6)H(4) with Trip = 2,4,6-(i)Pr(3)C(6)H(2); n = 1, 2; M = Sr, Ba, Eu) supported by sterically crowded, biphenyl- and terphenyl-substituented triazenido ligands afforded the first homoleptic stontium, barium, and europium triazenides [M{N(3)Dmp(Tph)}(2)] {M = Sr (2), Ba (4), Eu (5)}. Crystallization of 2 from an n-heptane/1,2-dimethoxyethane mixture gave the complex [Sr{N(3)Dmp(Tph)}(2)(dme)] (3). All new compounds have been characterized by (1)H and (13)C NMR spectroscopy (not 5), ele…
Structural analysis of copper(I) interaction with amyloid β peptide
2019
Abstract The N-terminal fragment of Aβ (β = beta) peptide is able to bind essential transition metal ions like, copper, zinc and iron. Metal binding usually occurs via the imidazole nitrogens of the three His residues which play a key role in the coordination chemistry. Among all the investigated systems, the interaction between copper and Amyloid β assume a biological relevance because of the interplay between the two copper oxidation states, Cu(II) and Cu(I), and their involvement in redox reactions. Both copper ions share the ability to bind Amyloid β. A huge number of investigations have demonstrated that Cu(II) anchors to the N-terminal amino and His6, His13/14 imidazole groups, while …
Synthesis and structural elucidation of novel antifungal N-(fluorophenyl)piperazinyl benzoxaboroles and their analogues
2019
Abstract Series of novel N-(fluorophenyl)piperazine derivatives of phenylboronic compounds including benzoxaboroles, phenylboronic acids and phenylboronic methyl monoester have been obtained by facile synthetic methods starting from 2-formylphenylboronic acid. Molecular and crystal structures of those novel derivatives have been investigated by single crystal X-ray diffraction method. The Bond Valence Vector Model was used to describe strains in the boron coordination sphere. Microbiological activity of novel benzoxaboroles as well as their corresponding acid analogues against: A. niger, A. terreus, P. ochrochloron, C. tenuis and F. dimerum has been evaluated. The presence of heterocyclic b…
Coordination properties of the ACE inhibitor captopril towards Me2Sn(IV)2+ in aqueous solution, and biological aspects of some dialkyltin(IV) derivat…
2003
Abstract The coordination of Me 2 Sn(IV) 2+ (M) to captopril { N -[( S )-3-mercapto-2-methylpropionyl]- l -proline, H 2 (cap), H 2 L} in aqueous solution was studied by means of potentiometric titration, electrospray mass spectrometry, 1 H-NMR spectroscopy and Mossbauer spectroscopy in the pH range 2–11 ( I =0.1 mol dm −3 NaClO 4 , 298 K). The results obtained with these methods proved that only monomeric complexes are formed in solution. In the acidic pH range, species with a metal-to-ligand ratio of 1:1 exist. The neutral complex ML, similarly to the complex Me 2 Sn(cap) crystallized in the same pH range, adopts a tbp structure with eq S − and ax COO − , while, instead of the coordina…
Copper(II)-assisted hydrolysis of 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (tpymt): syntheses, crystal structures and magnetic properties of [Cu(bpcam)…
2005
Abstract The reaction of the 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (tpymt) ligand with copper(II) perchlorate or sulfate in aqueous solution affords complexes [Cu(bpcam)(H2O)2]ClO4 · 3H2O (1), [Cu(bpcam)(H2O)2][Cu(bpcam)(H2O)(SO4)] · 2H2O (2) and [Cu2(bpcam)2(H2O)2(SO4)] · H2O (3) [bpcam = bis(2-pyrimidylcarbonyl)amidate], whose structures have been determined by single-crystal X-ray diffraction studies. Copper(II) promotes the hydrolysis of tpymt in mild conditions yielding the bpcam group which is present in the structures of 1–3 as a tridentate ligand. The structure of 1 consists of mononuclear [Cu(bpcam)(H2O)2]+ cations, uncoordinated perchlorate anions and water of crystallization. Th…
Induced Chirality in Confined Space on Halogen Gold Complexes
2015
The solubilization of HAuCl4 in toluene within optically active reverse micelles and lamellar structures formed by (1R,2S)-Dodecyl(2-hydroxy-1-methyl-2-phenylethyl)- dimethylammonium bromide (DMEB) has allowed us to evidence the complex phenomenology accompanying the confinement of Au salt within these nanostructures. Together with a chloride/bromide exchange process occurring in the first coordination sphere of an Au ion, UV−vis and electronic circular dichroism (ECD) spectra reveal the appearance of an induced dichroic signal attributable to Au complexes entrapped in the hydrophilic domain of the DMEB chiral nanostructures. Interestingly, change of the effective oxidation state and coordi…
Macrocycle-Based Spin-Crossover Materials
2009
International audience; New iron(II) complexes of formula [Fe(L1)](BF(4))(2) (1) and [Fe(L2)](BF(4))(2) x H(2)O (2) (L1 = 1,7-bis(2'-pyridylmethyl)-1,4,7,10-tetraazacyclododecane; L2 = 1,8-bis(2'-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by infrared spectroscopy, variable-temperature single-crystal X-ray diffraction, and variable-temperature magnetic susceptibility measurements. The crystal structure determinations of 1 and 2 reveal in both cases discrete iron(II) monomeric structures in which the two functionalized tetraazamacrocycles (L1 and L2) act as hexadentate ligands; the iron(II) ions are coordinated with six nitrogen atoms: four from …