Search results for "NICKEL"

Nickel(II), copper(II) and zinc(II) metallo-intercalators: structural details of the DNA-binding by a combined experimental and computational investi…

2014

We present a thorough characterization of the interaction of novel nickel(II) (1), copper(II) (2) and zinc(II) (3) Schiff base complexes with native calf thymus DNA (ct-DNA), in buffered aqueous solution at pH 7.5. UV-vis absorption, circular dichroism (CD) and viscometry titrations provided clear evidence of the intercalative mechanism of the three square-planar metal complexes, allowing us to determine the intrinsic DNA-binding constants (K(b)), equal to 1.3 × 10(7), 2.9 × 10(6), and 6.2 × 10(5) M(-1) for 1, 2 and 3, respectively. Preferential affinity, of one order of magnitude, toward AT compared to GC base pair sequences was detected by UV-vis absorption titrations of 1 with [poly(dG-d…

Description of hysteresis of Nickel Metal Hydride Battery

2012

A Dynamic Preisach Model for the description of the hysteresis in Nickel Metal Hydride Battery is presented. Both the hysteresis and the dynamical features of charging and discharging cycles are described. The identification of the model is obtained by using a neural network technique developed for magnetic systems. The model is validated by some experimental tests on commercial batteries.

One-dimensional iron(III) and two-dimensional iron(III)nickel(II) cyanide-bridged ferromagnetic arrays from hexacyanoferrate(III) and [Ni(cyclam)]2+ …

1999

Abstract The X-ray structures and magnetic properties of a iron(III) linear chain and a honeycomb-like layered iron(III)-nickel(II) cyanide-bridged compound are reported. The former contains alternating iron sites and unexpected ferromagnetic behaviour, justified on the basis of the axial distortion from regular octahedral geometry of one of the iron ions. The latter is metamagnetic with ferromagnetic intralayers and antiferromagnetic interlayers interactions with a Neel temperature, TN= 7.7 K. The field-induced transition from an antiferro- to a ferromagnetic state takes place at Hc= 5000 G. The antiferromagnetic ordered phase exhibits spin-canting and long range ferromagnetic ordering at …

Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination

2019

Abstract Oxidative chemical vapour deposition of (5,15‐diphenylporphyrinato)nickel(II) (NiDPP) with iron(III) chloride as oxidant yielded a conjugated poly(metalloporphyrin) as a highly coloured thin film, which is potentially useful for optoelectronic applications. This study clarified the reactive sites of the porphyrin monomer NiDPP by HRMS, UV/Vis/NIR spectroscopy, cyclic voltammetry and EPR spectroscopy in combination with quantum chemical calculations. Unsubstituted meso positions are essential for successful polymerisation, as demonstrated by varying the porphyrin meso substituent pattern from di‐ to tri‐ and tetraphenyl substitution. DFT calculations support the proposed radical oxi…

Nanostructured Ni Based Anode and Cathode for Alkaline Water Electrolyzers

2019

Owing to the progressive abandoning of the fossil fuels and the increase of atmospheric CO2 concentration, the use of renewable energies is strongly encouraged. The hydrogen economy provides a very interesting scenario. In fact, hydrogen is a valuable energy carrier and can act as a storage medium as well to balance the discontinuity of the renewable sources. In order to exploit the potential of hydrogen it must be made available in adequate quantities and at an affordable price. Both goals can be potentially achieved through the electrochemical water splitting, which is an environmentally friendly process as well as the electrons and water are the only reagents. However, these devices stil…

Dimensionally controlled hydrogen-bonded nanostructures: synthesis, structure, thermal and magnetic behaviour of the tris-(chelated)nickel(II) comple…

2002

Abstract Single crystals of the compound of formula [Ni(bipy)3]Cl2·5.5H2O (bipy=2,2′-bipyridine) have been prepared and structurally characterised by X-ray diffraction. The structure analysis reveals that the complex has an approximate D3 symmetry. The coordination sphere consists of six nitrogen atoms of the three-bipyridine ligands in an octahedral arrangement about the nickel. One of the chlorine ions is surrounded by twelve CH⋯Cl hydrogen bonds. Three kinds of layers are found in the crystal structure: (i) the Λ-[Ni(bipy)3]2+ cation; (ii) the water/chloride positions (O(1w)/Cl(21) to O(7w)/Cl(27)); (iii) the Δ-[Ni(bipy)3]2+ cation and a chloride ion (Cl(1)). The layers are stacked in t…

Ammonia Activation by a Nickel NCN-Pincer Complex featuring a Non-Innocent N-Heterocyclic Carbene: Ammine and Amido Complexes in Equilibrium

2015

A Ni0-NCN pincer complex featuring a six-membered N-heterocyclic carbene (NHC) central platform and amidine pendant arms was synthesized by deprotonation of its NiII precursor. It retained chloride in the square-planar coordination sphere of nickel and was expected to be highly susceptible to oxidative addition reactions. The Ni0 complex rapidly activated ammonia at room temperature, in a ligand-assisted process where the carbene carbon atom played the unprecedented role of proton acceptor. For the first time, the coordinated (ammine) and activated (amido) species were observed together in solution, in a solvent-dependent equilibrium. A structural analysis of the Ni complexes provided insig…

Exchange Coupling in Cyano-Bridged Homodinuclear Cu(II) and Ni(II) Complexes:  Synthesis, Structure, Magnetism, and Density Functional Theoretical St…

2001

The synthesis and structural characterization of several new cyano-bridged copper(II) and nickel(II) homodinuclear complexes is presented. The measure of magnetic properties for these complexes is complemented with a computational study of the exchange coupling for several model structures representing this family of compounds. The influence of several factors on the coupling constant has been examined, coordination position occupied by the bridging ligand, distortions of the coordination environment, and relative disposition of the cyanide ion with respect to the M-M vector. Comparison of experimental and calculated coupling constants allows for the rationalization of the most relevant fea…

A Tetrameric Nickel(II) “Chair” with both Antiferromagnetic Internal Coupling and Ferromagnetic Spin Alignment

2001

Complexation behaviour of hexadentate ligands possessing N2O4and N2O2S2cores: differential reactivity towards Co(ii), Ni(ii) and Zn(ii) salts and str…

2004

Reactions of divalent metal salts of Co, Ni and Zn with 1,2-di(salicylaldimino-o-phenylthio) ethane (H2L1) and 1,2-di(naphthaldimino-o-phenylthio) ethane (H2L2), having N2O2S2 cores, and 1,2-di(O-salicylaldimino-o-hydroxyphenyl) ethane (H2L3), having a N2O4 core, have been explored. Out of the three ligands and the nine products obtained from the corresponding reactions, two ligands and seven products were crystallographically characterized. However, all the ligands and the products were characterized by analytical and spectral methods. Reaction of H2L1 and H2L2 with Co(II) salts results in oxidative cleavage of the C-S bond to produce a Co(III) product bound to two dissimilar tridentate li…