Search results for "Cobalt"
showing 10 items of 1098 documents
Stepwise sequential redox potential modulation possible on a single platform.
2011
Step by step: The cluster [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) is an excellent platform for making a stepwise tunable redox potential system by dehydroiodination. With the addition of up to eight iodine substituents (purple; see picture), there is a fall in the E(1/2)(Co(III)/Co(II)) value from -1.80 V to -0.68 V (vs. Fc(+)/Fc; Fc = ferrocene). A practical application of this tunability has been observed in the growth of polypyrrole.
Expanding the 2, 2’-bipyrimidine bridged 1D homonuclear coordination polymers family: [MIIbpymCl2] (M=Fe, Co) magnetic and structural characterization
2013
One pot reaction of hydrated chloride salts of Fe(II) and Co(II) with stoichiometric amounts of 2, 2’-bipyrimidine (bpym) in a methanol/ acetonitrile mixture afforded the corresponding 1D homonuclear coordination polymers, [μ-(bpym)MCl2]n. Crystal structures of both complexes are isomorphous in the highly symmetric orthorhombic space group Fddd. The 1D coordination polymers are composed of almost orthogonal alternating bipyrimidine bridges linking the {MCl2} units. The magnetic behaviour of the Fe(II)compound can be well understood as a uniform S=2 chain with antiferromagnetic exchange interaction between metal ion sites. In the case of the Co(II) ion, also an antiferromagnetic interaction …
Electrochemical synthesis and structural characterization of Co(II), Ni(II) and Cu(II) complexes of N,N-bis(4,5-dimethyl-2-hydroxybenzyl)-N-(2-pyridy…
2009
The electrochemical oxidation of anodic metal (cobalt, nickel or copper) in a cell containing an acetonitrile solution of the ligand N,N-bis(4,5-dimethyl-2-hydroxybenzyl)-N-(2-pyridylmethyl)amine (H2L) affords complexes [Co2L2].H2O (1), [Ni3L3] (2) and [Cu2L2] 3H2O (4). On using nickel as the anode and the addition to the solution electrolytic phase of the amount of water necessary to saturate the solution, the electrolytic process gave rise to the new compound [Ni2L2(H2O)1.5].CH3CN (3). Compounds 1 and 4 are dimeric and the metal atoms are pentacoordinated. Compound 3 also consists of dimeric neutral molecules with the nickel atoms in both penta- and hexacoordinated environments. The cryst…
Study of the influence of the bridge on the magnetic coupling in cobalt(II) complexes.
2009
Two new cobalt(II) complexes of formula [Co(2)(bta)(H(2)O)(6)](n) x 2nH(2)O (1) and [Co(phda)(H(2)O)](n) x nH(2)O (2) [H(4)bta = 1,2,4,5-benzenetetracarboxylic acid, H(2)phda = 1,4-phenylenediacetic acid] have been characterized by single crystal X-ray diffraction. Compound 1 is a one-dimensional compound where the bta(4-) ligand acts as 2-fold connector between the cobalt(II) ions through two carboxylate groups in para-conformation. Triply bridged dicobalt(II) units occur within each chain, a water molecule, a carboxylate group in the syn-syn conformation, and an oxo-carboxylate with the mu(2)O(1);kappa(2)O(1),O(2) coordination mode acting as bridges. Compound 2 is a three-dimensional comp…
Coordination Chemistry of 6-Thioguanine Derivatives with Cobalt: Toward Formation of Electrical Conductive One-Dimensional Coordination Polymers
2013
In this work we have synthetized and characterized by X-ray diffraction five cobalt complexes with 6-thioguanine (6-ThioGH), 6-thioguanosine (6-ThioGuoH), or 2'-deoxy-6-thioguanosine (2'-d-6-ThioGuoH) ligands. In all cases, these ligands coordinate to cobalt via N7 and S6 forming a chelate ring. However, independently of reagents ratio, 6-ThioGH provided monodimensional cobalt(II) coordination polymers, in which the 6-ThioG(-) acts as bridging ligand. However, for 2'-d-6-ThioGuoH and 6-ThioGuoH, the structure directing effect of the sugar residue gives rise to mononuclear cobalt complexes which form extensive H-bond interactions to generate 3D supramolecular networks. Furthermore, with 2'-d…
Mass spectrometric studies on small open-chain piperazine-containing ligands and their transition metal complexes
2001
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry was used to characterize the complexes formed between open-chain piperazine-containing ligands and transition metal salts (Cobalt, Copper, Zinc, and Cadmium as chlorides, nitrates, and acetates). Only single-charged complexes were observed, formed of one ligand (L) and mainly one metal ion (M). Since the net charge of the complexes was one, a counterion (X) was attached to some of the complexes, with formation of [L + M + X]+ complexes, and a proton was lost from others, as in [L − H + M]+ complexes. In most cases the composition of the complexes was more dependent on the ligand than the metal salt. Collisio…
Co3O4/CeO2 and Co3O4/CeO2–ZrO2 composite catalysts for methane combustion: Correlation between morphology reduction properties and catalytic activity
2005
Abstract Co3O4/CeO2 and Co3O4/CeO2–ZrO2 composite catalysts have been prepared by two different techniques, co-precipitation by citrate method and impregnation with cobalt nitrate of pre-formed ceria and ceria–zirconia oxides. The materials, as prepared and after ageing at 750 °C 7 h, were tested for methane combustion and the catalytic performances were compared with those of a commercial Co3O4, used as reference. A significant improvement of the activity was observed in the composite oxide Co3O4(30 wt%)/CeO2(70 wt%), prepared by citrate method, which exhibits the lowest light-off temperature of methane (T50 = 400 °C) and does not suffer deactivation after calcination at 750 °C 7 h.
Oxygen evolution reaction on a N-doped Co0.5-terminated Co3O4 (001) surface
2020
The project AP05131211 “First principles investigation on catalytic properties of N-doped Co3O4.” was funded by the Ministry of Education and Science of the Republic of Kazakhstan. The work was partly supported by COST (European Cooperation in science and Technology) Action 18234 (YM and EK). The work of T. Inerbaev was performed under the state assignment of Sobolev Institute of Geology and Mineralogy Siberian Branch of the Russian Academy of Sciences. YM and EK thank Sun-to-Chem project of ERA Net.
High-precision measurements of the hyperfine structure of cobalt ions in the deep ultraviolet range
2023
Scientific reports 13(1), 4783 (2023). doi:10.1038/s41598-023-31378-1
The zero field self-organization of cobalt/surfactant nanocomposite thin films
2009
Cobalt nanostructures have been prepared by a chemical route based on the Co(II) reduction in the confined space of cobalt bis(2-ethylhexyl)sulfosuccinate (Co(DEHSS)(2)) reverse micelles dispersed in n-heptane. This procedure involves the rapid formation of surfactant softly coated Co nanostructures followed by a slow separation process of the magnetic-field responsive Co/surfactant nanocomposites from the liquid phase. The detailed structure of thin films of the Co/surfactant nanocomposites has been investigated by scanning force microscopy (SFM). The thin films were characterized by different anisotropic features. Micrometric long domains of self-aligned ellipsoidal NPs (tens of nanometer…