Search results for "Cobalt complexes"

A magnetic self-contained thermochromic system with convenient temperature range

2019

A new ionic liquid with sugar-based ligand has been prepared and used to coordinate cobalt(II), at low loading, in an ionic liquid solution. The system obtained reveals magnetic switching and marked thermochromism in solution/polymer films over a convenient temperature range (20–60 °C). This system is self-contained, devoid of any volatile substances, and reproducible over multiple thermal cycles. The colour change can be attributed to a change in the coordination geometry from octahedral (pink) at room temperature to tetrahedral (blue) on warming, monitored by 59Co NMR spectroscopy, which was used for the first time to study the change. This material may find applications in stimuli-respon…

Heterometallic CoII-CoIII-MII alkoxido-bridged heptanuclear motifs (M = Cu, Zn). Syntheses, crystal structures and magnetic properties

2018

Two new alkoxido-bridged heterometallic complexes of formula [CoIICoIII 3CuII 3(dea)6(CH3COO)3](ClO4)0.75(CH3COO)1.25 (1) and [CoII 2CoIII 2ZnII 3(tea)2(piv)6(CH3O)2(OH)2(CH3OH)2]·H2O 2 (H2dea=diethanolamine, H3tea=triethanolamine and Hpiv=pivalic acid) have been assembled using aminoalcohol ligands. The cationic core in 1 possesses a threefold crystallographic axis, and it exhibits a set of three copper(II), one cobalt(II) and three cobalt(III) ions arranged as a hexagon of alternating copper(II) and cobalt(III) ions around the central cobalt(II) ion. Each edge of the hexagon is defined by a double alkoxido bridge, the outer one being bis-monodentate with copper(II)-cobalt(III) pair wherea…

Ionic liquid-cobalt complexes: a thermochromic interaction

A two-dimensional magnetic architecture with bridging polynitrile and 2,2′-bipyrimidine ligands

2004

cited By 7; International audience; A new polymeric, two-dimensional compound [Co2(bpym)(dcne) 4 (H2O)2] (1) (dcne = [(CN)2CC(O) OEt)]- = 2,2-dicyano-1-ethoxyethenolate anion and bpym = 2,2'-bipyrimidine) has been synthesized and characterized by X-ray crystallography. The structure is monoclinic space group P21/a and consists of two-dimensional networks of octahedrally coordinated Co(II) ions, bridged by bis-bidentate 2,2'-bipyrimidine and μ2-dcne anions. Magnetic measurements revealed a broad maximum in the xm vs T plot at 20 K which is characteristic of antiferromagnetic exchange between the high spin cobalt(II) centres. © EDP Sciences.

Magnetic exchange interactions in the heteropoly complexes [M4(H2O)2(PW9O34)2]10− [M=Co(II) and Cu(II)]

1990

The magnetic properties of the heteropolyanions [M4(H2O)2(PW9O34)2]10− [M=Co(II) and Cu(II)] down to 4 K are reported. Their individual heteropoly molecules contain a rhomblike arrangement formed by four coplanar MO6 octahedra sharing edges. The magnetic properties support an intramolecular ferromagnetic exchange in the Co(II) tetramer, and antiferromagnetic exchange in the Cu(II) tetramer. These behaviors are discussed assuming anisotropic exchange in the Co(II) compound, and Heisenberg exchange in the Cu(II) compound. Carlos.Gomez@uv.es

Cobalt complex based on cyclam for reversible binding of nitric oxide

2008

We report the synthesis and theoretical calculations of nitrosyl cobalt complexes based on saturated tetraazamacrocycle for the reversible binding of nitric oxide (NO). Density-functional theory provides a rigorous theoretical framework for analysing, interpreting and investigating important parameters in order to further tune the properties of these complexes to the target application. We focus on understanding the stability of complexes in methanol solution as well as their reactivity and stability evolution in the presence of NO, O2 and higher nitrogen oxides intermediates. Calculations have been used to explore appropriate combinations of different macrocycles, metal centres and ligands…