Search results for "Ferro"
showing 10 items of 2451 documents
Dynamic magnetic materials based on the cationic coordination polymer [Cu(btix)2]n(2n+) [btix = 1,4-bis(triazol-1-ylmethyl)benzene]: tuning the struc…
2012
A three-dimensional coordination polymer, [Cu(btix)(2)(BF(4))(2)](n) [btix = 1,4-bis(triazol-1-ylmethyl)benzene], with antiferromagnetic interactions occurring via the organic ligand, has been prepared and characterized. It has been shown to permit the exchange of anionic species in the crystalline network with modification of the magnetic properties. Coordinated BF(4)(-) can be reversibly exchanged by different anions with (NO(3)(-) and Cl(-)) or without (PF(6)(-) and ClO(4)(-)) dynamic response of the organic ligand, which acts as the only linker between the metal centers. Interestingly, an irreversible exchange occurs with N(3)(-) anions to generate a new coordination polymer, [Cu(btix)(…
[3.3]Ferrocenophanes with guanidine bridging units as multisignalling receptor molecules for selective recognition of anions, cations, and amino acid…
2007
The synthesis, electrochemical, and optical properties of a new [3.3]ferrocenophane framework in which two ferrocene subunits, with similar electronic environments, are linked through two substituted guanidine moieties, are reported. The receptors 4-7 have been prepared in good yields by the reaction of bis(carbodiimide) 3 with primary amines. This architecture is exceptionally "tunable" because a variety of "legs" may be appended to the basic [3.3]ferrocenophane scaffold to give a wide range of signaling units. These receptors show remarkable ion-sensing properties, due to the presence of a redox active unit (ferrocene), and an amphoteric binding site (guanidine). In this nitrogen-rich str…
Influence of the anions on the structure and magnetic properties of a series of bis(µ-diphexono)-bridged linear trinuclear copper(II) complexes: an e…
2011
The reaction of H(2)L (N,N'-dimethyl-N,N'-bis(2-hydroxy-3-methoxy-5-methylbenzyl)-ethylenediamine) with different copper salts, in methanol and using a H(2)L/Cu = 2 : 3 molar ratio, led to four new bis(μ-diphenoxo)-bridged Cu(3) complexes of general formula [{Cu(S)(μ-L)}(2)Cu(H(2)O)(2n)]X(2) (S = CH(3)OH, n = 1 and X = BF(4)(-) for (1) or ClO(4)(-) for (2); S = Br(3)(-) anion and n = 1 without any X species for (3); S = H(2)O, n = 0 and X = NO(3)(-) for (4)). The use in the same reaction conditions of 4,4'-bipyridine (4,4'-bipy) as connector led to the chain complex [{Cu(μ-4,4'-bipy)(0.5)(μ-L)}(2)Cu(H(2)O)(2n)](ClO(4))(2)·17H(2)O (5). The structure of the centrosymmetric trinuclear unit in …
Transient and stable color centers in pure and Cu-doped LiNbO3
2003
The present work is devoted to investigation of stable and transient color centers that are induced by radiation and temperature in pure and Cu-doped LiNbO 3 single crystals. The transient changes of absorption of the crystals induced by pulsed electron beam (E=0.25 MeV) are studied in 0-5000 ns time range, as well as stable changes of absorption induced by reducing annealing and irradiation with γ-quanta, high energy electrons or fast reactor neutrons.
Sequestering aromatic molecules with a spin-crossover Fe(II) microporous coordination polymer.
2012
All in a spin: A series of three-dimensional porous coordination polymer {Fe(dpe)[Pt(CN)(4)]}⋅G (dpe = 1,2-di(4-pyridyl)ethylene; G = phenazine, anthracene, or naphthalene) exhibiting spin crossover and host-guest functions is reported. The magnetic properties of the framework are very sensitive to the chemical nature (aromatic or hydroxilic solvents) and the size of the included guest molecules.
Spin Frustration in Triangular Cu 3 II Complexes with 6‐Methyl‐2‐pyridyloxime as Ligand – Synthesis, Structural, and Magnetic Characterization
2013
In the present work, new examples of μ3-OH/oximato Cu3 triangles have been obtained by treatment of different copper salts with 6-methyl-2-pyridylaldoxime [6-MepyC(H)NOH, 6-mepaoH]. Depending on the anion, the compounds [Cu3(OH)(6-mepao)3(O2CPh)2] (1), [Cu6(OH)2(6-mepao)6(NO3)3](NO3)·H2O (2·H2O) and [Cu6(OH)2(6-mepao)6(ClO4)3](ClO4) (3) formed and were characterized. Complex 1 is an isolated triangle, whereas 2 and 3 are hexanuclear compounds with two triangular subunits linked by anionic bridges. Susceptibility measurements show very strong antiferromagnetic interactions and the presence of antisymmetric exchange at low temperature. The magnetic properties of these frustrated triangles hav…
[Mnii2(bpym)(H2O)8]4+ and [Miv(CN)8]4– (M = Mo and W) as building blocks in designing bpym- and cyanide-bridged bimetallic three-dimensional networks…
2002
One-pot reaction between the dinuclear [MnII2(bpym)(H2O)8]4+ complex and the mononuclear [MIV(CN)8]4− unit (M = Mo and W; bpym = 2,2′-bipyrimidine) in aqueous solution yields the novel heterobimetallic complexes of formula {(μ-bpym)[Mn(H2O)]2-(μ-NC)6M(CN)2} with M = Mo (1) and W (2). 1 and 2 are isostructural three-dimensional compounds where the manganese atoms are bridged by bisbidentate bpym and hexakismonodentate octacyanometalate units. Variable-temperature magnetic susceptibility data of 1 and 2 show the occurrence of a significant antiferromagnetic coupling between the high spin manganese(II) ions through bridging bpym (Jca. −1.1 cm−1, the exchange Hamiltonian being defined as H = −J…
Oxalate and 2,2′-bipyrimidine as bis-chelating ligands in the honeycomb layered compound {[Fe2(bpym)(ox)2]·5H2O}n
2002
The novel two-dimensional iron(II) compound of formula {[Fe2(bpym)(ox)2]·5H2O}n (1) [bpym = 2,2′-bipyrimidine and ox = oxalate dianion] is obtained by reaction of oxalic acid, iron(II) chloride and 2,2′-bipyrimidine in aqueous solution. The structure of 1 is made up of oxalato-bridged iron(II) chains cross-linked by bischelating bpym affording a honeycomb lattice. Variable-temperature magnetic susceptibility data of 1 show the occurrence of relatively large antiferromagnetic interactions between the high spin iron(II) ions separated by more than 5.5 A through bridging bpym [Jbpym = −4.0(2) cm−1] and ox [Jox = ca. −7.8(2) cm−1] ligands. These values compare well with those obtained in the ir…
2D and 3D coordination polymers based on 2,2′-bipyrimidine and cyanide bridging ligands incorporating coordinated and guest ammonia molecules. Synthe…
2005
The coordination polymers {[Ni(CN)4]2[(Ni(NH3)2)2(bpym)]·2H2O}n1 and {[Cu2(CN)2(bpym)]·NH3}n2 have been prepared from the reactions of M(NO3)2·nH2O [Cu(II), n = 3 and M = Ni(II), n = 6] with NaCN and bpym (2,2′-bipyrimidine) in concentrated aqueous ammonia, respectively. The structure of 1 is made of bipyrimidine bridged centrosymmetric dinuclear [Ni(NH3)2(μ-bpym)Ni(NH3)2] fragments connected by four [Ni(CN)4]2− anions giving rise to a 2D framework. Layers, which adopt a stair-like conformation, are stacked with an ABAB… repeat pattern. Water molecules are located in the interlayer space and are involved in hydrogen bond interactions with the non-bridging cyanide groups of the [Ni(CN)4]2− a…
Ferromagnetic coupling through a carbonate bridge in the copper (II) chain [Cu(CO3)(4-apy)2] · H2O (4-apy = 4-aminopyridine)
1999
Abstract Atmospheric CO2 fixation by aqueous solutions containing copper(II) bromide and 4-aminopyridine (4-apy) yields the first carbonatobridged copper(II) chain of formula [Cu(CO3)(4-apy)2] · H2O that exhibits an intrachain ferromagnetic coupling.