Search results for "HIF"
showing 10 items of 1515 documents
Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization
2014
Oxovanadium(IV) complexes with (ONNO)-type tetradentate Schiff base ligands: salen, acacen, aceten, acetph (H2salen = N,N'-ethylenebis(salicylideneimine), H2aceten = N,N'-ethylenebis(2-hydroxyacetophenoneimine), H2acacen = N,N'-ethylenebis(acetylacetonimine), H 2 acetph = N ,N ' -phenylene-1,2-b is (2-hydroxyacetophenoneimine)), were the first time investi- gated in ethylene polymerization and ethylene/1-octene copo- lymerization processes. In general, all these complexes are moderately active precatalyst for ethylene polymerization up- on activation with EtAlCl2 and they give high molecular weight linear polyethylenes. Their activity in copolymeriza- tion was found relatively low. However,…
Selective G-quadruplex stabilizers: Schiff-base metal complexes with anticancer activity
2014
The affinity of three square-planar nickel(II) (1), copper(II) (2) and zinc(II) (3) Schiff-base complexes for wild-type human telomeric (h-Telo) and protooncogene c-myc G-quadruplex (G4) DNA was investigated by UV-visible absorption spectroscopy and circular dichroism. DNA-binding constants (Kb) were determined by spectrophotometric titrations for both G4-DNA and B-DNA. The results obtained point out that the three metal complexes selectively bind G4-DNA with higher affinity, up to two orders of magnitude, with respect to B-DNA. The nickel(II) complex 1 was found to be the most effective G4-DNA stabilizer and the Kb values decrease in the order 1 > 2 ≈ 3. Innovative computational investigat…
Rare examples of diphenoxido-bridged trinuclear Ni II 2 Fe III complexes with a reduced salen type Schiff base ligand: Structures and magnetic proper…
2017
Abstract Three new trinuclear hetero-metallic complexes, [(NiLR)2Fe(N3)3] (1), [(NiLR(H2O))2Fe(C6H5CH2CO2)2]·(HSO4) (2) and [(NiLR(H2O))2Fe(C6H5CO2)2]·(HSO4)·(H2O)·(CH2Cl2) (3) have been synthesized using [NiLR] as a “metalloligand” (where H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine). All complexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD and magnetic study. In the angular trinuclear units of 1, the two terminals [NiLR] coordinate through double phenoxido bridges to the central FeIII ion which is penta-coordinated having terminally coordinated azide ion. The two terminal NiII centers are connected to each other and also to neighbouring…
Slow Magnetic Relaxation in a Co 2 Dy Trimer and a Co 2 Dy 2 Tetramer
2021
The combination of Co(III) and Dy(III) with a compartmental Schiff base ligand (H 3 L = 3-[(2-Hydroxy-3-methoxy-benzylidene)-amino]-propane-1,2-diol), presenting three different coordinating pockets, has allowed the synthesis of two novel Co(III)-Dy(III) complexes: [Co 2 Dy(HL) 4 ]NO 3 ·2CH 3 CN ( 1 ), a rare example of trinuclear linear Co III 2 Dy III complex (and the first with slow relaxation of magnetization in absence of a DC field) and [Co 2 Dy 2 (μ 3 -OH) 2 (HL) 2 (OAc) 6 ]·4.6H 2 O ( 2 ), the first tetranuclear Co III 2 Dy III 2 cluster with a rhomb-like structure where the Co(III) ions are connected along the short diagonal of the rhomb. 1 presents two different relaxation process…
A rare case of solution and solid state inter-conversion of two copper(II) dimers and a copper(II) chain
2011
Abstract Three Cu(II)-azido complexes of formula [Cu2L2(N3)2] (1), [Cu2L2(N3)2]·H2O (2) and [CuL(N3)]n (3) have been synthesized using the same tridentate Schiff base ligand HL (2-[(3-methylaminopropylimino)-methyl]-phenol), the condensation product of N-methyl-1,3-propanediamine and salicyldehyde). Compounds 1 and 2 are basal-apical μ-1,1 double azido bridged dimers. The dimeric structure of 1 is centrosymmetric but that of 2 is non-centrommetric. Compound 3 is a μ-1,1 single azido bridged 1D chain. The three complexes interconvert in solution and can be obtained in pure form by carefully controlling the synthetic conditions. Compound 2 undergoes an irreversible transformation to 1 upon de…
Polynuclear copper(II) complexes with hexadentate Schiff base directed by the counter ion. Syntheses, crystal structures and magnetic properties
2018
Abstract Four new complexes, [Cu 9 L 6 ( µ 3 -ClO 4 ) 2 ](ClO 4 ) 4 ·4CHCl 3 1 , [Cu 3 L 2 (H 2 O) 2 ](ClO 4 ) 2 ·3H 2 O 2 , [Cu 6 L 4 (N 3 ) 2 ](ClO 4 ) 2 3 and [Cu 2 L(CH 3 COO) 2 ] 4 , where H 2 L stands for the Schiff base N , N ′-bis[(2-hydroxybenzilideneamino)-propyl]-piperazine, were obtained and structurally characterized. Compounds 1 , 2 and 3 contain the Cu 3 L 2 2+ entities in which L 2− acts in an unsymmetrical mode with N 3 O donor set wrapped around marginal copper(II) and with the remained NO sets bound to the central copper ion. The marginal copper(II) ions are in distorted square pyramidal environment, whereas that of the central one is square planar. In 1 , the peripheral …
Synthesis and characterization of a novel dicyanamide-bridged Co(II) 1-D coordination polymer with a N 4 -donor Schiff base ligand
2017
The synthesis, structure and magnetic properties of a novel Co(II) 1D coordination polymer, [Co(L)(µ1,5-dca)(ClO4)2·MeOH]n (1) are described. Compound 1 contains two independent cationic Co(II) chains (CoA and CoB) which are parallel to the c direction and present short π-π and C-H⋯π interactions with two neighbouring chains along the b direction, giving rise to alternating layers of chains A and B in the bc plane. Variable-temperature magnetic susceptibility measurements shows a weak antiferromagnetic coupling among the adjacent cobalt(II) centres mediated through μ1,5-dca− bridge.
Formation of a dinuclear and a trinuclear Ni(II) complex on slight variation of experimental conditions: Structural analysis and magnetic properties
2017
Abstract A diphenoxido bridged dinuclear Ni(II) complex [Ni2L2(NO2)2] (1) and a μ2 and μ3-phenoxido, μ3-hydroxido, and μ2-nitrito (1κO:2κN) bridged trinuclear Ni(II) complex [Ni3L3(OH)(NO2)]·ClO4 (2), have been synthesized using a tridentate reduced Schiff base ligand HL (HL = 2-[(2-dimethylamino-ethylamino)-methyl]-phenol). Both complexes were characterized by X-ray structure determination and variable-temperature magnetic susceptibility measurements. In both complexes the nickel atoms are six-coordinated with a distorted octahedral environment. The interesting feature of the trimeric complex 2 is that the three mononuclear units are assembled around a μ3-hydroxido ion in such a way that t…
Homo- and heterometallic complexes constructed from hexafluoroacetylacetonato and Schiff-base complexes as building-blocks
2018
Three new homo- and heterotrimetallic complexes have been synthesized and crystallographically characterized: [Cu2(saldmpn)2(μ-OCH3)2Cu2(hfac)2] (1), [Ni2(valaepy)2(hfac)2] (2), [Cu(saldmpn)Co(hfac)2] (3) [H2saldmpn is the Schiff-base resulting from condensation of salicylaldehyde with 2,2-dimethyl-1,3-diaminopropane and Hvalaepy results from the reaction of o-vanillin with 2-(2-aminoethyl)pyridine)]. The structure of 1 consists of a neutral tetranuclear species that can be viewed as resulting from mutual coordination of one {(hfac)Cu(μ-OCH3)2(Cu(hfac)} and two {Cu(saldmpn)} building blocks. Compound 2 is a binuclear complex that results from two {Ni(hfac)(valaepy} fragments, the nickel(II)…
1,2,4-Triazole Schiff base directed synthesis of polynuclear iron complexes: Investigating the magnetic properties going from a dimer to a 1D chain t…
2018
Abstract Based on two functionalized Schiff base ligands 4-(1H-imidazol-5-ylmethylene-amino)-4H-1,2,4-triazole (imztrz) and 4-(p-tolylidene-amino)-4H-1,2,4-triazole (toltrz), a series of three triazole based polynuclear Fe complexes has been prepared. Compounds {[FeII(toltrz)2(C2O4)]·10H2O}n (1) and {[FeII(5-imztrz)(C2O4)]·2H2O}n (2) are oxalate bridged FeII complexes with 1 showing a linear 1D chain structure and 2 exhibiting a zigzag chain based 3D interpenetrating framework. Both structures show rather big voids in the 3D architecture (∼15% of the crystal volume). Compound (5-imztrzH)2[FeIII2(cit4−)2(H2O)2]·6H2O (3) is a binuclear FeIII complex bridging by two citrate ligands to form a f…