Search results for "dron"
showing 10 items of 4363 documents
A distorted honeycomb motif in divalent transition metal compounds based on 4-phosphonbenzoic acid and exchange coupled Co(II) and Cu(II): synthesis,…
2013
The first example of a two-dimensional inorganic hybrid material with cobalt as an open-shell transition metal ion and 4-phosphonbenzoic acid as a linker is presented together with its copper analogue. For both metal ions the inorganic part consists of edge-sharing metal–oxygen octahedra leading to a metal honeycomb motif. The magnetic properties of the cobalt compound are reported together with those of the corresponding copper compound based on the remarkably six-coordinated copper(II) ions.
Efficient Synthesis of High Molar Mass, First- to Fourth-Generation Distributed Dendronized Polymers by the Macromonomer Approach
2003
A homologous series of first- to fourth-generation (G1±G4) dendronized macromonomers, 5, 7, 10, and 12, was synthesized, and their poly- merization behavior under radical con- ditions investigated. These conditions were thermally induced radical poly- merization (TRP) and atom-transfer radical poymerization (ATRP). TRP was applied to all monomers and gave polymers PG1±PG4, whose molar masses range from several millions for PG1 to estimated several hundreds of thousands for PG2 and PG3, and to the oligomeric regime for PG4. ATRP was applied only to the G1 and G2 monomers 5 and 7. Kinetic studies on monomer 5 provide evidence that its polymerization proceeds in a control- led fashion. The hig…
Phase transitions and distortion of [BiCl6]3- octahedra in (C3H5NH3)3[BiCl 6] - DSC and single-crystal X-ray diffraction studies
2004
The DSC diagram of tris(allylammonium) hexachlorobismuthate(III), (C3H5NH3)3[BiCl6], revealed three anomalies at 152, 191 and 299 K. The structure of the salt was determined at 200 and 315 K, below and above the high-temperature phase transition at 299 K. In both phases the crystals are monoclinic. At 200 K the space group is C2/c whereas at 315 K it is C2/m. The structures, at both temperatures, are composed of [BiCl6]3− octahedra and allylammonium cations. The organic and inorganic moieties are attracted to each other by a network of the N-H. . .Cl hydrogen bonds. The relationship between corresponding parameters of the unit cells has been found. The phase transition at 299 K, of the orde…
"Dormant" secondary metal-alkyl complexes are not omnipresent.
2006
This theoretical study was inspired by the perpetual debate over the so-called “dormancy” of the active sites in propylene polymerization, i.e., a drop in their activity after a regioerror (2,1-insertion), which was reported to occur in many (although not all) catalytic systems. To explore the range of possible situations, we have selected two homogeneous systems of fundamentally different structure: an octahedral system of C 2 symmetry with a tetradentate O N N O ligand and a bridged indenyl catalyst. This choice was not accidental; it is in these two systems where the experimentalists cannot reach a consensus about dormancy. Our density-functional theory calculations explain why in certa…
Coordination behavior of cinoxacine: Synthesis and crystal structure of tris (cinoxacinate) cobaltate(II) of sodium hexahydrate (HCx = 1-ethyl-4(1H) …
1991
The synthesis, crystal, and molecular structure of Co(Cx)3Na6H2O are reported. The Cobalt(II) compound crystallizes in the trigonal system, space group R 3 with Z = 6, in a cell of dimensions a= 18.688(7) (A), c= 20.142(6) A. Least-squares refinement of 1331 reflections [I≥3σ(I)] gave a final R = 0.088 for all observed reflections. The structure consists of anionic monomeric units of (Co(Cx)3−) and sodium cations. Three Cinoxacinate ions are chelated through Oceto and Ocarbox atoms. The Co(II) ion positioned on the third axis is bonded to six oxygen atoms in a slightly distorted octahedral environment.
Oxidative DNA damage of mixed copper(II) complexes with sulfonamides and 1,10-phenanthroline
2003
Abstract Mixed coordination compounds of Cu(II) with sulfonamides and 1,10-phenanthroline as ligands have been prepared and characterised. Single crystal structural determination of the complex [Cu( N -quinolin-8-yl- p -toluenesulfonamidate) 2 (phen)] shows Cu(II) ions are located in a highly distorted octahedral environment, probably as a consequence of the Jahn–Teller effect. The FT-IR and electronic paramagnetic resonance (EPR) spectra are also discussed. The mixed complexes prepared undergo an extensive DNA cleavage in the presence of ascorbate and hydrogen peroxide. Two of the complexes have higher nucleolytic efficiency than the bis( o -phenanthroline)copper(II) complex.
Synthesis, crystal structures and magnetic properties of M(II)Cu(II) chains (M = Mn and Co) with sterically hindered alkyl-substituted phenyloxamate …
2011
A series of neutral oxamato-bridged heterobimetallic chains of general formula [MCu(L(x)2 (S)2] · p S · q H2O [p = 0-1, q = 0-2.5; L1 = N-2,6-dimethylphenyloxamate, S = DMF with M = Mn (1a) and Co (1b); L2 = N-2,6-diethylphenyloxamate, S = DMF with M = Mn (2a) and Co (2b) or S = DMSO with M = Mn (2c) and Co (2 d); L3 = N-2,6-diisopropylphenyloxamate, S = DMF with M = Mn (3a) and Co (3b) or S = DMSO with M = Mn (3c) and Co (3d)] were prepared by treating the corresponding anionic oxamatocopper(II) complexes [Cu(L(x))(2)]2- (x = 1-3) with M(2+) cations (M = Mn and Co) in DMF or DMSO as the solvent. The single-crystal X-ray structures of 2a and 3a reveal the occurrence of well-isolated, zigzag…
Sterically controlled self-assembly of tetrahedral M(6)L(4) cages via cationic N-donor ligands.
2014
Tripodal cationic N-donor ligands exhibit sterically controlled self-assembly of tetrahedral M6L4 coordination cages that promote selective anion encapsulation (PF6(-)OTf(-)) in the solid state. The described method is a potential template for stepwise assembly of hetero-ligand coordination cages and polymers.
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…
A giant hybrid organic-inorganic octahedron from a narrow rim carboxylate calixarene.
2020
Here we discovered an unprecedented giant octahedral coordination compound bearing 16 Zn2+, 12 Na+, 8 O2-, 4 OH-, 13 H2O and 6 L4- ligands [L4- = fully deprotonated tetra(carboxymethoxy)calix[4]arene]. Its structure was elucidated by single-crystal X-ray diffraction, wavelength-dispersive X-ray spectroscopy and MALDI-TOF mass spectrometry. This compound, Zn8Na6L6⊃Zn8Na6O8(OH)4(H2O)13 (external⊃internal), has eight tetrahedral zinc ions forming the coordination vertices of an outermost cube where carboxylate groups from the sodium calixarenes are anchored. Its core consists of eight Zn2+, six Na+, eight O2-, and four OH- distributed over three layers, besides thirteen coordinated H2O molecul…