117,673 research outputs found
Neurophysiological correlates of sleep leg movements in acute spinal cord injury
No full textAbstract not availableRaffaele Ferri, Paola Proserpio, Francesco Rundo, Andrea Lanza, Katrina Sambusida, Tiziana Redaelli, Fabrizio De Carli, Lino Nobil
Stabilisation of trivalent nickel through 1 : 2 co-ordination by cyclic terdentate ligands CH2CH2NH(CH2)2NH(CH2)2X (X = NH, O, or S)
No full textThe octahedral six-co-ordinated complexes [Ni(L2)2]2+ and [Ni(L3)2]2+(L2 and L3= 1 -oxa- and 1 -this-4,7-diazacyclononane, respectively)(donor set: N4O2 and N4S2, respectively) undergo a reversible one-electron oxidation process in MeCN and dimethyl sulphoxide (dmso) solution to give authentic NiIII species. These NiIII complexes present a distorted stereochemical arrangement, with the O and S heteroatoms occupying the axial sites of an elongated octahedron, and persist in solution for hours. Comparison with the corresponding complexes of 1,4,7-triazacyclonanane (L1)(donor set: N6) indicates that the relative stability of the trivalent species, expressed by the value of E1⁄2(NiIII–NiII), decreases along the series: L1 > L3 > L2, the trend reflecting the decrease in the strength of the Ni–X interactions (X = N, S, or O). The corresponding NiIII complexes of the open-chain analogues of the macrocycles L1 or L3 form at comparable potentials, but persist in solution only in the time-scale of the voltammetry experiment, thus demonstrating the existence of a purely kinetic macrocyclic effect in the stabilisation of high oxidation states of metals.
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User's beliefs toward technology: a social capital perspective
No full textThe paper illustrates how the different dimensions of group social capital may affect the individual use of technolog
Using long bis(4-pyridyl) ligands designed for the self-assembly of coordination frameworks and architectures
No full textFive long bis(4-pyridyl) ligands with different tether groups, namely 1,4-phenylenebis(4-pyridylmethanone)(L-1), bis(4-pyridyl)terephthalate (L-2), 1,5-bis(pyridin-4-ylmethoxy)naphthalene (L-3), 1,4-bis[2-(4-pyridyl)ethenyl]benzene (L-4) and 4,4'-bis(pyridin-4-ylmethoxy)biphenyl (L-5), have been synthesized and employed for the self-assembly of coordination polymers and architectures, with the aim of obtaining structural motifs characterized by long metal-metal separations. Six coordination products (compounds 1-6) have been obtained by reacting the ligands with cobalt(II) nitrate in all cases but one, in which zinc(II) triflate was used. The crystal structures show a variety of structural motifs. [Co(L-2)(NO3)(2)(MeCN)].MeCN (2) and [Co(L-5)(NO3)(2)] (5) contain one-dimensional polymeric chains (linear, with a period of 19.64 Angstrom in 2; zigzag, with a period of 38.65 Angstrom in 5). [Zn(L-1)(H2O)(4)](CF3SO3)(2).(L-1)(2). H2O (1) and [Co(L-4)(2)(H2O)(4)](NO3)(2).(L-4)(4).(H2O)(8) (4) exhibit extended three-dimensional and two-dimensional arrays, respectively, sustained both by coordinative and hydrogen bonds. Compound 3, [Co(L-3)(2)(NO)].(CH2Cl2), consists of two-dimensional layers of large rhombic meshes (diagonals of the rhombus 15.43 and 35.74 Angstrom), while compound 6, [Co-2(L-5)(4)(NO3)(4)].(Me2CO)(2), contains discrete dinuclear molecules, consisting of large rings with appendages, which exhibit an exceptionally long dimension of 62.84 Angstrom and form columnar supramolecular arrays
Parallel and inclined (1D -> 2D) interlacing modes in new polyrotaxane frameworks [M-2(bix)(3)(SO4)(2)] [M = Zn(II), Cd(II); Bix=1,4-bis(imidazol-1-ylmethyl)benzene]
No full textThe reactions of M-II sulfates (M = Zn, Cd) with the flexible ligand 1,4-bis(imidazol-1-ylmethyl)benzene (bix) yield the novel interesting coordination networks [M-2(bix)(3)(SO4)(2)], containing 1D polymeric motifs of alternating rings and rods, which show extended rotaxane-like mechanical links producing 2D sheets via unprecedented parallel (M = Zn) or inclined (M = Cd) interlacing modes of the chains
A new type of entanglement involving one-dimensional ribbons of rings catenated to a three-dimensional network in the nanoporous structure of [Co(bix)2(H2O)2](SO4)·7H2O [bix = 1,4-bis(imidazol-1-ylmethyl)benzene]
No full textCoII sulfate reacts with the flexible ligand 1,4-bis(imidazol-1-ylmethyl)benzene (bix) to yield the coordination network [Co(bix)2(H2O)2](SO4)·7H2O, containing polymeric ribbons of
rings which penetrate and catenate a 3D single frame of the CdSO4 topology, to produce an open-channel entangled architecture with nanoporous behaviour
Borromean links and other non-conventional links in 'polycatenated' coordination polymers: re-examination of some puzzling networks
No full textA number of coordination networks, exhibiting novel and fascinating types of entanglements of individual motifs have been reported throughout the years by many groups. The structural complexity of these species has caused, in some cases, misinterpretations regarding the correct nature of the entanglement. In this article, we analyse the structures of some polymeric networks of the 'polycatenanes' class, which have the peculiar feature of all the constituent motifs having lower dimensionality than that of the overall array. Unexpected topological features and new linkages, that had previously been overlooked, have been discovered. The most relevant finding concerns the first observation of examples of Borromean links in 3D and 2D arrays. These systems are comprised of layers that are not catenated but, nonetheless, inseparably entangled in an uncommon topological fashion.A number of coordination networks, exhibiting novel and fascinating types of entanglements of individual motifs have been reported throughout the years by many groups. The structural complexity of these species has caused, in some cases, misinterpretations regarding the correct nature of the entanglement. In this article, we analyse the structures of some polymeric networks of the 'polycatenanes' class, which have the peculiar feature of all the constituent motifs having lower dimensionality than that of the overall array. Unexpected topological features and new linkages, that had previously been overlooked, have been discovered. The most relevant finding concerns the first observation of examples of Borromean links in 3D and 2D arrays. These systems are comprised of layers that are not catenated but, nonetheless, inseparably entangled in an uncommon topological fashion
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