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Konstantis F. Konidaris Giannis S. Papaefstathiou Guillem Aromi Simon J. Teat Evy Manessi-Zoupa Albert Escuer Spyros P. Perlepes 《Polyhedron》2009,28(9-10):1646-1651
The synthesis, single-crystal X-ray structure and magnetic properties of [Cu3L2Cl2(DMF)4]n (1), where L2? is the 2,3-dioxyquinoxalinate(-2) ligand, are reported. The complex was prepared by the reaction of CuCl2 and 1,4-dihydro-2,3-quinoxalinedione (H2L′) under basic conditions using either solvothermal or normal laboratory techniques. Compound 1 is a 3D coordination polymer with an (82.10)-a, lig (LiGe) topology, containing the ligand in a novel 3.1111 (Harris notation) coordination mode. Variable-temperature and variable-field magnetic studies reveal that the ligand L2? propagates weak antiferromagnetic exchange interactions through its “quinoxaline” part. IR data are discussed in terms of the structural features of 1 and the coordination mode of L2?. 相似文献
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Constantina Papatriantafyllopoulou Marta Estrader Constantinos G. Efthymiou Despina Dermitzaki Konstantinos Gkotsis Aris Terzis Carmen Diaz Spyros P. Perlepes 《Polyhedron》2009,28(9-10):1652-1655
Employing the mononuclear complex [Ni{(py)C(Me)NO}2{(py)C(Me)NOH}] (1) as ‘ligand’ [(py)C(Me)NOH = methyl 2-pyridyl ketone oxime], the use of the ‘metal complexes as ligands’ approach has led to the synthesis of the mixed NiII/LnIII complexes [NiTb{(py)C(Me)NO}2(NO3)3{(py)C(Me)NOH}] (2), [Ni2Ln2{(py)C(Me)NO}6(NO3)4] (Ln = Dy, 3; Ln = Tb, 4) and [Ni2Tb{(py)C(Me)NO}6](NO3) (5). The structures of 2, 3, and 5, and the magnetic properties of 2 and 5 are briefly discussed. 相似文献
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Papatriantafyllopoulou C Stamatatos TC Wernsdorfer W Teat SJ Tasiopoulos AJ Escuer A Perlepes SP 《Inorganic chemistry》2010,49(22):10486-10496
The combined use of the anion of phenyl(2-pyridyl)ketone oxime (ppko(-)) and azides (N(3)(-)) in nickel(II) carboxylate chemistry has afforded two new Ni(II)(5) clusters, [Ni(5)(O(2)CR')(2)(N(3))(4)(ppko)(4)(MeOH)(4)] [R' = H (1), Me (2)]. The structurally unprecedented {Ni(5)(μ-N(3))(2)(μ(3)-N(3))(2)}(6+) cores of the two clusters are almost identical and contain the five Ni(II) atoms in a bowtie topology. Two N(3)(-) ions are end-on doubly bridging and the other two ions end-on triply bridging. The end-on μ(3)-N(3)(-) groups link the central Ni(II) atoms with the two peripheral metal ions on either side of the molecule, while the Ni···Ni bases of the triangles are each bridged by one end-on μ-N(3)(-) group. Variable-temperature, solid-state direct- (dc) and alternating-current (ac) magnetic susceptibility, and magnetization studies at 2.0 K were carried out on both complexes. The data indicate an overall ferromagnetic behavior and an S = 5 ground state for both compounds. The ac susceptibility studies on 1 reveal nonzero, frequency-dependent out-of-phase (χ(M)") signals at temperatures below ~3.5 K; complex 2 reveals no χ(M)" signals. However, single-crystal magnetization versus dc field scans at variable temperatures and variable sweep rates down to 0.04 K on 1 reveal no noticeable hysteresis loops, except very minor ones at 0.04 K assignable to weak intermolecular interactions propagated by nonclassical hydrogen bonds. 相似文献
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Athanassios Panagiotopoulos Spyros P. Perlepes Evangelos G. Bakalbassis Aris Terzis Catherine P. Raptopoulou 《Polyhedron》2010
A bioinorganic approach into the problem of the isomorphous substitution of calcium(II) by lanthanide(III) ions in biological systems is discussed. Reactions of malonamic acid (H2malm) with CaII and NdIII sources under similar conditions yielded the compounds [Ca(Hmalm)2]n (1), [Nd(Hmalm)2(H2O)2]n(NO3)n (2) and [Nd(Hmalm)2(H2O)2]nCln·2nH2O (3·2nH2O). Their X-ray crystal structure data show that the malonamate(-1) ligand presents two different ligation modes and coordinates through the two carboxylate and the amide-O atoms, thus bridging three CaII ions in 1 and two NdIII ions in 2 and 3·2nH2O. Complex 1 is a 3D coordination polymer based on neutral repeating units, whereas 2 and 3·2nH2O are 1D coordination polymers based on the same cationic repeating unit. Hydrogen bonding interactions further stabilize the 3D framework structure of 1 and assemble the 1D chains of 2 and 3·2nH2O into 3D networks. The three complexes were characterized spectroscopically (IR, far-IR, and Raman) and the thermal decomposition of 2 and 3·2nH2O was monitored by TG/DTA and TG/DTG measurements. Variable-temperature magnetic susceptibility data for 2 are also reported. The bioinorganic chemistry relevance of our results is discussed. 相似文献
17.
Massive photoinduced short- and medium-range structural changes (photopolymerization) in As-S glasses are induced by near-bandgap light and studied by Raman scattering. Structural changes involve bond restructuring in sulfur-rich nanodomains of these nanoscale-phase-separated glasses. The spectral dependence of the photopolymerization effect demonstrates that various wavelengths can be used to optically change the structure of As-S glasses. The immense structural changes are relevant to recent findings about the role of bandgap light illumination for fabricating channel waveguides in noncrystalline arsenic sulfides. 相似文献
18.
A Steiner system is called a Steiner quintuple systems of order v. The smallest order for which the existence, or otherwise, of a Steiner quintuple system is unknown is 21. In this article, we prove that, if an S(4, 5, 21) exists, the order of its full automorphism group is 1, 2, 3, 4, 5, 6, 7, or 10. 相似文献
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Dimitrios V. Stergiou Spyros C. Karkabounas Panayotis G. Veltsistas Nicholaos P. Evmiridis Athanasios G. Vlessidis 《Mikrochimica acta》2007,158(1-2):59-64
A kinetic-potentiometric method is described for the quantitative assay of formaldehyde (HCHO) in pharmaceutical and industrial
preparations. It is based on the reaction of HCHO with (ethylenediamine)-Cu(II)-sulfate [Cu(CH2NH2)2(H2O)2] · SO4. The changes in potential, resulting from the release of the Cu(II) cations, are monitored with a Cu(II)-ion selective electrode.
The calibration curve for the HCHO is linear in the concentration range 50–250 mg L−1, with a limit of detection of 8.5 mg L−1. The method shows very good reproducibility with an RSD of 2.6% for successive injections (n = 5) of 150 mg L−1 HCHO primary solution, while it is interference free. The method was successfully tested in various industrial and pharmaceutical
preparations. 相似文献