XPS as a Probe for the Bonding Nature in Metal Acetates

Metal carboxylates are an extensive family of coordination compounds of growing importance in Materials Science; hence, there is a need for improving the characterization methods for these complexes, especially at...

Synthesis, Spectroscopic, Thermal and Catalytic Properties of Four New Metal (II) Complexes with Selected N- and O-Donor Ligands

Four solid compounds with formulae: Co(OAc)₂(Im)·H₂O (I), Ni(OAc)₂(Im)_1.5·2H₂O (II), Cu₂(OAc)₄(Im) (III) and Zn(OAc)₂(Im)·H₂O (IV) (where: Im = 1H-Imidazole) were prepared and characterized by chemical and elemental analysis, powder X-ray diffraction patterns and FTIR spectroscopy. Catalytic properties of each complex for styrene oxidation reaction were investigated. Furthermore, thermal properties of compounds were studied using the TG-DTG and DSC techniques under dry air atmosphere. Additionally, volatile thermal decomposition and fragmentation products were also investigated using the TG-FTIR spectra in air.

Synthesis, characterization and biological activity of new mixed ligand complexes of Zn(II) naproxen with nitrogen based ligands

A series of novel Zn(II) complexes [Zn2(nap)4] (1), [Zn(nap)21,10-phen](2), [Zn(nap)22,9-dmphen] (3), [Zn(nap)2(2-ampy)2] (4), [Zn(nap)2(imid)2] (5), [Zn(nap)2(1,2-dmimid)2] (6) (nap = naproxen, 1,10-phen = 1,10-phenanthroline, 2,9-dmphen = 2,9-dimethyl-1,10-phenanthroline, 2-ampy = 2-aminopyridine, imid = imidazole, 1,2-dmimid = 1,2-dimethyl imidazole) were synthesized and characterized using IR, UV-Vis, (1)H NMR, (13)C{(1)H} NMR spectroscopy. The crystal structure of complex 3 was determined using single-crystal X-ray diffraction. In order to assess the effect of the metal ions on the anti-bacterial activity, complexes 1-6 have been screened in vitro, against (G(+)) bacteria (Staphylococcus aureus and Micrococcus luteus) and (G(-)) bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis and Escherichia coli) using the agar well diffusion method. Complex 2 was the only complex that showed antibacterial activity against P. aeruginosa, where the complexation of the parent ligand 1,10-phenathroline enhanced significantly the activity. All the complexes showed different activity against the different bacteria, and were compared with activity of the parent ligands. The complexes were tested also for their anti-malarial activity using two methods: a semi-quantitative micro-assay and a previously self-developed quantitative in-vitro method. Both were used to study the efficiency of these complexes in inhibiting the formation of the Malaria pigment. This is considered an important target of many known anti-malarial drugs such as Chloroquine and Amodaquine. Results showed that the efficiency of complex 3 in preventing the formation of β-hematin was 75%. The efficiency of Amodiaquine as a standard drug was reported to give 92.5.

Intra- and supra-molecular inter-actions in cis,mer-diaqua-tris-(1H-imidazole-κN(3))(terephthalato-κO)cobalt(II) monohydrate

In the title compound, [Co(C(8)H(4)O(4))(C(3)H(4)N(2))(3)(H(2)O)(2)]·H(2)O, the cisoid angles are in the range 85.59 (5)-93.56 (5)°, while two equal transoid angles deviate significantly from the ideal linear angle, the third being almost linear. One carboxyl-ate group is almost coplanar [1.23 (13)°] with the plane of its parent aromatic ring, although it has one O-atom donor involved in one coordination and one hydrogen bond as acceptor. The other carboxyl-ate group does not coordinate and is rotated out of this plane with a torsional twist of 17.27 (20)°. The coordination neutral entity, based on aqua ligands and two cyclic co-ligands seems, at first sight, monomeric. Strongly tight, via one intra-molecular hydrogen bond between aqua and carboxyl-ate O atoms, it brings out a quasi-planar six-membered ring around the Co(II) atom, turning the CoN(3)O(3) coordination octa-hedron into a new building block. The rigidity of this feature associated with several hydrogen-bonded arrays yields an extended structure. In the resulting supra-molecular packing, a binuclear hydrated Co(II) assembly, built up from triple strands driven by different heterosynthons, embodies the synergy of coordination, covalent and hydrogen bonds.

Synthesis, Crystal Structure, and Magnetic Properties of Oxalato-Copper(II) Complexes with 3,3-Bis(2-imidazolyl)propionic Acid, an Imidazole-Carboxylate Polyfunctional Ligand: From Mononuclear Entities to Ladder-Like Chains

The synthesis of five new Cu(II) compounds of formula [Cu(HBIP)(C(2)O(4))].H(2)O (1), [Cu(HBIP)(C(2)O(4))(OH(2))].2H(2)O (2), [{Cu(HBIP)Cl}(2)(&mgr;-C(2)O(4))].2H(2)O (3), [{Cu(BIP)}(2)(&mgr;-C(2)O(4))].2H(2)O (4) and [{Cu(BIP)}(2)(&mgr;-C(2)O(4))].6H(2)O (5), together with their spectral and magnetic characterization, is reported. Crystal structures of compounds 2, 3 and 5 have been solved. All these compounds crystallize in the triclinic system, space group P&onemacr;, with a = 7.3322(3) Å, b = 10.014(1) Å, c = 11.541(1) Å, alpha = 113.22(1) degrees, beta = 91.37(1) degrees, gamma = 94.51(1) degrees, Z = 2 for compound 2; a = 7.444(2) Å, b = 8.518(2) Å, c = 11.231(2) Å, alpha = 97.45(2) degrees, beta = 98.99(2) degrees, gamma = 97.95(2) degrees, Z = 1 for compound 3; and a = 7.977(1) Å, b = 8.656(1) Å, c = 11.807(1) Å, alpha = 69.06(1) degrees, beta = 86.07(1) degrees, gamma = 67.36(1) degrees, Z = 1 for compound 5. In compound 2 the asymmetric unit consists of one isolated neutral [Cu(HBIP)(C(2)O(4))(OH(2))] molecule and two noncoordinated water molecules. The Cu(II) ion is five-coordinated (4+1 coordination mode) with HBIP and oxalato entities acting as bidentate ligands and the water molecule as the fifth ligand. The structure of compound 3 is made up of centrosymmetric binuclear [{Cu(HBIP)(Cl)}(2)(&mgr;-C(2)O(4))] units and noncoordinated water molecules. The two copper atoms are linked through a bis-bidentate oxalato group leading to a metal-metal separation of 5.28(3) Å. The coordination stereochemistry of the CuN(2)O(2)Cl chromophore is approximately SP. Compound 5 exhibits a structure built of ladder-like chains. In these chains the rungs are constituted by the neutral dinuclear centrosymmetric [(BIP)Cu(C(2)O(4))Cu(BIP)] entities. The oxalato group bridges two copper atoms in a bis-bidentate fashion, whereas the BIP acts as a tridentate ligand, connecting through their carboxylate groups these dimeric units along the a axis. The copper atom is involved in a five-coordinated CuN(2)O(2)O' chromophore, with a coordination geometry intermediate between SP and TBP. The magnetic properties of all complexes have been investigated. Compound 1 and 2 follow a Curie-Weiss law with very low values of theta. The other three compounds exhibit an antiferromagnetic coupling, with 2J = -265 cm(-)(1) for 3, 2J = -108 cm(-)(1) for 4, and 2J = -5.7 cm(-)(1) for 5. The strength of the exchange interaction is discussed on the basis of the structural features and correlated with published magneto-structural data on similar oxalato-bridged copper(II) compounds.