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Mirzaei M.,Ferdowsi University of Mashhad | Eshtiagh-Hosseini H.,Ferdowsi University of Mashhad | Karrabi Z.,Ferdowsi University of Mashhad | Notash B.,Shahid Beheshti University | And 2 more authors.
Journal of Molecular Structure

One-dimensional coordination polymer, i.e., {(Hampy)[Cu(chel)(H2O)]2H2O}n (1, ampy = 2-amino-6-methylpyridine, H3chel = chelidamic acid), has been synthesized and characterized by elemental analysis, IR spectroscopy, solution studies and X-ray single-crystal diffraction. In the monomeric unit of compound 1 the metal center exhibits a distorted square-pyramidal coordination sphere. The Cu(II) ion is coordinated to chelidamic acid and water. These monomers are interlinked generating a 1D polymer by means of the para hydroxyl group of the ligand. Protonated 2-amino-6-methylpyridine rings act as counter cations. The crystal lattice is aggregated through intermolecular interactions, such as electrostatic attraction, N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonding and aromatic π stacking interactions. Hydrogen bond interactions between the water molecules led to formation of six-membered rings with chair conformation. These assemblies are described and analyzed by means of density functional theory (DFT) calculations since they play an important role in the construction of three-dimensional supramolecular frameworks. © 2014 Elsevier B.V. All rights reserved. Source

Barman N.,Jadavpur University | Banerjee S.,Jadavpur University | Brandao P.,University of Aveiro | Bauza A.,University Of Les Illesbalears | And 2 more authors.
Journal of Coordination Chemistry

Four complexes based on N,N′-bis(2-pyridylmethylene)-1,3-propanediamine (L) and different Cd(II) salts have been synthesized and characterized by single-crystal X-ray diffraction analysis. The complexes are [Cd2(L)2(μ-Cl)2](ClO4)2 (1), [Cd2(L)2(μ-Br)2](ClO4)2 (2), [Cd(L)I](ClO4) (3), and [Cd(L)(NCS)2] (4). L exhibits the same coordination mode in 1-4. The radius of each anion plays a role in affecting the structures and luminescent intensities of the final products. CdCl2, CdBr2, and CdI2 react with L to produce chloride or bromido-bridged binuclear complexes and mononuclear iodido complex, respectively, whereas an unusual mononuclear trigonal prismatic (TP) 4 is obtained when thiocyanate was used as a coligand. Photoluminescence properties of all the complexes show that the trend of fluorescence intensity is 1 > 4 > 2 > 3. All four complexes exhibit different supramolecular interactions such as C-H/σ, π-π, and C-H/π and hydrogen bonding interactions. The experimental findings are complemented by density functional theory (DFT) calculations. (Graph Presented). © 2016 Informa UK Limited, trading as Taylor & Francis Group. Source

Hazari A.,University of Calcutta | Kanta Das L.,University of Calcutta | Kadam R.M.,Bhabha Atomic Research Center | Bauza A.,University Of Les Illesbalears | And 2 more authors.
Dalton Transactions

Three new mixed valence trinuclear Co(ii/iii) compounds cis-[Co3L2(MeOH)2(N3)2(μ1,1-N3)2] (1), trans-[Co3L2(H2O)2(N3)2(μ1,1-N3)2]·(H2O)2 (2) and [Co3LR 2(N3)3(μ1,3-N3)] (3) have been synthesized by reacting a di-Schiff base ligand (H2L) or its reduced form [H2LR] (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine and H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine) with cobalt perchlorate hexahydrate and sodium azide. All three products have been characterized by IR, UV-Vis and EPR spectroscopies, ESI-MS, elemental, powder and single crystal X-ray diffraction analyses. Complex 1 is an angular trinuclear species in which two terminal octahedral Co(iii)N2O4 centers coordinate to the central octahedral cobalt(ii) ion through μ2-phenoxido oxygen and μ1,1-azido nitrogen atoms along with two mutually cis-oxygen atoms of methanol molecules. On the other hand, in linear trinuclear complex 2, in addition to the μ2-phenoxido and μ1,1-azido bridges with terminal octahedral Co(iii) centres, the central Co(ii) is bonded with two mutually trans-oxygen atoms of water molecules. Thus the cis-trans configuration of the central Co(ii) is solvent dependent. In complex 3, the two terminal octahedral Co(iii)N2O4 centers coordinate to the central penta-coordinated Co(ii) ion through double phenoxido bridges along with the nitrogen atom of a terminal azido ligand. In addition, the two terminal Co(iii) are connected through a μ1,3-azido bridge that participates in pnicogen bonding interactions (intermolecular N-N interaction) as an acceptor. Both the cis and trans isomeric forms of 1 and 2 have been optimized using density functional theory (DFT) calculations and it is found that the cis configuration is energetically more favorable than the trans one. However, the trans configuration of 2 is stabilized by the hydrogen bonding network involving a water dimer. The pnicogen bonding interactions have been demonstrated using MEP surfaces and CSD search which support the counter intuitive electron acceptor ability of the μ1,3-azido ligand. Complexes 1-3 exhibit catecholase-like activities in the aerial oxidation of 3,5-di-tert-butylcatechol to the corresponding o-quinone. Kinetic data analyses of this oxidation reaction in acetonitrile reveal that the catecholase-like activity follows the order: 1 (kcat = 142 h-1) > 3 (kcat = 99 h-1) > 2 (kcat = 85 h-1). Mechanistic investigations of the catalytic behaviors by X-band EPR spectroscopy and estimation of hydrogen peroxide formation indicate that the oxidation reaction proceeds through the reduction of Co(iii) to Co(ii). This journal is © The Royal Society of Chemistry 2015. Source

Mahmoudi G.,Islamic Azad University at Maragheh | Bauza A.,University Of Les Illesbalears | Rodriguez-Dieguez A.,University of Granada | Garczarek P.,Wroclaw University of Technology | And 2 more authors.

In this manuscript we report the synthesis and X-ray characterization of five complexes of Zn(ii) based on a N4O core carbohydrazone ligand (H2L); i.e. {[Zn4(HL)4](CH3OH)4(NO3)4} (1), {[Zn4(HL)4](ClO4)4} (2) {[Zn4(HL)4][Zn(SCN)4](NO3)2} (3) {[Zn(SCN)4](H4L)(CH3OH)2} (4) and {[Zn4(HL)4](NO3)4(H2O)} (5). Structurally characterized tetranuclear Zn(ii) complexes, as those reported herein, are scarcely found in the literature. In the crystal structures of several compounds, N-H⋯S hydrogen bonds, anion-π and π-hole interactions are described and analysed by means of density functional theory (DFT) calculations since they play an important role in the construction of three-dimensional supramolecular frameworks. Moreover, the noncovalent interactions have been also analysed using Hirshfeld surface analysis. © The Royal Society of Chemistry. Source

Mahmoudi G.,Islamic Azad University at Maragheh | Castineiras A.,University of Santiago de Compostela | Garczarek P.,Wroclaw University of Technology | Bauza A.,University Of Les Illesbalears | And 3 more authors.

Two new pyridine-based heterocyclic thiosemicarbazone ligands and their Ni(ii), Cd(ii), Mn(ii), Co(iii) and Cu(ii) complexes have been synthesized and characterized by structural, analytical and spectroscopic methods. The monodeprotonated anionic forms of the ligands coordinate in a tridentate fashion via two nitrogen and one sulphur donor atoms to yield seven complexes in which metal centres vary from four-coordinated square planar to six-coordinated distorted octahedral geometries. Single-crystal X-ray crystallography showed that the molecular complexes can aggregate into larger entities depending on the anion coordinated to the metal centre. We have analysed the interesting supramolecular assemblies observed in the solid state of some complexes by means of DFT calculations. These assemblies are formed by a combination of several noncovalent interactions, including chelate ring-π, π-π, and chalcogen bonding interactions, that have been characterized using Bader's Theory of "atoms-in-molecules". © The Royal Society of Chemistry 2016. Source

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