Home  About us  Contact
 

ZnII Center (znii + center)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Allosteric Tuning of the Intra-Cavity Binding Properties of a Calix[6]arene through External Binding to a ZnII Center Coordinated to Amino Side Chains

CHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2007
Ulrich Darbost Dr.
Abstract Molecular recognition by calix[6]arene-based receptors bearing three primary alkylamino side chain arms (1) is described. Complexation of ZnII ion provides the dinuclear ,-hydroxo complex , XRD characterization of which, together with solution studies, provided evidence of its hosting of neutral polar organic guests G. Treatment of this complex with a carboxylic acid or a sulfonamide (XH) results in the formation of mononuclear species , one of which (X = Cl) has been characterized by XRD. A dicationic complex is obtained upon treatment of with a mixture of an alkylamine and a strong acid. Each of these ZnII complexes features a tetrahedral metal ion bound to the three amino arms of ligand 1 and to an exogenous ligand (either HO,, X,, or RNH2) sitting outside of the cavity. As a result, the metal ion structures the calixarene core, constraining it in a cone conformation suitable for guest hosting. The receptor properties of these compounds have been explored in detail and are compared with those of the trisammonium receptor , based on the same calixarene core, as well as those of the trisimidazole-based dicationic Zn funnel complexes. This study reveals very different host properties, in spite of the common hydrophobic, ,-basic, and hydrogen-bonding acceptor properties of the calixarene cores. A harder external ligand produces a less polarized receptor that is consequently particularly sensitive to the hydrogen-bonding ability of its guest. The less electron-rich the apical ligand, and a fortiori the trisammonium host, the more sensitive the receptor to the dipole moment of the guest. All this stands in contrast with the funnel Zn complexes, in which the coordination link plays a dominant role. It is also shown that the asymmetry of an exo -coordinated enantiopure amino ligand is sensed by the guest. This supramolecular system nicely illustrates how the receptor properties of a hydrophobic cavity can be allosterically tuned by the environment. [source]

A novel parallel interpenetrating two-dimensional (4,4) network: poly[[,2 -1,4-bis(imidazol-1-ylmethyl)benzene](,2 -naphthalene-1,4-dicarboxylato)zinc(II)]

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009
Ya-Ping Li
In the title coordination compound, [Zn(C12H6O4)(C14H14N4)]n, the two ZnII centers exhibit different coordination environments. One ZnII center is four-coordinated in a distorted tetrahedral environment surrounded by two carboxylate O atoms from two different naphthalene-1,4-dicarboxylate (1,4-ndc) anions and two N atoms from two distinct 1,4-bis(imidazol-1-ylmethyl)benzene (1,4-bix) ligands. The coordination of the second ZnII center comprises two N atoms from two different 1,4-bix ligands and three carboxylate O atoms from two different 1,4-ndc ligands in a highly distorted square-pyramidal environment. The 1,4-bix ligand and the 1,4-ndc anion link adjacent ZnII centers into a two-dimensional four-connected (4,4) network. The two (4,4) networks are interpenetrated in a parallel mode. [source]

Nickel and zinc complexes with a monodentate heterocycle and tridentate Schiff base ligands: self-assembly to one- and two-dimensional supramolecular networks via hydrogen bonding

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009
Xiao-Hua Chen
In the complex (morpholine)[2-hydroxy- N,-(5-nitro-2-oxidobenzylidene)benzohydrazidato]nickel(II), [Ni(C14H9N3O5)(C4H9NO)], (I), the NiII center is in a square-planar N2O2 coordination geometry. The complex bis[,-2-hydroxy- N,-(2-oxidobenzylidene)benzohydrazidato]bis[(morpholine)zinc(II)], [Zn2(C14H10N2O3)2(C4H9NO)2], (II), consists of a neutral centrosymmetric dimer with a coplanar Zn2(,2 -O)2 core. The two ZnII centers are bridged by phenolate O atoms. Each ZnII center exhibits a distorted square-pyramidal stereochemistry, in which the four in-plane donors come from the O,N,O,-tridentate 2-hydroxy- N,-(2-oxidobenzylidene)benzohydrazidate(2,) ligand and a symmetry-related phenolate O atom, and the axial position is coordinated to the N atom from the morpholine molecule. There are intramolecular phenol,hydrazide O,H...N hydrogen bonds present in both (I) and (II). In (I), square-planar nickel complexes are linked by intermolecular morpholine,morpholine N,H...O hydrogen bonds, leading to a one-dimensional chain, while in (II) an infinite two-dimensional network is formed via intermolecular hydrogen bonds between the coordinated morpholine NH groups and the uncoordinated phenolate O atoms. [source]

A novel parallel interpenetrating two-dimensional (4,4) network: poly[[,2 -1,4-bis(imidazol-1-ylmethyl)benzene](,2 -naphthalene-1,4-dicarboxylato)zinc(II)]

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009
Ya-Ping Li
In the title coordination compound, [Zn(C12H6O4)(C14H14N4)]n, the two ZnII centers exhibit different coordination environments. One ZnII center is four-coordinated in a distorted tetrahedral environment surrounded by two carboxylate O atoms from two different naphthalene-1,4-dicarboxylate (1,4-ndc) anions and two N atoms from two distinct 1,4-bis(imidazol-1-ylmethyl)benzene (1,4-bix) ligands. The coordination of the second ZnII center comprises two N atoms from two different 1,4-bix ligands and three carboxylate O atoms from two different 1,4-ndc ligands in a highly distorted square-pyramidal environment. The 1,4-bix ligand and the 1,4-ndc anion link adjacent ZnII centers into a two-dimensional four-connected (4,4) network. The two (4,4) networks are interpenetrated in a parallel mode. [source]

Nickel and zinc complexes with a monodentate heterocycle and tridentate Schiff base ligands: self-assembly to one- and two-dimensional supramolecular networks via hydrogen bonding

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009
Xiao-Hua Chen
In the complex (morpholine)[2-hydroxy- N,-(5-nitro-2-oxidobenzylidene)benzohydrazidato]nickel(II), [Ni(C14H9N3O5)(C4H9NO)], (I), the NiII center is in a square-planar N2O2 coordination geometry. The complex bis[,-2-hydroxy- N,-(2-oxidobenzylidene)benzohydrazidato]bis[(morpholine)zinc(II)], [Zn2(C14H10N2O3)2(C4H9NO)2], (II), consists of a neutral centrosymmetric dimer with a coplanar Zn2(,2 -O)2 core. The two ZnII centers are bridged by phenolate O atoms. Each ZnII center exhibits a distorted square-pyramidal stereochemistry, in which the four in-plane donors come from the O,N,O,-tridentate 2-hydroxy- N,-(2-oxidobenzylidene)benzohydrazidate(2,) ligand and a symmetry-related phenolate O atom, and the axial position is coordinated to the N atom from the morpholine molecule. There are intramolecular phenol,hydrazide O,H...N hydrogen bonds present in both (I) and (II). In (I), square-planar nickel complexes are linked by intermolecular morpholine,morpholine N,H...O hydrogen bonds, leading to a one-dimensional chain, while in (II) an infinite two-dimensional network is formed via intermolecular hydrogen bonds between the coordinated morpholine NH groups and the uncoordinated phenolate O atoms. [source]