ChemInform Abstract: METAL ION CONTROLLED SYNTHESES OF NOVEL FIVE-COORDINATE ZINC AND CADMIUM COMPLEXES CONTAINING A HELICAL COORDINATION GEOMETRY AND THEIR TEMPLATE REACTION TO FORM COMPLEXES OF A PENTADENTATE MACROCYCLIC LIGAND

1974 ◽  
Vol 5 (50) ◽  
pp. no-no
Author(s):  
L. F. LINDOY ◽  
DARYLE H. BUSCH
Keyword(s):  
Metal Ion ◽  
Macrocyclic Ligand ◽  
Coordination Geometry ◽  
Cadmium Complexes ◽  
Template Reaction

scholarly journals Kinetics and mechanism of sol-gel transformation between some trivalent- and tetravalent-metal ions and Sodium alginate Anionic polyelectrolyte with formation of coordination Biopolymeric structure polymembranes Hydrogels of Capillary Structures Ex

2007 ◽  
Vol 3 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Ishaq Abdullah Zaafarany
Keyword(s):  
Sodium Alginate ◽  
Metal Ion ◽  
Sol Gel ◽  
Coordination Geometry ◽  
Large Excess ◽  
First Order ◽  
Pseudo First Order ◽  
The Stability ◽  
Kinetics Of ◽  
Overall Kinetics

Abstract          The kinetics of sol-gel transformation between A13+, La 3+ and Th4+ metal ion electrolytes and sodium alginate sol have been studied complexometrically at various  temperatures. In the presence of a large excess of sodium alginate sol concentration over that of metal ion electrolyte, the pseudo first–order plots of exchange showed sigmoidal curves with two distinct stages. The initial part was relatively fast and curved significantly at early times, followed by a slow decrease in the rates of exchange over longer time periods. The rate constants of gelation showed second-order overall kinetics which was first order in the concentration of both reactants. The thermodynamic parameters have been evaluated and tentative gelation mechanisms consistent with the kinetic results of gelation are suggested. The stability of these ionotropic metal-alginate complexes has been discussed in terms of the coordination geometry and strength of chelated bonds.

SYNTHESIS, SPECTRAL STUDIES, STRUCTURAL EVALUATION AND ANTIMICROBIAL ACTIVITY OF SOME NOVEL C R(III) COMPLEXES CONTAINING TETRADENTATE MACROCYCLIC LIGANDS

INDIAN DRUGS ◽  
2017 ◽  
Vol 54 (06) ◽  
pp. 20-29
Author(s):  
S Shukla ◽  
◽  
S. Gautam ◽  
S Chandra ◽  
A. Kumar
Keyword(s):  
Metal Complexes ◽  
Metal Ion ◽  
Metal Salt ◽  
Condensation Reaction ◽  
Macrocyclic Ligand ◽  
Agar Plate ◽  
Macrocyclic Ligands ◽  
Diffusion Method ◽  
Spectral Studies ◽  
Spectral Techniques

A string of novel coordination compounds of Cr(III) complexes have been derived and characterized from the macrocyclic ligands (L 1 -L 2 ) carried out by condensation reaction between ligands and the subsequent metal salt. The chemical composition of ligand was determined by analytical and spectral techniques i.e. elemental analysis, IR and Mass spectrocopy. Spectral techniques revealed tetradentate [N 4 ] the nature of ligand and its coordination mode to metal ion through nitrogen donor atoms. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, ePR studies. The geometry of these complexes was ascertained by molecular modelling study by using Gaussian 09 program. All metal complexes were found to exhibit octahedral geometry around the metal ion. The newly synthesized macrocyclic ligands and metal complexes were subjected for antimicrobial screening to determine the inhibition and control against tested microorganisms, bacteria ( S.lutea , S.aureus, S.albus and E.coli ) and fungi ( A.fulviceps, U . hordei, A. niger and P.catinus ) by using disc diffusion method and agar plate technique, respectively. The experimental results suggest that metal complexes exhibit enhanced inhibition zone than free macrocyclic ligand.

Thermodynamics and Structure of Isothiocyanate Complexes of Manganese(II), Cobalt(II) and Zinc(II) Ions in N,N-Dimethylacetamide

1995 ◽  
Vol 50 (1) ◽  
pp. 11-17
Author(s):  
Makoto Koide ◽  
Shin-ichi Ishiguro
Keyword(s):  
Physicochemical Properties ◽  
Metal Ion ◽  
Formation Constants ◽  
Coordination Geometry ◽  
Tetrahedral Coordination ◽  
Sterically Hindered

Abstract The complexation of manganese (II), cobalt (II) and zinc(II) with thiocyanate ions has been studied in N,N-dimethylacetamide (DMA) by calorimetry and spectrophotometry at 298 K. In these metal systems the formation of a series of four isothiocyanato complexes, [M(NCS)n](2-n)+ (n = 1÷4; M = Mn, Co, and Zn) was established, and their formation constants, enthalpies and entropies were determined. Interestingly, the complexation behavior in DMA is significantly different from that in N,N-dimethylformamide (DMF), despite of the similarity of the physicochemical properties of these solvents. The complexation is indeed enhanced significantly in DMA over DMF and is more exothermic in the former solvent. Furthermore, with cobalt(II) an octahedral to tetrahedral coordination geometry change was found to occur in DMA at an earlier step of complexation than in DMF. These results suggest that six-coordination of DMA molecules to a metal ion is severely sterically hindered.

One-dimensional CuIand AgIladder-like coordination polymers supported by 2-ethyl-1-(pyridin-3-ylmethyl)-1H-benzimidazole

2013 ◽  
Vol 69 (9) ◽  
pp. 1017-1021
Author(s):  
Liu-cheng Gui ◽  
Guang-ming Liang ◽  
Hua-hong Zou ◽  
Zhong Hou
Keyword(s):  
Hydrogen Bonds ◽  
Metal Ion ◽  
Three Dimensional ◽  
Coordination Geometry ◽  
Tetrahedral Coordination ◽  
Asymmetric Unit ◽  
Counter Anion ◽  
One Dimensional ◽  
Solvent Molecules ◽  
Distorted Tetrahedral Coordination

The title complexes, poly[[bis[μ2-2-ethyl-1-(pyridin-3-ylmethyl)-1H-benzimidazole-κ2N1:N3]copper(I)] tetrafluoroborate acetonitrile monosolvate], {[Cu(C15H15N3)2]BF4·CH3CN}n, (I), and poly[[bis[μ2-2-ethyl-1-(pyridin-3-ylmethyl)-1H-benzimidazole-κ2N1:N3]silver(I)] perchlorate methanol monosolvate], {[Ag(C15H15N3)2]ClO4·CH3OH}n, (II), are isostructural and exhibit one-dimensional ladder-like structures in which each asymmetric unit contains one metal ion (Cu+or Ag+), two 2-ethyl-1-(pyridin-3-ylmethyl)-1H-benzimidazole (bep) ligands, one counter-anion (tetrafluoroborate or perchlorate) and one interstitial molecule (acetonitrile or methanol). Each metal ion exhibits a distorted tetrahedral coordination geometry consisting of two pyridyl and two benzimidazole N atoms from four distinct ligands. Two metal ions are linked by two bep ligands to form a centrosymmetric 18-memberedM2(bep)2metallacycle, while adjacentM2(bep)2metallacycles are further interlinked by another two bep ligands resulting in a ladder-like array. In the extended structure, four adjacent ladder-like arrays are connected together through C—H...F, O—H...O and C—H...O hydrogen bonds between bep ligands, solvent molecules and counter-anions into a three-dimensional supramolecular structure.

scholarly journals Phosphorylcholine Phosphatase: A Peculiar Enzyme of Pseudomonas aeruginosa

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Carlos Eduardo Domenech ◽  
Lisandro Horacio Otero ◽  
Paola Rita Beassoni ◽  
Angela Teresita Lisa
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Adaptive Response ◽  
Metal Ion ◽  
Coordination Geometry ◽  
Choline Metabolism ◽  
Inhibitory Site ◽  
Closed Structure ◽  
Phosphorylcholine Phosphatase ◽  
Hydrolysis Of

Pseudomonas aeruginosa synthesizes phosphorylcholine phosphatase (PchP) when grown on choline, betaine, dimethylglycine or carnitine. In the presence of Mg2+ or Zn2+, PchP catalyzes the hydrolysis of p-nitrophenylphosphate (p-NPP) or phosphorylcholine (Pcho). The regulation of pchP gene expression is under the control of GbdR and NtrC; dimethylglycine is likely the metabolite directly involved in the induction of PchP. Therefore, the regulation of choline metabolism and consequently PchP synthesis may reflect an adaptive response of P. aeruginosa to environmental conditions. Bioinformatic and biochemistry studies shown that PchP contains two sites for alkylammonium compounds (AACs): one in the catalytic site near the metal ion-phosphoester pocket, and another in an inhibitory site responsible for the binding of the alkylammonium moiety. Both sites could be close to each other and interact through the residues 42E, 43E and 82YYY84. Zn2+ is better activator than Mg2+ at pH 5.0 and it is more effective at alleviating the inhibition produced by the entry of Pcho or different AACs in the inhibitory site. We postulate that Zn2+ induces at pH 5.0 a conformational change in the active center that is communicated to the inhibitory site, producing a compact or closed structure. However, at pH 7.4, this effect is not observed because to the hydrolysis of the [Zn2+L2−1L20(H2O)2] complex, which causes a change from octahedral to tetrahedral in the metal coordination geometry. This enzyme is also present in P. fluorescens, P. putida, P. syringae, and other organisms. We have recently crystallized PchP and solved its structure.

Synthetic and structural studies on metal complexes of tripyrrin

2003 ◽  
Vol 07 (01) ◽  
pp. 17-24 ◽  
Author(s):  
Martin Bröring ◽  
Carsten D. Brandt ◽  
Serguei Prikhodovski
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Metal Ion ◽  
Coordination Geometry ◽  
Structural Studies ◽  
Structural Investigations ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Step Procedure ◽  
Porphyrin Analogues

A general two-step procedure for the synthesis of metallotripyrrinates TrpyMOAc f with M = Co(II) , Cu(II) , Zn(II) and Pd(II) , and OAc f = trifluoroacetate, is described, starting from well-known monopyrrolic precursors and simple transition metal acetates. X-ray structural investigations were undertaken on four different complexes, and the results reveal, that the nature of the metal ion, rather than the ligand, determines the coordination geometry of these porphyrin fragment complexes. The finding of pseudotetrahedral and strained pseudoplanar coordination polyhedra at the metal centres makes a clear distinction between metalloporphyrins and metallotripyrrins and shows the latter to be related to some recently discovered metal chelates of macrocyclic porphyrin analogues.

(μ-3,4:9,10:17,18:23,24-Tetrabenzo-1,12,15,26-tetraaza-5,8,19,22-tetraoxacyclooctacosane-κ4 N 1,N 26:N 12,N 15)bis[aquadichloridocopper(II)]

2007 ◽  
Vol 63 (11) ◽  
pp. m2652-m2653
Author(s):  
Zhi-Fang Jia ◽  
Jian-Fang Ma ◽  
Lai-Ping Zhang ◽  
Ting-Ting Han
Keyword(s):  
Water Molecule ◽  
Macrocyclic Ligand ◽  
Complex Molecule ◽  
Dimensional Structure ◽  
Water Molecules ◽  
Coordination Geometry ◽  
One Dimensional ◽  
Tetragonal Pyramidal ◽  
Coordinated Water ◽  
Cl Atoms

In the title compound, [Cu2Cl4(C36H44N4O4)(H2O)2], the dinuclear complex molecule lies on an inversion centre. Each CuII atom shows a tetragonal–pyramidal coordination geometry formed by two Cl atoms, two N atoms from the macrocyclic ligand and one water molecule. The coordinated water molecules are hydrogen-bonded to the Cl atoms in adjacent molecules, generating a one-dimensional structure.

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