Search results for "Metal Ion"

Desferrioxamine as an appropriate chelator for 90Nb: Comparison of its complexation properties for M-Df-Octreotide (M=Nb, Fe, Ga, Zr)

2014

The niobium-90 radioisotope ((90)Nb) holds considerable promise for use in immuno-PET, due to its decay parameters (t½ = 14.6h, positron yield=53%, Eß(+)(mean) = 0.35 MeV and Eß(+)(max) = 1.5 MeV). In particular, (90)Nb appears well suited to detect in vivo the pharmacokinetics of large targeting vectors (50-150 kDa). In order to be useful for immuno-PET chelators are required to both stabilize the radionuclide in terms of coordination chemistry and to facilitate the covalent attachment to the targeting vector. Different chelators were evaluated for this purpose in terms of radiolabelling efficiency and stability of the radiolabelled Nb(V) complex and in order to determine the most suitable…

Reversible coordination of dioxygen by tripodal tetraamine copper complexes incorporated in a porous silica framework.

2010

The present study reports the synthesis and rational design of porous structured materials by using a templating method. A tetraethoxysilylated tripodal tetraamine (TREN) was covalently incorporated in a silica framework with a double imprint: A surfactant template and a metal ion imprint. The presence of a cationic surfactant (CTAB) endowed the material with a high porosity, and the tripodal or square-pyramidal topology of the ligand was preserved thanks to the use of the silylated Cu(II) complex. After removal of the surfactant and de-metalation, the incorporated tetraamine was quantitatively complexed by CuCl(2) and the material has shown after thermal activation that a reversible bindin…

Ditopic Aza-Scorpiand Ligands Interact Selectively with ds-RNA and Modulate the Interaction upon Formation of Zn2+ Complexes

2021

Nucleic acids are essential biomolecules in living systems and represent one of the main targets of chemists, biophysics, biologists, and nanotechnologists. New small molecules are continuously developed to target the duplex (ds) structure of DNA and, most recently, RNA to be used as therapeutics and/or biological tools. Stimuli-triggered systems can promote and hamper the interaction to biomolecules through external stimuli such as light and metal coordination. In this work, we report on the interaction with ds-DNA and ds-RNA of two aza-macrocycles able to coordinate Zn2+ metal ions and form binuclear complexes. The interaction of the aza-macrocycles and the Zn2+ metal complexes with duple…

Studies on mechanism and physico-chemical parameters at the origin of the cement setting II. Physico-chemical parameters determining the coagulation …

1996

The physico-chemical parameters determining the coagulation of cements grains previously identified as the first fundamental process of cement setting have been investigated in diluted suspensions using an adapted granulometric method. The analysis of the influence of the ionic concentration in solution on the coagulation reveals that calcium concentration is the parameter which determines the particle interactions. There exists a minimum critical concentration of calcium ions in solution which is required to occur the coagulation of cement particles and a dispersive effect appears for very high concentrations. The results are discussed in relation with DLVO theory and specific interactions.

Book Review: Ions in Solution: Basic Principles of Chemical Interactions. By J. Burgess

1989

Transportation of complexing agents released by pulp and paper industry: A Finnish lake case

1996

Complexing agents (EDTA, DTPA) are used to bind metal ions in pulp and paper industry. Their role will increase significantly when the total chlorine free (TCF) processes will be applied to a larger extent. EDTA and DTPA were analysed in the waters from the southern part of the Lake Saimaa (SE Finland) influenced by the effluents of three pulp and paper mills. The samples were collected at different distances from the points of emission. The results of analyses suggest that EDTA can persist in lake water and is able to propagate for considerable distances, while DTPA can be detected only in the near surroundings of the site of release. Some EDTA was found even in the sampling points that we…

Host molecules containing electroactive cavities obtained by the molecular assembly of redox-active ligands and metal ions

1995

Self-assembly processes of nickel ions with the redox-active ligand 1,4,8,11-tetra(ferrocenylmethyl)-1,4,8,11-tetraazacyclotetradecane (Fc4cyclam) induces the formation of a redox-active cavity of potential use in electrocatalysis.

Postsynthetic Improvement of the Physical Properties in a Metal-Organic Framework through a Single Crystal to Single Crystal Transmetallation

2015

As ingle crystal to single crystal transmetallation process takes place in the three-dimensional (3D) metal- organic framework (MOF) of formula Mg II 2{Mg II 4(Cu II 2- (Me3mpba)2)3}·45 H2 O( 1 ;M e 3mpba 4¢ = N,N'-2,4,6-trimethyl- 1,3-phenylenebis(oxamate)). After complete replacement of the Mg II ions within the coordination network and those hosted in the channels by either Co II or Ni II ions, 1 is transmetallated to yield two novel MOFs of formulae Co2 II {Co II 4(Cu II 2(Me3- mpba)2)3}·56 H2 O( 2 )a nd Ni2 II {Ni II 4(Cu II 2(Me3mpba)2)3}· 54 H2 O( 3). This unique postsynthetic metal substitution affords materials with higher structural stability leading to enhanced gas sorption and m…

Electrochemical Detection of High Oxidation States of Chromium( IV and V ) in Chromium‐Doped Cassiterite and Tin‐Sphene Ceramic Pigmenting Systems

2006

Solid-state electrochemistry is applied to detect the presence of chromium centres with high oxidation states in chromium-doped cassiterite and tin-sphene ceramic pigmenting systems. Voltammetric data indicate that CrV and CrIV centres with different coordinative arrangements exist in the studied materials, and yield proton-assisted reduction processes at +0.95, +0.42 AgCl/Ag in contact with 0.50 M H2SO4. Electrochemical measurements are correlated with spectroscopic data. The CrIV and CrV metal ions display a significant light-driven electrocatalytic effect on the oxidation of 1,4-dihydrobenzoquinone and Fe(CN)64– ions that involves the formation of surface-confined adducts. (© Wiley-VCH V…

Selective CO2 adsorption by a triazacyclononane-bridged microporous metal-organic framework.

2011

Metal-organic frameworks constructed by self-assembly of metal ions and organic linkers have recently been of great interest in the preparation of porous hybrid materials with a wide variety of functions. Despite much research in this area and the large choice of building blocks used to fine-tune pore size and structure, it remains a challenge to synthesise frameworks composed of polyamines to tailor the porosity and adsorption properties for CO(2). Herein, we describe a rigid and microporous three-dimensional metal-organic framework with the formula [Zn(2)(L)(H(2)O)]Cl (L=1,4,7-tris(4-carboxybenzyl)-1,4,7-triazacyclononane) synthesised in a one-pot solvothermal reaction between zinc ions a…