Search results for "metal ions"
showing 10 items of 282 documents
Algae in Biotechnological Processes
2018
As photoautotrophic organisms, algae possess all of the valuable features that determine their role as the primary producers in the biosphere. A wide range of tolerance based on their extremely efficient adaptation to biochemical processes, as well as the specific cellular structure of these organisms, when correlated with the ecological plasticity of microalgae in particular, predispose these biota to growing and developing under either laboratory or industrial conditions. Hence, the natural features of algae have opened wide the door for the multidirectional biotechnological use of these organisms, with a dynamically growing number of such applications fully supporting this thesis. Among …
New Multidimensional Coordination Polymers with μ 2 ‐ and μ 3 ‐dcno Cyano Carbanion Ligand {dcno – = [(NC) 2 CC(O)O(CH 2 ) 2 OH] – }
2006
New polymeric materials [M(dcno)2(H2O)2] [M = FeII (1), CoII (2)] and [M(dcno)2] [M = CuII (3), MnII (4)] with dcno– =[(NC)2CC(O)O(CH2)2OH]– = 2,2-dicyano-1-(2-hydroxyethoxy)ethenolate anion have been synthesised and characterised by IR spectroscopy, X-ray crystallography and magnetic measurements. In compounds 1 and 2, each organic ligand acts in a bridging mode with its two nitrogen atoms bound to two different metal ions, while in compounds 3 and 4, each organic anion acts as a μ3-bridging ligand through its two nitrogen atoms and the oxygen atom of the OH group. Each metal ion has a pseudo-octahedral trans-MN4O2 environment with four nitrogen atoms from four different organic ligands an…
Homo- and Heterobinuclear Cu2+ and Zn2+ Complexes of Ditopic Aza Scorpiand Ligands as Superoxide Dismutase Mimics
2017
Two polytopic aza-scorpiand-like ligands, 6-[7-(diaminoethyl)-3,7-diazaheptyl]-3,6,9-triaza-1-(2,6-pyridina)cyclodecaphane (L1) and 6-[6′-[3,6,9-triaza-1-(2,6-pyridina)cyclodecaphan-6-yl]-3-azahexyl]-3,6,9-triaza-1-(2,6-pyridina)cyclodecaphane (L2), have been synthesized. The acid–base behavior and Cu2+, Zn2+, and Cu2+/Zn2+ mixed coordination have been analyzed by potentiometry, cyclic voltammetry, and UV–vis spectroscopy. The resolution of the crystal structures of [Cu2L2Cl2](ClO4)2·1.67H2O (1), [Cu2HL2Br2](ClO4)3·1.5H2O (2), and [CuZnL2Cl2](ClO4)2·1.64H2O (3) shows, in agreement with the solution data, the formation of homobinuclear Cu2+/Cu2+ and heterobinuclear Cu2+/Zn2+ complexes. The m…
Low temperature optical spectroscopy of cobalt-substituted hemocyanin from Carcinus maenas
1993
In this work we report the optical absorption spectra of three cobalt-substituted derivatives of hemocyanin (He) from Carcinus maenas, in the temperature range 300–20 K. The derivatives studied are the mononuclear (Co2+)-He with a single cobalt ion in the “CuA” site, the binuclear (Co2+)2-He and the binuclear mixed metal (Co2+-Cu1+)-He. At low temperature three main bands are clearly resolved; the temperature dependence of their zeroth, first and second moments sheds light on the stereodynamic properties in the surroundings of the chromophore. Within the limits of the reported analysis, in the binuclear derivatives the motions coupled to the chromophore appear to be “essentially harmonic” i…
Pseudopeptidic ligands: exploring the self-assembly of isophthaloylbisglycine (H2IBG) and divalent metal ions.
2012
We present a systematic study of the complexation of the new pseudopeptidic ligand isophthaloylbisglycine (H(2)IBG) with divalent metal ions of varying ionic radius. This work represents the initial employment of H(2)IBG in the coordination chemistry of alkaline earth, 3d transition, Zn(II) and Cd(II) metal elements. Infrared, NMR, thermal, magnetic, adsorption and theoretical studies of these compounds are also discussed.
Cysteamine and its homoleptic complexes with group 12 metal ions. Differences in the coordination chemistry of ZnII, CdII, and HgII with a small N,S-…
2005
2-Ammoniumethanethiolate, (-)SCH(2)CH(2)NH(3)(+), the first structurally characterized zwitterionic ammoniumthiolate, is the stable form of cysteamine (HL) in the solid state and in aqueous solution. Reactions of ZnCl(2), Cd(Oac)(2), and HgCl(2) with cysteamine and NaOH in a 1:2:2 ratio, respectively, lead to the homoleptic complexes ML(2). Their single-crystal X-ray structures demonstrate basic differences in the coordination chemistry of Zn(II), Cd(II), and Hg(II). While chelating N,S-coordination modes are found for all metal ions, Zn(II) forms a mononuclear complex with a distorted tetrahedral Zn(N(2)S(2)) coordination mode, whereas Hg(II) displays a dimer with Hg(N(2)S(2)) coordinated …
Palladium(II) sequestration by phytate in aqueous solution. Speciation analysis and ionic medium effects.
2010
Environmental context.In the last 20 years, the demand for palladium and other platinum-group elements has intensified, causing a significant increase in their concentration in the environment, with particular accumulation in urban areas. Knowledge about Pd2+ speciation in aqueous media is fundamental for the understanding of its biological and environmental activity in contaminated areas. Phytic acid appears to be a good sequestering agent towards Pd2+ under various conditions, indicating its potential use in the remediation of contaminated sites. Abstract. Palladium(II) speciation in the presence of phytate (Phy12–) was studied by H+ ion selective electrode (ISE) potentiometry at 25°C in…
Expanding the NUIG MOF family: synthesis and characterization of new MOFs for selective CO2 adsorption, metal ion removal from aqueous systems, and d…
2021
Metal organic frameworks (MOFs) have attracted considerable attention in recent years due to their use in a wide range of environmental, industrial and biomedical applications. The employment of benzophenone-4,4'-dicarboxylic acid (bphdcH2) in MOF chemistry provided access to the 3D mixed metal MOFs [CoNa2(bphdc)2(DMF)2]n (NUIG2) and [ZnK2(bphdc)2(DMF)2]n (NUIG3), and the 2D homometallic MOF [Co2(OH)(bphdcH)2(DMF)2(H2O)2]n(OH)·DMF (1·DMF). 1·DMF is based on a dinuclear SBU and consists of interpenetrating networks with an sql topology. Dc magnetic susceptibility studies were carried out in 1·DMF and revealed the presence of weak antiferomagnetic exchange interactions between the metal centr…
Synthesis, characterization, and complexation of tetraarylborates with aromatic cations and their use in chemical sensors.
2005
Five aromatic borate anions, namely tetrakis(4-phenoxyphenyl)borate (1), tetrakis(biphenyl)borate (2), tetrakis(2-naphthyl)borate (3), tetrakis(4-phenylphenol)borate (4), and tetrakis(4-phenoxy)borate (5), have been prepared and tested as ion-recognition sites in chemical sensors for certain aromatic cations and metal ions. To gain further insight into the complexation of the cations, some complexes have been prepared and structurally characterized. The complexation behavior of 1 and 2 towards N-methylpyridinium (6), 1-ethyl-4-(methoxycarbonyl)pyridinium (7), tropylium (8), imidazolium (9), and 1-methylimidazolium (10) cations has been studied, and the stability constants of the complexes o…
A Co2O2 metallacycle exclusively supported by l-valine
2008
Abstract [Co2(OH)2( l -valine)4]·2.5H2O has been prepared under hydrothermal conditions and constitutes the first example of a [Co2O2] core supported exclusively by aminoacids. This synthetic dimetallic model for redox active metalloenzymes is one of the few binary aminoacid compounds of biologically relevant metal ions that has been structurally characterized, showing the possibilities of this synthetic approach for preparation of models in bioinorganic chemistry.