Copper Complex

By reaction of (NH4)6Mo7O24·4H2O, Cu(NO3)2·2.5H2O and 1-methylimidazole (mim) under hydrothermal conditions the novel copper molybdate [Cu(mim)4]2[α-Mo8O26] is obtained in the form of blue, rectangular-shaped crystals. The title compound crystallizes with monoclinic lattice symmetry in the space group P21/n. The predominant structural feature of the title compound is a two-dimensional framework that is constituted by [α-Mo8O26]4−octamolybdate units as framework nods and

methanobactin and copper. NMR and mass spectrometry reveal that some lots of methanobactin contain a second species of methanobactin that is missing its C- terminal methionine residue. Both these species bind Cu(II) and can be readily separated from one another in the copper-complexed state using HPLC. However, attempts to separated the two species in an uncomplexed state leads to extensive

New macrocyclic polyaza compoundscontaining the 1-methylpyrazole moiety are synthesizedin high yield by [2+ 2] dipodal condensation andreduction. The ring contracted structure of the Schiffbase has been elucidated by NMR. Two of thesemacrocycles form ...

Copper complexation in marine systems is mainly controlled by organic matter, partially produced by micro- and macroalgae that release exudates with the capacity to bind metals. This feature is important as it influences bioavailability, bioaccumulation, toxicity, and transport of copper through biological membranes. The release of Cu-complexing ligands by seaweeds cultured under copper excess was studied in the laboratory. Five macroalgae belonging to different functional groups were used, including the filamentous Chaetomorphafirma (Chlorophyta), the foliose Ulvalactuca (Chlorophyta) and Porphyra columbina (Rhodophyta), the corticated Gelidium lingulatum (Rhodophyta), and the leathery Lessonia nigrescens (Phaeophyceae). The concentration of ligands and their copper-binding strength (logK') of exudates released by each species was determined by anodic stripping voltammetry (ASV). The selected algae released exudates in a wide range of concentration (42-117 nM) after 48h of culture, and addition of 157nM copper increased the production of ligands up to 8 times. A relationship between structural complexity or thallus thickness and the amount of ligands released was not observed. The binding strength (logK') varied among species from 7.6 to 8.9, a response that was not modified by exposure to sub-lethal copper excess. The kelp L. nigrescens showed a fast response to copper excess, releasing ligands that reduced toxicity of the metal in hours. Results suggest that intertidal and shallow subtidal macroalgae might have been overlooked regarding their role as producers of organic ligands and, therefore, as modulators of metal complexing capacity in coastal waters.

Copper complexation in marine systems is mainly controlled by organic matter, partially produced by micro- and macroalgae that release exudates with the capacity to bind metals. This feature is important as it influences bioavailability, bioaccumulation, toxicity, and transport of copper through biological membranes. The release of Cu-complexing ligands by seaweeds cultured under copper excess was studied in the laboratory. Five macroalgae belonging to different functional groups were used, including the filamentous Chaetomorphafirma (Chlorophyta), the foliose Ulvalactuca (Chlorophyta) and Porphyra columbina (Rhodophyta), the corticated Gelidium lingulatum (Rhodophyta), and the leathery Lessonia nigrescens (Phaeophyceae). The concentration of ligands and their copper-binding strength (logK') of exudates released by each species was determined by anodic stripping voltammetry (ASV). The selected algae released exudates in a wide range of concentration (42-117 nM) after 48h of culture, and addition of 157nM copper increased the production of ligands up to 8 times. A relationship between structural complexity or thallus thickness and the amount of ligands released was not observed. The binding strength (logK') varied among species from 7.6 to 8.9, a response that was not modified by exposure to sub-lethal copper excess. The kelp L. nigrescens showed a fast response to copper excess, releasing ligands that reduced toxicity of the metal in hours. Results suggest that intertidal and shallow subtidal macroalgae might have been overlooked regarding their role as producers of organic ligands and, therefore, as modulators of metal complexing capacity in coastal waters.

... Vulcanization accelerators such as 2-morpholinothiobenzothiazole, N-cyclohexyl-2-benzothiazole sulfenamide and 2,2-dithiobisbenzothiazole are derived from 2-mercaptobenzothiazole (MBT) (55. Niessen ... El-Shekeil, A., Al-Maydamah, H., Al-Karbooly, A. and Khalid, M. 1999. ...