Oxidation of Cobalt(II) Bispidine Complexes with Dioxygen

2017 ◽  
Vol 70 (5) ◽  
pp. 576 ◽  
Author(s):  
Peter Comba ◽  
Bianca Pokrandt ◽  
Hubert Wadepohl
Keyword(s):  
Metal Ions ◽  
Coordination Sphere ◽  
Tertiary Amine ◽  
Cobalt Complexes ◽  
Decay Process ◽  
Oxidation States ◽  
Redox Potentials ◽  
Aerobic Conditions ◽  
High Degree ◽  
Derivatives Of

Bispidine (3,7-diazabicyclo[3.3.1]nonane) ligands, derivatives of diazaadamantane, possess a very rigid backbone and have a high degree of pre-organization for cis-octahedral coordination geometries. Despite their rigidity, they exert a flexible coordination sphere, resulting in stable complexes with a variety of metal ions in various oxidation states. Due to the known high III/II redox potentials of their cobalt complexes, the CoII bispidine complexes are generally resistant to oxidation by dioxygen. Discussed in the present study are various CoII bispidine complexes with tetra- and pentadentate bispidines, with one of these complexes shown to be unstable under aerobic conditions. The decay process has been identified as an oxidative elimination of the 2-methylene pyridine substituent at one of the tertiary amine donors, resulting in picolinate, which is found coordinated to a CoIII product, where the dealkylated N-donor remains unprotonated. The mechanism of this interesting reaction has been studied, and details of the resulting structure of the product complex are discussed.

Ammonia removal in a pilot-scale WSP complex in Northeast Brazil

1996 ◽  
Vol 33 (7) ◽  
pp. 165-171 ◽  
Author(s):  
J. Soares ◽  
S. A. Silva ◽  
R. de Oliveira ◽  
A. L. C. Araujo ◽  
D. D. Mara ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Surface Waters ◽  
Wastewater Treatment Plants ◽  
Pilot Scale ◽  
Ammonia Removal ◽  
Northeast Brazil ◽  
Environmental Legislation ◽  
Aerobic Conditions ◽  
High Degree

Ammonia removal was monitored in a waste stabilisation pond complex comprising ponds of different geometries and depths under two different operational regimes. It was found that a high degree of ammonia removal commenced in the secondary maturation ponds, with the highest removals occurring in the shallowest ponds as a consequence of improved aerobic conditions. The tertiary maturation ponds produced effluents with mean ammonia concentrations of < 5 mg N/l, the maximum permitted recommended by Brazilian environmental legislation for the discharge of effluents of wastewater treatment plants into surface waters. Ammonia removal in the secondary facultative and maturation ponds could be modelled using equations based on the volatilization mechanism proposed by Middlebrooks et al. (1982).

scholarly journals Using internal electrostatic fields to manipulate the valence manifolds of copper complexes

2021 ◽  
Author(s):  
Alexander B. Weberg ◽  
Samuel P. McCollom ◽  
Laura M. Thierer ◽  
Michael R. Gau ◽  
Patrick J. Carroll ◽  
...  
Keyword(s):  
Coordination Sphere ◽  
Copper Complexes ◽  
Photophysical Properties ◽  
Redox Potentials ◽  
Electrostatic Effects ◽  
Electrostatic Fields ◽  
Secondary Coordination Sphere

Secondary coordination sphere electrostatic effects tune the valence manifolds of copper centers, impacting molecular geometries, photophysical properties, and redox potentials.

Fluorescence Enhancement of Polyamine Derivatives of 1,8-Naphthalimide with Transition Metal Ions

2006 ◽  
Vol 19 (6) ◽  
pp. 506-510 ◽  
Author(s):  
Guo-tao Wen ◽  
Man-zhou Zhu ◽  
Zhuo Wang ◽  
Xiang-ming Meng ◽  
Hui-yuan Hu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Fluorescence Enhancement ◽  
Transition Metal Ions ◽  
Derivatives Of ◽  
Polyamine Derivatives

Radioactive Tracer Study Performed in a Dipole Geometry in a Highly Conductive Fracture Zone

1990 ◽  
Vol 212 ◽  
Author(s):  
Johan Byegård ◽  
Gunnar Skarnemark ◽  
Mats Skålberg
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Fracture Zone ◽  
Radioactive Tracer ◽  
Tracer Experiment ◽  
Tracer Study ◽  
Redox Potentials ◽  
Chemical Analogue

ABSTRACTA radioactive tracer experiment has been performed in a highly conductive fracture zone, using a dipole geometry. Anions (131I− and 82Br−) and complexed metal ions (51Cr-EDTA, 58Co-EDTA, 111In-EDTA, 140La-DOTA, 160Tb-EDTA, 169Yb-EDTA and 177Lu-DOTA) have been injected and their properties as non-sorbing tracers were evaluated. Besides, studies of slightlysorbing cations (24Na+, 58Co2+, 86Rb+ and 201T1+) were performed. 99mTcO4 and its chemical analogue 186ReO4 were also injected to study the behaviour of Tc at low redox-potentials. Breakthrough was obtained for Re and for all metal complexes and anions. Some differences in the recovery yields could be seen. No transport of cations, except for Na, could be measured. No breakthrough of Tc could be observed. This indicates that TcO4− was reduced and sorbed.

Enhancement of Efficiency of the Ural Region Surface Water Sources Water Treatment in Terms of Metal Ions and their Compounds

2012 ◽  
pp. 96-108
Author(s):  
Keyword(s):  
Water Treatment ◽  
Surface Water ◽  
Metal Ions ◽  
Water Purification ◽  
Solid Phase ◽  
Ural Region ◽  
Iron Aluminum ◽  
High Degree ◽  
Water Hydrogen ◽  
Sorption Characteristics

Sorption characteristics of “Ekozol-401” high-dispersed solid-phase agent in water solutions containing ions of iron, aluminum and manganese have been studied. Influence of the sorbent content, extracted metals’ concentration, saline background, hardness and alkalinity, water hydrogen indicator value as well as amount of modifier contained in the solid-phase agent have been stated. High degree of water purification in terms of the said ions has been demonstrated.

A new Late Cambrian pentastomid and a review of the relationships of this parasitic group

2005 ◽  
Vol 96 (2) ◽  
pp. 163-176 ◽  
Author(s):  
Dieter Waloszek ◽  
John E. Repetski ◽  
Andreas Maas
Keyword(s):  
Systematic Position ◽  
Host Group ◽  
Upper Cambrian ◽  
Late Cambrian ◽  
Lower Ordovician ◽  
Stem Lineage ◽  
New Form ◽  
Available Information ◽  
High Degree ◽  
Derivatives Of

ABSTRACTPentastomida, tongue worms, are a taxon of about 130 species of parasites, living exclusively in the respiratory tracts of vertebrates. Three-dimensionally preserved Upper Cambrian larvae already demonstrate a high degree of adaptation to parasitism, striking morphological conservatism, and a high diversification by the Late Cambrian, thereby suggesting a likewise diversified host group. Not least due to their highly modified morphology, the systematic affinities of pentastomids remain controversial. The two major alternatives place the group as either close to branchiuran crustaceans or as stem-lineage derivatives of the Euarthropoda. To this set of Cambrian fossil representatives of the pentastomids we can add a new form from Lower Ordovician boundary beds from Sweden, most likely reworked from Upper Cambrian horizons. Based on this new species, named Aengapentastomum andresi gen. et sp. nov., and the available information about fossil and Recent pentastomids, we review the diverging ideas on the systematic position of this fully parasitic taxon.

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