Carcinogenicity of cobalt, antimony compounds, and weapons-grade tungsten alloy

The complete evaluation of the carcinogenicity of cobalt, antimony compounds, and weapons-grade tungsten alloy will be published in Volume 131 of the IARC Monographs.[Excerpt] In March, 2022, a Working Group of 31 scientists from 13 countries met remotely at the invitation of the International Agency for Research on Cancer (IARC) to finalise their evaluation of the carcinogenicity of nine agents: cobalt metal (without tungsten carbide or other metal alloys), soluble cobalt(II) salts, cobalt(II) oxide, cobalt(II,III) oxide, cobalt(II) sulfide, other cobalt(II) compounds, trivalent antimony, pentavalent antimony, and weapons-grade tungsten (with nickel and cobalt) alloy. For cobalt metal and the cobalt compounds, particles of all sizes were included in the evaluation. These assessments will be published in Volume 131 of the IARC Monographs.1 Cobalt metal and soluble cobalt(II) salts were classified as “probably carcinogenic to humans” (Group 2A) based on “sufficient” evidence for cancer in experimental animals and “strong” mechanistic evidence in human primary cells. Cobalt(II) oxide and weapons-grade tungsten alloy were classified as “possibly carcinogenic to humans” (Group 2B) based on “sufficient” evidence in experimental animals. Trivalent antimony was classified as “probably carcinogenic to humans” (Group 2A), based on “limited” evidence for cancer in humans, “sufficient” evidence for cancer in experimental animals, and “strong” mechanistic evidence in human primary cells and in experimental systems. Cobalt(II,III) oxide, cobalt(II) sulfide, other cobalt(II) compounds, and pentavalent antimony were each evaluated as “not classifiable as to its carcinogenicity to humans” (Group 3).[...

Synthesis and Characterisation of Cobalt(II) Complexes of 3-Hydroxyflavone

The syn theses of diaquabis (3-hydroxyflavonato) cobalt(II) and bis(pyridine) bis (3hydroxyflavonato) cobalt(II) are described. Results from infrared spectra clearly show that the 3-hydroxyflavonato anion forms a chelate through the 3-hydroxy 4-keto groups. The electronic spectra of both complexes indicate that cobalt(II) has an octahedral geometry. Quantitative analyses of the isolated products gave good agreement with calculated values. Magnetic moment measurements show that both compounds are high spin £ cobalt(II) complexes. The powder diffraction pattern of the pyridine adduct gave almost 1:1 correspondence with tTans-bis (pyridine) bis (3-hydroxyflavonato) nickel (II) which has an octahedral geometry. Therefore, it is highly likely that bis(pyridine)bis(3hydroxyflavonato) cobalt(II) is octahedrally co-ordinated with two chelating 3-hydroxyflavonato anions and two pyridine molecules occupying tTans positions

Spectroscopic and Potentiometric Studies of N-(2- Hydroxybenzyl)-L-&#945-Valine Cobalt (II) Complex

A Schiff base was prepared from the reaction of 2-hydroxybenzylaldehyde and L-valine. The reaction of the Schiff base and cobalt (II) chloride formed 2-hydroxybenzylaldehyde and L-valine cobalt (II) complex. The Schiff base is crystalline white and has a yield of 66%. The prepared complex is pale brown, has a yield of 68% and decomposition temperature of 274oC. The Schiff base and its cobalt (II) complex are insoluble in most common solvents however they are soluble in ethanol-water mixture. The molar conductance of the cobalt (II) Schiff base complex compound determined is 5.2 ohm cm2 mol-1. The infra-red spectra of the Schiff base showed band in the range 1480 -1520cm-1, assignable to v(C=N) stretching vibrations, the same band is observable in the cobalt (II) Schiff base complex. The broad band in the range 3270 - 3420cm-1 observed in Schiff base is assigned to v(O-H) stretching vibrations. The dissociation constant (pKa) of N – (2 – hydroxybenzyl) - L -a - valine Schiff base determined is 8.84. The average number of the Schiff base to cobalt (II) ion is 1 (one)

Determination of Cobalt in Cobalt(III) Complexes - A Comparative Study

Cobalt in cobalt(III) complexes was determined by a gravimetric method, weighing cobalt as cobalt(II) sulfate after heating the complexes with concentrated sulfuric acid; by a spectrophotometric method, measuring the color of cobalt(II)-thiocyanate complex in water-acetone mixture after reducing cobalt(III) to cobalt(II) with chromium(II), and by atomic absorption. The three methods were compared for accuracy of results and for convenience in routine analysis

Tris(ethyl-enedi-amine)-cobalt(II) dichloride.

The title compound, [Co(II)(C2H8N2)3]Cl2, was obtained unexpectedly as the product of an attempted solvothermal synthesis of cobalt selenide from the elements in the presence of NH4Cl in ethyl-enedi-amine solvent. The three chelate rings of the distorted octa-hedral [Co(C2H8N2)3](2+) complex cation adopt twisted conformations about their C-C bonds. The spread of cis-N-Co-N bond angles [80.17 (6)-98.10 (6)°] in the title compound is considerably greater than the equivalent data for [Co(III)(C2H8N2)3]Cl3 [Takamizawa et al. (2008 ▶). Angew. Chem. Int. Ed. 47, 1689-1692]. In the crystal, the components are linked by numerous N-H⋯Cl hydrogen bonds, generating a three-dimensional network in which the cationic complexes are stacked in columns along [010] and separated by columns of chloride anions

Synthesis and Evaluation of Polymer Supported Homogenous Oxidation Catalysts

Polystyrene bis(salicylaldehyde)-propylene-1,3-diiminato Cobalt (II) [salen] and Polystyrene bis(2,4-pentanedione)-propylene-1,3-diiminato Cobalt (II) [BAE] were prepared stepwise from chloromethylated polystyrene. In addition, a new preparation of a Schiff base was attempted resulting in Polystyrene bis(salicylaldehyde)-isobutylene-1,3-diiminoato Cobalt (II) being produced. Optimum reaction conditions were determined with regard tot ime, temperature, reaction ratios and solvent for each step for the reaction. The ability of the above named Cobalt (II) Schiff bases to oxidize 3-methyl indole to give the corresponding o-formylaminoacetophenone was also studied. One polymer-bound Schiff base cobalt catalyst (co-salen) demonstrated a very small amount of catalytic activity resulting in a minimum amount of o-formylaminoacetophenone being produced

In Vitro Study: Effect of Cobalt(II) Chloride Against Dengue Virus Type 1 in Vero Cells

Dengue virus (DENV) serotypes DENV-1 to DENV-4 are enveloped viruses that belong to the genus Flavivirus of the Flaviviridae. Dengue vaccine or antiviral has not yet been clinically approved for humans, even though there have been great efforts toward this end. Antiviral activity against DENV is needed to develop to be an alternative drug for DENV virus. Cobalt(II) chloride have been used in the treatment and prevention of diseases of humans since ancient times. The aim of this study is to investigate the antiviral effects and Cytotoxicity of Cobalt(II) chloride. This compound was further investigated for its inhibitory effect on the replication of DENV-1 in Vero cells. Antiviral activity and Cytotoxicity measured by WST-1 assay. The IC50 value of the Cobalt(II) chloride for DENV-1 was 0.38 μg/ml. The cytotoxicity of Cobalt(II) chloride to Vero cell suggest that the CC50 value was 2.91 µg/ml The results of this study demonstrate the anti-dengue serotype 1 inhibitory activity of Cobalt(II) chloride was a high toxic compound

The Reaction of Ethylenediamine with Cobalt (II) Perchlorate and Oxygen in Dilute Aqueous Solutions

Cobalt (II) perchlorate was reacted with ethylenediamine and molecular oxygen. Various mole ratios of ethylenediamine to cobalt (II) were oxygenated and studied by photometric, potentiometric, conductometric, magnetic susceptibility, freezing point depression, electron spin resonance and cobalt (II) extraction methods. The fact that the complex was brown in color, diamagnetic, contained ethylenediamine to cobalt to oxygen in a mole ratio of 4:2:1 was confirmed. The complex underwent elation to form a polymeric species with excess base. The complex could not be oxidized to a green paramagnetic complex by reacting it with sodium peroxydisulfate, potassium bromate, bromine or chlorine. Ammonia was added to a 2:1 mole ratio solution of ethylenediamine to cobalt (II) perchlorate before oxygenation. Upon oxygenation this solution also turned brown. This ammonia- containing-complex underwent no elation reaction and was postulated by analogy to contain ammonia: ethylenediamine:cobalt:oxygen in a mole ratio of 2:4:2:1. Crystals of this ammonia- containing-complex were obtained

SYNTHESIS OF A COBALT COMPLEX OF A SULFONATED BINUCLEATING SCHIFF BASE LIGAND

Current synthesis of cobalt (II) complexes of sulfonated binucleating Schiff base ligands requires the reaction be run under nitrogen.1 This research introduces a novel process in which the complex can be prepared in open air. The cobalt (II) complexes are prepared with synthesized 5- sulfosalicylaldehyde, and then analyzed by IR and UV-Vis spectrophotometry