Ferreiros-Martinez, Raquel published the artcileMacrocyclic receptor showing extremely high Sr(II)/Ca(II) and Pb(II)/Ca(II) selectivities with potential application in chelation treatment of metal intoxication, Safety of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, the publication is Inorganic Chemistry (2011), 50(8), 3772-3784, database is CAplus and MEDLINE.
Herein the authors report a detailed study of the complexation properties of the macrocyclic decadentate receptor N,N’-Bis[(6-carboxy-2-pyridyl)methyl]-4,13-diaza-18-crown-6 (H2bp18c6) toward different divalent metal ions [Zn(II), Cd(II), Pb(II), Sr(II), and Ca(II)] in aqueous solution This ligand is especially suited for the complexation of large metal ions such as Sr(II) and Pb(II), which results in very high Pb(II)/Ca(II) and Pb(II)/Zn(II) selectivities (in fact, higher than those found for ligands widely used for the treatment of lead poisoning such as EDTA), as well as in the highest Sr(II)/Ca(II) selectivity reported so far. These results were rationalized from the structure of the complexes. X-ray crystal diffraction, 1H and 13C NMR spectroscopy, as well as theor. calculations at the d. functional theory (B3LYP) level were performed. The authors’ results indicate that for large metal ions such as Pb(II) and Sr(II) the most stable conformation is Δ(δλδ)(δλδ), while for Ca(II) the authors’ calculations predict the Δ(λδλ)(λδλ) form being the most stable one. The selectivity that bp18c62- shows for Sr(II) over Ca(II) can be attributed to a better fit between the large Sr(II) ions and the relatively large crown fragment of the ligand. The x-ray crystal structure of the Pb(II) complex shows that the Δ(δλδ)(δλδ) conformation observed in solution is also maintained in the solid state. The Pb(II) ion is endocyclically coordinated, being directly bound to the 10 donor atoms of the ligand. The bond distances to the donor atoms of the pendant arms (2.55-2.60 Å) are substantially shorter than those between the metal ion and the donor atoms of the crown moiety (2.92-3.04 Å). This is a typical situation observed for the so-called hemidirected compounds, in which the Pb(II) lone pair is stereochem. active. The x-ray structures of the Zn(II) and Cd(II) complexes show that these metal ions are exocyclically coordinated by the ligand, which explains the high Pb(II)/Cd(II) and Pb(II)/Zn(II) selectivities. The authors’ receptor bp18c62- shows promise for application in chelation treatment of metal intoxication by Pb(II) and 90Sr(II).
Inorganic Chemistry published new progress about 1128304-86-8. 1128304-86-8 belongs to pyridine-derivatives, auxiliary class Pyridines, name is 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid, and the molecular formula is C26H36N4O8, Safety of 6,6′-((1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem