Stereochemical control of oxygen activation in synthetic oxygen carriers

• Published in: Journal of molecular catalysis Vol. 49; no. 1; pp. 9 - 19
• Main Authors: STRASAK, M, LAUCOKOVA, J, NOVOMESKY, P, SERSEN, F
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.12.1988; Elsevier Sequoia
• Subjects: Biological and medical sciences; Medical sciences; Pharmacology. Drug treatments
• ISSN: 0304-5102
• DOI: 10.1016/0304-5102(88)80051-8

A series of mixed ligand complexes of cobalt(III) containing a linear tetradentate amino acid derivative EBAA 2 2 Abbreviations used: EBAA = ethylenebisamino acidate; EBG = ethylenebis-glycinate; EDDA = ethylenediamine- N,N'-diacetate; EBA = ethylenebis(α-alaninate); EBABA = ethylenebis(aminobutyric acidate); EBV = ethylenebis(valinate); EBL = ethylenebis(leucinate); EBPhe = ethylenebis(α-phenylalaninate); EBP = ethylenebis(prolinate); Im = imidazole; bzIm = benzimidazole. and imidazole has been synthesised and characterized. It has been established for their cobalt(II) analogues that they are able to reversibly bind atmospheric oxygen in aqueous solution. By means of the combined use of visible-UV, IR, 13C NMR and ESR spectroscopy, paper electrophoresis and elemental analyses, the tentative structure of these cobalt dioxygen complexes has been proposed. Possible stereochemical control of the uptake of molecular oxygen by cobalt(II) complexes in solution in light of earlier investigations is discussed. For ternary complexes of EBAA and a heterocyclic nitrogen base B, binuclear dioxygen complexes are formed without hydroxo bridges, presumably because all of the available coordination positions of the cobalt atom are occupied by the ligand donor groups and the dioxygen molecule, whereas in the case of binary complexes of EBAA binuclear dibridged μ(O 2, OH) complexes are formed. These complexes may be used as models for active sites in some metalloproteins, including respiratory proteins.