Copper(II) and zinc(II) complexes of a macrocyclic bis-(amine-amide-hydroxamate) siderophore analogue. Formation constants and coordination chemistry

摘要

The interaction of a dihydroxamate derivative of dioxacyclam (DOCYDMAHA) with copper(II) has been investigated in aqueous solution by a combination of potentiometry, electronic and ESR spectroscopy and also magnetic measurements. The formation constants for the complexes have been measured and discussion on their structure is reported. Conclusions on the coordination modes of the complexes are drawn based mostly on the absorption and ESP spectra as well as on the comparison with the behavior of some analogs. The zinc(II) complexation was also studied by potentiometry and ~1H NMR spectroscopy. Evidence was obtained for the binding of the ligand to the copper(II) ion involving a preferential 4 * N (amine/amide) coordination with eventual cooperation of one or two hydroxamate oxygens; the binding to the zinc(II) ion should involve (O,O)-hydroxamate coordination. No evidence was observed for the formation of bimetallic complexes.