Synthesis and characterization of the sorption properties of oxygen- binding cobalt complexes immobilized in nanoporous materials

Cobalt(II) bis(3-fluorosalicylaldehyde)ethylenediamine (Co(fluomine)), an organometallic complex of known oxygen-binding capacity, has been synthesized in such a way as to anchor this material on the anion sites of selected nanoporous substrates. The O₂- and N₂-binding capacities of the resulting bulk materials were then characterized. The resulting O₂ sorption isotherms of these materials were more reversible than those of the free material. They also exhibit the positive slope with oxygen pressure that is desirable for applications. X-ray photoemission spectroscopy (XPS) analysis indicated a difference in the electronic nature of the cobalt atoms present in the free Co(fluomine) as compared to those of the material immobilized on the surface of type X zeolite, indicating possible coordination of Co(II) at the axial position by zeolitic framework oxygen. Stability testing of these materials, however, did not result in increased stability over that observed in the free Co(fluomine).