Complexing Absorption of NO by Cobalt(Ⅱ)-Histidine

摘要

To develop an alternative to ferrous complexes, which easily lose nitric oxide (NO) binding ability as a result of oxidation by O-2 in the complexing absorption process, experiments about the NO absorption characteristics of cobalt complexes were performed. First, a screening experiment was conducted, and cobalt(II)-histidine (CoHis) manifested to be the most potent absorbent to both NO and O-2 in neutral conditions among industrially available cobalt complexes. Then, the concentration of the cobalt nitrosyl complex, i.e., CoHis-NO, in the NO absorption liquid was measured by the NO transfer reaction with ferrous ethylenediaminetetraacetate [Fe(II)EDTA], thereby the standard curve for CoHis-NO quantification by spectrophotometry was plotted. At last, as implied by NO absorption experiments, the absorption of NO can be promoted by reducing the absorbent temperature, increasing the Collis concentration, or increasing the absorbent pH appropriately. Furthermore, it was found that CoHis could not promote NO disproportionation.