Interaction of aminopyridines with metal hexacyanoferrates(II)

Copper(II) and zinc(II) hexacyanoferrates(II) have been found to be effective adsorbents for aminopyridines, such as 2-amino-, 3-amino-, and 4-aminopyridines. The maximum adsorption was found at neutral pH (pH = 7.0). The adsorption trend followed a Langmuir adsorption isotherm. The Langmuir constants, K-L and X-M, were determined. The overall adsorption trend was found to be in the order 3-amino- > 4-amino- > 2-aminopyridine. Infrared spectral studies of the adsorption adducts indicate that adsorption takes place through an interaction between the adsorbate molecule and the outer divalent metal ion of metal hexacyanoferrates(II). The results of the present study suggest the importance of metal hexacyanoferrates(II) and metal ions in the stabilization of biomolecules from degradation on primitive earth.