Aspartic acid interaction with cobalt(II) in dilute aqueous solution: A 57Co emission Mössbauer spectroscopic study

Abstract

Emission ( 57 Co) Mössbauer spectra of the aspartic acid-57 CoCl 2 system were measured at T = 80 K in frozen aqueous solution and in the form of a dried residue of this solution. The Mössbauer spectra, besides a weak contribution from after-effects, showed two Fe 2+ /Co 2+ components which were ascribed to octahedrally and tetrahedrally coordinated 57 Co II microenvironments in the Asp-cobalt(II) complex. This dual coordination mode may be due to the involvement of the second terminal carboxylic group of aspartic acid in the coordination sphere of Co.