Chelating behaviour of alizarin dyes with divalent metal ions [Mn[2+], Co[2+], Ni[2+], Cu[2+], Zn[2+]]

The physico-chemical characteristics of some new complexes of divalent metal ions such as [Mn[2+], Co[2+], Ni[2+], Cu[2+] and Zn[2+]] with Alizarin [Aliz.] dyes [Aliz. Red S and Aliz. yellow R] have been investigated. A spectrophotometric method has been used to determine the dissociation constants of the dyes as well as the stability constants of their complexes. The order of increasing stability of the formed complexes was found to be Co[2-+] < Zn[2-+]