Physico-Analytical Studies on some Heterocyclic Azo Dyes and their Metal Complexes with some Transition Metals

In this investigation the azo dyes prepared through diazotizing 3-phenyl-5-aminopyrazole (PAP) and coupling the resulting diazonium salt with Schäffer acid [2-(3 ‛ -phenyl-5 ‛ -pyrazolyl azo) Schäffer acid (la)] and resorcinol [2-(3 ‛ -phenyl-5 ‛ -pyrazolyl azo) resorcinol (Ib)]. These compounds are used as chromogenic reagents for the spectrophotometric determination of copper, nickel, cobalt and zinc. The conditional acid dissociation constants of these azo dyes (la, Ib) and the stability constants of its metal ion complexes have been determined by spectroanalytical methods. The molar absorptivity and Sandell's sensitivity values of the complexes have been evaluated. The stability constants of the formed complexes have been determined. This will be the subject of future studies concerning the biotechnological applications of our results in the effort to obtain possible new anticancer drugs.