Abstract: A family of 1:2 Fe-complexed formazan dyes is described. The dyes unexpectedly afford reddish-violet, violet, blue and black shades on natural and synthetic substrates. Methods for synthesizing the dyes and for dyeing a substrate are described. The dyes represent environmentally friendly alternatives to conventional Cr- and Co-based azo and formazan dyes.

Abstract: Disclosed is an original approach to solving the environmental problem associated with the use of Cr-based metallized azo dyes to deliver black shades on natural and synthetic substrates. This invention affords methods for both the synthesis of metallized dyes and the generation of black dyeings using those dyes without employing metals designated as priority pollutants at any stage in either method. The key element of the disclosure is the use of black 1:2 Fe complexes of azo dyes in lieu of currently used Cr-based complexes which are based on environmentally unfriendly priority pollutant metals without compromising the desirable high fastness properties of the latter complexes, an accomplishment heretofore assumed unachievable.