@article{edwards_freeman_2005, title={Synthetic dyes based on environmental considerations. Part 3: Aquatic toxicity of iron-complexed azo dyes}, volume={121}, DOI={10.1111/j.1478-4408.2005.tb00284.x}, abstractNote={In previous papers it has been shown that chromium or cobalt in metal-complexed azo dyes can be replaced by iron without adversely affecting the dyeing or mutagenic properties. Before commercial exploitation could be considered, an assessment of the aquatic toxicity of the iron complex dyes was important. The effect of replacing chromium and cobalt with iron on the aquatic toxicity of metal complex acid dyes for polyamide and protein substrates has been assessed in terms of the effect on Lemna minor (duckweed). A similar assessment has been carried out to show the effect on toxicity of dyebath decolorisation using ozonolysis. The results confirm that iron-complexed dyes are generally less toxic than the corresponding chromium or cobalt complexes, and that ozonolysis of aqueous solutions causes an increase in both pH and toxicity to Lemna minor. Received: 30 April 2005; Accepted: 23 June 2005.}, number={5}, journal={Coloration Technology}, author={Edwards, L. C. and Freeman, H. S.}, year={2005}, pages={265–270} }
 @article{edwards_freeman_2005, title={Synthetic dyes based on environmental considerations. Part 4: Aquatic toxicity of iron-complexed formazan dyes}, volume={121}, DOI={10.1111/j.1478-4408.2005.tb00285.x}, abstractNote={It has been shown in previous papers that iron can replace toxic metals such as chromium and cobalt in a range of azo metal complexes without adversely affecting their technical or mutagenic properties. Part 3 of this series reported aquatic toxicity assessment of a series of iron complex azo dyes using Lemna minor. The present paper extends this to a range of formazan dyes. The effect on aquatic toxicity of using iron as the complexing metal, and of dyebath decolorisation by ozonolysis, have been examined. The results confirm that iron-complexed formazan dyes are generally nontoxic. On the other hand, unlike the azo dyes studied previously, ozonolysis of aqueous solutions of iron complex formazan dyes was not found to cause a decrease in pH and therefore any increase in toxicity to Lemna minor. Received: 30 April 2005; Accepted: 23 June 2005.}, number={5}, journal={Coloration Technology}, author={Edwards, L. C. and Freeman, H. S.}, year={2005}, pages={271–274} }
 @article{edwards_freeman_claxton_2004, title={Developing azo and formazan dyes based on environmental considerations: Salmonella mutagenicity}, volume={546}, ISSN={["1873-135X"]}, DOI={10.1016/j.mrfmmm.2003.10.002}, abstractNote={In previous papers, the synthesis and chemical properties of iron-complexed azo and formazan dyes were reported. It was shown that in certain cases iron could be substituted for the traditionally used metals such as chromium and cobalt, without having an adverse effect on dye stability. While these results suggested that the iron analogs were potential replacements for the commercially used chromium and cobalt prototypes, characterization of potentially adverse environmental effects of the new dyes was deemed an essential step in their further development. The present paper provides results from using the Salmonella/mammalian microsome assay to determine the mutagenicity of some important commercial metal complexed dyes, their unmetallized forms, and the corresponding iron-complexed analogs. The study compared the mutagenic properties of six unmetallized azo dyes, six commercial cobalt- or chromium-complexed azo dyes, six iron-complexed azo dyes, six unmetallized formazan dyes, and six iron-complexed formazan dyes. The results of this study suggest that the mutagenicity of the unmetallized dye precursors plays a role in determining the mutagenicity of the iron-complexes. For the monoazo dye containing a nitro group, metal complex formation using iron or chromium decreased or removed mutagenicity in TA100; however, little reduction in mutagenicity was noted in TA98. For the formazan dye containing a nitro group, metal-complex formation using iron increased mutagenicity. Results varied for metal-complexes of azo and formazan dyes without nitro groups, but in general, the metal-complexed dyes based on mutagenic ligands were also mutagenic, while those dyes based on nonmutagenic ligands were nonmutagenic.}, number={1-2}, journal={MUTATION RESEARCH-FUNDAMENTAL AND MOLECULAR MECHANISMS OF MUTAGENESIS}, author={Edwards, LC and Freeman, HS and Claxton, LD}, year={2004}, month={Feb}, pages={17–28} }
 @article{freeman_berthelon_edwards_2004, title={Studies towards lightfast automotive dyes for polyester}, volume={3}, number={4}, journal={Journal of Textile and Apparel Technology and Management}, author={Freeman, H. S. and Berthelon, N. and Edwards, L. C.}, year={2004}, pages={14} }
 @inbook{freeman_edwards_2000, title={Iron-complexed dyes: Colorants in green chemistry}, ISBN={9780841236783}, DOI={10.1021/bk-2000-0767.ch003}, abstractNote={Few textile and dye chemists would argue against the suggestion that textile wastewater containing toxic metal ions is a matter of considerable concern, and that a pollution prevention/source reduction approach to addressing this concern would be better than currently available waste treatment methods. With that point in mind, this chapter reflects work pertaining to the design and synthesis of metal-complexed dyes that contain potential replacements for metals now designated as "priority pollutants". The focus of the present report is on dye structures and their properties rather than the synthetic reactions employed. The goal of this research was the development of environmentally friendly metal complexed dyes. It was hoped that this would provide a green chemistry approach to minimizing the need to treat wastewater after the dyes are manufactured and/or applied to textiles, by eliminating the source of dye wastewater containing toxic metals. Our strategy was to identify alternative metal complexes that could replace chromium-, cobalt-, and copper-based synthetic dyes. This chapter includes discussion of the metals that are used to prepare metal-complexed dyes and the properties of key intermediates (ligands) from which the dyes are made.}, booktitle={Green chemical syntheses and processes}, publisher={Washington, DC: American Chemical Society}, author={Freeman, H.S. and Edwards, L.C.}, editor={P. T. Anastas, L. G. Heine and Williamson, T. C.Editors}, year={2000} }