Benzyl-containing azobenzene-based disperse dyes: Relationship between molecular packing and alkali-resistant stability

Abstract

Although azobenzene disperse dyes with planar structures and alkali-resistant (AR) stability are recently reported, those with easily hydrolyzed groups and twisted molecular structures and their related effective design strategies are not yet explored. Herein, sterically hindered and planar benzyl group is introduced into the adjacent location of cyano to deeply explore the AR stability of the dyes. These designed dyes, with the final fixation higher than 98% and final fixation difference between conventional and alkali condition smaller than 1%, are further applied on one-step dyeing of PET fabrics, which reduce of 60% water consumption, 40% energy and 60% wastewater. Careful analysis of their alkali-hydrolysis behavior and crystal structures confirmed that benzyl group can lead to diverse intermolecular interactions. The strong intermolecular interactions result in compact molecular arrangement and actually beneficial for the AR stability by preventing the nucleophilic reagent. Incorporating an understanding of these packing structures into the design of organic colorants can assist in developing high-performance chemicals.