Crystallographic study of two monoazo disperse dyes with a D–π–A system

Abstract

Two azo disperse dyes, 2,6‐dichoro‐4‐nitro‐4′,4′‐N‐cyanoethyl‐N‐benzyl‐azobenzene (D1) and 3‐(3‐methyl‐4‐N‐ethyl‐N‐benzyl‐phenyldiazenyl)‐5‐nitro‐2,1‐benzisothiazole (D2), were synthesised and characterised. The crystal morphologies and single crystal structures were measured. The various packing and supramolecular interactions were described. D1 formed stellate crystals. The two benzene rings bilateral to the azo unit were not coplanar. Their dihedral angle was 75.72°. They were linked by the azo unit and were twisted. The coupling‐component N‐substituted benzyl and benzene rings were not coplanar. The chemical structure was not the typical azo structure. A dimeric packing mode was formed between adjacent molecules in a head‐to‐head and tail‐to‐tail manner. One molecule was inserted between two dimeric molecules in a head‐to‐tail manner. D2 formed globe crystals. The isothiazole and benzene rings of the azo unit were coplanar, with the typical π–π conjugated structure. The benzene rings of the azo unit and the coupling‐component N‐substituted benzyl were vertical. Their torsion angle was 179.9°.

Synthesis and Application to Polyester and Nylon 6 Fabrics of Hetaryl Bis-Azo Disperse Dyes Based on 6-Amino-2,4-Dihydroxypyrimidine and 4-Methoxy-2-Nitroaniline Moieties

“…Thus, they do not pose ecological problems. In addition, the deep bright colors produced by the heterocyclic compounds could be explained using resonance theory, in which case, the ring system often has resonance stabilization energy to lose excitation compared with those based on the benzene rings [6][7][8][9].…”

Level dyeing property and aggregation morphology of reactive black 5 on cotton fabric in a salt-free and less-water dyeing system

“…Previously, some reports have described studies of the diffusion of dye to fiber using various methods, such as 2D IR spectroscopy, 33 Laser Raman imaging, 34 fiber slices, 35 scanning tunnelling microscopy, 36 etc.…”

“…Previously, some reports have described studies of the diffusion of dye to fiber using various methods, such as 2D IR spectroscopy, 33 Laser Raman imaging, 34 fiber slices, 35 scanning tunnelling microscopy, 36 etc. Although the dyeing properties of dyes have been investigated through experiments with different methods, it has been difficult to clarify the diffusion process of reactive dyes in the non-aqueous medium/less-water dyeing system.…”