Correlation between dye structure with dyeing properties in anhydrous dyeing systems: Insights from Crystallographic, DFT, kinetic, and thermodynamic analyses

The dyeing performance of different disperse dyes in D5 non-aqueous media dyeing varies greatly, and dye structure is closely related to dyeing performance. Therefore, in this paper, the influence of dye molecular structure on the dyeing properties in D5 non-aqueous media was studied by incorporating X-ray crystal diffraction analysis, density functional theory (DFT), and dyeing experiments. The results showed that cyano group on the azo component increased the coplanarity of the aromatic ring, forming a stronger 7C-7C stacking. Meanwhile, introducing a smaller steric effect substituent on the coupling component also facilitated the formation of tighter molecular arrangements. The thermodynamic and kinetic parameters of dyeing showed that the close molecular stacking and arrangement could effectively increase the adsorption amount of disperse dye on the polyester fabric but reduce the diffusion in the fiber, which helped to improve the dyeing uptake. These results helped us understand the relationship between dye structure, molecular stacking, and dyeing performance in D5 non-aqueous medium dyeing and provided a theoretical basis for screening and optimizing D5 dyeing system-specific dyes.