Design, Synthesis, Computational Investigation, and Technical Evaluation of Disperse Dyes from a Novel Disazo-pyrazolin-5-ones-Based Phenol Scaffold on Polyester Fabrics

The present study delves into the synthesis, computational investigation, and technical evaluation of bisazo-pyrazolin-5-one dyes, Dye 1–Dye 3, derived from a unique phenolic scaffold. The synthesis involved coupling diazotized anilines with 3-(2-hydroxyphenyl)-1-phenyl-4-(2-phenylhydrazono)-1H-pyrazol-5(4H)-one 2, resulting in novel disperse dyes. The primary objective was to explore the dyeing behavior of Dye 1–Dye 3 on polyester fabrics under varying conditions of time, temperature, shades, and pH levels. Upon systematically altering the dyeing parameters, such as temperature and duration, we observed a significant impact on the color strength (K/S values) of polyester samples colored with the synthesized disperse dyes. Increasing the dyeing temperature from 110 to 130 °C and extending the dyeing duration from 10 to 30 min yielded enhanced coloration. This investigation amalgamated experimental measurements with theoretical density functional theory (DFT) calculations to elucidate the influence of functional groups (CH₃, NO₂) on the dyeing performance. DFT calculations provided insights into electronic properties, including HOMO/LUMO energies, band gap, and electrophilicity index. The study revealed that introducing a CH₃ group in Dye 2 augmented color strength compared to Dye 1, while a NO₂ group in Dye 3 exhibited the highest color strength (K/S = 30.9). This integration of experimental and computational approaches demonstrates the potential for optimizing dye design and improving dyeing performance tailored to specific textile applications.