Synthesis, spectroscopic characterization and dyeing performance of novel bis azo dyes derived from benzidine

Area of Science:

• Organic Chemistry
• Materials Science
• Dye Chemistry

Background:

• Azo-hydrazo compounds derived from benzidine serve as precursors for novel heterocyclic dyes.
• Pyrazole derivatives are known for their diverse applications, including coloration.
• Understanding dye-fiber interactions is crucial for textile dyeing processes.

Purpose of the Study:

• To synthesize and characterize novel bis-pyrazole derivatives from benzidine.
• To investigate the spectral properties and pH sensitivity of the synthesized dyes.
• To evaluate the dyeing performance of these dyes on polyester fabric.

Main Methods:

• Synthesis of azo-hydrazo intermediates followed by cyclization with hydrazine derivatives.
• Characterization using spectral analysis (e.g., NMR, IR, Mass Spectrometry).
• Spectrophotometric analysis to determine pH sensitivity (λmax).
• Dyeing of polyester fabric using a dispersion agent and evaluation of color strength (K/S), dye exhaustion (%E), and reflectance.
• Density Functional Theory (DFT) calculations to estimate electronic properties and elucidate the dyeing mechanism.

Main Results:

• Successfully synthesized and characterized novel bis-pyrazole derivatives (compounds 5-7).
• Synthesized dyes exhibited significant sensitivity to pH variations, with minor influence from coupler moieties.
• Good dyeing results on polyester fabric were achieved, with measurable color strength, exhaustion, and reflectance.
• DFT calculations provided insights into dye performance and suggested a potential dyeing mechanism.

Conclusions:

• Novel bis-pyrazole derivatives were synthesized and characterized, demonstrating potential as dyes.
• The synthesized dyes show pH-dependent spectral behavior, useful for specific applications.
• The dyes exhibit satisfactory performance for dyeing polyester fabric, supported by DFT analysis.