Synthesis and spectral properties of novel cationic fazo dyes and calix[4]arene macromolecule: Application studies towards the cationic dyeing and dye effluent water purification technology

Herein, we synthesized three novel pyridone based cationic azo dyes and calix[4]arene macromolecule. All the synthesized molecules are characterized and confirmed by NMR, IR, and HRMS analysis. The structural optimization, vibrational frequencies, HOMO and LUMO energy calculations were obtained from Gaussian 09 program package on the B3LYP level using 6–311 G basis set. Theoretical vibrational frequencies are good agreement with experimental values. FT-IR and NMR results confirm that pyridone cationic dyes exist in hydrazone tautomeric form. Dyeing experiments were performed with these dyes on modacrylic fabrics in an aqueous medium. All three dyes displayed good color strength in acidic pH. The binding interactions between the fiber and dyes have been proposed. Calix[4]arene macromolecule is used to extract these dyes from the wastewater. The removal efficiency of calix[4]arene is over 95% observed for all three cationic azo dyes. The excellent adsorption capacity was maintained up to three cycles. These results suggest that calix[4]arene based macromolecule is an attractive candidate for removing cationic dyes from the wastewater due to easy synthesis and low cost.