Synthesis, characterization, and application of diester/diurethane tethered azo disperse dyes: A new strategy to improve dye's fastness properties

• A series of new azo disperse dyes were synthesized through tethering.
• The tethered dyes featured appropriately increased dye's molecular size.
• The enhanced van de Waals force of the tethered dyes with fibres was observed.
• The tethered dyes exhibited dramatically improved fastness properties.
• It is an attractive new strategy to improve dye's fastness properties.

A series of new kinds of diester/diurethane tethered azo disperse dyes were synthesized through the reaction between the hydroxyl group in disperse dyes, such as C. I. Disperse Red 1 (1a), C. I. Disperse Red 13 (1b), and C. I. Disperse Blue 106 (1c), and terephthaloyl chloride or p-phenylene diisocyanate. Structures of these new dyes were fully characterized with NMR, MS, and FT-IR. Visible absorption measurement in DMF indicated that all new diester/diurethane tethered dyes exhibited a little shorter maximum absorption wavelength and much higher molar extinction coefficient than their prototypes. Moreover, the fastnesses to wash and sublimation of dyeing on polyurethane fibre were dramatically improved due to the dye's moderately increased molecular size. It is an attractive new strategy to synthesize a library of tethered dyes with improved fastness properties using various different tethering agents or disperse dyes.

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