Synthesis of 4-arylazo-2-( N -pyrazolylcarboxamido)thiophene disperse dyes for dyeing of polyester and their antibacterial evaluation

The current article aims to synthesize some new arylazo-thiophenes for dyeing polyester fabrics and screen their antimicrobial activities. The new 4-arylazo-2-( N-pyrazolylcarboxamido)-thiophene dyes 4a–e were prepared by the reaction of 2-acetyl-2-arylazo-thioacetanilide derivative 1 with 2-chloro- N-(3-methyl-1 H-pyrazol-5-yl)acetamide derivative 2. The structures of these prepared analogues were established via Fourier-transform infrared and ¹ H/ ¹³ C nuclear magnetic resonance spectra. The synthesized dyestuffs were applied to polyester fabrics after establishing the optimal dyeing conditions at 130 ºC, high pressure, 3% shade, and liquor ratio 20:1 at pH 5. Furthermore, the dyed fabrics obtained under these optimal conditions resulted in proper colorfastness toward washing, rubbing, sublimation and perspiration, and were adequate for light fastness. They showed respectable antibacterial effectiveness against two bacterial strains, Staphylococcus aureus (Gram-positive) and Salmonella typhimurium (Gram-negative) bacteria. The dyed fabric with dye 4d displayed the best antibacterial activities with percentage reduction of 88% and 76% against S. aureus and S. typhimurium bacteria, respectively.