Synthesis, characterisation, and applications of isoindigo/Pechmann dye heteroanalogue hybrid dyes on polyester fabric

A series of new dyes based on the N‐analogue of Pechmann hybrid dyes were prepared by the condensation of different 5‐aryl derivatives of pyrrolinone ester (phenyl, 4‐bromophenyl, thienyl, and biphenyl) with isatin. N‐Alkylated derivatives were also prepared using bromoethyl acetate. Full 1H and 13C NMR assignment was performed. All prepared dyes were soluble in most organic solvents: N‐alkylated derivatives had better solubility than non‐alkylated derivatives. The UV‐vis absorption spectra of the derivatives under study are quite similar and exhibit maxima in the 509–526 nm range. No E/Z photoisomerisation is observed. The dyeing process, dye exhaustion on polyester, and the fastness properties of the dyes were examined.