: In this work, the important features, electrochemical, optical and thermal stability as antioxidant, of four new donor-acceptor–π–acceptor-donor architecture, antioxidant dyes based on thiadiazole were studied. The four dyes carry aryl amino groups as the donors, two 1, 3, 4-thiadiazole moieties as the acceptors and azo and phenyl groups as π spacers. The effect of different aryl amino substitue...