5′-Alkoxy-2,2′-bithiophene azo dyes: a novel promising series of NLO-chromophores

A series of bithienyl azo dyes have been prepared from their corresponding coupling components, 5-alkoxy-2,2′-bithiophenes. The solvatochromic behaviour of the compounds was investigated. The hyperpolarizabilities β of derivatives 3–5 were measured using hyper-Rayleigh scattering and thermogravimetric analysis (TGA) was used to evaluate their thermal stability. The experimental results indicate that good nonlinearity–thermal stability is well balanced for azo-bithiophene NLO-chromophores 3–5 making them good candidates for NLO applications.