Chiral donor–π-acceptor azobenzene dyes

Four chiral donor–π-acceptor azobenzene dye conjugates were synthesized and characterized. Chiral moieties, namely (S)-(+)-2-(6-methoxy-2-naphthyl)propionic acid (naproxen) and (S)-2-aminopropionic acid (l-alanine), were attached to either the donor end or the acceptor site of the azo compound using ester or amide bonds, respectively. The structures of the molecules were verified using 1H NMR, 13C NMR and ESI TOF mass spectrometry; spectral properties were evaluated with UV–vis and CD spectrometry whilst thermal stability was determined by TGA. The compounds displayed a broad absorption maximum in the visible region between 433 and 483 nm. All compounds showed relatively high thermal stability, decomposition temperatures being ∼200 °C.