Synthesis and Optical Properties of Near-Infrared (NIR) Absorbing Azo Dyes

This chapter provides a general overview and information on near-infrared (NIR) absorbing azo dyes. In this work, we have developed an efficient and simple protocol for the synthesis of novel A- π -D- π -A NIR azo dyes. The near-infrared absorbing azo dyes were synthesized by using 2-hydroxy-1,4 naphthoquinone (Lawsone) and different substituted aromatic primary amines. Furthermore, author developed push-pull chromophores of A- π -D- π -A type containing an electron-withdrawing azo core, phenazine moieties, and a hydroxyl group as electron donor. The benzo[a]quinoxalino[2,3-i]phenazin-5-ol moiety was introduced to make the system planer as well as to increase the π -conjugation. The optical properties of these dyes were studied in N,N -dimethylformamide (DMF).