Abstract: A novel diamino-azobenzene dye was designed and synthesized as a Raman indicator for NO. The Raman chemical transformation of the diamino-azobenzene structure is based on the reactivity of diamines with NO in the presence of dioxygen. The N-nitrosation of the diamino-azobenzene, yielding the benzotriazole-based compounds which exhibit a strong propensity to bind to Ag nanoparticles, offers a simple protocol for the direct detection of NO. As the addition of NO, the SERS spectra of the system changed evidently in the range of 1200—1700 nm and turned out a strong SERS peak at 1300 nm. The effects of the concentration of the dye, the aggregation of the nanoparticles and the pH of the solution were evaluated in detail. The result shows that the detection limit of the SERS probe reaches 10^-8 mol/L and the system is independent of pH in the range of 4.5—7.5.

Key words: NO, Diamino-azobenzene, Surface-enhanced Raman scattering