Abstract Five aromatic azo dyes with hydroxyl groups (1–5) were designed and synthesized by coupling reactions. The relationships between structures of the compounds and the spectroscopic properties were investigated. The absorption spectra of these compounds upon titration with K+, Ca 2+, Al 3+, Mg 2+, Ni 2+, Mn 2+, Cd 2+, Cr 3+, Fe 3+, Cu 2+, Zn 2+, Co 2+, Hg 2+, and Pb 2+ ions in neutral aqueous solutions were reported. The results are ...
