Heterocyclic azodyes of the pyridylazonaphthol and pyridylazoresoicino
l series containing tuned hydrophobic chains have been prepared. Due t
o their chelating properties, the dyes are suitable candidates for pre
concentration and selective separation of transition metal ions. After
a discussion on the choice of the best synthetic pathway, physical an
d spectral uv/visible properties are presented and correlated with the
structural features. A detailed analysis of nmr spectra allowed the c
larification of currently unresolved signal assignments.