Influence of transition-metal ions on the aggregation behavior of a single-chained ammonium amphiphile carrying an o-hydroxyazobenzene unit

A novel, single-chained ammonium amphiphile that carries an o-hydroxyazoben zene unit at the terminus of its hydrophobic chain has been synthesized. Th is compound forms ordered thread-like aggregates upon dispersion in water. These aggregates exhibit a phase transition at 56 degrees C. The o-hydroxya zobenzene unit binds several transition-metal ions in a 2:1 stoichiometry. Binding of these metal ions results in a lowering of the critical aggregati on concentration. From the changes in the UV absorption spectrum it is conc luded that the Cu2+ complex forms more tightly packed aggregates in water t han the Zn2+ and Ni2+ complexes.