Alternate stacking of transition metal ions and terephthalic acid molecules for the fabrication of self-assembled multilayers

Self-assembled multilayers consisting of transition metal ions and biscarboxyl acid molecules have been fabricated by a layer-by-layer chemisorption technique. As transition metal ion, zirconium (Zr(IV)) or titanium (Ti(IV)) was employed, while terephthalic acid (TPA) was used as biscarboxyl molecule. In the multilayers, two TPA monolayers were bridged by one monolayer of Zr(IV) or Ti(IV) most likely through coordination bonds between the metal ions and the carboxyl groups in the TPA molecules. Although the both transition metal ions were successfully applied to construct multilayers, the multilayer structure of the Ti-TPA system was more disordered than that of the Zr-TPA system as revealed by grazing incidence X-ray reflectivity.