In this paper, we studied the influence of solvent on the morphology of zinc protoporphyrin and zinc
octacarboxylphthalocyanine films transferred onto gold surface by dipping. In these films, carboxylic acid
groups borne in periphery of macrocycles allow anchoring to gold via ionic interaction. First, we followed
by UV–Visible absorption spectroscopy the solvation state of these conjugated macrocycles in pure DMF,
in pure ethanol and in various ethanol/DMF mixtures. We show that the increase in ethanol proportion
promotes interactions between macrocycles. Second, molecular layers of macrocycles spontaneously
adsorbed from these various solutions onto gold surface were analyzed by ellipsometry, water contact
angle measurements, UV–Visible absorption spectroscopy and atomic force microscopy. Results evidenced
the layers were mainly composed of grains whose size of a few nanometers was directly related
to the solvation conditions of molecules. In addition, Q band splitting was observed in the absorption
spectrum of zinc octacarboxylphthalocyanine grain films which indicates specific organization of those
molecules. Therefore solvent is shown to have a profound influence on the nanostructuration of as-prepared
macrocycle layers on gold surface by promoting pre-organization in solution, and its composition
enables to better control the morphology of those films by tuning the solubilization of macrocycles.

Zinc protoporphyrin Zinc phthalocyanine Solvent Aggregation Self-assembled monolayer Gold surface