Two-Dimensional Aggregation of Crown-Phthalocyanine Ligand at Air-Water Interface

Physico-chemical properties of monolayers of tetra-15-crown-5-phthalocyanine ligand were studied using Langmuir-Blodgett technique and fiber optic spectroscopy. Dependences between concentration of monolayer forming solution and phthalocyanine ligand aggregation degree in monolayer were established. True stable monolayers of tetra-15-crown-5-phthalocyanine ligand at the air/water interface were formed with orientation of phthalocyanine macrocycle planes parallel to the subphase surface. It was proven that absence of aggregates in solution does not guarantee absence of aggregation in the monolayer upon its formation. It was shown that studied substance generates columnar aggregates upon compression even in monolayer formed from extremely diluted solutions. Using special IR-spectroscopy techniques, it was shown that orientation of molecules relative to the substrate surface remains the same upon formation of solid ultrathin films by Langmuir-Blodgett technique.