The influence of molecular structure and π-system extent on nano- and microstructure of Langmuir layers of copper azaporphyrins

Comparative analysis of the structure of floating layers formed by copper tetra-tert-butylsubstituted phthalocyanine (CuPctBu4) and tetrabenzotriazaporphyrin (CuThptBu4) dissolved in a number of solvents is performed. The influence of the π-system extent (tetra-tert-butylsubstituted copper porphyrazine and phthalocyanine: CuPaztBu4 and CuPctBu4) on the structure of Langmuir layers of copper azaporphyrins is studied. It is shown that both the lack of one meso-atom and the increase of the extent of the π-system cause the balance between intermolecular interactions (AP–AP) — (AP-water) to shift to the latter and lead to formation of stable monolayers with the most open face-on structure of nanoaggregates instead of the edge-on one, all other factors being equal, in Langmuir layers prepared from solutions in aromatic solvents. The micro-level structural difference of copper tetra-tert-butylsubstituted porphyrazine (CuPaztBu4) and phthalocyanine (CuPctBu4) resulted from the structural difference of two-dimensional nanoaggregates forming the layers was shown using Brewster angle microscopy.