Supramolecular assembly formation in monolayers of tert-butyl substituted copper phthalocyanine and tetrabenzotriazaporphin

The effect is studied of the layer formation conditions on the molecular ar rangement of copper tetra- tert-butyl phthalocyanine (CuPctBu(4)) and coppe r tetra- tert-butyl tetrabenzotriazaporphin (CuThptBu(4)) at the air-water interface. The decrease in initial surface concentration of these compounds is shown to affect the molecular orientation, as indicated by the increase in the area per molecule. The data are interpreted in terms of formation o f CuPctBu(4) and CuThptBu(4) monolayers with a 'face-on' molecular arrangem ent when the initial surface concentration is sufficiently small (N less th an 1.6 x 10(-7) mole/m(2) for CuPctBu(4) and N less than 4 x 10(-7) mole/m( 2) for CuThptBu(4)) and changes in the molecular orientation to 'edge-on' w hen the N values are higher. It is emphasized that the 'edge-on' orientatio n on the water surface is not only a molecular but a collective property of the azaporphyrine supramolecular assembly.