Supramolecular organization of subphthalocyanines in Langmuir and Langmuir-Blodgett films

Interfacial studies of a series of subphthalocyanine (SubPc) macrocycles 1- 3, 5 and 6, differently substituted either in the periphery (with polar and donor groups) or in the axial position of the macrocycle (with a chlorine atom or a trihexylsiloxy group), have been carried out. Remarkable changes in the orientation of the macrocycles at the air/water interface have been observed by varying the number of polar groups in the periphery or adding a bulky group in the axial position. The morphology of the monolayers has be en carefully studied by Brewster angle microscopy. Monolayers made of compo unds 1-3 could be efficiently transferred onto hydrophobic substrates. LB f ilms of SubPc 1 were characterized in detail by UV-VIS and IR spectroscopie s, and X-ray diffraction and ellipsometry experiments. These studies indica te that the LB films of SubPc 1 are surely Y-type, formed by layers of a we ll-defined average thickness of ca. 16 Angstrom. Preliminary studies on the nonlinear optical (NLO) properties of these materials have been carried ou t. In particular,second harmonic generation (SHG) experiments have been per formed on LB films of SubPc 1.