NOVEL AMPHIPHILIC PHTHALOCYANINES - FORMATION OF LANGMUIR-BLODGETT AND CAST THIN-FILMS

The synthesis and solution and thin film characterization of four octa substituted phthalocyanines (Pcs) are reported. ctakis(dodecylcarboxyl ato)phthalocyaninato]copper, 24-octakis(N-dodecylamide)phthalocyaninat o]copper, and [2,3,9,10,16,17,23,24-octakis(2-(benzyloxy)- ethoxy)phth alocyaninato]copper, and the corresponding zinc phthalocyanine analog, were prepared and their aggregation properties characterized in chlor oform solutions. The octa-ester-modified Pcs showed the greatest tende ncy toward solution aggregation (K-agg greater than or equal to 4.8 x 10(6)), and the octakis((benzyloxy)ethoxy)-modified Pcs showed the lea st tendency toward aggregation (290 less than or equal to K-agg less t han or equal to 1300). Both cast and Langmuir-Blodgett (LB) thin films of these compounds showed the tendency toward formation of columnar a ggregates, as evidenced by their blue-shifted Q-band absorbance spectr a. Fully compressed thin films of these Pcs show the rings tilted by c a. 50-60 degrees with respect to the surface normal, with essentially cylindrical symmetry of the side chains about each aggregate. The octa ester Pcs, which showed the strongest solution aggregation tendencies, proved to form the most highly ordered LB thin films, as evidenced by the dichroism in several key vibrational bands. Molecular dynamics si mulations are presented which show hypothetical structures for single molecules of each of the above compounds, as well as pentamer linear c ofacial aggregates which demonstrated stability in these calculations and which are structures consistent with the spectroscopic characteriz ations of these materials.