The synthesis and solution and thin film characterization of four octasubstituted phthalocyanines (Pcs) are reported. [2,3,9,10,16,17,23,24-octakis(dodecylcarboxylato)phthalocyaninato]copper, [2,3,9,10,16,17,23,24-octakis(N-dodecylamide)phthalocyaninato]copper, and [2,3,9,10,16,17,23,24-octakis(2-(benzyloxy)ethoxy)phthalocyaninato]copper, and the corresponding zinc phthalocyanine analog, were prepared and their aggregation properties characterized in chloroform solutions. The octa-ester-modified Pcs showed the greatest tendency toward solution aggregation (K agg ≥ 4.8 × 106), and the octakis((benzyloxy)ethoxy)-modified Pcs showed the least tendency toward aggregation (290 ≤ K agg ≤ 1300). Both cast and Langmuir−Blodgett (LB) thin films of these compounds showed the tendency toward formation of columnar aggregates, as evidenced by their blue-shifted Q-band absorbance spectra. Fully compressed thin films of these Pcs show the rings tilted by ca. 50−60° with respect to the surface normal, with essentially cylindrical symmetry of the side chains about each aggregate. The octaester 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 simulations are presented which show hypothetical structures for single molecules of each of the above compounds, as well as pentamer linear cofacial aggregates which demonstrated stability in these calculations and which are structures consistent with the spectroscopic characterizations of these materials.

Spectroscopic, electrochemical and spectroelectrochemical, and scanning probe microscopic characterization of thin films of (2,3,9,10,16,17,23,ethoxy)phthalocyaninato)copper, and its dihydrogen analogue, in contact with aqueous electrolytes is described. These materials form highly ordered Langmuir-Blodgett (LB) thin films, where the phthalocyanine (Pc) rings orient with the plane of the ring nearly perpendicular to the compression direction on the LB trough. The resultant thin films show remarkable mechanical stability on the trough, and atomic force microscopy studies show that the transferred thin films, in their fully compressed states, consist of stable bilayers of the Pc. X-ray diffraction studies indicate partial overlap of the benzyl-terminated side chains in adjacent Pc columns. While the DMF solution electrochemical behavior of these molecules showed a single quasi-reversible oxidation process, LB thin films showed two poorly resolved oxidation processes. Two electrochemically distinct domains in these thin films are indicated, which are a function of the aggregation behavior of these materials, and result from electrochemically driven changes in film morphology.

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