Synthesis and characterization of octasubstituted phthalocyanines

Abstract

Substituted phthalocyanines (Pcs) have been studied intensely for decades as pigments because of their high molar absorptivities, thermal stability, and stability towards light exposure. These materials also show promise as electron and hole transport layers in a variety of device applications such as organic field effect transistors and photovoltaics. This dissertation describes the synthesis of several new phthalocyanines (Pcs) and the fabrication of highly ordered supramolecular assemblies. Efforts to increase the coherence of Pc assemblies have included the incorporation of side chains containing polymerizable and hydrogen bonding moieties. The synthesis of 2,3,9,10,16,17,23,24-octa thioether substituted Pcs was designed to allow the incorporation of diverse thioether side chains. The synthesis is shorter and uses milder conditions than the previous synthetic methods explored in the O'Brien and Armstrong groups. Serendipitously, the thioether linkage allow for chalcogen-chalcogen interactions, increasing the attraction of the Pcs sufficiently to provide for crystal growth. The order of the supramolecular materials has been examined in thin films as well as in solution. The UV-Visible and IR spectroscopic data, Langmuir-Blodgett (LB) film forming behavior, thermotropic properties, and photovoltaic properties are reported for each Pc derivative prepared. Although each compound prepared displays some degree of order, the degree to of this order is controlled by the nature of the side chain. The Pcs exhibit long range ordering on a macroscopic level, as can be seen from polarized optical microscopy, atomic force microscopy, IR, and X-ray diffraction techniques.