Asymmetric, carboxy and ester functionalized fluorophthalocyanines: synthesis, adsorption, and reactivity

Strong electron-deficient compounds, fluorinated metal phthalocyanines (FxPcM), exhibit enhanced photosensitizing properties, making them optimal candidates for photocatalytic studies. Perfluoroalkyl-substituted phthalocyanines are notably thermally robust materials that are chemically inert and resistant to electrophilic, nucleophilic, and radical, including reactive oxygen species (ROS) attacks. These properties can be attributed to their ‘Teflon-like’ inert organic shield that surrounds a reactive metal center, as well as their complete (x = 16, 40, 64), or almost complete (x = 48) lack of C-H bonds. Third-generation, functionalized, asymmetric phthalocyanines are of interest due to their ability to bind to oxidic supports via a carboxyl group, resulting in refractory organic-inorganic hybrid materials. Their purification, isolation, and solubility are advantageously increased if the carboxylic group is esterified, but their binding to oxidic supports should diminish if the carboxylic group serves as an anchoring point. We report the synthesis and characterization of two asymmetric ester-functionalized phthalocyanines, F48H7(COOEt)PcZn and F48H7(COOEt)PcCu, together with previously reported carboxyl derivatives. The para- and diamagnetic asymmetric fluorinated phthalocyanines, with M = Cu and Zn, respectively, bearing both carboxyl and ester functionalities, were investigated to elucidate the influence of the metals and functionalities in binding to oxidic supports. In addition, studies on the stability of these compounds on oxidic supports and their photo-reactivity with a chlorothioether were performed. Lastly, recrystallization of these PNs and Pcs were conducted to draw conclusions regarding their inter- and intramolecular interactions, as well as the innate Lewis Acidity of the metal center.