Sapphyrins : aggregation and anion binding behavior in polar, protic media
Sapphyrin was the first expanded porphyrin to be reported in the literature and remains among the most extensively studied of all expanded porphyrins. Much of the interest in this macrocycle reflects its ability to bind anions, a phenomenon that has been examined in solution and in the solid state by a wide range of experimental techniques. The first chapter of this dissertation provides a history of the anion binding chemistry of the sapphyrins, as well as a review of the synthetic methodologies employed to make them. The second chapter builds upon this work by examining the interactions of several water soluble sapphyrins with phosphate and chloride anions in aqueous media. The binding of phosphate and chloride anions in this milieu was found to be closely related to the aggregation state of sapphyrin, the study of which by optical spectroscopic techniques is also discussed in Chapter 2. In order to study the aggregation behavior of sapphyrins further, several 10,15-diaryl sapphyrins were prepared. The preparation and characterization of these systems is discussed in Chapter 3. The dimerization constants of these systems were measured in methanol, and a preliminary study of their anion binding behavior in organic solvents was performed. Finally, in Chapter 4, the synthesis of a new bipyrrole is laid out and several sapphyrin systems that could be prepared from this precursor are proposed. Future directions for the work described in this dissertation are also presented in this chapter. Experimental methods and characterization data for compounds synthesized by the author are presented in Chapter 5.