Formylated dipyrromethane based phosphate derivatives receptors
Anions are key components in many biological and industrial processes. They play crucial roles in both health and the environment. In many cases, it is important to control the concentration of anions or their removal in order to mediate their deleterious effects. Therefore, recognition of anions is of interest to researchers. However, the recognition of many anions remains challenging due to their relative large size-to-charge ratios, diverse geometries, and higher energies of solvation. This doctoral Dissertation summarizes the author's effort to design, synthesize, and study various receptors that were intended to overcome those challenges. In Chapter 1, a brief introduction to anion binding chemistry is provided with a particular focus on phosphate anion recognition. The common defining feature of the receptors reviewed is the pyrrole ring. The new structures are often designed via modification of known macrocyclic molecules. In Chapter 2, structural modifications of a Schiff-base receptor (2,6-diamidopyridine dipyrromethane) and incorporation of that modified receptor into polymeric materials are discussed. These polymeric materials were studied for their anion binding properties in methylene chloride and tested for their ability to extract dihydrogenphosphate from water. In Chapter 3, a series of four-fold formylated bisdipyrromethane (tetrakis(1H-pyrrole-2-carbaldehyde)) receptors is reported. The anion binding properties of these receptors were studied with dihydrogenphosphate along with other possibly competitive anions (e.g., chloride and hydrogensulfate). Data to support the contention that the receptors undergo conformational reorganization in order to accommodate the bound oxoanions both in chloroform solution and in the solid state are also provided. In Chapter 4, an electroactive analogue of the systems, discussed in Chapter 3, along with a new binding-site-enriched analogue are presented. These analogues exploit the binding characteristics of the tetrakis(1H-pyrrole-2-carbaldehyde) series. Taken in concert the findings detailed in these Chapters are expected to lead to a greater understanding of phosphate binding in the case of formylated dipyrromethane based anion receptors.