The synthesis and evaluation of 2,3-dihydroxyterephthalamides as actinide chelators

The 2,3-dihydroxyterephthalamides are characterized as chelators for actinide(IV) ions and are investigated as potential nuclear waste remediation agents. Chapter One details the nuclear waste situation in the United States: the formation of nuclear waste, the reason waste cannot remain in its current state, and current approaches to nuclear waste remediation are covered. The properties of the 2,3-dihydroxyterephthalamides as Fe(III) chelators are reviewed, with a discussion of the reasons these ligands are suitable targets as actinide(IV) chelators.; In Chapter Two the coordination chemistry of the 2,3-dihydroxyterephthalamides with the metal ions Zr(IV), Ce(IV), Th(IV), and Pu(IV) is presented. Crystal structures of Zr(IV) and Th(IV) complexes of a simple terephthalamide illustrate that this ligand can accommodate several different coordination geometries about the metal center. Solution thermodynamic studies of the Th(IV) and Pu(IV) complexes of this ligand indicate that the terephthalamides have very high stability constants with these metals and are suitable as chelators in solutions with basic pH.; In Chapter Three several terephthalamides are presented that function as liquid-liquid extractants of Fe(III). Two different ligand designs were developed to neutralize the charge on the resulting metal complex: one containing an ammonium for an internal cation, and the other utilizing cetylpyridinium as a lipophilic counter cation. The constants for Fe(III) extraction with each were determined. A water-soluble version of one of these ligands incorporates one amine into each side chain and has a higher formation constant with Fe(III) than any previously examined terephthalamide. Parallels between the aqueous formation constants and extraction constants are discussed.; In Chapter Four a shorter synthetic route to the terephthalamides is presented. The route avoids the protection and deprotection of the catecholate oxygens, reducing the time, cost, and hazards associated with the typical synthesis. This method is particularly useful for synthesis of the liquid-liquid extractants discussed in Chapter Three.; In Chapter Five the incorporation of the terephthalamides into a new separation procedure is discussed. The water-soluble polymer polyethyleneimine was functionalized with terephthalamides to produce a water-soluble chelating polymer, and this was used in conjunction with a size-exclusion membrane to remove dilute concentrations of Pu(IV) from aqueous solutions.