Solution Chemistry of Catecholate Metal Complexes

摘要

Chapter II is a thermodynamic study of the complexation of divalent metal ions with a di-, tri-, and tetracatecholyamide, to evaluate the specificity of the catechoylamide ligands for Fe(III) or Pu(IV). Chapter III describes the stability and protonation behavior of a series of N-substituted catechoylamide complexes of Ga(III) and Fe(III) as determined by potentiometric and spectral titration, and infrared analysis. These ligands show lower affinity for Ga(III) or Fe(III) than unsubstituted catechoylamides and they remove Fe(III) from diferric transferrin a a slower rate. Results of the first in vitro experiments of complexation of catechoylamide ligands with plutonium are presented in Chapter IV. Electrochemical techniques have allowed the elucidation of the protonation behavior of Pu(IV)-- and Pu(III)-catechoylamide complexes. These results are compared to the protonation behavior of catechoylamide complexes of Ce(IV and Ce(III). Above pH 12 it is thought that a Pu(IV)tetrakiscatecholate complex and a Pu(III)triscatecholate complex is formed. At neutral pH, a triscatecholate-Pu(IV) complex appears to be present, indicating that the full denticity of the tetracatecholate is not utilized in vivo. The complexation of americium was studied by electrochemical and spectroscopic methods. Results indicate that catechoylamide ligands bind Am(III). The lack of evidence of the Am(IV)/(III)-catecholate electrochemical couple indicates that the potential of the free ion Am(IV)/(III) reduction couple is greater than +2.6 volts. (ERA citation 08:049584)