Stabilities of metal complexes of tetraazamacrocyclic tetraacetates and triazacyclononane triacetate /
| Main Author: | |
|---|---|
| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1989.
|
| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The protonation constants of the tetraazamacrocyclic tetraacetates, [12]AneN4-4ac (DOTA), [13]AneN4-4ac (TRITA), and [14]AneN4-4ac (TETA), were determined by potentiometric titration methods in KNO3 electrolyte (0.100 M, 25.0 °C). A correction was made for the influence of the potassium complex that was formed with DOTA in KNO3 electrolyte by determining the protonation constants of DOTA in "inert" tetramethylammonium chloride with tetramethylammonium hydroxide. In addition, the metal binding constants of the complexes of the alkaline earth metal cations with DOTA, TRITA, and TETA were determined in KNO3 electrolyte (0.100 M, 25.0 °C), while the metal affinities of the bivalent transition metal cations of Co(II), Ni(II), Zn(II) and Cu(II) in complexes with the same tetraazamacrocyclic tetraacetate ligands were determined by batch methods which allowed for equilibrium measurements over long periods of time. The impetus for this work was that the results of two different research groups in the literature stand in disagreement for the stabilities of the complexes of alkaline earth and bivalent transition metal ions with DOTA, TRITA, and TETA. The stabilities of the complexes of the trivalent metal cations of La(III), Gd(III), Fe(III), Ga(III), and In(III) with DOTA, TRITA, and TETA were determined by batch methods and ligand exchange methods in KCl electrolyte (0.100 M, 25.0 °C). The lanthanide complexes of the tetraazatetracarboxylate macrocyclic ligands are used as NMR solvent relaxation agents for the imaging of tissues, whereas complexes of Ga(III), and In(III) are used as radiopharmaceuticals. The stability constants of the lanthanide and Ga(III) and In(III) complexes of the tetraazamacrocyclictetraacetates are low compared to the stability constant of the Fe(III) complex with DOTA. In addition, the stabilities of the complexes of Fe(III), Ga(III), and In(III) with the triazatricarboxylate macrocyclic ligand, [9]AneN3-3ac (NOTA), were determined in KCl electrolyte (0.100 M, 25.0 °C). The stability constants of the Ga(III) and In(III) complexes with NOTA are greater than those of the tetraazamacrocyclic tetraacetates, while the stability constant of the Fe(III) complex with NOTA is comparable to that of the Fe(III)-DOTA complex. The high stabilities of the Ga(III) and In(III) complexes with NOTA imply a preferential interaction of the small trivalent metal cations with potentially six-coordinate NOTA. |
|---|---|
| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xviii, 186 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |