First Advisor
Mark Woods
Date of Award
Summer 8-13-2026
Document Type
Thesis
Degree Name
Bachelor of Science (B.S.) in Biochemistry and University Honors
Department
Chemistry
Language
English
Subjects
MRI contrast agents, Ligand design, Lanthanide substitution, Gadolinium complexes, Metal coordination
Abstract
Lanthanide coordination chemistry is important for the development of magnetic resonance imaging (MRI) contrast agents because changes in metal-ligand interactions can influence coordination geometry, stability, and properties related to water exchange. Macrocyclic ligands such as DOTA and its derivatives are particularly useful because they strongly chelate lanthanide ions, while structural modifications to the ligand can alter the coordination environment and potentially affect MRI performance. This study investigated how lanthanide identity and ionic radius influence the coordination behavior of the DOTA derivative DOTBA across a selected series of lanthanide ions from Ce³⁺ to Yb³⁺. The complexes were characterized using 1H NMR spectroscopy to examine changes in proton environments, coordination geometry, and stereoisomer distributions. Across the series, TSAP was the dominant coordination geometry, ranging from 68.6% for HoDOTBA to 99.4% for CeDOTBA, while SAP populations ranged from 0.6% to 31.4%. The SAP population increased from CeDOTBA through HoDOTBA before decreasing for ErDOTBA and TmDOTBA and increasing again for YbDOTBA. The RRRR diastereoisomer was strongly favored for all complexes, ranging from 91.9% for YbDOTBA to greater than 99% for DyDOTBA, HoDOTBA, ErDOTBA, and TmDOTBA. These results demonstrate that lanthanide identity influences the coordination behavior of DOTBA, with the changes in SAP/TSAP populations indicating that metal-ligand fit and ionic radius contribute to coordination preferences. The strong RRRR and TSAP preferences observed across the series extend previous EuDOTBA studies to a broader range of lanthanides and provide a structural basis for further investigation of DOTBA complexes as potential MRI contrast agents.
Recommended Citation
Daher, Muna F., "Metal Substitution in LnDOTBA Complexes for Improved MRI Contrast Agents" (2026). University Honors Theses. Paper 1912.
Included in
Chemistry Commons, Medical Biochemistry Commons, Medical Biomathematics and Biometrics Commons, Organic Chemicals Commons