Doctor of Philosophy (PhD)
First Advisor's Name
First Advisor's Committee Title
Second Advisor's Name
Second Advisor's Committee Title
Third Advisor's Name
Third Advisor's Committee Title
Fourth Advisor's Name
Fourth Advisor's Committee Title
Fifth Advisor's Name
Fifth Advisor's Committee Title
Date of Defense
Lanthanides (Ln), also known as rare earth metals, have been utilized for industrial and biological purposes and are commonly encountered in the 3+ oxidation state as Ln3+. The presence of Ln in spent nuclear fuel introduces problems during the transmutation and partitioning of actinides (An) due to the Ln high neutron cross-sections. Therefore, designing ligands for Ln3+ complexation, can be helpful for their separation from An3+ in nuclear technology. Also, the biomimetic roles of Ln3+ could be suitable for studying the biological macromolecules, such as the Ca2+-binding EF-hand proteins that are otherwise inaccessible for detailed structural analysis. In this study, we report a bis(quinoline)-dipicolinamide ligand (DQPDH2), as well as ortho- nitrobenzyl cage ligands (DM-nitrophen and H2-cage) that bind and/or separate Ln3+. We studied DREAM, a Ca2+ EF-hand protein, to analyze its interaction with Ln3+. UV- Vis absorption and fluorescence spectroscopy, circular dichroism, extraction, isothermal titration calorimetry (ITC) and photophysical spectroscopy were used for studying the interaction of Ln3+ and ligands/proteins. Our results indicate that DQPDH2 showed high binding affinity to Ln3+ with 1-1 complexation ratio, as confirmed by spectroscopic and solvent extraction studies. The X-ray crystal structure of the Nd3+-DQPDH2 complex indicated a 1-1 binding pattern, which is consistent with our spectroscopic studies. DM-nitrophen, showed high binding affinity to Ln3+ by absorption spectroscopy and ITC. Photoacoustic calorimetry has been performed on DM-nitrophen and Tb3+DM-nitrophen photodissociation and the resulting kinetic and thermodynamic data indicated successful release of Tb3+ upon photocleavage of DM-nitrophen. H2-cage showed modest binding affinity with Ln3+ by UV-Vis absorption spectroscopy, yet it was also shown to be an effective Ln3+ extractant. Fluorescence spectroscopy studies of Ca2+ binding proteins with Ln3+ showed efficient energy transfer from the protein to central Ln3+ and possible conformational changes upon Ln3+ binding to protein by observing a decrease in tryptophan emission and an increase in emission of hydrophobic probe and DREAM complex.
In summary, our results demonstrated that dipicolinamide-derived ligands can be used for complexation and separation of Ln3+. Furthermore, o-nitrobenzyl cages and Ln3+DREAM interaction studies can be used as probes for studying the function of Ca2+-binding EF-hand proteins in future.
Sakhdari, Setareh, "Lanthanide Interactions with Ligands and Biomolecules: Spectroscopic and Extraction Studies" (2021). FIU Electronic Theses and Dissertations. 4747.
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).