Surface Immobilization and Electrochemical Studies of Molecular Lanthanide and Actinide Complexes

Abstract

Due to their unique properties and emerging applications in materials, the chemistry of the lanthanides and actinides has become a thriving area of research. While much work has been done to probe the electronic, magnetic, luminescent, and catalytic properties of molecular lanthanide and actinide species, one area that has received less attention than it deserves is that of surface immobilization. The ability to successfully and selectively immobilize complexes on surfaces is crucial to the advancement of materials in fields such as sensor technologies, separations science, and catalysis. While most surface immobilized complexes contain d-block metals, this work focuses on the surface immobilization of complexes containing metals from the f-block. While Chapter 1 serves as a broad overview of the field of surface immobilization, Chapter 2 of this thesis discusses the synthesis and characterization of four new tripodal lanthanide complexes (Ln = Ce, Nd, Sm, Eu) capable of undergoing immobilization on graphitic surfaces. Characterization by NMR and XPS support that these lanthanide complexes retain their molecular structure in solution and after immobilization. Electrochemical studies of the redox active cerium complex allowed for the surface stability and interfacial electron transfer rates of the immobilized complex to be directly quantified. Chapter 3 of this thesis discusses the synthesis and characterization of two new molecular actinide species capable of noncovalent surface immobilization. Specifically, two new uranyl ([UO2]2+) complexes have been synthesized and characterized by methods such as NMR and XRD. Following immobilization, electrochemical methods were used to probe the immobilized properties of these uranyl complexes using the presence of the U(VI/V) redox couple. These complexes demonstrated enhanced surface stabilities compared to the tripodal lanthanide complexes, as well as high rates of interfacial electron transfer.