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Access Type
WSU Access
Date of Award
January 2023
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Chemistry
First Advisor
Matthew J. Allen
Abstract
This thesis is a collection of five chapters that discuss the photophysical properties of lanthanides with respect to visible-light-promoted photochemical reactions. The studies described in this thesis focus on the influence of ligands on the photophysical properties of lanthanides and how varying the properties of ligands alters their influence on lanthanides. These studies were conducted to elucidate trends in ligand properties that will guide further efforts towards the rational design of lanthanide-based complexes for visible-light-promoted photochemical reactions. An overview of the visible-light luminescence properties of lanthanides with respect to photochemical reactions is described in Chapter 1. This chapter describes previous reports of lanthanide-based complexes that show reactivity in visible-light-initiated reactions. The lanthanides described in detail are SmII, EuII, and CeIII. Trends among ligands that form complexes with these lanthanides are also discussed. This overview introduces the photophysical properties of lanthanides that are relevant to visible-light-promoted photochemical reactions and provides context for why guidelines for the rational design of lanthanide-based complexes in important. A study on the influence of amine-based ligands on the photophysical and electrochemical properties of EuII is discussed in Chapter 2. Complexes of amine-based ligands with EuII were synthesized and characterized via UV–visible and luminescence spectroscopy, cyclic voltammetry, X-ray crystallography, Job plots, and computational studies. Characterization of these complexes assisted in the elucidation of trends of amine-containing ligands and their influence on the photophysical properties of EuII. These studies revealed that amine-based ligands bathochromically shift the absorbance of EuII when they are of denticity greater than three, macrocycles, and amines of lesser degrees of functionalization. Chapter 2 also evaluates the reactivity of EuII–amine complexes that have favorable photophysical and electrochemical properties for visible-light-promoted photochemical reactions. As a follow-up to the previous study, a proof-of-concept study evaluating the design of a ligand based on the trends observed in Chapter 3 was described in Chapter 4. A dimeric derivative of 1,4,7-triazacyclononane was synthesized and characterized via UV–visible and luminescence spectroscopy, cyclic voltammetry, and a Job plot. The dimeric derivative of 1,4,7-triazacyclononane was synthesized to have increased denticity, more coordinating nitrogen atoms, and increased chelating effect compared to 1,4,7-triazacyclononane when complexed to EuII. The results of this study aligned with our hypothesis and the complex between EuII and the dimeric derivative of 1,4,7-triazacyclononane yielded a greater bathochromic shift on the absorbance of EuII and a more negative reduction potential than the complex between EuII and 1,4,7-triazacyclononane. Understanding the trends among ligands and their influence on the photophysical properties of lanthanides is important because it creates a basis for the rational design of lanthanide-based complexes that are promoters for visible-light-promoted photochemical reactions. Chapter 5 summarizes the conclusions of the studies described in this thesis and summarizes the future directions for these studies. The future directions of these studies are focused on optimizing the reactivity of EuII-amine-containing complexes that show some reactivity and synthesizing further ligands to evaluate the trends among amine-containing ligands and their influence on the photophysical properties of EuII.
Recommended Citation
Barraza, Ramiro, "Influence Of Ligands On The Photophysical Properties Of Lanthanides For Visible-Light-Promoted Photochemical Reactions" (2023). Wayne State University Dissertations. 3775.
https://digitalcommons.wayne.edu/oa_dissertations/3775