Date of Award

2017

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

College of Arts and Sciences

First Advisor

Natalia Shustova

Abstract

The global energy demand is undoubtedly rising at an alarming rate, and as a result, humanity faces the problem of finding alternative energy supplies. Approximately 80 percent of the world’s energy currently comes from fossil fuels, and only a small fraction, 10 percent, from renewable energy sources. The study of energy transfer (ET) processes is a rapidly developing area of interest due to the necessity for more efficient photovoltaic devices, which are crucial to meet the growing energy demand. A promising approach to further advance organic photovoltaics is to precisely arrange many lightharvesting chromophores (e.g., porphyrin derivatives), attainable through a self-assembly process, to make a highly ordered network of light-harvesting antennae, much like what is observed in the natural photosystem. The large network of ordered porphyrincontaining derivatives could then funnel the collected energy in a predesigned pathway to a specific location to be stored or used, for instance, for photocatalysis. Metal-organic frameworks (MOFs) can be used as a tool to self-assemble hundreds of chromophores in a large light-harvesting ensemble with high level of precision, similar to the natural photosystem. MOFs are highly modular, and with a plethora of organic linkers and metal choices available, limitless combinations are possible, which allows for a number of topologically different structures, and new ways to tailor the physiochemical properties of the material. Modularity and tunability give MOFs an advantage over traditional materials, because they can be fine-tuned and tailored to meet the specific criteria demanded by various applications.

This work presented within the following five chapters is focused on the design, synthesis, and characterization of MOFs that target the fundamental understanding of ET processes in predesigned pathways. In the first chapter, a brief introduction of ET mechanisms and MOF synthesis are explained. The second chapter describes a photoswitchable MOF that is capable of exhibiting fluorescence modulation through integrated diarylethene photoswitch linkers. The third chapter discusses the photoswitchable properties of diarylethene and spiropyran-based derivatives in the solidstate, solution, and coordinatively immobilized as pillars in a MOF. Chapter four describes how fullerene derivatives were self-assembled with a porphyrin-based compound, creating a highly-ordered donor-acceptor MOF with the capability for ultrafast electron/energy transfer. Lastly, chapter five discusses how MOFs were used as a mimic of the green fluorescent protein (GFP) β-barrel to suppress low energy vibrational modes of a confined chromophore.

We envision that MOFs can be utilized as a unique platform to assemble welldefined, highly-ordered, versatile, modular structural arrays capable of efficient ET. Materials with the ability to precisely control the mutual orientation and organization of ligands could be vital for the advancement of organic photovoltaic or energy storage devices, sensors, or molecular electronics.

Rights

© 2017, Derek E. Williams

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