Master of Science
Wisner, James A.
Photochromic molecular subunits capable of supramolecular complexation mediated by hydrogen bonds have the potential to produce materials with novel and dynamic light responsive properties. This thesis reports on the synthesis and photochemical and complexation characterization of seven hemiindigo-based compounds. Furthermore, the ability of indigo to act as a complementary hydrogen bond array is discussed along with the subsequent synthesis and photochemical/physical characterization of a self-associating indigo based hydrogen bond array. Poor to excellent photochemical/physical properties were observed for the photoswitchable hemiindigo and indigo derivative(s) where complexation has been found to be limited. Indigo has been shown to act as an AA array in the presence of various HBD (hydrogen bond donor) arrays. The potential of these compounds to then be incorporated into polymers to make supramolecular polymers and subsequent materials with dynamic light responsive properties will be discussed.
Summary for Lay Audience
Materials that can change their macroscopic properties upon external stimulation are of particular interest in society due to the unique and broad range of plausible application. These materials can be made from molecular architectures known as supramolecular polymers that are formed by appending individual subunits capable of non-covalent complexation onto classical polymers. In particular, hydrogen bonds are usually the chosen non-covalent interaction used to mediate complexation due to their relative strength, reversibility and directionality. Supramolecular complexes can be sensitive to many different external stimuli such as changes in pH, temperature as well as light. Compounds that are capable of photochromism, coined photoswitches, are of particular interest to be used as scaffolds for individual supramolecular subunits due to the simplicity of using light as well as the spatial control they offer. By careful design, photoswitches can contain a series of hydrogen bond donors (HBDs) and/or hydrogen bond acceptors (HBA) in a particular sequence that can facilitate hydrogen bonded supramolecular complexation in one configuration but not the other.
Indigo is one of the world’s most well-known commercial dyes. The compound itself is not capable of photochromism but photochromism can be induced by chemical modification to substituted indigos or hemiindigo compounds. This thesis discusses the synthesis of seven hemiindigo based compounds as well as their photochemical/physical and complexation properties. Furthermore, the ability of indigo to act as a complementary HBA array is discussed along with the subsequent synthesis to a self-complementary photoswitchable array. With these results, the potential of incorporating these compounds into polymers to make supramolecular polymers, and subsequently materials, with dynamic light responsive properties is discussed.
Winiarz, Paul, "Indigo and Hemiindigo-Based Photoswitchable Hydrogen Bond Arrays" (2023). Electronic Thesis and Dissertation Repository. 9691.
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