Investigation of Electronic Molecular Materials with Magneto-Optical and Magnetic Properties

Abstract

This thesis is divided into three parts. Part 1 summarizes the design, synthesis, and properties of novel small-molecule and polymeric magneto-optical materials. Part 2 discusses synthetic advances for the development of redox-active pyrrole-fused small molecules and polymers. Part 3 details the synthetic work and investigation of selectively deuterated and perdeuterated BDPA radicals as polarizing agents in Overhauser dynamic nuclear polarization.

In Chapter 1, we introduce the magneto-optical phenomenon known as Faraday rotation and its manifestation in organic materials. Current frontiers in performance, applications, and mechanistic underpinnings of the Faraday effect in organic-chromophore thin films are discussed.

In Chapter 2, we evaluate the Faraday rotation in thin films of metallocene/PMMA composites. We discuss the development of ferrocenium-based optical-quality thin films, their resulting MO responses, and the desirable and unique MO features of C-term materials geared toward applications.

In Chapter 3, we expand on the work established in Chapter 2 by developing functional polymers with magneto-optically active ferrocenium units embedded through their backbone. We observe a 30% increase in Verdet constants over the previously obtained ferrocenium/PMMA thin films.

In Chapter 4, we evaluate the Faraday rotation in thin films of several phthalocyanine and porphyrin derivatives, which exhibit large A-term Faraday responses. We observe maximum Verdet constants greater than those found in competing inorganic materials. The effect of various chemical modifications is discussed.

In Chapter 5, we expand the scope of organic Faraday rotators exhibiting large A-term Faraday rotation via the synthesis of novel liquid crystalline azacoronenes. Significant gains in the Faraday rotation of solid-state samples can be achieved via molecular alignment through the liquid crystalline phase.

In Chapter 6, we investigate the Faraday rotation in thin films of chiral π-conjugated polymers. We discuss the impact of chirality, structural order, and film thickness on the magnetooptical rotation of polymeric systems and report among the largest Verdet constants observed to date in organic thin films.

In Chapter 7, we summarize our synthetic efforts toward the development of redox-active pyrrole-fused small molecules and polymers, expanding the synthetic landscape of molecules alike to ones discussed in Chapter 5. The synthesis of novel pyrrole-fused precursors, monomers, and polymers are discussed.

In Chapter 8, we describe the synthesis of selectively deuterated α,γ-bisdiphenylene-βphenylallyl (BDPA) radicals and their investigation as polarizing agents in Overhauser dynamic nuclear polarization (OE-DNP), shedding light on the mechanism of polarization transfer in OEDNP in insulators, which has yet to be established.

In Chapter 9, we follow up on the work established in Chapter 8 with the synthesis of perdeuterated BDPA radicals. We establish that the substitution of the 1 H spins with 2 H on the phenyl moiety increases the positive enhancement from the BDPA core by 50%.