Date of Award

Spring 2026

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Natalia B. Shustova

Abstract

Photochromic materials exhibit properties that can be dynamically tailored as a function of light exposure and represent a rapidly expanding field driven by applications ranging from molecular computing, nanotechnology, or photopharmacology to programable heterogeneous catalysis. For example, the possibility to tune a material’s catalytic activity “on demand” through exposure to a noninvasive stimulus is a transformative concept that could shift the paradigm in chemical industry by allowing for in-situ suppression of byproduct formation, isolation of reactive intermediates, and even control over product yield and selectivity. Development of the mentioned photochromic materials is based on stimuli-responsive molecular building blocks which undergo switching between two or more states with distinct properties (e.g., optical profile, geometry, polarity, or metal binding affinities). However, one of the challenges associated with photochromic material development is that many of the well-established classes of photochromic compounds (e.g., spiropyran, azobenzene, and hydrazone derivatives) undergo significant structural rearrangement upon photoisomerization, resulting in limited or even inaccessible photoisomerization in the solid-state due to close molecular packing. Thus, one of the effective design strategies for stimuli-responsive materials is integration of photochromic moieties within porous matrices, such as metal-organic frameworks (MOFs) or covalent-organic frameworks (COFs), which possess sufficient voids to promote isomerization of sterically-demanding photochromic molecules.

The work presented in the following dissertation introduces the state-of-the-art applications for stimuli-responsive materials and explores the synergy between photochromic molecules and solid-state host matrices, such as MOFs, COFs, and hybrid perovskite-related materials. In particular, this dissertation showcases the roles of matrix topology, dimensionality, and photochromic compound connectivity on the overall material photoresponse, with an emphasis on how integrated photochromic units can be used to modulate bulk material properties and performance.

Herein, three transformative design strategies are developed to unlock previously inaccessible photochromic behavior through careful engineering of photoswitch microenvironment in solid-state platforms. First, the role of three-dimensional (3D) versus two-dimensional (2D) matrix topology on the photoresponse of an integrated photochromic moiety is explored through installation of hydrazone and spiropyran derivatives within 3D MOFs and 2D COFs for the first time. Second, this dissertation addresses one of the pervasive and fundamental challenges associated with photochromic materials development by introducing a method for breaking the photoswitch “speed limit”. Specifically, engineering a solvent-free photoswitch environment within MOF pores results in the fastest reported photoisomerization rates for any photochromic molecules in solution or in the solid state to date, creating a pathway for stimuli-responsive materials to transition from fundamental studies to device applications. Finally, the first successful examples of photochromic molecule integration within bulk 2D layered structures are developed through strategic tailoring of material flexibility by incorporating long aliphatic chains alongside light-responsive units as “molecular grease”. Taken together, the three case studies presented herein develop guiding principles for rational selection of host  matrix-photochromic compound pairs for a desired material performance. Outside of fundamental studies of the photophysical properties of photochromic materials, this dissertation also illustrates how the described stimuli-responsive platforms can be applied in the areas of visible light-harvesting and energy transfer processes, optoelectronics relying on tailorable photoisomerization rates, energy storage materials based on wavelength-dependent phase transitions, and beyond.

Rights

© 2026, Grace C. Thaggard

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