Developing MOF-Based Thermal Sensors and Self-Assembled Microstructures using Conjugated Polyelectrolytes

Abstract

In recent years, there has been a growing interest in the development of new thermal sensor materials. Metal-organic frameworks (MOFs), with their broad range of applications, have garnered significant attention in the context of sensing. Their appeal as promising candidates arises from their high surface area, tunable porosity, and the ability to adjust the structure of their building blocks. Herein, we study the unique photophysical properties of UiO-66 MOFs, specifically UiO-66-NH2, a variant distinguished by its amine-functionalization, which exhibits a pronounced thermally induced fluorescence response. This MOF revealed enhanced fluorescence upon heating, a characteristic that was maintained even after cooling, indicating a distinct thermal memory. These findings were characterized and validated through various spectroscopic methods, including the use of a steady-state fluorescence spectroscopy and fluorescent microscope, providing a comprehensive analysis of the MOF's unique thermal response. Progressing to the second project, the thesis broadens its scope to include a comparative analysis of three Zr-based MOFs incorporating naphthalene dicarboxylate linkers (e.g.: 1,4-NDC, 2,6-NDC, and NDC(OH)2). Each MOF, chosen for its unique structural and functional attributes, is shown to also exhibit unique thermal responses upon heating. This comparative study is designed to unravel the influence of specific functionalization and structures on the thermal properties of UiO-66 MOFs, offering a deeper understanding of MOF design for targeted thermal sensing applications. The closing chapter of this thesis introduces a pioneering new class of self-assembled materials: PolyMOF, a hybrid material that synergizes the optical properties of conjugated polyelectrolytes, exemplified here by poly (phenyl ethylene) (PPE-CO2), with the structural integrity of Zr-MOFs. This innovative combination aims to harness the unique attributes of both components to create a material with enhanced optical properties opening avenues for multifunctional applications.