Synthetic and Post-Synthetic Methods towards Fine Tuning the Chemical and Physical Properties of Metal-Organic Frameworks

Abstract

This thesis explores synthetic and post-synthetic strategies for tailoring the chemical and physical properties of metal-organic frameworks (MOFs), with a particular emphasis on modulating redox activity, framework composition, and ionic conductivity. The first part of the work focuses on leveraging MOF-embedded polynuclear metal clusters for multi-electron redox chemistry. A square-planar tetramanganese cluster was shown to reversibly interconvert between molecular oxygen and metal-oxo species via a four-electron pathway. This reactivity was then investigated by varying the identity and redox potential of the metal centers within the tetrametal cluster. The Fe(II) and Co(II) analogs reveal distinct metal-specific behavior and provide insight into the tunability of redox-active SBUs within MOFs. Next, post-synthetic cation exchange was employed to access a previously unreported Zn-based MOF, ZnZnBTT, which exhibits significant Zn-ion conductivity due to mobile charge-balancing cations. This material demonstrates the potential of MOFs in next-generation solid-state battery technologies. Finally, the impact of linker electron donicity on cluster structure and reactivity was explored using a new mixed-azolate ligand. Four isostructural MOFs incorporating Co, Ni, Cu, and Cd were synthesized, revealing that the electron-rich pyrazolate groups modulate cluster composition and redox behavior. Notably, CoBTDP exhibits O₂ reactivity, unlike its all-tetrazolate counterpart, underscoring the role of linker design in tuning MOF function. Together, these studies demonstrate how careful control over MOF synthesis and post-synthetic modification can be used to fine-tune redox behavior, framework composition, and ion transport, providing new avenues for the design of functional porous materials.