Critical factors in tuning the architecture and properties of metal-organic frameworks

Metal-organic frameworks (MOFs) are porous crystalline materials that allow fine-tuning of their structural and chemical properties towards specific applications. Among them, the material known as MOF-74 has a large surface area and high density of Lewis acid sites, enabling the strong binding of CO2 or molecules with donor atoms, which act as Lewis bases. This thesis discusses the role of donor chiral molecules in the synthesis of chiral Zn-MOF-74 materials and the impact for catalytic as well as sensing applications. Chapter 1 gives an overview of the synthetic strategies used for obtaining chiral MOFs and their application in asymmetric catalysis. Chapter 2 demonstrates that cinchona alkaloids act as coordination modulators in the crystallisation process of Zn-MOF-74. It also highlights the role of the solvent in the formation of supramolecular isomers and their transformation to the most stable isomer. In chapter 3, the formation of defects and the pore blocking effect that arise from the post-synthetic modification of Zn-MOF-74 with L- or D-proline, are proven using complementary spectroscopic characterisation techniques as well as theoretical molecular simulations. Chapter 4 discusses the influence of chiral additives and solvents in the crystallisation of isoreticular Zn-MOF-74. Finally, chapter 5 demonstrates the suitability of Zn-MOF-74 for CO2 sensing at ambient conditions. Due to its selective CO2 adsorption and high proton conductivity, an impedance sensor based on Zn-MOF-74 showed fast response by changing the humidity and CO2 concentration.