Powder diffraction is a powerful tool for studying crystal structures, especially as it relates to interactions of small organic molecules with inorganic compounds. The first part of this dissertation involves small organic ligands interacting with metal-organic framework, MOF-74. The first and simplest iteration involves the crystal structure solution of a neat, liquid loading of n-propylmercaptan to the open metal sites within the MOF-74 pores. Later studies investigate the leveraging of a similarly sized bitopic ligand in the solution loading of 1,2-ethanedithiol, which results in the amorphization of MOF-74. Having no crystallinity, amorphous or severely defected materials can be a challenge to study. Herein, our studies reveal that the defects occur via protonation of the native framework and dislocation of the metal cations. The result is a material with fluorescent properties and quenching specific to the exposure to aqueous silver(I). Additionally, defected MOF-74 remains porous upon loadings of up to 10%.
In the second portion of this dissertation, the family of cobalt(II) hydroxide materials was explored utilizing an interesting ligand candidate, sorbate. The neat packing observed in other sorbate compounds lends itself to the organizing of densely packed hybrid layers in cobalt(II) hydroxide sorbate [Co(OH)(sorb)]. Due to the cluster-forming habit of Co(OH)(sorb), the structure is solved by powder diffraction techniques. Additionally, a transformation of the material after exposure to high pressures is explored. The material is determined to be antiferromagnetic below 41.7 K with a large hysteric effect indicative of canted antiferromagnetic ordering.
The final section of this dissertation will be pure structure solution of two important chemicals of the last century, zineb and potassium sorbate. Zineb is a fungicide which has found use since 1943, where it was marketed under the tradename Dithane Z-78. Despite such a long tenure of use, the crystal structure remained unsolved for decades. Using powder techniques, we can solve the crystal structure, which serves as a proxy to the other fungicides in this family. Additionally, the food preservative, potassium sorbate, crystallizes in a polycrystalline fashion, explaining the lack of crystal structures present in major crystallography databases. Potassium sorbate’s crystal structure is solved as a complement to the cobalt(II) hydroxide hybrid material research, but also to understand why potassium sorbate doesn’t undergo topochemical reactions. The crystal structure reveals misaligned π-orbitals, precluding any reactivity toward polymeric or [2+2] dimer products.
Nicolay V. Tsarevsky
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Lefton, Jonathan, "Leveraging Non-Covalent Interactions between Small Organic Molecules and Inorganic Scaffolds in the Design of Advanced Materials" (2023). Chemistry Theses and Dissertations. 42.