1. Attempts to Prepare Porous Materials Based on Thiols and Fluorinated Precursors 2. Self-Sorting of Complex Libraries during Kinetically Controlled Acylations
Liang, Xiao 1990-
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This thesis presents three studies in supramolecular chemistry. First is the synthesis and characterization of dynamic covalent disulfide bond based metal-organic framework (MOF), second is development of the fluorinated and imine-based non-covalent organic framework (nCOF), and the third is of molecular recognition between nucleophiles and acyl chlorides. Chapter One follows the ligand design and post-synthetic tailoring as the two most important strategies in synthesizing new metal-organic frameworks (MOFs). Organic dynamic covalent ligand 4,4’-dithiobisbenzoic acid (DTBA) was designed to synthesize a new MOF with metal Cu. These new Cu-DTBA MOF crystals were then tested by reduction on reversible disulfide moieties in the organic ligand but the resulting product could not be further recrystallized. Cu-DTBA templated inter-molecular self-sorting between two disulfide ligands could be achieved successfully, but intra-molecular self-sorting from the single cross-linked disulfide ligand produced a different type of material which did not show the exchangability of disulfide bonds. Chapter Two shows the development of the nCOFs’ structures based on the previous trispyrazole nCOF studies. The necessity of the terminal pyrazole and its trigonal ligand topology were confirmed by synthesizing and characterizing the following two nCOFs. Partially fluorinated trisphenyl nCOF replaced the terminal pyrazole by phenyl ring, which eliminated the hydrogen bonding, as well as linear imine-based nCOF which formed a different topology. The single crystal X-ray result of the two showed a three-dimensional infinite network structure, but with very little voids that cannot be useful as porous solids. Chapter Three introduces the simultaneous ordering and categorizing processes, i.e., self-sorting, which can occur under both thermodynamic and kinetic control. Thermodynamically controlled self-sorting phenomena widely exist in nature, while kinetically controlled self-sorting usually requires stimuli to help simplify the complex. Therefore, acylations between nucleophiles and acyl chlorides as fully kinetically controlled self-sorting systems were conducted. A series of [2×2] systems was conducted in order to find reactivity differences among nucleophiles as well as acyl chlorides. Furthermore, nine successful [3×3] systems achieved successful self-sorting with high selectivity.