Supramolecular assembly in f-element hybrid materials Open Access
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The primary focus of this dissertation has been to investigate comprehensively the syntheses, characterization, and structure-property relationships of rare earth and actinide bearing hybrid materials. These hybrid materials are constructed from metal centers that have been judiciously paired with selected organic moieties to promote non-covalent assembly. We have determined the crystal structure for each material, and these results provide valuable information on structural and supramolecular systematics in both rare earth and actinide systems. Throughout this dissertation we focus on hybrid materials that utilize non-covalent assembly to link ‘tectons’ via ‘synthons.’ In both RE3+ and [UO2]2+ systems the immediate coordination sphere of the metal cation is considered a tecton (or building unit) which may then be linked via halogen bonding or other interactions (synthons). Means of non-covalent assembly in a rare earth or uranyl material are governed by coordination preferences of the metal centers as well as the location, and number, of synthon sites at the periphery of the tectons. As such, the foundations of an acceptor-donor pairing hierarchy are developed in rare earth and uranyl systems, thereby providing routes to promote halogen bonding in rare earth complexes or non-covalent assembly with the nominally terminal oxo atoms in uranyl materials. Luminescence spectra and lifetimes were collected for rare earth materials to evaluate the effects the chelating N-donors 1,10-phenanthroline and 2,2’6’2”-terprydine had on visible and near-IR luminescent properties. Additionally, magnetic measurements were taken on selected rare earth complexes to determine if non-covalent assembly had any effects on magnetic behavior. In uranyl systems, luminescence and vibrational spectroscopy measurements have allowed for an evaluation of the effects of electron donating ability of equatorial ligands on resulting spectra, and the vibrational redshifts that correlate with increasing electron donating ability were explicitly highlighted for the first time. Actinyl force constants, which are calculated based on vibrational spectroscopy results, allow for experimental quantification of supramolecular interaction ‘strength’ while also indicating that oxo atom participation in non-covalent assembly weakens the U=O bond.