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dc.contributor.authorRowe, Jennifer Mariaen_US
dc.date.accessioned2018-07-07T08:00:43Z
dc.date.available2018-07-07T08:00:43Z
dc.date.issued2018-07-06
dc.identifier.othervt_gsexam:15830en_US
dc.identifier.urihttp://hdl.handle.net/10919/83875
dc.description.abstractThe synthesis, characterization and photophysical properties of three Zr-based Metalorganic frameworks (MOFs) assembled from 2,6-anthracenedicarboxylic acid (2,6-ADCA, 2,6- MOF) and 1,4-anthracenedicarboxylic (1,4-ADCA, 1,4-MOF), and 9,10-anthracenedicarboxylic acid (9,10-ADCA, 9,10-MOF) are described. The crystal structure of the 9,10-MOF was elucidated by synchrotron powder X-ray diffraction (PXRD) analysis and is isostructural with the well-known UiO-66 framework. The 2,6-MOFs also form highly crystalline, octahedral-shaped structures and was characterized by PXRD. Le Bail refinement of the powder pattern revealed that the 2,6-MOF also has UiO-type crystal structure. Conversely, incorporation of the 1,4-ADCA ligand results in large rod-shaped crystals. The excited-state properties of the MOFs were examined using steadstate diffuse reflectance, steady-state emission spectroscopy and time-correlated single photon counting (TCSPC) spectroscopy and are compared to those of the corresponding ligand in solution. Both the unique fluorescent properties of the ligand as well as individual framework structure, result in distinctive luminescent behavior and dictate the extent of intermolecular interactions. Specifically, the 2,6-MOF displays monomeric emission with a fluorescence lifetime (t) of 16.6 ± 1.1 and fluorescence quantum yield (Ff). On the other hand, the 1,4-MOF displays both monomeric and excimeric emission, with corresponding lifetime values of 7.5 ± 0.01 and 19.9 ± 0.1, respectively and a quantum yield of 0.002 ± 0.0001. The propensity for photon upconversion through sensitized triplet-triplet annihilation (TTA-UC) was probed in the three anthracene-based MOFs. The MOFs were surface-modified with Pd(II) mesoporphyrin IX (PdMP) as the triplet sensitizer. Upconverted emission from the 9,10-MOF was observed, with a quantum efficiency (FUC) of 0.46 % and a threshold intensity (Ith) of 142 mW/cm2 . The variation of the spacing between the anthracene units in the MOFs was found to have significant impact on TTA-UC. As a result, upconverted emission is only displayed by the 9-10-MOF. The distance between anthracene linkers in the 2,6-MOF are too large for TTA to occur, while the short distances in the 1,4-MOF inhibit upconversion through competitive excimer formation. To further explore the effects of chromophore spacing on energy transfer processes, a series of zinc-based mixed-ligand MOF were constructed from Zn(II) tetrakis(4- carboxyphenyl)porphyrin (ZnTCPP) and pyrazine, 2,2′-bipyridine (pyz) or 4,4′-bipyridyl (bpy) or 1,4-di(4-pyridyl)benzense (dpbz), comprising ZnTCPP/Zn paddlewheel layers. Across this series, the porphyrin spacing was approximately 6 Å, 11 Å and 16 Å for pyz, bpy and dpbz, respectively. The photophysical properties of the MOFs were explored using stead-state diffuse reflectance spectroscopy and steady-state and time-resolved emission spectroscopies. Florescence quenching studies examined the correlation between porphyrin spacing and efficiency of energy transfer.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis item is protected by copyright and/or related rights. Some uses of this item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectMetal-Organic Frameworksen_US
dc.subjectPhotophysicsen_US
dc.subjectPhoton Upconversionen_US
dc.subjectEnergy Transferen_US
dc.titleDesign and Synthesis of Photoactive Metal-Organic Frameworks for Photon Upconversion and Energy Transfer Studiesen_US
dc.typeDissertationen_US
dc.contributor.departmentChemistryen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineChemistryen_US
dc.contributor.committeechairMorris, Amandaen_US
dc.contributor.committeememberTissue, Brian M.en_US
dc.contributor.committeememberMorris, John R.en_US
dc.contributor.committeememberTanko, James M.en_US


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