Multi-porphyrin arrays: Self -assembly, solution dynamics and deposition on surfaces.
Item
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Title
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Multi-porphyrin arrays: Self -assembly, solution dynamics and deposition on surfaces.
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Identifier
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AAI3074664
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identifier
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3074664
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Creator
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Milic, Tatjana.
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Contributor
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Adviser: Charles Michael Drain
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Date
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2003
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Analytical
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Abstract
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Porphyrins and metalloporphyrins are versatile molecules that play an important role in nature; in photosynthesis and other oxido-reduction events. They are also excellent building blocks for the synthesis of large multiporphyrin systems, which may be used as biomimetic models or components of molecular electronics and novel materials.;In nature, weak noncovalent interactions between molecules lead to the spontaneous formation of highly complex and functional molecular assemblies. Similarly, in modern material chemistry, introduction of specific noncovalent molecular interactions is seen as the most promising way toward the synthesis of functional nanoscale materials. Among many types of noncovalent interactions, metal-ion coordination has proved to be a successful approach for design of multi-porphyrin arrays because of its directionality, stability and tenability of the photophysical and electronic properties of the final assemblies.;In this work we utilized external ligand-metal interactions to bring together various meso-(4-pyridyl)porphyrin derivatives using platinum(II) or palladium(II) dichloride complexes. By choosing the appropriate porphyrin substitution and metal ion binding geometry, various structures can be formed. In case of the formation of the most complex array made of nine porphyrin units: 4 "L"-shaped porphyrins serve as corners, 4 "T"-shaped porphyrin as sides, and 1 "+"-shaped porphyrin as the center. Self-assembly of these porphyrin units is accomplished by addition of 12 equivalents of a metal complex.;However, self-assembly and supramolecular reorganization proceeds through many stages, and the final products are columnar stacks that are ∼6 nm in diameter and 0.4 nm to ∼10 nm tall. If nine equivalents of a first-row transition metal, such as Co(II) or Zn(II), are added to the solution that forms the self-assembled multi-porphyrin array, each porphyrin in the array coordinates the added metal internally, so that the final result is the self-organization of 30 to ∼300 entities, of five different chemical types.;The size of the aggregates is pre-determined by the choice of appended alkyl group, solvent, porphyrin metalation, and an understanding of the secondary organization kinetics. Moreover, these materials can be deposited onto a variety of surfaces with high structural fidelity, with the choice of surface chemistry affording an additional modality for size selection.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
