Investigations of host -guest systems based on mesoporous materials.
Item
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Title
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Investigations of host -guest systems based on mesoporous materials.
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Identifier
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AAI3127875
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identifier
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3127875
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Creator
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Guo, Haiquan.
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Contributor
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Adviser: Daniel L. Akins
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Date
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2004
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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, Physical
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Abstract
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The work presented here is a compilation of different molecules encapsulated within ordered mesoporous materials, especially MCM-41. Due to their ordered pore structures and highly specific surface areas, mesoporous materials have been regarded as "molecule factories" to manufacture aligned, well-dispersed molecules within their pore structures. The objective of this dissertation is to introduce guest molecules (organic and inorganic compounds) to the pore channels of the mesoporous material for the purpose of creating new nanocomposites with unique properties or properties of the guest molecules that are improvement of these of the isolated component.;For these reasons, several molecules were successfully encapsulated as the guests, such as aggregate dyes, a laser dye molecule with twisted intramolecular charge transfer (TICT) property, and magnetic nanoparticles. Upon encapsulation, many properties of these compounds are found to be modified as a result of confinement within the mesoporous materials.;In particular, we formed the J-aggregated Tetrakis (p-sulfonatophenyl) porphyrin (TSPP) and 1,1', 3,3'-tetraethyl-5,5 ', 6,6'-tetrachloro-benziinidazolo-carbocyanine (TTBC) within aluminosilicate mesostructures. The composite structures represent new "ship-in-a-bottle" type nanomaterials whose properties derive from energy states and dynamics that result from quantum confinement. This quantum confinement is associated both with the restricted growth region available to the spontaneously self-assembled molecular aggregates as well as the inherent confinement of the exciton's movement among a subset of coherently responding molecules within the physical aggregate.;We also have been able to observe dual emission from DCM, a laser dye, by encapsulation of dye molecules within an alumino-MCM-41. The interaction between DCM and the internal surface of MCM-41 was found to modify the optical properties of the confined DCM molecules. The dynamics of DCM in MCM-41 was found to correspond to a biexponential relaxation with one component of 0.6 ns (57%) and a very long component of 1.9 ns (43%).;Lastly, we report the development of a new functional nanocomposite material, MCM-41 loaded at a high level with Fe2O3 whose functionality involves an enhanced absorption of microwave energy, even in the absence of an applied magnetic field. Different factors, such as Fe2O 3 loading level and the opening size of the mesopourous materials, have significant influence on the microwave absorption ability.
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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.
