Spectroscopic studies of aggregated molecules encapsulated in mesoporous materials.
Item
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Title
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Spectroscopic studies of aggregated molecules encapsulated in mesoporous materials.
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Identifier
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AAI3024847
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identifier
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3024847
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Creator
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Xu, Wei.
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Contributor
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Adviser: Daniel L. Akins
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Date
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2001
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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 | Chemistry, Physical
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Abstract
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We report the formation of monomeric and aggregated tetrakis( p-sulfonatophenyl) porphyrin (TSPP), 1,1'-3,3 '-tetraethyl-5,5',6,6'-tetrachlorobenzimidazolocarbocyanine (TTBC) or 1,1'-diethyl-3,3'-di(4-sulfobutyl)-5,5 ',6,6'-tetrachlorobenzimidazolocarbocyanine (TDBC) encapsulated within aluminosilicate or silicate mesostructures, specifically, MCM-41 and SBA-15, under different pH conditions. It was necessary to stabilize the synthesized MCM-41 through use of a silylation reagent, aminopropyltriethoxysilane, which cross-links oxygen on the surface (thus rigidifying the walls of the mesoporous material) and functionalizes the interface for proper guest-host interaction. On the other hand, due to its thicker walls, the framework of SBA-15 is well maintained when the J-aggregated cyanine is formed within the channels, hence, even though silylation was also utilized, main purpose was to modify SBA-15 is to meet the requirement of electrostatic interaction. NMR, XRD, UV-vis absorption, Raman scattering, and fluorescence measurements are used as spectroscopic tools to characterize the various products. Nitrogen adsorption/desorption isotherms and SEM were also applied to study the mesostructure of MCM-41 and SBA-15. Additionally, the difference of J-aggregated TSPP formed within modified MCM-41 from that formed in the presence of an ionic vesicle suspension are compared and analyzed. The composites consisting of either J-aggregated TTBC or TDBC and the aluminosilicate/silicate represent new fluorescent nanomaterials that possess the properties of the aggregate, yet avoid the essentially unfettered topography and physical length that accompanies the formation of an aggregate in solution or adsorbed onto an interface.
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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.
