Date of Award

5-1-2013

Degree Type

Dissertation

University or Center

Clark Atlanta University(CAU)

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Dr. Xiu-ren Bu

Abstract

The research presented in this dissertation is focused on the design, synthesis, photophysical characterization, and nitro aromatic compounds-sensing properties of planar geometry imidazoles. hi addition, a new series of carbazone compounds have been developed and explored for the detection of explosives such as Trinitrotoluene (TNT).

The objective of this research is to explore the use of fluorescence spectroscopy for the indirect detection of Hexamethylene Triperoxide Diamine (HMTD) explosives, including direct sensing of TNT and dimethlyformaide (DMF). Imidazole compounds were investigated for their ability to sense aromatic nitro compounds. Phrenanthrenequinone imidazole (PI) has demonstrated a unique property in solution state as a fluorescence probe for nitroaromatic compounds. It is found that PI fluorescence is quenched by aromatic nitro compounds and hasan excellent response. It is concentration based quenching and the detection sensitivity is in the range of parts per million.

We prepared solid film from different imidazole compounds (e.g. PI) which gave us unique detection specificity for DMF. The luminescence intensityindicates the response of the sensor slide is reasonably fast, and potentially reusable, rendering the PI in KBr pellet film a sensor for practical applications.

Also we prepared nanocomposites from SWNT-COOH with LPI, 4MBI and PI. We specifically examined sensing properties from LPI and PIbased nanocomposites Fluorescence spectra were found to give direct evidence for the interaction of imidazole (such as LPI, PI) and the nanotubes.This implies the formation of an imidazole-nanotube nanocomposite, in which the LPI would be expected to adsorb to the surface of the nanotubes with a less bundled structure. The intensity of the LPI fluctuated in the presence of TNT solution. It is reasonable that LPI molecules on the SWNT-COOH surface are partially replaced by TNT molecules and in return the LPI molecules end up in the solution. This solution states trade-off causes the fluorescence intensity to fluctuate from quenching to enhancement and vice versa.

In addition, a series of carbazone compounds were prepared and aimed to explore optical response upon the interaction with nitro aromatic compounds. Generally these compounds are not fluorescent. The initial investigation of Aggregation emission spectroscopy is initiated and potentially has fluorescence "turn on", and "turn off' effect results indicate of the potential that further enhancement could be possible.

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