Date of Award

4-2011

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Dr. Elke Schoffers

Second Advisor

Dr. James Kiddle

Third Advisor

Dr. Silvia Rossbach

Fourth Advisor

Dr. Ekkehard Sinn

Abstract

1, 10-Phenanthroline and its derivatives are compounds of great interest for applications in organic and inorganic chemistry as well as in biology and medicinal chemistry. Recent examples include their use in chiral catalysis, bioaffinity assays, medicine and sensors. This research project focused on the synthesis of novel 1, 10- phenanthroline derivatives that were functionalized in the 5- and 6-position. The long term goal is their application as catalysts in asymmetric reactions, as bioactive molecules, or as sensors to detect harmful chemicals such as warfare agents or environmental pollutants.

5,6-Dihydro-1,10-phenanthrolines were prepared via epoxide opening with oxygen and nitrogen nucleophiles. The corresponding products were obtained as a mixture of enantiomers or diastereomers depending on the nature of the nucleophile. Racemic mixtures were resolved employing lipase-catalyzed transesterification reactions, whereas diasteromeric mixtures were separated usmg column chromatography or crystallization. The stereochemistry was assigned via circular dichroism, X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy. The complexation behavior towards transition metals was studied by reacting selected ligands with copper(II) and nickel(II) salts, and by analyzing them via X-ray crystallography.

B-Ring functionalized 1,10-phenanthroline derivatives that contained a fully conjugated phenanthroline scaffold were synthesized via oxidation and dehydration reactions of 5,6-dihydro-1,10-phenanthrolines.

The antimicrobial activity of some 1,10-phenanthrolines was tested on the opportunistic pathogens Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa using disc diffusion assays. We found that a fully planar phenanthroline moiety was required for increased antimicrobial effects.

The optoelectronic properties of several re-aromatized compounds were investigated. We found that 5-amino-1,10-phenathroline derivatives possessed relatively high quantum yields and solvochromatic shifts due to their intramolecular charge transfer character. Measurements showed that the oxazoline derived from oxidation of 2-hydroxybenzylamine exhibited dual fluorescence. The low-energy emission band was associated with a structural change in the exited state caused by an excited state intramolecular proton transfer.

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Dissertation-Campus Only

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