Date of Graduation

Spring 2015

Degree

Master of Science in Chemistry

Department

Chemistry

Committee Chair

Eric Bosch

Keywords

halogen bonding, crystal engineering, self-complementary dimers, polyaromatic molecules, sonogashira coupling reactions

Subject Categories

Chemistry

Abstract

This research was to design and successfully engineer crystals using the non-covalent halogen bonding interaction. A halogen bond is an attractive interaction between a positive electrostatic potential on a halogen atom and a negative site on another molecule. Halogen bonds are increasingly recognized as an effective force for the self-assembly of molecules in predictable patterns to produce new materials with certain desirable properties. The research focused on the formation of large planar polyaromatic assemblies of molecules containing halogen bond donor and acceptor sites. The planar polyaromatic compounds were synthesized using multiple Sonogashira Coupling reactions. This is a cross-coupling reaction that forms carbon-carbon bonds between a terminal alkyne and an aryl halide using palladium catalysts. The X-ray crystal structures of the series of iodo- and bromo-phenylethynylphenylethynylpyridines were shown to form self-complementary dimers in the solid state. The perfluoroiodo- and perfluorobromophenylethynylphenylethynyl derivatives, 3-[{4-[(2-bromo-3, 4, 5, 6- tetrafluorophenyl)ethynyl]phenyl}ethynyl]pyridine, 3-[{4-[(2, 3, 4, 5-tetrafluoro-6-iodophenyl)ethynyl]phenyl}ethynyl]pyridine and 2-[{4-[(3-bromo-2, 4, 5, 6-tetrafluoro- phenyl)ethynyl]phenyl}ethynyl]pyridine, formed self-complementary halogen-bonded dimeric units in the solid state. In contrast, 3-[{4-[(2-bromo-4, 5-difluorophenyl)ethynyl]phenyl}ethynyl]pyridine formed a C−H...N hydrogen- bonded dimer.

Copyright

© Lisa Michelle Kirchner

Campus Only

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