Title page for etd-0906112-145044


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URN etd-0906112-145044
Author Mei-Chun Tzeng
Author's Email Address No Public.
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Department Chemistry
Year 2011
Semester 2
Degree Ph.D.
Type of Document
Language English
Title DIBENZO[a,c]PHENAZINE AND 2,3-
DIPHENYLQUINOXALINE DISCOGENS WITH
PHENANTHROLINE AND CROWN ETHER, AND
FLUOROUS POLYCATENAR LIQUID CRYSTALS
Date of Defense 2012-07-30
Page Count 209
Keyword
  • phenanthroline
  • 3-diphenylquinoxaline
  • 2
  • crown
  • perfluorinated polycatenar
  • discotic liquid crystal
  • dibenzo[a
  • c]phenazine
  • Abstract In this PhD thesis, there are two major motifs: dibenzo[a,c]phenazine- and 2,3-diphenylquinoxaline novel discogens and fluorous polycatenar liquid crystals. The thermo properties of these new compounds were elucidated using optical microscopy, differential scanning calorimetry and powder X-ray diffraction. In the phenanthroline series (Chapter 2), 1,10-phenanthroline core incorporated into dibenzo[a,c]phenazine structure exhibit columnar mesophases with extremely wide width. X-ray diffraction study pinpoints to that half-shaped mesogens with reduced symmetry has preferential intra-molecular parallel conformation in the mesophase. This molecule has gel ability with different solvents. In dimeric crown ether series (Chapter 3A), 2,3-diphenylquinoxaline-based mesogens containing dibenzo-18-crown-6 has hexagonal columnar mesophase with extremely narrow width. Incorporation potassium metal ion into crown moiety dramatically enhanced mesomorphic stability and for metal complexes, as side chain increases, hexagonal mesophases predominate over rectangular mesophases. Furthermore, both in hexagon or rectangle, per columnar slice consist of two molecules. All of prolonged long glassy formation up to one year at room temperature. In monomeric crown ether series (Chapter 3B), metal-free molecules fail to be mesomorphic, but complexation with lithium and sodium metals enhanced thermo stability and rectangular mesophase (C2mm) were found. Also, per columnar slice was comprised of four molecules. Last (Chapter 4), a series of tri- and tetra-catenar mesogens containing various combinations of hydrocarbon and semiperfluorocarbon chains has been prepared to elucidate the fluorophlic-fluorophobic effect on mesomorphism. Tricatenar with one terminal semiperfluoro- and two hydrocarbon chains are aligned into lamellar periodicity driven by the mutual incompatibility of the hydrocarbon and fluorocarbon portions. But unsymmetric tetracatenar mesogens show rectangular mesophase.
    Advisory Committee
  • Chung-Kung Lai - chair
  • Tsu-Hsin Chang - co-chair
  • Kwang-Ming Lee - co-chair
  • Jyh-Tsung Lee - co-chair
  • Chi-Wi Ong - advisor
  • Files
  • etd-0906112-145044.pdf
  • Indicate in-campus at 99 year and off-campus access at 99 year.
    Date of Submission 2012-09-06

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