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Title:Solvophobically-Driven Folding of Non-Biological Oligomers and the Solid Phase Synthesis of Phenylacetylene Oligomers
Author(s):Nelson, James Curtis
Doctoral Committee Chair(s):Moore, Jeffrey S.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Polymer
Abstract:The ordered sequence of monomers in phenylacetylene oligomers can serve as a repeating motif to produce helical structures in solution which posses a tubular cavity. Calculations with modest size oligomers show stable helical conformations with as few as 8 monomer units. Oligomers with triglyme monomethyl ether benzoate functionalized monomers (R = -COO(CH$\rm\sb2CH\sb2O)\sb3CH\sb3)$ reveal dramatic chain-length-dependent aromatic chemical shifting in CD$\sb3$CN, indicative of aromatic stacking and helical structure. In addition. when chain length reaches 12 monomer units, oligomers begin to strongly aggregate which may be a result of helical oligomers associating like their corresponding macrocycles in a face-to-face parallel fashion. Chain length dependence of UV/Vis and $\sp1$H NMR spectra provide strong evidence of the ordering of monomers and intramolecular aromatic stacking which is consistent with the formation of helical structures. Using UV/Vis absorption at 303 nm as an indication of helical structure, reversible thermal helix-coil transitions were measured in 4/6, $\rm CH\sb3CN/CHCl\sb3.$ In agreement with the calculations, the octadecamer possesses the largest shift in $\rm\delta\sb{A},$ the best resolved $\sp1$H NMR spectra of the oligomers longer than 12 monomers, and the largest hypochromic shift at 303 nm which is attributed to intramolecular aromatic stacking.
Issue Date:1997
Description:115 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.
Other Identifier(s):(MiAaPQ)AAI9812719
Date Available in IDEALS:2015-09-25
Date Deposited:1997

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