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Moore, Jeffrey S. Nelson, James Curtis 2015-09-25T22:14:15Z 2015-09-25T22:14:15Z 10000-01-01 1997 1997 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. Made available in DSpace on 2015-09-25T22:14:15Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 9812719.pdf: 5315887 bytes, checksum: bd7d1ac55ba895b3cdd71d46c346e558 (MD5) Previous issue date: 1997 Embargo set by: Seth Robbins for item 85668 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 115 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997. http://hdl.handle.net/2142/84387 (MiAaPQ)AAI9812719 eng Chemistry, Polymer Solvophobically-Driven Folding of Non-Biological Oligomers and the Solid Phase Synthesis of Phenylacetylene Oligomers text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.