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Conformational ordering of apolar, chiral m-phenylene ethynylene oligomers
1Departments of Chemistry and Materials Science & Engineering, 600 South Mathews Avenue, The University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Tec.
Abstract:
A series of m-phenylene ethynylene oligomers containing nonpolar, (S)-3,7-dimethyl-1-octanoxy side chains have been synthesized and studied. In apolar alkane solvents, oligomers of sufficient length (n > 10) were found to adopt a helical conformation with a large twist sense bias. In contrast, in chloroform the oligomers adopt a random coil conformation. Surprisingly, the strong twist sense bias was determined to be highly time dependent and is partially attributed to intermolecular aggregation.