We have been studying a number of conjugated oligomers to probe their various aspects of properties, including supramolecular assembly, semiconducting and opto-electronic capabilities. Monodispersed synthetic oligomers capable of manifesting tailored chain conformations, i.e., foldamers, have also been designed to emulate and assist better understanding the higher-order structures formation by biological macromolecules, as the folding of both synthetic and natural systems are dictated by non-covalent forces of similar chemical nature. In this presentation, a specific example will be discussed, elucidating important information about the folding dynamics of a phenylene ethynylene oligomer, which is believed to aggregate intermolecularly under both folded and unfolded conformations. Specifically, foldamers of sufficient chain lengths comprising alternating ortho- and para-phenyleneethynylene units in the backbone were proven to assume a helical conformation, driven by intramolecular aromatic stacking interactions. Such chain molecules bearing different side chains exhibited the same helical structure in varied, respectively suitable solvents, in accordance to the polarity of side chains.Different folding dynamics were manifested when the solvophobic and aromatic stacking interactions were intensified by varying the solvation conditions. The observed folding stability and unique folding dynamics is believed to be related to the competition of intermolecular aggregations in the folded and unfolded states.

Helical folding dynamics in association with intermolecular aggregation

246th National Meeting (2013)

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