Helical polycarbodiimides have been shown to display a wide variety of interesting and potentially fruitful properties. One of which that has been of particular interest is the reversible solvo- and thermo- driven chiroptical switching phenomenon observed in certain polycarbodiimides containing bulky aromatic pendant groups (i.e., anthryl, naphthyl, etc). Much is still unknown about the specific conformational reorientation that causes the observed chiroptical switching, however. In order to elucidate the cause and possible driving forces behind this phenomenon, poly(N-naphthyl-N'-octadecylcarbodiimide), the most versatile of all switching polycarbodiimides, was subject to nitrogen-15 enrichment and subsequent 15N NMR analysis. This new data suggests that the chiroptical switching process is consequence of varying populations of two distinct polymer conformations  . The populations are able to be specifically modulated simply by altering either the solvent or temperature. Here in, we report the use of vibrational circular dichroism (VCD) spectroscopy coupled with density functional theory (DFT) calculations to determine overall secondary structure of both states.

Investigating the reversible chiroptical switching phenomenon in polycarbodiimides using <sup>15</sup>N NMR and VCD spectrocopy

245th National Meeting (2013)

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Investigating the reversible chiroptical switching phenomenon in polycarbodiimides using 15N NMR and VCD spectrocopy

Investigating the reversible chiroptical switching phenomenon in polycarbodiimides using ¹⁵N NMR and VCD spectrocopy