Chiroptical spectroscopic studies of polydiacetylenes

A new class of optically pure, chiral, soluble polydiacetylenes have been synthesized. These show both solvato- and thermo-chromism, with behaviours similar to those reported for the well-studied analogous achiral m-butoxycarbonylmethylurethane (mBCMU) class of polydiacetylenes. Although it is now generally agreed that this chromic behaviour is a direct result of the order-disorder transformation of the dissolved polymer, there still remains disagreement about the conformation and state of aggregation of the various forms. The chiral structure of these new polymers allows these general questions to be addressed through the use of circular dichroism spectroscopy. We report measurements obtained on both solution and thin film samples. These have allowed us to characterize more precisely the various states involved.