Synthesis, Structure, Chromatic Properties, and Induced Circular Dichromism of Polydiacetylenes with an Extended Conjugated System in the Side Chain

We synthesized PDAs with a 4-carboxyphenyl substituent directly connected to the conjugating main chain in order to investigate the effects of the side chain structure on the chromatic properties of the polymers. A series of 1,3-alkadiynyl-4-benzoic acids (m,Ph-DA-CO 2 H) and their 1-naphthylmethylammonium salts (m,Ph-DA-Naph) were prepared and polymerized under UV and γ-ray irradiation. The resulting poly(m,Ph-DA-CO 2 H)s had absorption bands in their UV-vis spectra in a wavelength region longer than those for the poly(m,Ph-DA-Naph)s and the other PDAs. We report the first example of the induced circular dichromism of poly(m,Ph-DA-CO 2 H) in the combination with a chiral (1-cyclohexyl)ethylamine in the dispersion and in the solid state by an acid/base interaction.