Optical Properties of a Supramolecular Assembly Containing Polydiacetylene

We report polarized optical measurements of a new type of single-crystal supramolecular assembly containing isolated chains of polydiacetylene (PDA): poly(1,6-bis(nictonyloxy)-2,4-hexadiyne). Room-temperature spectra reveal a large anisotropy, confirming the low-dimensional nature of the material. In particular, the characteristic optical signature of PDA correlates well with the chain orientation from the X-ray crystal structure. A near-infrared charge-transfer band is also observed, which we attribute to low-energy charge transfer from the polymer backbone to the pyridine rings. Temperature-dependent spectra reveal a weak doublet splitting of the optical bands, indicating a slight distortion of the side chains which contain the pyridine ring at low temperature.