Effect of Chain Rigidity and Effective Conjugation Length on the Structural and Photophysical Properties of Pyridine-Based Luminescent Polymers

We report on the characterization of a number of random copolymers of “para” poly(2,5-pyridinediyl) (PPY) and “meta” poly(2,6-pyridinediyl) (PmPY). We demonstrate some ability to control the photophysical properties by variation of the ratio of the monomeric components of the copolymers. These effects, in both film and solution, are then related to the chain rigidity and effective conjugation length of each copolymer as determined by light scattering, ellipsometric, and optical measurements. We find that, as expected, the more rigid the polymer chain, the more delocalized the backbone π-electrons become in the solid state. However, in solution this does not appear to be the case.