MOLECULAR-DYNAMICS SIMULATION OF SUBSTITUTED CONJUGATED IONIC POLYACETYLENES

Molecular dynamics simulations were carried out on the model systems of a recently reported new class of substituted polyacetylenes possessing extensive backbone conjugation and high charge densities. Our results show that for models of these polymers with charged pyridinium substituents and bromide counterions, the polymer backbones are highly extended, which is in complete contrast to uncharged, substituted polyacetylenes. For the trans-transoidal conformer the counterions located between the positively charged pyridine rings have strong electrostatic attractive interactions with aromatic hydrogen atoms. It is shown that the enhanced electrostatic interactions are mainly responsible for the observed planar extended geometry in these ionic polyacetylenes. It is concluded that the Coulomb interactions play a dominant role in the conformation and dynamics of such systems.