Synthesis and Characterization of a Water-Soluble Conjugated Polymer from the Uncatalyzed Polymerization of Ethynylpyridine

A water-soluble ionic conjugated polymer was prepared via uncatalyzed polymerization of 2-ethynylpyridine using iodomethane. The polymerization proceeded well to give a moderate yield of polymer. A polymerization mechanism is proposed where the reaction of 2-ethynylpyridine reacts with iodomethane to form an activated triple bond, which undergoes a linear identical propagation process. The chemical structure of polymer was characterized by NMR (H-1-, C-13-), IR, and UV-visible spectroscopies. The photoluminescence spectrum of polymer showed that the PL peak is located at 568 nm corresponding to the photon energy of 2.19 eV. The cyclic voltammogram of this conjugated polyelectrolyte shows a well-defined and stable redox process.