Received: 29 November 2020 Accepted: 22 January 2021
Methine-bridged type π-conjugated polymer was synthesized using a Migita–Kosugi–Stille polycondensation reaction in the presence of a Pd(0) catalyst followed by oxidation with 2,3-dichloro-5,6-dicyano-p-benzoquinone. The chemical structure of the obtained polymer was confirmed by infrared absorption spectroscopy. The optical properties of the polymer were confirmed by ultraviolet visible optical absorption and photoluminescence spectra. Vapor phase iodine doping was performed to generate a charge carrier in the polymer. The magnetic properties of the carrier were examined by electron spin resonance (ESR). The doped polymer exhibited Pauli’s para-magnetism with constant ESR linewidths and g-values, whereas the ESR intensity increased with decrease in temperature. This indicated the formation of charge carriers on the backbone of the polymer by iodine doping, which is typical behavior of polarons in conductive polymers. The present study describes the first synthesis of a methane-bridged π-conjugated polymer using a Migita–Kosugi–Stille type polycondensation.