Intramolecular charge transfer induced by deprotonation of hydroxyl groups in π-conjugated polymers with π-deficient aromatic rings

π-Conjugated polymers consisting of p-phenylene (Ph) and 1,3,4-oxadiazole (Oz) or 4-octylphenyl-1,3,4-triazole (OctOz) rings [polymer-1: (Ph-Oz)n and polymer-2: (Ph-OctTz)n] and those consisting of 9,9-dihexyl-2,7-fluorene (Flu) and Oz or 1-(4-hydroxyphenyl)-1,3,4-triazole (HOPhTz) rings [polymer-3: (Ph-Oz-Py-Oz-Flu)n and polymer-4: (Ph-HOPhTz-Py-HOPhTz-Flu)n (Py = 2,5-pyridine)] were synthesized by polymerization promoted by polyphospholic acid and catalyzed by a Pd complex, respectively. Model compounds (model-1: Ph-Oz-Py-Oz-Ph, model-2: Ph-HOPhTz-Py-HOPhTz-Ph, and model-3: Ph-OctPhTz-Py-OctPhTz-Ph) were synthesized. The fact that the λmax wavelengths of the polymers were longer than those of the model compounds suggests the expansion of the π-conjugation system along the polymer chain. The reaction of polymer-4 and model-2 with NaH caused the dehydration of the OH groups, which induced an intramolecular charge transfer (ICT) from the ONa group to the Tz ring. The ICT affected the optical properties of the polymers and the model compounds. The cast films of polymers obtained in this study underwent electrochemical reduction and oxidation.