Synthesis and Characterization of Novel Polythiophenes Containing Pyrene Chromophores: Thermal, Optical and Electrochemical Properties

Abstract

A novel series of pyrene containing thiophene monomers TPM1–5 were synthesized and fully characterized by FTIR, MS, ¹H- and ¹³C-NMR spectroscopy; their thermal properties were determined by TGA and DSC. These monomers were chemically polymerized using FeCl₃ as oxidizing agent to give the corresponding oligomers TPO1–5) and they were electrochemically polymerized to obtain the corresponding polymer films deposited onto ITO. All oligomers exhibited good thermal stability, with T₁₀ values between 255 and 299 °C, and T_g values varying from 36 to 39 °C. The monomers showed an absorption band at 345 nm due to the S₀ → S₂ transition of the pyrene group, whereas the fluorescence spectra showed a broad emission band arising from the “monomer” emission at 375–420 nm. The obtained polymers exhibited two absorption bands at 244 and 354 nm, due to the polythiophene and the pyrene moieties, respectively. The fluorescence spectra of polymers showed a broad “monomer” emission at 380–420 nm followed by an intense excimer emission band at 570 nm, due to the presence of intramolecular pyrene-pyrene interactions in these compounds.