“Synthesis and characterization of novel luminescent polythiophenes containing pyrene units and oligo(ethylene glycol) spacers: Thermal and optical properties”

• Luminescent polythiophenes bearing pyrene.
• Excimers.
• Intramolecular interactions.

A novel pyrene containing thiophene monomer 3-methyl-4-(4-(pyren-1-yl)butoxy) thiophene was synthesized and fully characterized by FTIR and 1H and 13C NMR spectroscopies. This monomer was polymerized and copolymerized in the presence of 3-methyl-4-(tetraethoxy) thiophene, 3-hexylthiophene, 3-decylthiophene, and 3-dodecylthiophene using FeCl3 as oxidizing agent, to give the corresponding homopolymer HP3 and copolymers (CP1, CP2, CP3, CP4,CP5 and CP6). These polymers exhibited good thermal stability with T10 values between 312 and 414 °C, and Tg values varying from −38 to 24 °C. CP5 exhibited two absorption bands at 246 and 416 nm whereas CP6 absorbed only at 242 nm. The emission spectra of both polymers showed a monomer emission at 376–396 followed by an intense excimer emission at 570 nm, which reveals the presence of intramolecular non parallel pyrene–pyrene interactions.