Mechanism of photoinduced step polymerization of thiophene by onium salts: Reactions of phenyliodinium and diphenylsulfinium radical cations with thiophene

Yagci Y., JOCKUSCH S., TURRO N. J.

MACROMOLECULES, cilt.40, sa.13, ss.4481-4485, 2007 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 40 Sayı: 13
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1021/ma070586a
  • Dergi Adı: MACROMOLECULES
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.4481-4485
  • İstanbul Teknik Üniversitesi Adresli: Evet

Özet

Laser flash photolysis and EPR studies were performed to elucidate the mechanism of photoinduced step polymerization of thiophene by using diphenyliodonium (Ph2I+) and triphenylsulphonium (Ph3S+) ions as photoinitiators. Photoexcitation of these ions generated phenyliodinium (PhI center dot+) and diphenylsulphinium (Ph2S center dot+) radical cations, which were readily quenched by thiophene with rate constants of k(q) = 1.26 x 10(10) and 1.7 x 10(5) M-1 s(-1), respectively. The transient absorption spectra of the corresponding thiophene radical cations were not directly detectable because of the spectral overlap with the precursor salts. However, the related electron-transfer reaction was confirmed by quenching of the PhI center dot+ radical cation with bithiophene to form the radical cation of bithiophene, which absorb strongly at 420 nm. EPR studies also confirmed the proposed electron-transfer mechanism through the direct detection of the radical cation of thiophene.