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Highly Conjugated Poly(thiophene)s − Synthesis of Regioregular 3‐Alkylthiophene Polymers and 3‐Alkylthiophene/Thiophene Copolymers
Author(s) -
LèrePorte JeanPierre,
Moreau Joël J. E.,
Torreilles Christophe
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200104)2001:7<1249::aid-ejoc1249>3.0.co;2-f
Subject(s) - thiophene , conjugated system , electrochromism , chemistry , polymer chemistry , polymer , photochemistry , copolymer , conductive polymer , organic chemistry , electrode
Tributyltin derivatives of 2‐bromo‐3‐octylthiophene and 5‐bromo‐4‐octyl‐2,2′‐bi(thiophene) have been selectively prepared. Condensation reactions in the presence of Pd 2 (dba) 3 (CHCl 3 )/4 PPh 3 led to high yields (ca. 90%) of regioregular poly(3‐octylthiophene) ( M w = 21.4 × 10 4 , M w / M n = 1.48) and poly[4‐octylbi(thiophene)] ( M w = 3.8 × 10 4 , M w / M n = 1.1). The regioregularity of the head‐to‐tail (HT) coupling has been determined by 1 H NMR, which showed HT > 95% for poly(3‐octylthiophene) and HT > 90% for the new poly[4‐octylbi(thiophene)]. The conjugation properties of these materials have been characterized by FT‐IR and UV/Vis spectroscopy. Compared to the corresponding random polymers, the absorption maxima of the new regular polymers are shifted to higher wavelengths (λ max = 448 and 466 nm, respectively). The mean conjugation length increases with increasing regioregularity of the coupling and with fewer substituents along the conjugated chain. The electroactive properties of the materials have also been studied. The new poly[4‐octylbi(thiophene)] shows an oxidation peak at a low potential, and, compared to poly(3‐octylthiophene), a reduction peak is also observed at a lower potential indicating a higher electron affinity. Both polymers exhibit reversible blue‐red electrochromic behavior associated with the reversible redox properties.