Effects of structural regularity on the properties of poly(3-alkylthienylenevinylenes)

Attempts were made to prepare completely regioregular poly(3-dodecylthienylenevinylene) (PDDTV) and the completely regiorandom PDDTV. However, attempts to prepare the regioregular PDDTV by a Heck polymerization of 2-bromo-3-dodecyl-5-vinylthiophene leads to a regioirregular PDDTV that also contains cross-conjugated defects. Attempts to prepare a regiorandom PDDTV by a Stille polymerization of 2,5-dibromo-3-dodecylthiophene with (E)-1,2-(bistributylstannyl)ethylene) led to a polymer that is at least 90% regioregular. Poly[(3-dodecylthienylenevinylene) (4'-3-dodecylthienylenevinylene)] was also synthesized from a symmetric dimer using Stille cross-coupling in order to compare the three polymers. The structural and physical properties of these polymers are compared by UV/vis, NMR, X-ray, and electrical conductivity measurements. We have also examined the MALDI MS of these polymers, and information on molecular weights and end-group structures are given. The role of dominant catalyst effects is discussed.