Synthesis of π-conjugated polymers possessing 1,3-butadiene-1,4-diyl units by reactions of regioregular organometallic polymer having titanacyclopentadiene moieties in the main chain

• DOI: 10.1016/j.synthmet.2009.02.003
• Publication Date: 2009-03-06T10:42:24Z
• Authors: Kiyohiko Atami; Tomoko Kino; Wei-Min Zhou; Hiroki Nishiyama; Ikuyoshi Tomita
• Keywords: Organosilicon; Hydrochloric acid

Abstract The synthesis and properties of π-conjugated polymers possessing phenylene-1,4-diyl and 1,3-butadiene-1,4-diyl alternating units in the main chain by reactions of a regioregular organometallic polymer having titanacyclopentadiene-2,5-diyl unit are described. The polymerization of 1,4-diethynyl-2,5-dioctyloxybenzene with a low-valent titanium complex, generated in situ from titanium(IV) isopropoxide and isopropyl magnesium chloride, was carried out at −78 °C to −50 °C for 12 h to give the regioregular organotitanium polymer. The diene-containing π-conjugated polymers were obtained by the reactions of the organotitanium polymer with electrophiles such as hydrochloric acid and iodine. For example, the reaction with hydrochloric acid gave a diene-containing polymer in a 61% yield whose M n and M w / M n were estimated as 5700 and 1.61, respectively (by GPC). The π-conjugated character of the resulting polymer could be supported by its UV–vis spectrum. That is, the absorption maximum ( λ max ) of the polymer was observable at 470 nm, which was bathochromically shifted by 115 nm compared to that of a model compound (1,4-bis(2-methoxyphenyl)-1,3-butadiene, λ max = 355 nm).