Living polymerization of substituted acetylenes

Abstract

For many years, considerable research efforts have been dedicated to -conjugated polymers because of their extraordinary electronic, optical, and structural properties. The employed transition-metal-based initiating systems comprise not only simple transitionmetal salts but also rather sophisticated mixtures of two, three, or four compounds and even highly defined single-component systems such as transition-metal alkylidene complexes. Extensive fine-tuning of the electronic and steric properties of initiator-monomer systems eventually allowed the tailor-made synthesis of conjugated materials via living polymerization techniques. This article focuses on recent developments in the field of the living polymerization of substituted acetylene derivatives. Ill-defined group 5 and 6 transition metal halide-based initiators, well-

Substituted polyacetylenes

“…12,13 A comprehensive and informative review article has recently been published concerning the living polymerization of substituted acetylenes. 14,15 The above-stated progress of various transition metal-based polymerization catalysts enabled the synthesis of a wide variety of polymers from acetylene derivatives including monosubstituted and disubstituted acetylenes, [8][9][10][11][16][17][18] and a,x-diynes. 19,20 Unlike polyacetylene, substituted polyacetylenes having bulky substituents are usually soluble in many common solvents and stable enough in air for a long period of time.…”

“…As described in the part of novel polymers, Si-containing poly(diphenylacetylenes), poly(13a) and poly (14) are totally soluble in common solvents such as toluene and CHCl 3 to provide tough membranes by solution casting. Quite interestingly, their Po 2 values were considerably large (ca.…”

“…To inspect this hypothesis, the synthesis of soluble derivatives of poly (12) was examined by introducing a trimethylsilyl group to 12. 79,80 Consequently, 1-phenyl-2-(p-trimethylsilyl)phenylacetylene (13a) and 1-phenyl-2-(mtrimethylsilyl)phenylacetylene (14) polymerized with TaCl 5 -cocatalyst systems to provide in more than 70% yields new polymers having M w over 1 Â 10 5 . As cocatalysts, n-Bu 4 Sn, Et 3 SiH, and 9BBN were especially effective.…”

“…13,14 The living polymerization of 1 was first accomplished by Noyori and coworker in 1994. 63 The excellent ability of an isolated catalyst, (Ph 3 P) 2 (nbd)Rh-C:C-Ph, to achieve quantitative yields of poly(phenylacetylenes) with narrow MWD (M w /M n $ 1.1) in the presence of 4-(N,N-dimethylamino)pyridine (DMAP) was demonstrated.…”

“…Membranes of poly(13a) and poly (14) were desilylated with trifluoroacetic acid. Poly(13a) underwent desilylation completely, while poly(14) did not.…”