Highly fluorescent mono‐substituted poly(arylacetylene)s containing tolane chromophores

Abstract

A new class of highly fluorescent mono-substituted polyarylacetylenes (P1-P3) has been successfully prepared with good yields and high molecular weights from a series of phenylethynylene-substituted arylacetylenes (M1-M3), using Wbased catalyst. These polymers are readily soluble in common organic solvents (e.g., THF, toluene, and chloroform) and thermally stable up to $350 8C. Both 1 H NMR and IR studies confirmed that all the monomers were selectively polymerized at the terminal triple bond. The 1 H NMR results showed that both P1 and P2 have essentially trans-polyene backbone structures, while P3 contains significant amounts of both cis-and trans-structures. Coincidently, the photoluminescence (PL) intensity of P3 is also much lower than both P1 and P2. Nevertheless, the PL intensity of P1-P3 are all much higher than that of PPA, suggesting that the introduction of phenylethynylene group to the phenyl rings of PPAs have made the in general nonemissive PPAs to become highly photoluminescent. Most interestingly, although P1 did not contain any substituent group on its tolane pendant group, it is already highly soluble in common organic solvent and emitting blue fluorescence (416 nm) with a reasonably good quantum yield (0.36). V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: [5483][5484][5485][5486][5487][5488][5489][5490][5491][5492][5493][5494][5495][5496][5497][5498] 2008

Synthesis of polyarylacetylenes by γ‐ray‐induced polymerization of terminal alkynes. Nanostructures of ortho‐substituted derivatives

“…Therefore, the chemical yields and polymer properties of P4–P6 do not strictly derive from the activation source (irradiation vs. metal catalysis), but appear to be related to the nature of the growing carbon chain imposed by the ortho substituent in the course of the polymerization process. In the case of transition metal catalysis, it has been suggested that undesired chain transfer and termination events are limited in bulky propagating species 23–25. Remarkably, poly( o ‐CF 3 PA) obtained by catalysis of W(CO) 6 under UV irradiation exhibited higher MWs than poly( m ‐CF 3 PA) or poly( p ‐CF 3 PA), and the M w values increased with decreasing monomer concentration in solution 26…”