Synthesis and photoluminescence properties of poly(1-hexyl-2-aryl acetylene)s, poly(1-phenyl-2-fluorenylacetylene), and poly(1-fluorenyl-2- fluorenlacetylene)

Abstract

The metathesis polymerizations of 1-hexyl-2-arylacetylenes [n-C 6H 13CCAr; Ar = phenyl (1a), naphthyl (1b), biphenyl (1c), fluorenyl (1d)] were examined using NbCl 5, TaCl 5, and WCl 6. When NbCl 5/n-Bu 4Sn was used as a catalyst in their polymerization, high-molecular-weight polymers (2a-2d) were obtained in good yield compared to TaCl 5/n-Bu 4Sn and WCl 6/Ph 4Sn. 1-Hexyl-2-[2-(9,9-dialkylfluorenyl)]acetylenes (1e-1h) also polymerized by NbCl 5/n-Bu 4Sn to give corresponding polymers (2e-2h) with relatively high molecular weights. Diarylacetylene polymers (2i and 2j) were obtained by the metathesis polymerization using TaCl 5/n-Bu 4Sn. All the poly(1-hexyl-2-arylacetylene)s (2a-2h) emitted blue-colored lights, and the fluorenyl group-containing polymers exhibited strong photoluminescence. However, the fluorenyl group-containing polymers with long alkyl groups such as n-butyl and n-octyl groups at the 9-position on fluorene rings showed weak emissions because the steric hindrance of long alkyl groups prevents to form intramolecular excimers. The emission spectra of diarylacetylene polymers red-shifted, and 1-phenyl-2-[2-(9,9-dimethylfluorenyl)]acetylene (2i) and 1-(2-fluorenyl)-2-[2-(9,9-dimethylfluorenyl)]acetylene (2j) showed green-colored and yellow-colored emissions, respectively. © 2011 Elsevier B.V. All rights reserved.