Metathesis cyclopolymerization of 1,6-heptadiyne derivative toward triphenylamine-functionalized polyacetylene with excellent optoelectronic properties and nanocylinder morphology

Metathesis cyclopolymerization of 1,6-heptadiyne derivatives is readily utilized to synthesize triphenylamine-functionalized polyacetylenes (TPA-PAs) by a third-generation Grubbs catalyst, which selectively generated TPA-PAs with a five-membered ring and all-trans microstructure. The TPA pendants endowed PAs with good solubility and excellent optoelectronic properties (maximum absorption wavelength of 592-605 nm in CHCl₃, HOMO level of around -5.04 eV, and energy bandgap of 1.82-1.77 eV). When bis-TPA side group was introduced into the PA backbone, the resultant polymer, poly(M2), displayed desirable oxidative stability (up to 30 days stored in THF) and high fluorescence quantum yield (up to 12.3%) in the family of PA derivatives. In addition, poly(M2) could spontaneously self-assemble into the nanocylinder architecture without requiring any tedious postsynthetic treatments. This is the first report that the rigid and immobile conjugated PA segment assembled into the novel cylindrical nanostructure with the aid of π-π interaction of TPA side group.