Synthesis and photoluminescence properties of fluorine-containing poly(phenylene vinylene) bearing hexafluorocyclopentene-fused phenanthrene unit

The intramolecular oxidative photocyclization of 1,2-diarylhexafluorocyclopentene ( 1 ) under light irradiation (λ = 365 nm) provided hexafluorocyclopentene-fused phenanthrene with formyl groups ( 2 ) in moderate yield. The copolymerization of 2 with tetraethyl(2,5-bis(dodecyloxy)-1,4-phenylene)bis(methylene)diphosphonate by the Horner–Wadsworth–Emmons reaction gave a fluorine-containing poly(phenylene vinylene), Polymer-2, in 41% yield. For comparison, a diphenylethene-type copolymer, Polymer-1, was also prepared analogously. The number-average molecular weights of Polymer-1 and Polymer-2 were 8900 and 3300 g mol^?1, respectively. The copolymers showed high thermal stability, as revealed by their thermogravimetric analysis. UV–visible spectra of the copolymers in CHCl₃ showed π–π* transition peaks at around 420 nm, and the peaks shifted to longer wavelengths by ca 10 nm for samples in film form. The photoluminescence spectra of Polymer-1 and Polymer-2 exhibited peaks at 542 and 560 nm in CHCl₃, respectively, whereas the photoluminescence intensity of Polymer-2 was very low in the solid state, presumably owing to the partial aggregation of the polymer molecules. © 2021 Society of Industrial Chemistry.