Fluorescence emission and image patterning from selective photocyclic aromatization of cis–cisoid helical poly(phenylacetylene)s in situ in a film via top-down photodegradation

Jin, Young-Jae; Park, Hyosang; Lee, Chang‐Lyoul; Teraguchi, Masahiro; Kaneko, Takashi; Aoki, Toshiki; Kwak, Giseop

doi:10.1016/j.dyepig.2017.10.035

Cited by 2 publications

(1 citation statement)

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“…Poly(phenylacetylene) derivatives (PPAs) are popular π-conjugated helical polymers that attracted considerable attention in the last two decades [6,7,8,9,10,11,12,13,14,15]. PPAs with highly stereoregular head-to-tail sequences and high cis -isomer contents are commonly synthesized using the [Rh(norbornadiene)Cl] 2 –NEt 3 catalyst system under mild conditions [16,17].…”

Section: Introductionmentioning

confidence: 99%

Methoxy-Group Control of Helical Pitch in Stereoregular Poly(2-ethynylmethoxynaphthalene) Prepared by Rhodium Complex Catalyst

Mawatari

Yoshida

Huang³

et al. 2019

Polymers

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The position of the methoxy group in a poly(n-methoxy-2-ethynylnaphthalene) (PnMeO2EN) was found to control the helical pitch of the π-conjugated polymer in the solid state. These PnMeO2ENs were stereoregularly synthesized using an Rh-complex catalyst in ethanol or toluene as the solvent. The helical structure in the solid phase was confirmed by conventional analytical methods, namely diffuse reflective ultraviolet–visible light (UV–Vis) and Raman spectroscopies, X-ray diffraction, and 13C cross-polarization magic angle spinning NMR spectroscopy, together with molecular mechanics calculations, because the as obtained polymers were insoluble in common solvents. The color of poly(6-methoxy-2-ethynylnaphthalene) (P6MeO2EN) (yellow or red) depended on the polymerization solvent, whereas no such dependency was observed for the yellow-colored P7MeO2EN and P8MeO2EN. The helical structures energetically optimized by molecular mechanics indicate that the red- and yellow-colored P6MeO2ENs form contracted and stretched helices, respectively. Due to the relatively unconstrained rotations of the 6-methoxynaphthyl moieties, the methoxy groups in P6MeO2EN are less sterically hindered along the helical axis. On the contrary, P7MeO2EN and P8MeO2EN have stretched helices due to the considerable steric hindrance imparted by their methoxy groups. The thermal cis-to-trans isomerization of P6MeO2EN in the contracted-helix form required a somewhat higher temperature than that of the stretched helix.

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