Tuning the optical properties of ethynylene triptycene-based copolymers via oxidation of their alkyne groups into -diketones

The synthesis of ethynylene triptycene-based copolymers with various aromatic spacers (3a-d) is reported using the palladium-catalyzed Sonogashira cross-coupling reaction. The alkyne groups of 3a-d were oxidized into their respective -diketone copolymers 4a-d. Formation of 3,4a-d was confirmed by several characterization techniques, such as, gel permeation chromatography (GPC), H-1 and C-13 nuclear magnetic resonance (NMR), FT-infrared (FTIR), UV-vis absorption, and emission spectroscopies. It was found that the nature of the aromatic spacer influences the emission properties of the target -diketone triptycene copolymers, causing either a red or blue-shift with respect to that of their ethynylene triptycene copolymer synthons. Copolymers 4a-c with fluorene spacers reveal emission in the range of 440-475 nm, thus, qualifying them to act as blue emitters. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 931-937