Synthesis and characterization of eumelanin‐inspired poly(indoylenearylenevinylene)s and poly(indoylenearyleneethynylene)s

ABSTRACT Four novel conjugated polymers containing the eumelanin‐inspired indole core have been successfully synthesized using common cross coupling reactions. These polymers differed by the arylene and the carbon–carbon bond linkage. Optoelectronic experiments of these polymers suggest that the ethynylene linkage contributed to the red‐shifted absorption spectra and blue‐shifted emission spectra when compared to the vinylene linkage polymers. Furthermore, the optical bandgaps of the poly(indoylenearyleneethynylene)s (PIAEs) were smaller compared to the poly(indoylenearylenevinylene)s (PIAVs). Surprisingly, the HOMOs of these polymers were less affected by the nature of the carbon–carbon linkage. However, the LUMOs of the PIAEs were lower in comparison to the PIAVs. These eumelanin‐inspired PIAEs and PIAVs are good fluorophores with fluorescence quantum yields ranging from 0.12 to 0.67 and have good thermal stability for applications such as in organic light‐emitting diodes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 457–463 Four novel conjugated polymers were synthesized using the eumelanin‐inspired indole core. The effects of carbon–carbon linkages and arylenes on the optoelectronic properties were investigated. These eumelanin‐inspired poly(indoylenearyleneethynylene)s and poly(indoylenearyleneevinylene)s are good fluorophores and show promise for applications such as in organic light‐emitting diodes.