Highly near-infrared emissive boron di(iso)indomethene-based polymer: Drastic change from deep-red to near-infrared emission via quantitative polymer reaction



It is challenging to realize the near-infrared (NIR) emission with large brightness and sharp spectra from the conjugated polymers. In this study, we demonstrate the strategy for receiving strong and pure NIR emission from polymeric materials using organoboron complexes and the modification after polymerization. A series of NIR emissive conjugated polymers with boron di(iso)indomethenes (BODINs) and fluorene or bithiophene were synthesized by Suzuki–Miyaura coupling reaction. The obtained polymers exhibited high emissions in the range from deep-red to NIR region (quantum yields: ϕPL = 0.40–0.79, full width at half maximum height: Δλ1/2 = 660–940 cm−1, emission maxima: λPL = 686–714 nm). Next, the demethylation of the BODIN-based polymer with o-methoxyphenyl groups was carried out. The transformation of the polymer structure quantitatively proceeded via efficient intramolecular crosslinking through the intermediary of the boron atom. Finally, the resulting polymer showed both drastically larger red-shifted and sharper photoluminescence spectrum than that of the parent polymer with deep-red emission (ϕPL = 0.37, Δλ1/2 = 460 cm−1, λPL = 758 nm). © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013