Highly Fluorescent Red-Light Emitting Bis(boranils) Based on Naphthalene Backbone

Abstract

Ten bis(boranils) differently substituted at the boron atom and iminophenyl groups were synthesized from 1,5-dihydroxynaphthalene-2,6-dicarboxaldehyde using a simple one-pot protocol. Their photophysical properties can be easily tuned in a wide range by the variation of substituents. Their absorption and emission spectral bands are significantly red-shifted (λ_max = 495-590 nm, λ_em = 533-683 nm) when compared with simple boranils, whereas fluorescence quantum yields are strongly improved to reach 83%. The attachment of pendant NO₂ and NEt₂ groups at the opposite positions of the π-conjugated bis(boranil) scaffold resulted in the formation of an unprecedented system featuring push-pull architecture.