Synthesis and Optical Properties of α,β‐Unsaturated Ketones Bearing a Benzofuran Moiety

Abstract

AbstractFive π‐expanded α,β‐unsaturated ketones have been prepared from a strongly electron‐rich benzofuran derivative via Knoevenagel reaction and aldol condensation. The incorporation of two 6‐didodecylaminobenzofuran‐2‐yl groups at the periphery of D‐π‐A and D‐π‐A‐π‐D molecules resulted in dyes with excellent solubility in the majority of organic solvents. In contrast to the majority of α,β‐unsaturated ketones, these dyes emit relatively strongly in the red region with a fluorescence quantum yield up to 40 %. They also display strong solvatofluorochromism with emission shifting from 570 nm in toluene to 670 nm in CHCl3. Depending on the chemical structure, they two‐photon cross‐sections (σ2) are up to 1700 GM (1 GM=1050 cm4 s photon−1).