Red and Near-Infrared Photoluminescence of D‑π-A-Type Compounds Based on a 1,4-Diaryl-1-thio-1,3-butadiene Conjugated System in a Dibenzobarrelene Skeleton

1,4-Diaryl-1-thio-1,3-butadiene
derivatives having a π-donor
dimethylamino group and several π-acceptor substituents at both
terminals of the conjugated system were synthesized by intramolecular
[4 + 2] cycloaddition of 1-thio-enynes and subsequent chemical transformations.
They displayed largely red-shifted absorption and emission spectra
in solution, the powder state, and in polymer films. The derivatives
with a 2,2-dicyanoethenyl group as the π-acceptor exhibited
inverted solvatochromism in both optical absorption and fluorescence
spectroscopies.