Triplet conformation in chromophore-fused cyclooctatetraene dyes

Cyclooctatetraene (COT) is predicted to have a planar aromatic triplet state. Using femtosecond-to-microsecond transient absorption spectroscopy, we show that acene chromophore-fused COT dyes also have a planar COT ring in their triplet states, although they are not aromatic.