Luminescent bichromophoric spiroindolones – synthesis and electronic properties

Novel bichromophoric spirocyclic indolones have been synthesized by an insertion–coupling–isomerization–Diels–Alder domino reaction. The emission colors are strongly affected by the substituents: N-Boc leads to intense blue fluorescence, N-dansyl causes turquoise emission, whereas a 1-anthryl substituent on the butadiene results in yellow luminescence. The latter behavior is rationalized by TDDFT computations as a result of significant geometrical changes.