Highly fluorescent, π-extended indenopyrido[2,1-a]isoindolone derivatives prepared by a palladium-catalysed cascade reaction

Article abstract of DOI:10.1002/ejoc.201201575

A new family of heterocyclic pentacyclic compounds have been prepared by a cascade reaction involving 2,5-dihalopyridines and (2-formylphenyl)boronic acids. Most of the compounds exhibit high quantum yields of fluorescence in dichloromethane. In some cases, small changes in the substitution pattern caused fluorescence quenching. To rationalize this effect, a detailed photophysical study combined with electrochemical and computational studies was performed on four representative derivatives. It appears that the fluorescence quenching is caused by a thermally activated non-radiative deactivation process that can be prevented in a rigid matrix such as ethanol at 77 K or a PMMA polymer.