1,3-Diiminoisoindoline (DII) and the closely related molecule, iminoisoindolinone are important precursors in the synthesis of macrocycles and chelates such as phthalocyanines, and bis(arylimino)isoindolines, as well as chromophores including aza-BODIPY dyes. A series of seven ylideneisoindolinones are presented in this report. The reaction of various organic CH acids and iminoisoindolinone produce compounds that show strong [Formula: see text]* transitions in the UV region. The chromophores have been characterized spectroscopically and the X-ray structures show electronic delocalization across the chromophore. Additionally, DFT and time-dependent DFT calculations confirm the lower energy absorbances are primarily HOMO-LUMO transitions.