In this paper we report on a novel fluorescent core skeleton, 9-aryl-1, 2-dihydropyrrolo [3, 4- b] indolizin-3-one, which we named Seoul-Fluor, having tunable and predictable photophysical properties. Using a concise and practical one-pot synthetic procedure, a 68- member library of new fluorescent compounds was synthesized with diverse substituents. In Seoul-Fluor, the electronic characteristics of the substituents, as well as their positional ...