Room-temperature phosphorescence in solution and in solid state from purely organic dyes

Phosphorescence has seldom been observed in purely organic dyes in the solution at room temperature. We herein report efficient phosphorescence in the solution from (E)-3-benzylideneimidazo[1,2-a]pyridin-2(3H)-one and its derivatives. This opens up a new class of purely organic dyes to applications in the phosphor design. In the solid state, the ordered columnar stacking arrangements, intermolecular close contacts, and lateral intermolecular hydrogen bonding interactions between neighboring columns make these luminogenic molecules highly phosphorescent at room temperature, and lead to phosphorescent color changes (from yellow in the solution to aurantiacus-red in the solid state). Here, using these luminogenic molecules, a series of new purely organic phosphors are color-tuned to emit yellow, aurantiacus, orange, nacarat and red in the solid state, which are promising candidates for potential applications in organic light-emitting diodes for display. (C) 2012 Elsevier Ltd. All rights reserved.