Enhanced three-photon absorption and excited up-conversion fluorescence of phenanthroimidazole derivatives.

Two novel phenanthroimidazole derivatives were synthesized for efficient three-photon excited fluorescence and absorption. By introducing spirobi [9H-fluorene] to replace fluorene, the three-photon-excited fluorescence and cross-section are significantly enhanced to 3.56 ± 0.15 × 10 −78 cm 6 s 2 photon −2 , which is among the highest reported values for organic molecules. Our results supply a useful method to develop novel materials for applications of three-photon excited fluorescence and absorption. [ABSTRACT FROM AUTHOR]