New Two-Photon Absorbing Fluorene Derivatives: Synthesis and Nonlinear Optical Characterization

Efficient Pd-catalyzed Heck coupling methodology was employed to provide two new fluorene derivatives with phosphonate ( 2 ) and nitro ( 3 ) electron-withdrawing functionalities. Both derivatives exhibit two-photon absorption (2PA), as determined by nonlinear absorption measurements using a femtosecond pump/white light continuum probe “NLO spectrometer”. Both fluorene derivatives have high 2PA cross sections (650 and 1300 × 10 - 50 cm 4 s photon - 1 molecule - 1 for compounds 2 and 3, respectively).