Synthesis, Characterization, Two-Photon Absorption, and Optical Limiting Properties of Ladder-Type Oligo-p-phenylene-Cored Chromophores

This paper reports on the two-photon absorption (TPA) and related up-converted emission properties of a novel series of chromophores containing ladder-type oligo-p-phenylenes with various pi-conjugation lengths. The design and synthesis of these ladder-type two-photon chromophores are first discussed. An increase in the pi-conjugated length of the ladder-type oligo-p-phenylene for these chromophores leads to an increase in TPA cross-section together with ail increased fluorescence quantum yield. These chromophores exhibit high fluorescence quantum yields because of the rigid planar structure of the ladder-type oligomers. The chromophore with ail enhanced TPA cross-section together with an increased fluorescence quantum yield would provide significant benefits for two-photon excited fluorescence based applications. An improved optical limiting behavior was also demonstrated using the ladder-type pentaphenylene cored chromophore.