Fluorenylethynylpyrene Derivatives show Strong Two-Photon Absorption and Brightness

What is it about?

New pyrene-based chromophores with D–π–A, D–π–A–π–D and A–π–D–π–A structural motifs with 1, 2 or 4 fluorenyl groups linked by acetylene π-bridges have been synthesized. The tetra-substituted molecules are shown to have large two-photon cross sections of 1500 to 2500 GM in the 700 to 900 nm spectral range. The fluorescence quantum yields for the mono= and di-substituted molecules are close to 1 and the tetra-substituted molecules have yields of ~ 0.6.

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Why is it important?

Molecules with large two-photon cross sections and high fluorescence quantum yields are of great interest for 3D imaging in materials and biological samples. The high two-photon brightness of these molecules, in the range of 247 to 1380 GM, could enable two-photon fluorescence imaging with reduced intensity.