A versatile synthetic strategy to access a set of highly fluorescent
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-conjugated triphenylamines bearinga functional linker at various positions on one phenyl ring is described. These compounds were designedfor large two-photon absorption (2PA) and in particular for labeling of biomolecules. The monoderivatizedtrisformylated or trisiodinated intermediates described herein allow introduction of a large variety ofelectron-withdrawing groups required for large 2PA as well as a panel of chemical functions suitable forcoupling to biomolecules. The monoderivatized three-branched compounds and in particular thebenzothiazole (TP-3Bz) series show remarkable linear (high extinction coefficients and high quantumyield) and nonlinear (high 2-photon cross sections) optical properties. Interestingly the presence offunctional side chains does not disturb the two-photon absorption. Finally, monoderivatized two-branchedderivatives also appear to be valuable candidates. Altogether the good optical properties of the newderivatizable
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-conjugated TPA combined with their small size and their compatibility with bioconjugationprotocols suggest that they represent a new chemical class of labels potentially applicable for the trackingof biomolecules using two-photon scanning microscopy.