Novel triphenylamine-cored two-photon absorbing dyes for labeling of biomolecules

Abstract Two novel, V-shaped and Y-shaped dipicolinate derivatives branched from triphenylamine, {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinyl]}- N -phenyl- N -{4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinylphenyl]}aniline ( 1 ) and {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl) vinyl]}- N , N -bis {4-[(E)-2-(2,6-dimethoxycarbonyl pyridin-4-yl)vinylphenyl]}aniline ( 2 ) were synthesized. These compounds were designed for large two-photon absorption and in particular for labeling of biomolecules. Their linear absorption, fluorescence properties and their two-photon absorption properties as well as two-photon fluorescence cell imaging were examined. When excited at 800 nm, the two-photon absorption cross-section values of chromophores 1 and 2 in THF were 208 GM, 376 GM, respectively. These two-photon absorbing dyes possess reasonable water solubility, strong chelating ability and display a large set of reactivity for coupling to biomolecules, which are apparently due to the two methoxycarbonyl groups in pyridine ring. This work suggests that chromophores 1 and 2 are promising labels potentially applicable for the tracking of biomolecules using two-photon scanning microscopy.