A novel two-photon absorbing dye derived from a V-shaped chromophore containing triphenylamine and dipicolinate: Synthesis and application as probe for proton, water, mercury ion and cell imaging

A novel two-photon absorbing dye (TP-Py) was synthesized by introduction of a formyl group into the triphenylamine fragment of a V-shaped compound (compound 1). Compared to the corresponding compound 1, TP-Py exhibits enhanced two-photon absorption activity. When measured by Z-scan technique at 800 nm, the two-photon cross-section of TP-Py in THF was 1380 GM. Meanwhile, the introduction of a formyl group in compound 1 greatly improves the potential application of the molecule. TP-Py exhibits significant absorption and fluorescence spectral sensitivities in response to changes in pH. Especially, the pK(a) value of the pH probe is in the range of 4.5-6.5, which is critical for precisely assessing the cellular acidic environments. The fluorescence of TP-Py can be made to measure water content of organic solvents. The detection limit was calculated to be 0.04% for THF. The probing behaviors of TP-Py toward metal ions were investigated via absorption spectra as well as one-and two-photon fluorescence changes. The results indicated that TP-Py exhibits high sensitivity and selectivity for mercury ion. TP-Py was also chosen for two-photon cell imaging. The two-photon scanning microscopy experiment suggests that TP-Py is a promising label potentially applicable for the tracking of biomolecules. (C) 2014 Elsevier B.V. All rights reserved.