Synthesis, photophysical properties, and DNA-binding of novel A-π-D-π-A' two-photon absorption chromophores

Three novel two-photon absorption chromophores (1BI, 2TAZ, and 3PyB), which have trans-1,4-divinylbenzene pi-bridge, methoxy donors, and different acceptors, were synthesized. Their structures were elucidated by means of hydrogen-1 nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, Fourier transform infrared spectroscopy, and high-resolution mass spectrometry. Their photophysical properties, including linear absorption, single-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated in various solvents. The structure-property relationships were studied aided with the density functional theory calculations. In addition, the absorption, single- and two-photon fluorescence spectra of 3PyB-ctDNA were examined to evaluate whether 3PyB could be used as a DNA stain. The possible interaction mechanism of 3PyB-ctDNA was also studied by the NaCl titration and the viscosity experiment. The results indicate that 3PyB may serve as a potential DNA fluorescent probe.