Synthesis and photophysical study of novel 3-triazinyl- and 3-pyridinyl-substituted coumarins

A series of 3-triazinyl- and 3-pyridinyl-coumarin dyes were designed, synthesized and studied in terms of linear and nonlinear optical properties as well as charge transfer. The triazine- and pyridine-containing fluorophores were emitted green and blue light in the visible region of the spectrum, respectively, with high quantum yields. Two-photon fluorescence properties were measurement and 4b showed high two-photon absorption cross-section value (δ2PA = 285.5 GM). The dyes exhibited second-order NLO properties with static hyperpolarizability β0 in the range of 43–78 × 10−30 esu. Photophysical studies supported DFT calculations showed that the push-pull fluorophores 3g-j generated photoinduced intramolecular charge transfer states. Obtained experimental and theoretical data strongly suggests that these novel coumarin dyes are promising candidates for cell imaging.