Crystal structures,optical properties and theoretical calculation of novel two-photon polymerization initiators

Three novel A–π–D–π–A type compounds 3,6-bis2-(4-pyridyl)ethenyl]-9-ethylcarbazole (1), 3,6-bis2-(2-pyridyl)ethenyl]-9-ethylcarbazole (2), 3,6-bis2-(4-pyridyl)ethenyl]-9-ethylpyridylcarbazole (3) were conveniently synthesized by Pd-catalyzed Heck coupling methodology and characterized by single crystal X-ray diffraction determination. One-photon fluorescence, one-photon fluorescence quantum yields, one-photon fluorescence lifetime, and two-photon fluorescence have been investigated. The calculated two-photon absorption cross-sections for the three initiators by quantum chemical method are as high as 947, 943 and 815 × 10⁻⁵⁰ cm⁴ s photon⁻¹, respectively. Two-photon initiating polymerization microfabrication experiments have been carried out and the possible polymerization mechanism was also discussed. The results show that they are good two-photon absorbing chromophores and effective two-photon photopolymerization initiators.