Synthesis and characterization of 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles with two-photon fluorescence properties

Four novel 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles that exhibit strong two-photon absorption and enhanced two-photon excited fluorescence were designed and synthesized based on“push-core-pull-core-push”molecules built from embedding electron-transporting 1,3,4-oxadiazole in aromatic conjugated system through Wittig-Horner reaction.Their chemical structures were determined to show trans-vinylene character according to infrared(IR)and 1H nuclear magnetic resonance(NMR)spectra.A very effective energy transfer from the excited units to the p-conjugated bridging unit can enhance the two-photon absorption and two-photon fluorescence.