Diamino-Terephthalonitrile-based Single Benzene Fluorophores Featuring Strong Solution State Fluorescence and Large Stokes Shifts

J Org Chem. 2023 Nov 17;88(22):15708-15716. doi: 10.1021/acs.joc.3c01685. Epub 2023 Nov 6.

Abstract

1°- and 2°-amines react with tetrafluoroterephthalonitrile through SNAr chemistry, creating the strongly emissive para-diamino-terephthalonitrile type single benzene fluorophores. The regioselectivity of reaction is dictated by the sterics of the initial secondary amine adduct. The molecules exhibit strong green-yellow emission and large (nearly 150 nm) Stokes shifts. Excited state analysis reveals a cooperative effect between the para-positioned amino groups through the electron-poor terephthalonitrile unit resulting in the fluorescence amplification.