Unexpected Photoluminescence of Fluorinated Naphthalene Diimides

Two new amino core‐substituted naphthalene diimides (cNDIs) bearing fluorinated side chains have been synthesised. Steady‐state and time‐resolved fluorescence spectroscopy reveals unprecedented optical properties for the cNDIs with high quantum yields of ∼0.8 and fluorescence lifetimes of ∼13 ns in a range of solvents. These properties are apparent at the level of single molecules, where the compounds also show exceptional photostability under pulsed‐laser excitation. Photon emission is remarkably consistent with very few long timescale (millisecond or longer) interruptions with molecules regularly undergoing >107 cycles of excitation and emission. Intermittencies owing to triplet‐state formation occur on a sub‐millisecond timescale with a low yield of 1–2 %, indicating that the presence of the fluorine atoms does not lead to a significant triplet yield through the heavy‐atom effect. These properties make the compounds excellent candidates for single‐molecule labelling applications. Don′t blink: Two core‐substituted naphthalene diimides (NDIs) with fluorinated moieties have been synthesised. The NDIs show unprecedented optical properties with high quantum yields of ∼0.8 and fluorescence lifetimes of ∼13 ns in a range of solvents. As single molecules, they display high photostability and consistent photon emission with very few intermittencies or ‘blinks’. The compounds thus have considerable potential for single molecule imaging and labelling applications.