Synthesis and Self‐Assembly of Bay‐Substituted Perylene Diimide Gemini‐Type Surfactants as Off‐On Fluorescent Probes for Lipid Bilayers

Interest in bay‐substituted perylene‐3,4:9,10‐tetracarboxylic diimides (PDIs) for solution‐based applications is growing due to their improved solubility and altered optical and electronic properties compared to unsubstituted PDIs. Synthetic routes to 1,12‐bay‐substituted PDIs have been very demanding due to issues with steric hindrance and poor regioselectivity. Here we report a simple one‐step regioselective and high yielding synthesis of a 1,12‐dihydroxylated PDI derivative that can subsequently be alkylated in a straightforward fashion to produce nonplanar 1,12‐dialkoxy PDIs. These PDIs show a large Stokes shift, which is specifically useful for bioimaging applications. A particular cationic PDI gemini‐type surfactant has been developed that forms nonfluorescent self‐assembled particles in water (“off state”), which exerts a high fluorescence upon incorporation into lipophilic bilayers (“on state”). Therefore, this probe is appealing as a highly sensitive fluorescent labelling marker with a low background signal for imaging artificial and cellular membranes.