Structurally Diverse 6‐Amino‐2,3‐naphthalimides: Synthesis, Solvatochromic Properties, and Utility in Cellular Imaging

The burgeoning reliance on fluorescence techniques to detect analytes of interest and visualize cellular processes has heightened the need for synthetic approaches to readily access new and underrepresented fluorophore classes, including those based on the 2,3‐naphthalimide scaffold. To address the lack of robust synthetic methodology, a general route to access structurally diverse fluorescent 2,3‐naphthalimides has been developed. Following the synthesis of the key 6‐bromo‐2,3‐naphthalic anhydride building block, imide formation and subsequent amination via Buchwald–Hartwig cross‐coupling methodology afforded a number of 6‐aminonaphthalimides with solvatochromic properties. Microscopy experiments in A549 cells highlight their potential as fluorescent probes for bio‐relevant imaging, with a 6‐piperazino‐2,3‐naphthalimide variant demonstrating pH‐responsive fluorescent behavior via photoinduced electron transfer.