Diversity-Oriented Facile Access to Highly Fluorescent Membrane-Permeable Benz[<i>c,d</i>]indole <i>N</i>‑Heteroarene BF₂ Dyes

A diversity-oriented one-pot synthesis of a series of membrane-permeable BF2-rigidified benz­[c,d]­indole N-heteroarene BBN and BBC dyes has been achieved from the condensation of two commercial components (benz­[c,d]­indol-2-one and a set of N-heteroarene derivatives that can be selected from thousands of commercially available sources) and the subsequent in situ BF2 complexation reaction. These dyes enjoy a set of excellent photophysical properties including the large Stokes shift, high solution and solid-state fluorescence, and excellent photostabilities.