Red-emitting Boron Difluoride Complexes with Mega-large Stokes Shift and Unexpectedly High Fluorescent Quantum Yield Introduction of a tetrahydroquinoxaline donor into boron difluoride complexes largely extended their emissions (617-684 nm), highly improved the fluorescent quantum yields (up to 0.68) and greatly increased the Stokes shifts (up to 209 nm). These new fluorescent dyes showed reversible ratiometric solid-state fluorescence changes upon switched acid/base fumings.
