Phenalenyl-based boron–fluorine complexes: Synthesis, crystal structures and solid-state fluorescence properties

A novel series of phenalenyl-based boron–fluorine complex-type fluorophores, with a drastic fluorescence quenching in solution but high fluorescence emission in the solid-state, have been synthesized. The X-ray structure demonstrates that the bulky substituents result in steric hindrance and prevent the fluorophores forming short intermolecular interaction thereby enhancing the solid-state fluorescence emission.