Structural characterisation of difluoro-boron chelates of quino[7,8-h]quinoline

► Improved synthesis for quino[7,8-h]quinoline and 4,9-dichloroquino[7,8-h]quinoline. ► Structural comparisons of the neutral and protonated ligands. ► Structural analysis of boron difluoride complexes of quino[7,8-h]quinoline. ► Boron complexes have a good size match to the neutral chelating ligand. ► Weak fluorescence and moderate SERS enhancement is observed for the complexes.