Difluoroborate complexes based on 2′-hydroxyphenones as solid-state fluorophores

Difluoroborates complexes based on 2′-hydroxyphenones were synthetized and their optoelectronic properties studied in both solution and solid state. These new dyes exhibit fluorescence emission in the visible region at similar wavelengths, intriguingly with higher quantum yields in the solid state than in solution. The enhanced emission in the solid state is rationalized on the basis of the crystal structure of the dyes. [Display omitted] •The synthesis of five boron complexes based on 2′-hydroxyphenone ligands is presented.•They are weakly emissive in solution.•Their emission intensity increases upon crystallization.•Changing the substituents tunes their absorption and emission spectra.