Synthesis and fluorescence properties of isoindoline-benzazole-based boron difluoride complexes

In this article, a series of isoindoline-benzazole-based boron difluoride complexes (7-12) were synthesized and characterized. Analysis of the X-ray crystal structures of compounds 7, 8 and 10-12 indicates the existence of pi-pi stacking and H-bond (F-H-C, O-H-N, N-H-C) interactions. These novel boron complexes exhibit large Stokes shifts (3300-8400 cm(-1)) and moderate quantum yields (0.15-0.64). Time-dependent DFT (TD-DFT) calculations reveal that the maximum absorption bands for 7-12 are attributed to the HOMO -> LUMO transitions, and that the calculated absorption wavelengths agree well with the experimental trends.