Manipulating non-innocent π-spacers: the challenges of using 2,6-disubstituted BODIPY cores within donor-acceptor light-harvesting motifs

The syntheses and physicochemical properties for a series of 2,6-disubstituted-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes are reported. The use of chromophores or redox active species as pi-spacers, such as BODIPY, requires the inclusion of a sufficiently conjugated donor in order to achieve appropriate charge separation upon photoexcitation. The information derived from this study offers guiding principles for incorporating strongly absorbing, non-innocent pi-spacers in organic dye design.