To develop molecular catalysts for the generation of dioxygen, the photophysical properties of cobalt complexes of boradiazaindacene (BODIPY) derivatives were studied. It is found that the intramolecular energy transfer due to d–π interaction between boradiazaindacene (BODIPY) and the cobalt central in aqua-cobalt complexes, which was confirmed by DFT calculation, leads to the quenched fluorescence emission being recovered completely. The effect of link spacers (benzyl groups) on the intramolecular d–π interaction was discussed. Results show that cobalt complexes of BODIPY derivatives can be photo-sensitizers and a good blue LED light driven precatalyst for the oxidation of water. The dioxygen generation was further confirmed by the photooxidization of 1,5-dihydroxylnaphthalene (DHN) catalyzed by cobalt complexes using water as the oxygen source. This will give a new path to design photo-active complexes to be used as PDT in hypoxic environments.