We report the novel cooperative properties of a complex obtained by self-assembling in solution a tetracationic cobalt porphyrin, (CoP4+)-P-II, and a tetraanionic sulfoaluminum phthalocyanine, (AlPc4-)-Pc-III. In the ground state, the complex displays a charge transfer character, CoII-delta P4+/((AlPc4-)-Pc-III)(+delta), and the oxidation of the phthalocyanine moiety is catalyzed in the presence of its partner. In aerated media, the neutral complex strongly binds molecular oxygen to form a stable zwitterionic species, (-O2CoP4+)-P-II/((AlPc4-)-Pc-III)(+degrees). The zwitterion can revert to the neutral form CoII-deltaP4+/((AlPc4-)-Pc-III)(+delta) upon vigourous bubbling of the solution with an inert gas (N-2, Ar) Or under light stimuli. In the excited stare, the complex photoejects the oxygen and relaxes to the ground state via a triplet excited state. The latter species can transfer its excess energy to neat-by oxygen molecules. The mechanism of photoproduction of O-1(2) was studied via steady-state and time-resolved absorption and fluorescence techniques over a wide time window, from nanoseconds to hundreds of femtoseconds. We also investigated the potentiality of the neutral and zwitterionic complexes as a sensitizer for the photodynamic inactivation of cancer cells.