The first catalytic oxidation reactions with cofacial bisporphyrins using molecular oxygen as the terminal oxidant are presented. The photocatalytic reactions proceed under mild conditions (ambient temperature and pressure) without the need for a co-reductant. A systematic reactivity study of the photooxidation of dimethyl sulfide (DMS) with a homologous series of bisiron(III) mu-oxo porphyrins containing dibenzofuran, xanthene, or no bridge reveals that the facility of these processes is markedly dependent on the vertical flexibility of the catalyst to provide a phototriggered molecular spring.