We developed the synthesis of the caged oxygen donor (l-peroxo)(l-hydroxo)bis[bis(bipyridyl)cobalt(III)] complex (HPBC) as nitrate salt,which has,compared with the perchlorate-form described previously [MacArthur,R., Sucheta,A.,Chong,. & Einarsdottir,O¨ . (1995) Proc. Natl Acad. Sci. USA, 92,8105–8109],greatly enhanced solubility. Now,the quantum efficiency of the photolytical release of dioxygenwas determined tobe per photon at a laser wavelength of 308 nm,which was used to observe biological reactions
