Chemical reactivity at the air—water interface: Redox properties of the tetrapyridino porphyrazinium ring

Abstract

The redox properties of the tetrapyridino [3,4-b:3′,4′-g:3″,4″-1:3‴,4‴-q] porphyrazinium ring (S in the text) are studied i and at the air-water interface as a highly ordered monolayer. The macrocycle is found to be very easily reducible in solution and spontaneously reduced by water at the air-water interface. This latter result arises from the agreement of the high oxidation potential of the ring S with the interfacial effect due to the local surface potential created at the surface of water by the close packed monolayer. A simple model derived from the Gouy-Chapman theory clearly shows that spontaneous reduction is likely to occur.