Electrical and optical properties of porphyrin monomer and its J-aggregate

We have investigated the electrical and optical properties of a water-solub le porphyrin monomer and its J-aggregate both in solution and in the solid state. Specifically, we find that water enhances the electrical conductivit y, of both the monomer and the J-aggregate. The luminescence quantum effici ency and spectrum are also affected quite dramatically by the presence of w ater. The J-aggregate also shows an electrochromic effect in the presence o f moisture. We show that the electrochromic effect arises because the J-agg regate converts to the monomer.